# My PM-940 CNC Modifications



## cut2cut

I've been slowly making modifications to my turnkey Precision Mathews PM 940 CNC mill with the Variable speed motor option since it arrived in January 2017

So far I don't have a lot of time testing the changes I've made, so I can't say for certain if they are wise or not, but a number of people have been asking about various things so I thought I'd start a separate thread rather than Hijack the other one. 

Ok, so here she goes with just the bare facts which I'll outline in further detail later on and update this post as more things are changed out or modified.

1 )  Spindle, drive train and Motor "upgrade"
Removed Spindle Gear Box completely
Replaced with Belt and Pulley
Replaced Spindle Motor ( has encoder built in )
Requires Better spindle bearings

2 ) Control hardware and software
Removed the nMotion USB controller
Replaced with the Mesa 7i76E ( E stands for Ethernet ) controller
Replaced Mach 3 with Linux CNC control software ( required with Mesa controller )

Future :
3 ) "Power" Drawbar

4 ) Servo motors

5 ) Enclosure

6 ) Other cool stuff, hopefully !  lol

Each section will have a parts list and links to where I got them.

Cheers,

Jake


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## cut2cut

Part 1 ) Spindle , Gear train and Motor "upgrade"

I used quotes around the word "upgrade" because I have yet know if its an vertical move, or lateral !  

For instance, the Motor probably doesn't produce more HP but it appears to be better quality and also has an encoder for better speed control with an appropriate VFD.  Depending on the speed control ( VFD ) the encoder can be used as feedback for the VFD to help maintain speed more consistently, and also should maintain better torque.  I believe the Delta VFD-E that comes with the PM940 CNC VS has this capability with an optional card, but I am not sure.  I also bought , but have yet to use, a Durapulse VFD with a feedback card.  So far, its collecting dust due to time constraints mostly.  The Delta seems to be working pretty well after someone on this forum suggested settings that match this particular motor better than the default settings that the VFD comes with.

april 15 2017 edit
[  So, I should go into more detail about the spindle bearing upgrade.  You need a large press to remove the spindle bearings  and put it all back together with the new AC bearings,  Also, you need a bearing puller to remove the standard bearing race(s) (this is a tricky step because there isn't much lip for the puller to access).
The AC bearings do not have a separate bearing race like the standard bearings, so when you assemble it, it has to be pressed into each part in a logical order or it will put stress / harm the new ball bearing and/or races.   The upper bearing on the inner bearing surface (of the spindle itself) can either be cooled and the bearing warmed to allow the bearing to be seated, OR you can do what I did which was create a slip fit for the inside of the upper bearing by turning the spindle on a lathe with a bit of sandpaper to buff it down a small amount.  The problem with this approach is you could introduce some runout by creating too much of a slip fit.  Also if you aren't consistent you may make your spindle "seat" out of round.  My greatest worry is that I'd take too much off and certainly this would result in increased runout.   Even a slight amount of heat (created by the sanding process) would throw off the measurement and could cause you to keep sanding due to heat expansion.    If I were to do it again I'd have some way to cool the spindle after each session of sanding it ( with 1000 grit sandpaper and slightly warm the bearing before testing bearing fit after each attempt at sanding more off.     Its a bit tedious but worth the extra concern, imho. ]

There is more detail needed and I will add more detail but don't have time right now.  ZZZZ... sleep is calling me.   However I am providing a parts list for those that just don't care about details and live dangerously   Note that items with double asterisk (  **  ) need and will get more detail.

Here is the motor I used:
http://dealerselectric.com/145THTR15540.asp

The AC bearings for the spindle :
qty 1 - VXB Brand 7207C P5 High Precision Angular Contact Bearing 35x72x17 ABEC-5
qty 1 -VXB Brand 7206C-P5 7206C P5 High Precision Angular Contact Bearing 30x62x16 ABEC-5

Pulley ( 2 to one ratio )
**qty 1 :   5.6 inch 10 groove J - Profile pulley
http://www.ebay.com/itm/291936349578?ul_noapp=true
( requires some of the head case to be modified for this pulley to fit inside the gearbox cavity )
** Taper bushing not listed yet... it depends on your motor shaft size ...)
** 2.8 inch 12 groove J profile PULLEY
http://www.ametric.com/p-18443-12j281108.aspx

** taper bushing for 2.8 inch pulley for 28mm spindle ID
http://www.ametric.com/p-13391-110828.aspx
( requires some thin shim as spindle OD is slightly less than 28mm )
( requires a key to be fabricated to go in spindle grooves so Pulley isn't only a friction fit )

** Ametric brand BELT -10 ribs Micro V J groove
http://www.ametric.com/p-30298-260j10.aspx
( the Ametric belt is what I used, but I believe an 8 groove GoodYear brand one is better after some people on this forum suggested the good year brand over Gates, which I think is what Ametric sells, possibly )   McMaster Carr has GoodYear brand :
** 9003K89    Ultra-Flexible J-Section V-Belt 8 Bands, Trade Size 260J8, 26.3" Outer Circle
( could be a bit bigger than the Ametric one... hard to say if its too large.   I have one coming so I'll be able to try it and update this )

Cheers,
Jake

note,  the motor mount plate is just temporary, something sexy will be made when I decide on how to configure a double pulley arrangement.


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## rodjava

Jake,
For servos, check out DMM Technology at http://www.dmm-tech.com/

This a true plug and play, complete servo system and the pricing is not bad.

I have the 4 axis AC servos on my cnc router and they setup and work perfectly.
You can ask and  read more at cnczone.com.

Btw, thank you for sharing your upgrades.  I might do the same in the future.


Rod


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## cut2cut

rodjava said:


> Jake,
> For servos, check out DMM Technology at http://www.dmm-tech.com/
> 
> This a true plug and play, complete servo system and the pricing is not bad.
> 
> I have the 4 axis AC servos on my cnc router and they setup and work perfectly.
> You can ask and  read more at cnczone.com.
> 
> Btw, thank you for sharing your upgrades.  I might do the same in the future.
> 
> 
> Rod



Hey Rod,
I am considering the Clearpath servos but I'll check these out too.  Thanks !  I really really like that my pulley and belt spindle is whisper quiet now... would be cool to have the benefits of a closed loop and also they are whisper quiet too !
And while we are on the subject of quiet, one of the reasons I switched out the motor was the one I got doesn't have a fan at all and doesn't need one either !, so its way more peaceful when the machine is on, but not cutting.
Cheers,
Jake


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## phazertwo

Any more updates on this?  I'm very interested in the spindle motor setup, mine makes enough noise to drive you nuts while it's running. 

PZ


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## pburgh

Jake,
I just got the PM-940 CNC with the nMotion card.  Still getting my feet wet with the original config.  I'm going to be switching it to a Centrod Acorn controller.  What models of the Clear Path motors are you looking to use for the X, Y and Z axes?  Also, what are your plans for the power draw bar?  Thanks,
Regards,
Doug


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## megaplow

cut2cut said:


> 2 ) Control hardware and software


Very excited to see how this goes. I would like my whole shop to use the same control technology. If all goes well on your end, I will follow your lead and then do the same to the laser.


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## cut2cut

I really haven’t done much with the mill as I haven’t had projects in the last 6 months.  So I haven’t felt compelled to upgrade to servos or much of anything.   Sadly, it appears Linux cnc really has stalled in development as far as I can tell so I can’t say it’s ever going to be plug and play.  The best options are probably Masso or it appears the Acorn ?  I have no experience with either but they seem to be a decent alternative to Mach 3.

Jake


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## phazertwo

Were you able to get Linux CNC running at all?  I was actually hoping to start installing it this week and see if I could get it running correctly.

I was assuming that the last release of LinuxCNC (July 2017) was good enough that they didn't need any more tweaking.  If it's not cutting the cheese that's a serious bummer.  Acorn looks cool, but I liked the idea of open source...

PZ


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## cut2cut

phazertwo said:


> Were you able to get Linux CNC running at all?  I was actually hoping to start installing it this week and see if I could get it running correctly.
> 
> I was assuming that the last release of LinuxCNC (July 2017) was good enough that they didn't need any more tweaking.  If it's not cutting the cheese that's a serious bummer.  Acorn looks cool, but I liked the idea of open source...
> 
> PZ


Yes,   I have Linux cnc working mostly .  It’s just not perfect ( has its own flaws ) and in my experience will be difficult and very time consuming to install the proper version for the controll hardware you need and then to setup.  You would need an alternate controller as the nMotion is Mach3 only.  This required a fair bit of re-wiring of the control electronics and a very specific install of Linux cnc with the appropriate kernel, etc. This took me quite a lot of energy and left a lot to be desired as open source has a lot of dead ends too.   If you like a challenge or have a good Linux background already,  you could go with Linux cnc.  If you want to use your mill sooner than later, i’d suggest trying a Masso.  However,  I don’t have a Masso either so it’s tough for me to say that is the best alternative or not.  Good luck !


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## phazertwo

Hmmmm... I did some looking at the Acorn, which looks like a decent setup, however I want a true real-time system (which it looks like you can do with LinuxCNC).  Also the Acorn lacks a 5th axis, which honestly I'll probably never have/use, but I really don't want to limit myself.

I JUST now for the first time googled Masso... Looks like it cost lots o' the monies... but you don't need a PC to go with it and judging by that fact it's likely running real time.  And it's 5 axis capable, and I don't have to have an additional PC...  Defiantly need to do more research on it (guess I know what I'm doing with my lunch break today...)

I have very little patience for things that are finicky/unreliable and I bought the mill to be able to make parts for other projects not so much to be a project itself.  If spending ~$600 on a controller gets me up and running, it will be money well spent... after all I have bulldozer parts that need makin'

PZ


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## megaplow

I was looking into all in one purpose build systems, like the CNC4940. They look cool, but the price tag... geez!


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## megaplow

Just ordered my 7I76e... wish me luck!


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## cut2cut

GoodLuck !

Start by reading at the link below

( p.s. I’ll try outline what I did to get mine to work ( above in my initial posts .    No promises but when time permits i’ll try ! ))

For now,  this link below outlines a way to install Linux cnc on the mint flavor of Linux.

Jake

https://forum.linuxcnc.org/9-instal...32-64-rtai-or-preempt-with-rip-install-or-deb


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## pburgh

The Acorn is their entry level controller.  They have 2 other DIY cards, and they are pricier.  But they will do a lot more. I'm going to start out with the Acorn and move up from there as i want more features.  The nice thing is that the Centroid software is the same for all models.   So there is no learning curve there.  Also, i briefly talked to Matt about the Acorn and he said he liked the Centroid software as he's used it before.  Says it's very robust.  Guys are starting to post more about the Acorn card and a guy just posted a setup using Lead Shine yesterday.  Here's the link: 





          He has alot of other good videos too.

Here's a good comparison between Clear Path and DMM.  





I was leaning towards Clear Path until i watched this video.  Sam has some other good videos.  He puts a lot of good info into them.  After watching this one, i'm leaning towards the DMM solution.  Also, the Clear Path folks weren't very helpful when i called.  I guess they don't want to waste too much time on one offs.  I hope DMM is better.

Too many decisions....  But i decided that i don't want to waste my time learning Mach.  I fired up my mill to make sure everything moves and runs the way i expect, but i'm going to switch to the Acorn card for now since i already purchased it.  Still trying to decide the best option for a power drawbar.


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## cut2cut

The Acorn Centroid looks like a great solution.  I may get one and convert over as it’s likely going to provide all that I need for $265 + $100 for the pro software.  Looks great  and shouldn’t be hard to convert over.  Only thing that could be tricky is the wiring for the vfd ( controlling direction ) as far as I can tell. Thanks for suggesting it!
Way easier than Going the Linux cnc route.
I suppose the only possible negative is that it’s running windows that theoretically could introduce crashes and maybe timing errors.  That’s hopefully not an issue. 

Jake


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## phazertwo

Acorn does look nice... but it's lacking the real-time that I'm hoping for... and in order to give it linear encoder feedback (which I would really like to do some day) you have to upgrade to one of their higher end controllers which look like they only work with nice servo systems (as in not step and direction).

I really want 3 things in a controller:

Real-time processing (Most of my current problems would be fixed in a real-time system... I think)
Capability of 5 axis (probably never make it to 5 axis but I like to dream big)
Capable of tracking spindle speed, AND having an encoder on each axis
And yeah, cheap would be nice too AND if they can do it in a package like the Masso that doesn't need a PC to go with it 

I guess in reality I need to look at my bank account and remind myself that I'm a hobbyist, not a pro...

PZ


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## phazertwo

Also, after more lunch reading, I cannot find anywhere that the Acorn accepts a MPG... Am I just missing this?


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## cut2cut

Yes, currently no MPG it appears however they say TBA for a USB MPG,  so maybe there is hope.
Assuming TBA means “ to be announced”


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## phazertwo

Yeah, I wonder if it will be compatible with the current board... hopefully just a firmware update and not buy a new board.

Also, looks like the software won't run on my windows 2k pro machine 

PZ


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## cut2cut

For anyone that is upgrading their PM 940CNC from the supplied nMotion controller ( for Mach3)  to the 7176e ( for use with linuxcnc ) here is the wiring schematic that my brother made for me.  Its been a bit since i got it up and going,  so I don't recall the details but hopefully it is of some help.  Assuming the wiring on yours is the same as my PM940CNC that I got January 2017 with the Delta VFD.
Best Regards,
Jake


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## phazertwo

Been doing a ton of research on different controllers.  Stumbled across this as a good solution for no MPG for Centroid Acron:





In all my searching, I think I've come to the conclusion that Centroid Acorn is the way to go. Masso is also a good option and probably easier to setup, but Centroid builds industrial gear... they know exactly what they are doing.  Also, I can upgrade my mill computer, buy the card and software for about the same price as the Masso... So the cost is kinda a wash.

PZ


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## cut2cut

phazertwo said:


> Been doing a ton of research on different controllers.  Stumbled across this as a good solution for no MPG for Centroid Acron:
> 
> 
> 
> 
> 
> In all my searching, I think I've come to the conclusion that Centroid Acorn is the way to go. Masso is also a good option and probably easier to setup, but Centroid builds industrial gear... they know exactly what they are doing.  Also, I can upgrade my mill computer, buy the card and software for about the same price as the Masso... So the cost is kinda a wash.
> 
> PZ



Previously you mentioned that the Acorn wasn't realtime vs LinuxCNC.  Did you resolve that it wasn't an issue since it has an onboard motion control CPU so it shouldn't incur any loss of "timing" ? I looked around for any comparisons on the subject and couldn't find any, which is why I'm asking.   I do think the Acorn looks great and the company has been around the block a few times so they probably are putting out a good well thought out product and at great price point.  I think Precision Mathews should consider using this as a controller, IMHO.

Thanks,

Jake


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## pburgh

Hey Guys, good to hear that your onboard with the Acorn.  Hopefully you see this post.  If you're going to go this route, you'll want to purchase the board and upgrade to the pro software now before jan 3 2018.  They are going to be raising the price of the card and software.  There is a post on the Centriod Acorn forum that I read today about it.    I'll be posting some info to the forum about the 940 and the setup to be sure that i'm looking to make this change from the nMotion to the Acorn  without any issues.  So, keep an eye out for it and you'll probably get some questions answered too.  Also I found info that they are developing a driver for a wireless  MPG they are testing now (might already be good to go).    Something I discovered going into this is that i'm going to have to purchase a 5vDC power supply for the LeadShine drives.  Looks like the 5vDC is provided by the nMotion now.    Well, here we go.  I'm going to craft the initial post now.  Hopefully this is helpful to everyone.


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## cut2cut

pburgh said:


> Hey Guys, good to hear that your onboard with the Acorn.  Hopefully you see this post.  If you're going to go this route, you'll want to purchase the board and upgrade to the pro software now before jan 3 2018.  They are going to be raising the price of the card and software.  There is a post on the Centriod Acorn forum that I read today about it.    I'll be posting some info to the forum about the 940 and the setup to be sure that i'm looking to make this change from the nMotion to the Acorn  without any issues.  So, keep an eye out for it and you'll probably get some questions answered too.  Also I found info that they are developing a driver for a wireless  MPG they are testing now (might already be good to go).    Something I discovered going into this is that i'm going to have to purchase a 5vDC power supply for the LeadShine drives.  Looks like the 5vDC is provided by the nMotion now.    Well, here we go.  I'm going to craft the initial post now.  Hopefully this is helpful to everyone.



Thanks for the heads up Pburgh! 
I'm haven't counted up the number of ins and outs to see if the Acorn has enough for the 940cnc.  
Please leave a link here pointing to your post there, so we don't have to hunt for it.
Cheers,

Jake


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## pburgh

Hey Jake,
Here you go, freshly minted: http://centroidcncforum.com/viewtopic.php?f=60&t=1270
Hopefully, this will help.


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## cut2cut

pburgh said:


> Hey Jake,
> Here you go, freshly minted: http://centroidcncforum.com/viewtopic.php?f=60&t=1270
> Hopefully, this will help.



I need to verify a few things, but I think the schematic drawing I posted "above" for the Mesa 7176e is going to come in handy for wiring the Acorn to the Delta VFD.   I just need to retrace my emails to verify that...

Jake


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## pburgh

Thanks Jake, that would be great.  I was looking at some posts in the Acorn forum.  I searched on Precision Matthews and there is a post in there of a guy who fried his VFD.  I don't want to do that, so i'm a little apprehensive.  They didn't give me a manual on the VFD and I have to get the info on the one that's in there.  Did you get a manual with yours?  I'm a little annoyed at the lack of info that came with this unit.  Even though they are priced better than most of what's out there it's still a lot of money for something with such poor info.  I was looking at a Grizzley unit to try to get an idea on how to connect the coolant pump and I was impressed by how well the documentation was setup.  Do you know if the nMotion card provides 5vDC?  I didn't see anything on the schematic or in the cabinet that generates 5v.


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## cut2cut

My PM940CNC came with a DVD for the Delta VFD-E however, you can get the manual here :
http://www.delta.com.tw/product/em/.../manual/DELTA_IA-MDS_VFD-E_UM_EN_20150302.pdf

Yeah, I have yet to connect the coolant pump.... but coincidently I intend to wire it up tomorrow. If you have any pointers, I'd appreciate it.  It should be simple but if I remember right, its not clear cut.

I think you are right, it appears to me the 5v to the stepper drives are provided by the nMotion card itself via wire 055.
We can probably use a USB cable/charger for an iPhone as the 5v source.  So its not a huge hurdle.




Jake


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## pburgh

Thanks for the info on the VFD Jake.  I didn't get much with the mill.  I got the manual in a binder with the schematics and breakdown of parts, and I got a usb thumb drive for the nMotion card with the config xml file for Mach, the driver dll for Mach and a watered down version of the the nMotion manual and that's all.

As far as the coolant pump, Matt told me to connect the wires to one of the terminals with the capacitor leads and the one terminal without the capacitor leads.  See the pic below.  I connected mine with the hot legs on the terminals with the red arrows and the ground on an obscure threaded hole in the pump case where the green arrow is pointing.  I'm embarrassed to say that I used to be a construction electrician and I've hooked up my fair share of all kinds of motors, but I've never run into a peckerhead that is setup like this one.  The Chinese nomenclature for how they label their terminals threw me off.  And the ground is very close to the one terminal so be careful of the clearance.   I haven't tested this yet, but that's how I set mine up.  Hope this helps.


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## phazertwo

cut2cut said:


> Previously you mentioned that the Acorn wasn't realtime vs LinuxCNC.  Did you resolve that it wasn't an issue since it has an onboard motion control CPU so it shouldn't incur any loss of "timing" ? I looked around for any comparisons on the subject and couldn't find any, which is why I'm asking.   I do think the Acorn looks great and the company has been around the block a few times so they probably are putting out a good well thought out product and at great price point.  I think Precision Mathews should consider using this as a controller, IMHO.
> 
> Thanks,
> 
> Jake



I didn't totally resolve the realtime situation, however you are correct.  Since the thing has a dedicated motion control CPU I think it works quite differently than these Chinese controllers that are "good enough".  Also, it's very interesting how specifically they spec their computer, but they don't need a video card?  Considering video takes up a HUGE chunk of the processing overhead int he computer, I'd be worried it would have the same issues I have now.

Bottom line: in a solid couple days of researching I cannot find anyone who is not really happy with their Acorn... and they make industrial equipment... AND THEY ARE IN THE US!



pburgh said:


> Hey Guys, good to hear that your onboard with the Acorn.  Hopefully you see this post.  If you're going to go this route, you'll want to purchase the board and upgrade to the pro software now before jan 3 2018.  They are going to be raising the price of the card and software.  There is a post on the Centriod Acorn forum that I read today about it.    I'll be posting some info to the forum about the 940 and the setup to be sure that i'm looking to make this change from the nMotion to the Acorn  without any issues.  So, keep an eye out for it and you'll probably get some questions answered too.  Also I found info that they are developing a driver for a wireless  MPG they are testing now (might already be good to go).    Something I discovered going into this is that i'm going to have to purchase a 5vDC power supply for the LeadShine drives.  Looks like the 5vDC is provided by the nMotion now.    Well, here we go.  I'm going to craft the initial post now.  Hopefully this is helpful to everyone.



Why do they have to go and do that right at x-mass when everyone is hurting for money?!  Was there any indication of how much the price was going to increase?

Also, adding a 5v power supply can be very cheap if you have any old ATX computer power supplies laying around.

PZ


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## pburgh

PZ,
Here's a link on their forum that gives a breakdown of the increase:
http://centroidcncforum.com/viewtopic.php?f=60&t=1259&sid=541bdec3a81ed975e863ed290737ccf8
Hope this helps,
Doug


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## pburgh

Actually they bump the price of the card and pro software up a little bit, but they reduced the price of their ultimate software.  I originally purchased the Acorn with the pro software, but i'm probably going to upgrade to the ultimate once I get going on this.


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## pburgh

Guys, I've been getting some very good feedback from the Centroid forum:  *http://centroidcncforum.com/viewtopic.php?f=60&t=1270*
Check it out.

Regards,
Doug


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## phazertwo

Well hell, it's about a $100 savings... Guess I'm going to need to make the decision next week.

The response that your thread at Centroid is getting is awesome and quite encouraging!

PZ


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## pburgh

Pull the trigger.  I don't think you'll be disappointed.
Merry Christmas,
Doug


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## cut2cut

pburgh said:


> Guys, I've been getting some very good feedback from the Centroid forum:  *http://centroidcncforum.com/viewtopic.php?f=60&t=1270*
> Check it out.
> 
> Regards,
> Doug



That’s great !  A good head start !!   Note however,  your wiring diagram and the one Orin created for you looks accurate,  HOWEVER,  MY limit and home wires are numbered different than what your manual shows !  Yours are 88, 89,90,  etc ,  but mine ( on both my mill and my supplied manual are 35, 37,39, etc !  Thankfully my documtation is accurate but it’s worth noting for Phazer and anyone else that has a PM940 that they need to check as they obviously make running changes!  AND you should double check that your home and limit wires are accurately labeled too!   

And it looks like we will need to daisy chain our limit switches together with the EStop,  but that shouldn’t be too hard.
Cheers,

Jake


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## phazertwo

Alright... It's done.  One Acron and CNC12 Pro are headed my way...

This video is finally that finally sold me on it:





The fact that they are a pro level CNC retrofitter, make their own machines, and the computer software and controller are made by the same company were the prime reasons. Can't wait to get started... Though I have to order another $300 worth of computer parts before I can even consider getting off the ground.

And this is just funny (rough language, be ware if you're using speakers):





PZ


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## pburgh

Sorry guys, i went dark for a few days with the holiday and some personal tragedy.  I'm going to get started again to follow through with setting up the changes i need to make.  I ordered a power supply that Marty recommended from Jameco and a jog switch for the  reference limits setup.  He put the link for the power supply in the Centroid thread, but i think they removed it.  Here it is if you're interested:  https://www.jameco.com/webapp/wcs/s...yzPSTU=&ddkey=https:StoreCatalogDrillDownView

PZ, i think you made the right choice.  I also went with Centroid's recommendation and got a NUC with windows 10 pro from New Egg.  they were going for a little under 500 with the os which i didnt think was a bad deal for something compact.  Marty walks through setting up a fuller sized pc that would probably save a few bucks, but the NUC was worth it to me.  Hope to come back soon with some progress.


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## phazertwo

Your thread is still up... It's just on page two.
http://centroidcncforum.com/viewtopic.php?f=60&t=1270

Yeah, the NUC is a good option, however I was worreid about getting all the bloatware off the factory installation of Windows.  I have had the laptop that I am typing this on right now for just over a year and I STILL haven't figured it out.  It's about to the point that I'm going to order a new copy of Windows 10 and start with that!

Anyway, I build computers pretty frequently so building one specialized for CNC is no big deal.  I am going to re-use most of the old Mach 3 PC, and I am donating what I'm not using to my Dads CNC router project.  I'm really looking forward to see your progress... You should start a new thread about it, so we can stop tying up Jacks thread!!

PZ


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## pburgh

phazertwo said:


> Your thread is still up... It's just on page two.
> http://centroidcncforum.com/viewtopic.php?f=60&t=1270
> 
> Yeah, the NUC is a good option, however I was worreid about getting all the bloatware off the factory installation of Windows.  I have had the laptop that I am typing this on right now for just over a year and I STILL haven't figured it out.  It's about to the point that I'm going to order a new copy of Windows 10 and start with that!
> 
> Anyway, I build computers pretty frequently so building one specialized for CNC is no big deal.  I am going to re-use most of the old Mach 3 PC, and I am donating what I'm not using to my Dads CNC router project.  I'm really looking forward to see your progress... You should start a new thread about it, so we can stop tying up Jacks thread!!
> 
> PZ


Yeah i saw that when i visited the page again.  Sometimes i think i'm having a senior moment.  Sure i can start a new thread to document this change.  Keep in mind in one of Jake's post above that the wire numbers may not be the same.  I can't imagine them making these machines and not keeping the wiring numbers consistent for like machines.  But it's good to know.  So i'll also go thru and post what i'm going to do on the Centroid thread to be sure that they are all in agreement.  I don't want to fry anything by making a mistake.


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## phazertwo

pburgh said:


> ...I can't imagine them making these machines and not keeping the wiring numbers consistent for like machines...



You obviously don't deal with low end Chinese manufacturing on a daily basis .  These things are defiantly a big step above some of the Alibaba equipment that I've worked on, but it still wouldn't surprise me at all if they were not wired the same.

PZ


----------



## pburgh

Guys,
Here is a Podcast that i came across on You Tube about the Acorn.  Some interesting info from Keith at Centroid.  For those of you interested in the Acorn board, it would be a good listen.  



Enjoy!
Doug


----------



## cut2cut

pburgh said:


> Guys,
> Here is a Podcast that i came across on You Tube about the Acorn.  Some interesting info from Keith at Centroid.  For those of you interested in the Acorn board, it would be a good listen.
> 
> 
> 
> Enjoy!
> Doug



A Great listen !!!  Thanks!!!

Always cool to hear some history about what appears to be a really good company.  Keith sounds like a legit guy trying to fill a need and it appears he’s done it.   The Masso is in a similar vein,  so having these guys compete for a great , all,  or nearly all in one solution is pretty cool and good for entrepreneurs, startups , and hobbyists alike.  

I ordered an Acorn and look forward to converting from LinuxCNC.   I just hope the usb MPG becomes a reality very soon !

Jake


----------



## megaplow

Gave up on the 7I76e for now...
I did get the electronics on the wall though!!!


----------



## cut2cut

megaplow said:


> Gave up on the 7I76e for now...
> I did get the electronics on the wall though!!!



Looks good !  

Yeah,  Linux cnc / 7176e was a hard road.  My desire to use path pilot was why I went for the 7176e and Linuxcnc.  After the minimum  install of Linux cnc and wiring the 7176e it was apparent I was in over my head and fear it ever needing rebuilding, much less getting path pilot to work.    I was going to offer to sell my working LinuxCNC 7176e setup to you if you really wanted to go down that path but your too far down the rabbit hole already !  I will say,  after you get it going,  it feels like you have done something amazing !  Hope you can keep at it and reach the summit , so to speak.  
Jake


----------



## megaplow

Glad you like it,
I got a machine running linux and linux cnc so I am good to go. I thought I should do the wall installation and get the machine is good working order before tearing its guts out again.

Happy new year.


----------



## cut2cut

megaplow said:


> Glad you like it,
> I got a machine running linux and linux cnc so I am good to go. I thought I should do the wall installation and get the machine is good working order before tearing its guts out again.
> 
> Happy new year.



Very cool.

Happy Nee Year !


----------



## megaplow

Do you know where to find the nmotion mach3 plugin?


----------



## cut2cut

Did your mill come with a USB drive ?  I believe the installer on the usb memory stick has the needed software.


----------



## cut2cut




----------



## megaplow

That drive is currently misplaced. I was hoping to find a download, but haven't found one yet.


----------



## cut2cut

I believe this is all you need.  See the attached files


----------



## megaplow

Thank you,
That was the ticket! The thing is moving in three directions. Now for limits, spindle control and 2010 screenset tuning.


----------



## phazertwo

Wall mount looks very nice.

Every time I look at that stupid pink USB stick, this is all I can think of:





Well, with all three of us on the centroid train now I hope it's a good setup!

Happy new year gents.

PZ


----------



## cut2cut

phazertwo said:


> Wall mount looks very nice.
> 
> Every time I look at that stupid pink USB stick, this is all I can think of:
> 
> 
> 
> 
> 
> Well, with all three of us on the centroid train now I hope it's a good setup!
> 
> Happy new year gents.
> 
> PZ



Yes sir !  Happy New Year!

Just realized it’s been one year with the pm 940 !!!   What an adventure !

Jake


----------



## pburgh

Guys I took PZ's advice and started a new thread so not to hijack Jake's thread.  
Here is the link:  https://www.hobby-machinist.com/thr...ontroller-conversion-to-centroid-acorn.65196/

I'll post my progress there.
Regards,
Doug


----------



## cut2cut

Below are a bunch of my PNCconf configuration files for Linux CNC and the Mesa 7i76e.  Perhaps it can help Mega set up his, or help someone else.   I figured I'd better do this before I started rewiring for the Acorn Centroid.
Cheers,

Jake


----------



## megaplow

Thank you for the wiring and screenshots! I am still trying to move forward w Mach... currently I the nMotion board is seeing my limit and direction switches, but those values are not being passed to Mach3. I think I know what pins to use, but what port should I be mapping to?


----------



## cut2cut

megaplow said:


> Thank you for the wiring and screenshots! I am still trying to move forward w Mach... currently I the nMotion board is seeing my limit and direction switches, but those values are not being passed to Mach3. I think I know what pins to use, but what port should I be mapping to?


 
have you looked at my old post on the other thread ?  

https://www.hobby-machinist.com/threads/pm-940m-cnc-pre-assembled.49011/post-458178


----------



## cut2cut

I've got some good news... ok,  so it is a bit of both, good and a far bit less bad news.  If you are like me, its good news, because I found what I believe to be the reason my mill has more backlash than it should and it is fixable.  The bad news is, it probably will cost 6 angular contact bearings and milling some new bearing / stepper motor mounts to do this the "right" way however there may be a way to do it inexpensively too ( see below ).  In explaining this  I am going to focus just on the X axis but this should apply to all three axis.    On my PM 940 CNC the X axis stepper motor is on the left side of the "table".   A nut is used to tighten a set of bearings that fix the end of the ball screw directly to the "table".  This nut, when tightened should apply enough force to remove backlash but the bearings should allow the ball screw to rotate without any friction unless the nut is overly tight.   I had tightened mine up sufficiently to ensure I *should* have a minimum amount of backlash defined by the balls and the screw itself.  The ball screws in the PM940 are supposed to be be of a good grade, so I was hoping for the best.  Sadly, I'm seeing a minimum of .002 of backlash.  I kind of put it out of my mind as other things needed attention but it always bothered me that my mill had a significant deficiency.  HOWEVER, I remembered something I read about ball screw ends from china sometimes are designed poorly. Basically they use two bearings but stupidly  the inner races are allowed to touch each other.  Basically the two bearings are back to back, acting as one bearing.  So even if they were two sets of angular contact bearings, if the inner races are allowed to tighten against each other they have no value other than allowing low friction when turning.  The bearings side play is then what defines the amount of backlash.  Check out my little video that shows the two bearings spinning together with just a small amount of force squeezing them together by hand.   



Also, they don't appear to be angular contact...

One additional detail is that the right side of the table also has a nut assembly that holds the hand cranks.    When I first got the mill I removed all the hand cranks and nuts to ensure that the ball nut assembly would not be bound up with opposing force. 

There is one possible way to do this on the cheap and use the existing castings and possibly the existing bearings.   Just find a sufficient washer and place it between the large outer races.   I haven't tried to remove the existing bearings because they appear to have been pressed in with no way to press them out without damaging ( pressing via the inner races is not good, but maybe necessary ),  I haven't tried.    I'm going to order replacement bearings before I try to remove them.   Then I'l at least have a way to machine something that willl replace the castings, etc, if needed.

sleepy... gnite

Jake


----------



## cut2cut

The needed bearings aren't too bad....  $25 for TWO from VXB... maybe not the highest grade.. but worth trying ! ( shipping adds about $15 )

Kit10872 Angular Contact Bearing 7204B 20x47x14
https://www.vxb.com/2-Angular-Contact-Bearing-7204B-20x47x14-p/kit1087.htm


----------



## phazertwo

Great post!

Careful with those bearings you spec'ed... doesn't look like they are sealed.

PZ


----------



## cut2cut

phazertwo said:


> Great post!
> 
> Careful with those bearings you spec'ed... doesn't look like they are sealed.
> 
> PZ



Good point. I wasn't thinking about the exposed side ( toward the table ) !

btw,  I was thinking that maybe you might need to remove the hand cranks as they might be causing some additional drag.  If you have little backlash it might be that both sides are opposing each other, giving you very little backlash, but could wear out your ball screws quickly... if that is indeed what is happening. Hopefully, yours is just fine the way it is though... 

Jake


----------



## phazertwo

I defiantly want to dig into mine.  When I bought this I bought it as something that I hoped I could upgrade to be on par of very near a Tormach 1100... So motor/ball screw mounts are in my future for sure.

PZ


----------



## cut2cut

Ok,  some rather good news related to the backlash fix.  As noted above I dug into my X table ball screw end bearings on the left side.  Tonight I pressed out the existing bearings using a harbor freight hydraulic press.  Added a McMaster 35mm ID 45mm OD spring steel shim in **between** the two bearings Large OD races of the existing angular contact bearings (  a side note... one had its shield removed so it was exposed so it was pretty dirty ).  Then I pressed the old bearings back in sandwiching the single shim in between the two bearings and voila... I didn't do much of a test due to lack of time but my X axis is now below .001 for sure and could very easily be at or below .006 , whereas it was clearly .002 before.   So I'm pretty happy now.     New bearings on the way and I'l do the Y and Z when they get here.  

Note, I still believe it may be necessary to remove the "other side nut and hand cranks or at least loosen it to allow it to have lots of slop.  Otherwise you could end up ruining the ball bearings or the ball screw itself.

and here is the link to the the 35mm ID x  45mm OD x  1mm shim I used :

https://www.mcmaster.com/#98055A346

Cheers,

Jake


----------



## phazertwo

Well this is good news!  Did you order the bearings from VXB you linked above?


----------



## cut2cut

phazertwo said:


> Well this is good news!  Did you order the bearings from VXB you linked above?


Yes,  hopeful they will get me  by until I have time to make new bearing holders,  then i’ll fork out the money for higher quality AC bearings with shields.


----------



## cut2cut

TomS,
Not much to see really, its fairly simple.  My first posts on this thread actually outline what I used to implement the pulley and belt system.   The only "tricky" part was to create a key for the splines on the spindle.  ( Whoa !   _*splines*_ and _*spindle*_ use the same letters !!!  Spooky !  )

Here are a few pictures.   The secondary pulley ( red 3d printed part with a small belt ) is for the encoder for rigid tapping.  I'm still working on that... so stay tuned....

Nothing sexy yet... once I get to rigid tapping I'll be cranking more stuff out to make the mill look better. 

Cheers,

Jake


----------



## TomS

cut2cut said:


> TomS,
> Not much to see really, its fairly simple.  My first posts on this thread actually outline what I used to implement the pulley and belt system.   The only "tricky" part was to create a key for the splines on the spindle.  ( Whoa !   _*splines*_ and _*spindle*_ use the same letters !!!  Spooky !  )
> 
> Here are a few pictures.   The secondary pulley ( red 3d printed part with a small belt ) is for the encoder for rigid tapping.  I'm still working on that... so stay tuned....
> 
> Nothing sexy yet... once I get to rigid tapping I'll be cranking more stuff out to make the mill look better.
> 
> Cheers,
> 
> Jake
> 
> View attachment 257212
> View attachment 257214
> View attachment 257215



Thanks for the pictures.  Looks like you have eliminated the spindle drive sleeve with your setup and "locked" it in position.  I'm still using the drive sleeve because I need about an inch of spindle travel to actuate my tool changer.  Guess I'll have to live with the spline noise.

Not my mill but the configuration is the same.


----------



## cut2cut

TomS said:


> Thanks for the pictures.  Looks like you have eliminated the spindle drive sleeve with your setup and "locked" it in position.  I'm still using the drive sleeve because I need about an inch of spindle travel to actuate my tool changer.  Guess I'll have to live with the spline noise.
> 
> Not my mill but the configuration is the same.
> View attachment 257253



That looks nice.  Yeah, if I wanted the quill action, I'd have used this method and not locked down the quill movement.   Does it allow the use of a power draw bar ?


----------



## phazertwo

Hey Jake, I don't suppose you could get the shaft dimensions off the old motor?  I picture would be great too.

Thanks!
PZ


----------



## cut2cut

phazertwo said:


> Hey Jake, I don't suppose you could get the shaft dimensions off the old motor?  I picture would be great too.
> 
> Thanks!
> PZ


Shaft diameter is 24mm.  
Shaft length is roughly 45mm
Roughly 166mm between holes ( very rough +- 3mm )  no time to check further right now 
200 OD of motor plate 
130mm inner OD of motor plate ( ridge )


----------



## phazertwo

Awesome, thanks!

I think I'm going to give it a shot with the factory motor!

PZ


----------



## TomS

cut2cut said:


> That looks nice.  Yeah, if I wanted the quill action, I'd have used this method and not locked down the quill movement.   Does it allow the use of a power draw bar ?



Yes, you can use a PDB with my setup.  I have a Ultron Snap Change manual quick change tooling system on mine.  Nearly as fast as a PDB.


----------



## cut2cut

Doug,  I totally forgot to post these pictures of the transmission cavity.  Here they are.  Sorry for the delay !

( the red 3d printed thing is to drive a belt to my spindle encoder )


----------



## pburgh

Thanks Jake,
No problem, I was wrestling with my lathe all weekend, so I haven't done much with the mill.  Is the collar with the phillips head screws below the spindle pulley where the spindle sleeve sits that has the small gear (33) attached?  Also, do I understand correctly that TomS' pic about can use the quill feature?

Regards,
Doug


----------



## TomS

pburgh said:


> Thanks Jake,
> No problem, I was wrestling with my lathe all weekend, so I haven't done much with the mill.  Is the collar with the phillips head screws below the spindle pulley where the spindle sleeve sits that has the small gear (33) attached?  Also, do I understand correctly that TomS' pic about can use the quill feature?
> 
> Regards,
> Doug



Yes, with my belt drive conversion setup I have about 1" to 1-1/2" of quill travel.


----------



## phazertwo

Hey Jake, anyway you could snap a picture of the name plate off your motor... The way mine is mounted it's hard to read.

Also, do you know what the gear ratio was for high or low?

Thanks
PZ


----------



## cut2cut

phazertwo said:


> Hey Jake, anyway you could snap a picture of the name plate off your motor... The way mine is mounted it's hard to read.
> 
> Also, do you know what the gear ratio was for high or low?
> 
> Thanks
> PZ


----------



## cut2cut

Yeah,  I was wondering if the site was causing huge issues ,  or you were having huge issues with the belt conversion.  Actually, that part is significantly easier and less stressful than replacing the bearings in the spindle, imho.


----------



## phazertwo

Thanks for the pic!



cut2cut said:


> Yeah,  I was wondering if the site was causing huge issues ,  or you were having huge issues with the belt conversion.  Actually, that part is significantly easier and less stressful than replacing the bearings in the spindle, imho.



Think I'm going to do the bearings at the same time... I'm thinking AC bearings will be better for the PDB.

PZ


----------



## cut2cut

If you are into VFD and motor settings especially for rigid tapping, you can join or follow along in this other thread.

https://www.hobby-machinist.com/threads/motors-minimum-rpm-wrt-rigid-tapping.66280/

Cheers,

Jake


----------



## cut2cut

Ok,  long time, no see !  Well,  here we go,  POWER DRAW BAR TIME !   I've collected a bunch of the necessities and now need to mill the parts.  I am in need of someone that can make a steel "top hat" for the belleville washers since I don't have a capable lathe and not much experience with it either !   So anyone out there, please let me know if its in your wheel house and can do it for me !? ( see attached drawing ( in inches ))

 I'll be posting details later today but here is the render of the model.   Its adding some weight to the head, so I'll be using struts on the head to take some of the load away.   Details to come !

Cheers,

Jake


----------



## phazertwo

I'd reach out to Shooter123456.  He's pretty handy on the lathe, and seems willing to help!

PZ


----------



## cut2cut

Haha,  love the popcorn gif.   i’ll see if mrshooter can help.  Much appreciated.   

Cheers,
Jake


----------



## cut2cut

Welp,  this Power Draw bar project has been kicking my ass.   I think I have an issue with my Z axis stepper which I'm in the middle of trouble shooting.     So its putting the possibility of me upgrading to DMM servos to the forefront. ( Phazer, calm down....  Don't eat that popcorn too fast, I wouldn't want to be the reason for you untimely demise ! 

So, my question is, is it worth the extra money to go for DYN4 drivers, or just go with the cheaper, and less powerful DYN2 drivers ?     Also wondering if the 750Watt will be adequate for the Z or will I regret it.  Likely I'll add a counterweight as the gas struts I just added don't seem to be doing the trick so that would help a lot.  It is still possible I could be facing a g-code gremlin.   I will say, my Z axis has always been noisy and the Z ball screw has a whip to it so there are many things that could be adding up to my Z issues.  I'm tempted to also buy a Z axis double nut kit from ArizonaVideo but really wouldn't look forward to installing it.  That PM940 column and head is heavy and tough to deal with.    Alas,  servos are the way to go so I figure I may as well go for it now and enjoy the benefits regardless of what the real issue is with the Z.

Jake


----------



## phazertwo

Well, I'm equally excited to watch some DMM servos get hooked up to a 940!!

I think the Leashine 86HS85 stepper on our Z axis actually only produces about 2-3 nm of torque at the speeds and resolution we run it at...  So I would want something better than that on my Z.  I've been thinking a 1.0 KW or even the 1.3 KW and don't worry about a counter weight. or gas struts.  Though I also want my Z to be able to move at least 100 ipm, preferably even faster.  I would also do 0.75 KW drives on my X and Y... I'd rather have too much than end up wishing I had bigger motors later.

As for DYN 2 vs 4... i'd go with 4.  They can be programmed to turn an output on if they loose position, which would be very nice.  Also, they run on 240 VAC, so there is no need for a big DC power supply, which nice for a few reasons.  Not only does that mean less wiring, but it means more room freed up in the cabinet.  Only thing that might mess that up is the 24 VDC holding break... not sure if needs an external 24 VDC.  I'll have to do some more reading on it.  Please keep in mind that I have priced NONE of this out, I have only read spec sheets and am dreaming big.

PZ


----------



## cut2cut

phazertwo said:


> View attachment 280498
> 
> 
> Well, I'm equally excited to watch some DMM servos get hooked up to a 940!!
> 
> I think the Leashine 86HS85 stepper on our Z axis actually only produces about 2-3 nm of torque at the speeds and resolution we run it at...  So I would want something better than that on my Z.  I've been thinking a 1.0 KW or even the 1.3 KW and don't worry about a counter weight. or gas struts.  Though I also want my Z to be able to move at least 100 ipm, preferably even faster.  I would also do 0.75 KW drives on my X and Y... I'd rather have too much than end up wishing I had bigger motors later.
> 
> As for DYN 2 vs 4... i'd go with 4.  They can be programmed to turn an output on if they loose position, which would be very nice.  Also, they run on 240 VAC, so there is no need for a big DC power supply, which nice for a few reasons.  Not only does that mean less wiring, but it means more room freed up in the cabinet.  Only thing that might mess that up is the 24 VDC holding break... not sure if needs an external 24 VDC.  I'll have to do some more reading on it.  Please keep in mind that I have priced NONE of this out, I have only read spec sheets and am dreaming big.
> 
> PZ



The sales guy at DMM has been very helpful.  I asked about DYN2 vs DYN4. Basically the DYN2 drive powered by our existing 48VDC power supply with their 86M-DHT .75kW servo would run at 1200rpm.  With our 5 turn per inch ball screws that equals 240 ipm.    ( I could be wrong and our big DC power supply provides 60VDC ?  which would give us 300 ipm )   Basically speed is directly related to the voltage.    The DYN4 drives apparently double the speed by being 220/240 V AC  but they have no other performance advantage over the DYN2 other than top speed.  They both have the same holding and "cutting" power.   I perceive this as being that the motor is the limitation, not the speed control, however voltage dictates rpm, so the DYN4 has the advantage of 220v AC but if you don't intend to go faster than 240 ipm, I am told there is no advantage.   I, however, have opted for the DYN4 due to exactly what you said Phazer,  being able to remove the existing big DC power supply and basically a cleaner wiring and if ever, being able to use the equipment being more versatile if used on another setup.  The DYN4 drives are fairly large, so its almost a necessity to fit them in the existing cabinet.        I do plan to add a counter weight, but regardless, will also pay the hefty cost for 24v brake option  as added insurance if the counter weight ever should fail it could really result in a nasty crash.   The added benefit of adding a Z counter weight, is that I will be able to get the .75kW ( 750watt ) motor for all three axis.    Also, they have servo motors with 14mm shafts, so it should basically drop right into our pm940cnc with little to zero fuss as the 4 mounting holes are with 2mm ( on the diagonal )  of being correct, I don't see this as being a "show stopper" however could require some small modification to the servo motors to make it fit.    
However, if you go with the "N" version ~  86N-DHT the bolt pattern is exactly the same so it drops right in with only one issue, the shaft is 1/2 inch, which requires different shaft couplers / "lovejoy" couplers.   I think VXB bearings has the shaft couplers needed for $50 each.  ( Correct me if I'm wrong, but I measured 14mm on the motor side and 16mm on the Ball screw, at least on the X axis. )  If they are 14x14 then they can be found much much cheaper on ebay but expect them to take longer to arrive from China.   All in all, the DYN4 DMM Servo setup should cost around $1500 to $2000.  A few hundred less if you go with DYN2.    

attached is what I milled last night, one of two for the PowerDraw bar project.   

ok, enough for now,  gotta join the thanksgiving festivities...  


Cheers,
Jake


----------



## phazertwo

One other note, at least on my machine, the power supplys are just transformers.  The Stepper drives run off 60VAC, which means I would need to get a big DC power supply if I wanted to run DYN2 drives.  The smaller of the two transformers just provides 24 VAC for all the Chinese control circuitry.

PZ


----------



## cut2cut

Just an update.... a rather good one.  I have a working Power Draw Bar !   I was lucky and found a used 3 stage pneumatic cylinder on eBay for $50 with free shipping.    I designed around the cylinders  "significant" size which barely rubs the spindle motor when "actuated"  It provides just enough force at about 100 PSI to do the job.   The cylinder itself is rated for over 150 psi, however one of my goals was to use a small compressor so noise could be reduced as much as possible.  I can post more details however, credit for the general design belongs to Sam ( link to his Power Draw Bar videos ).  I also relied on his advice on a number of things along the way.  Be sure to check out his videos here :  





Attached are a few pictures and a couple short videos of my Power Draw bar in action.   

Cheers,

Jake


----------



## phazertwo

Wow man, this is looking super nice.  I'm going to have to start peaking at Flebay more often to see if I can score a cylinder like that!  

How do you have it wired/plumbed?  I was thinking the best way to control it would be though the Acorn, as in a button to the Acorn then the Acorn output actually releases the tool.  Then the Acorn could decided if it should actually release to tool or not, as in if it's choochin' at 5k RPM not a good time to release the tool.  I'm kinda assuming the Acorn is capable of this.

PZ


----------



## cut2cut

phazertwo said:


> Wow man, this is looking super nice.  I'm going to have to start peaking at Flebay more often to see if I can score a cylinder like that!
> 
> How do you have it wired/plumbed?  I was thinking the best way to control it would be though the Acorn, as in a button to the Acorn then the Acorn output actually releases the tool.  Then the Acorn could decided if it should actually release to tool or not, as in if it's choochin' at 5k RPM not a good time to release the tool.  I'm kinda assuming the Acorn is capable of this.
> 
> PZ



It has been a bit of a long winding road to get it to work.   I hope to outline the entire project when I'm sure it works as it should, consistently, and then I'll provide the details.   I think I made enough errors and experienced most of the possible pitfalls that it should help others from making the same mistakes.  In just the last day or two I am to the point where it works ok, I think ! lol.     One of the main things that hindered me over the last couple weeks was the solenoid that directs air to the cylinder ( for retraction and extension ) was faulty.    I bought a "Fastek" from ebay that somewhere stated it was made in the good ole USA.  Well, although that may be true, I find it unlikely because it so closely resembles all the clones from China ( and I mean it really looks like a rolex copy... from 5 feet you would say they are the same ).   Perhaps a company in the USA just assembled the parts here  ?  I don't know, but the one I have is not a good product and I will be looking for a refund.    Ultimately, I ended up "re-purchasing" another brand ( for the same cost $29 ) which is the same ( Airtac- made in Tawian supposedly ) as Sam / CNC4XR7 used (the youtube which I referenced above.)     I believe he used another thread size / pitch, however.  This is what I have :  Airtac brand Air Pneumatic Solenoid Valve 2 position 5 way 1/4" 4V310-08-B-DC24V
I have it wired with a switch to manually actuate it.  The switch is NO so it won't release the tool until its manually powered by me to do so.   Personally,  I would only have Acorn actuate it if I had a tool changer.   That is a future project that I hope to get to,  but I kind of doubt the Acorn has the capability of that anyway.   One of Centroids other , more expensive, DIY controller cards does have this capability since it is a closed loop controller capable of reading absolute servo position.     There may be ways around having absolute position for a tool changer but it seems like it would be more of a headache to implement.  That being said, I haven't really looked into it much.  

So basically the solenoid , in its normal un-powered state allows air flow to the cylinders retract piston which makes sure the piston won't push out at all due to gravity.  Even if it did protrude on its own, it cannot provide enough force to compress the "belleville" spring washers to release the TTS tool holder.   When the solenoid is actuated by the switch, the solenoid redirects the air flow to the ( 3 stage cylinder ) ( instead of to only one of the cylinders to retract ) to compress the belleville washers.  Some multi stage cylinders have an air port for each stage but this one has internal "ducting" so added external hoses daisy chaining them isn't needed.  I suppose this is only negative in that one could , if they wanted to, reduce the number of active pistons to reduce the power of the cylinder.    

I mean to give all the details and part numbers for the entire project but I want to know its working 100%. So I will, in more detail, outline the pitfalls I experienced so others won't have to experience them. If you watch the video I posted I kind of edited out a flaw.  So if you look closely, there is a delay from the time I actuate the switch to the time the cylinder actually pushes the piston out.   This is caused by the faulty solenoid !    The solenoid would sometimes have a short short delay, but other times it would get very very long... as long as 8 seconds after powering it via the switch.  As well, it appears it somehow was restricting air flow.  At this time I don't know how much, but it seems as though it was not giving the full 100psi to the cylinder.  As soon as I changed the solenoid to the Airtac brand,  the cylinder seemed to produce the needed force to release the tool with only 50 psi and would be instant when flipping the switch.  

I need to remake two items that I had to make on my little crappy 9x30 ?  harbor freight lathe I got years back for $500 new.  ( I really need a better lathe ! )  Why, because currently the drawbar nut and belleville washers show signs of a wobble so I need to re-do the nut and clamping "top cap" to fit a bit tighter on the spindle shaft.  Its tricky to make it loose enough so it won't bind, but tight enough that it won't be unbalanced / wobble.  The lathe has cross slides that are so sloppy the cutting bits chatter and grab making perfect cuts inconsistent and rough too.  Any suggestions on lathe's are appreciated.  I've considered another Precision Mathews lathe but with the current tariff war the PM 1340's are over $5k.  I missed out on a south bend lathe locally for under $1k recently, which likely would have been a good option... but that's another story altogether.....

On another note,   I have another spindle encoder option coming in the next month or two to test.  If it works well, it is ideal for the PM940 with belt drive if one wants to do rigid tapping.   Should be under $200 in total but very reliable and consistent.    

Best,

Jake


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## phazertwo

I was thinking it would be a matter of safety to have the signal go through the Acorn.  Ideally it would keep the cylinder from firing if the spindle was on...

I have seen some threads about ATCs and Acorn, and it works on the lathes... so I would imagine it can be done on mills too.

I'm looking forward to your full post.  I just got all the parts I need to get mine running again yesterday, and hoping to get it all going again in the next two weeks.  Once it's up and running I have some small projects, but then I want to get after the PDB and possibly and automatic 2 speed setup.

My friend has a Grizzly G4003G and it's very nice.  He added a DRO after the fact, and IMO it's a critical update for a lathe.

PZ


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## cut2cut

phazertwo said:


> I was thinking it would be a matter of safety to have the signal go through the Acorn.  Ideally it would keep the cylinder from firing if the spindle was on...
> 
> I have seen some threads about ATCs and Acorn, and it works on the lathes... so I would imagine it can be done on mills too.
> 
> I'm looking forward to your full post.  I just got all the parts I need to get mine running again yesterday, and hoping to get it all going again in the next two weeks.  Once it's up and running I have some small projects, but then I want to get after the PDB and possibly and automatic 2 speed setup.
> 
> My friend has a Grizzly G4003G and it's very nice.  He added a DRO after the fact, and IMO it's a critical update for a lathe.
> 
> PZ



Thanks for the lathe suggestion, looks nice for sure and a good size for me.  Its not an urgent thing since I'm still trying to focus on the mill so I doubt I'll jump on any lathe just yet.   

May I ask what you are doing to your mill currently that has it "down" ?   Automatic 2 speed setup ?  interesting !

Ok, I see what you are saying wrt the PDB only actuating if the Acorn allows it while the spindle is not turning.   I'll search for some threads about ATC to see how people are achieving it.  I assume through a relay.  I just kind of figured if a mechanical switch was inline it would be safest ( like an E-stop , if no power is getting to the solenoid, its default position is that it cannot fire ).   

I'll will be detailing the PDB project as soon as I get to test out the holding strength on my next project which should be in next week.

Cheers,

Jake


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## phazertwo

You certainly may ask.

I got tired of the noise coming from the gear train int he head so I yanked it all apart to put a belt drive on it.  Pretty sure that was in April... Anyway, getting ready for a kid, and having a kid, I haven't got her up and running again.  Life has been settling a bit so I have has some time to work on it.  I also have a servo motor that I'm going to use as a spindle motor, that should get me more RPM than the thing can actually handle, but we'll see.

As for the automatic two speed... If it works it will be very cool, though I need to do more research to see if Acorn can select gears, but I'm pretty sure it can.

PZ


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## cut2cut

Well, having a kid is surely life changing but for me, without a kid, going from gear train noise to none, THAT was life changing .   The servo motor as a spindle seems to be a really elegant solution too.   You are sure to be happy with these mods, I know the noise drove me nuts so just that alone was worth doing.   

Cheers,
Jake


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## pburgh

Hey Guys,
Jake that looks really good.  Man, I've been out of it for a while.  I haven't been getting any email from the forum that there's been any activity.  I'm going to have to check into that.  I have some catching up to do.  Got side tracked with some other projects....

Regards,

Doug


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## cut2cut

Hey Guys,  

I'm hopeful someone with the (pm940) quill still operational can do me a favor by measuring the diameter of the spindle.  My thought is to replace my spindle with one of the standard sized ( usually 80 and 100mm it seems ) spindles.  I imagine it would need an adapter sleeve.    

Because my spindle is locked down due to a pulley system modification I cannot easily extend it ( no quill action ) without some significant disassembly.


What has peaked my interest in spindle options is this youtube video  :  



Its a 24000 rpm spindle.  I assume it would not be adequate for low rpm use required for rigid tapping, but thats one of the few negatives about going this direction.  

I'm also curious about the type of taper to go with, so that's a subject of its own.    With the fall and winter here turning sour here in the Pacific Northwest its pushing my interests back to the mill project  

Hope all is well with the PM940 gang !

Jake


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## pburgh

Hey Jake,
I still have my quill setup.  I'll measure it for you when I get home tonight.    Good to hear from you.  Haven't talked to you guys for a while.  Shout out to you too PZ.

Doug


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## cut2cut

pburgh said:


> Hey Jake,
> I still have my quill setup. I'll measure it for you when I get home tonight. Good to hear from you. Haven't talked to you guys for a while. Shout out to you too PZ.
> 
> Doug



Hi Doug,

Phazertwo has it drawn up I guess so he will likely give me the needed dimensions tonight. I’ll post it here for reference after I get it.
Hope all is good on your end. Any mods to the rig ?

Cheers,

Jake 


Sent from my iPhone using Tapatalk


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## pburgh

Hey Jake,
Not much going on here for now.  I've switched back to my plasma table to get it working again.  I left it sit too long and now it's a pain getting going again.  I took a measurement for the diameter of the quill and got between 74 and 75 mm.  Hope this helps.  Hopefully PZ will have a closer measurement.  I went to use my digital caliper and the battery is dead, so i had to take a manual.  I've got to jump back into things.  Good to hear from you.
Take care,
Regards,
Doug


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## phazertwo

Good to hear from you guys!  These spindles really look cool, I'd be VERY interested in seeing someone get one installed.  I'm getting pretty tired of this R8 spindle with TTS holders.

When I modeled the head of the 940, I measured the spindle at 75mm.  So that' a little shy for this spindle, though I would imagine it could be bored out.  It's a deep hole, so it might not be easy to find a shop to do it... maybe an engine shop?  Or, build a new head, which could be a lot of work.  In one of that guys earlier videos, he showed the un-packing and it looked like it came with a spindle clamp.  Could be a really fun project.

If I were going to go about this, I think I would look at one with a BT30 taper.  The ISO tapers don't have drive lugs that the BT tapers do, which I think will be important for our mills (I cut a lot of steel).  It's pretty easy to find BT30 tools balanced to 20krpm, so maybe have the max RPM set to 20k so you don't blow anything up.  Probably best to talk with them first and make sure that the BT30 spindle actually has the drive lugs... cause the picture doesn't look like it.

PZ


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## cut2cut

Thank you both.  Hmmm, so 75mm.... thats not what I was hoping for at all.   If only it was over 80mm !    Yeah,  building a new head might be a fun project too.  Maybe even take it all a step further and build a linear rail Z axis too that bolts to the existing "tower".  The imagination runs wild     Boring the existing hole out was my first thought too after seeing 75mm but not optimal... I wonder if there is enough material to do that and have a good clamping action.  There may be smaller spindles out there too.  I haven't really done any research.

I still like the idea of an all in one - motor and ATC / spindle, but it does not allow for gear ratio changes which would help for cutting things like steel, I imagine.   Good advice on the spindles PZ, thank you, I am not sure exactly what you mean by "drive lugs" but I'll be sure to look into that.  I assume its the square bits that interface to the spindle ?   Doug, glad to hear you are getting back into the fray with the Plasma table  !  Keep in touch guys.  I'll let you know if I start getting back into it.  That spindle sparked my interest, obviously ! 
Cheers,

Jake


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## pburgh

Hey Jake,
Here's an alternative that Tormach was using for a high speed spindle using a Kress.  



The only thing is that it doesn't have an ATC.  But if the weight won't be a factor, you might be able to adapt the one that Fox reviews in your post above to your current setup.  Funny, this is a true story.  I was looking at that exact spindle he reviews to add to my plazma table.  I was also looking at one from CNC Depot, the S30.  It's a very sweet looking unit, but it comes at a higher cost.  Too many toys to choose from!

Regards,
Doug


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