# Another PM940-CNC-VS Thread...



## phazertwo (Mar 29, 2018)

If your only interested in pics/tech/the good stuff… skip this next paragraph, trust me, I’d do the same thing.  Also you will find a thread index at the end of this post, it should be useful for navigating to what you want to see and skipping all the BS 

I’m FINALLY getting around to making a upgrade thread on my PM-940-CNC-VS, but first a little background.  I have been interesting in fabricating ever since I realized a drill bit could cut metal, not just wood.  Just out of high school I got a job as an apprentice machinist working for a crazy SOB, but I got plenty of hands on experience learning the ins and outs of, as some would call it, a “clapped out old Bridgeport milling machine” and some junky Chinese lathe.  Later I was working for a different company where we had access to a small prototype machine shop, with a much nicer Bridgeport and a much nicer Cincinnati lathe.  My interest in manual machining peaked during this time, after I made a few parts for my Toyota Pickup, which was modified for rock crawling.  While working this job I was introduced to CNC machining via a vendor I became friends with…  Fast forward years, and years, and actually over a decade later and 3 more jobs where I was always on the edge of learning CNC and I finally decided to take the plunge and buy a 3 axis bench top unit.

I had been thinking hard about buying a CNC, and of course dreamed of owning my own Tormach 1100, but not only am I not rich, I tend to be pretty cheap.  So when I stumbled across the PM-940-CNC-VS (from here on out will call it the PM-940) I suddenly felt like I could actually own my own machine… That was in Januaryish of 2017 and the mill was in my garage setup and running by February…

Loaded on the trailer.





Wanted to put it in the truck as it would have been a smoother ride, but no way to get it out of something that high at home.

Didn't take any pics of unloading it.  I had 3 buddies waiting for me when I got home and we made it happen in about 30min.  It's current home:





Inside the cabinet:






I got a clamp set and a vise with the mill (forgot to take pics), turns out that the vice I ordered was out of stock, so they upgraded me for free  BOO YA!

I do have to say, Precision Mathews has been an absolutely awesome vendor to work with.  Questions answered extremely fast, all my pesky little OCD questions answered (like 20 emails worth)!  I HIGHLY SUGGEST them.  Keep in mind that I have had this mill for over a year before I even considered starting this thread and I still say that.  The mill was completely functional out of the box, all upgrades that I’ve made or are making are because I’m serious tinkerer and I have a passion for precision/accuracy.

Anway, this thread will follow my adventures of upgrading this machine to hopefully be a bad-mamba-jamba that can keep up with a Tormach 1100, but for less money and with me learning a great deal more about CNC!

Here are two similar (like SUPER similar) threads that I follow, and that have inspired me:

cut2cut:
https://www.hobby-machinist.com/threads/my-pm-940-cnc-modifications.57976/

pburgh:
https://www.hobby-machinist.com/thr...ontroller-conversion-to-centroid-acorn.65196/

More to come!
PZ

Thread Index:


First Chips - PG 1
Ditching the nMotion
Acorn Upgrade
NC vs NO E-stop
First chips with Acorn
First metal chips
Removing Z manual crank and gears
Mist coolant
Aluminum fixture plate
First steel part


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## phazertwo (Mar 29, 2018)

Right out of the box I was impressed with the quality of the machine.  Everything was smooth, and short of some flaking paint was in good order.  I promptly loaded Mach 3 on a computer and started setting up the machine.  At the time I was eyeballs deep in a engine swap for my Toyota and desperately needed some custom fuel line clamps, so I designed them based on a piece of UHMW I had laying around and started programming.  This was the first real part that I ran, and I ran 5 at a time, with profiling since I didn’t have the correct size ball end mill.  I was ecstatic.  I worked under the truck the whole time the machine was running and just listened for it to stop, at which point I would change tools and set it back in motion.







One of the finished parts:





At this point I was all smiles!

PZ


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## phazertwo (Mar 29, 2018)

The honey moon didn't last long though.  I had some issues that probably could have been resolved, like getting the limits to work right (which could have actually been loose wiring), the machine being very "jerky" and last but most importantly, I couldn't get the e-stop to be an e-stop.  I would hit the e-stop and good two seconds would co buy before the machine would actually start to decelerate.  After messing up a corner of my pretty vice and trashing two test parts and some mills when the machine didn't stop on time, I had had it.  The nMotion and M3 were just not cutting it.  So I started doing research on better controllers, you can read about some of the options and the decision I ended up making here, on page 2-3 of cut2cut's thread:
https://www.hobby-machinist.com/threads/my-pm-940-cnc-modifications.57976/

The Centroid Acorn was at introductory pricing at the very end of 2017, so I ponied up and made it happen!

While I was waiting on it to ship... This happened:





Never again would a lack of e-stop destroy a part, tool, or vice.

PZ


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## phazertwo (Mar 31, 2018)

ACORN!

When I went to install the acorn, I realized that the back plane in the cabinet was setup for 3 or 4 drives, which makes sense because PM offers a 4th axis.  So first things first was to move all the drives over to make some extra room.
Before moving the drives:





After moving the drives and with the Acorn in it's final resting place:





I used a simple piece of 1x2x11ga rectangular tubing and the original mount for the nMotion to mount the Acorn.  It’s not the prettiest thing I have ever made, but it works quite nice.

The Acorn does not rob 5v from the computer, so a 5v power supply is needed.  I used this cheapo mean well from amazon, seems to do the trick just fine.  It mounted quite nicely behind the Acorn.  I should have enough from for a 4th axis drive if I ever get one.






One thing I did that was against the recommendation of Centroid, but has caused no issues so far, is a shielded bulkhead connector for the ethernet cable.  I would have liked to send it out the bottom, to keep crap from falling in it, but I didn’t have enough cable to pull it off, so its sticking out the top.





The specs for the computer to run the Centroid software is well above M3, so a new computer was in order.  I was able to order components to upgrade mine for about $350.  Hind sight being 20/20, I converted my dads router to Acorn as well and was able to buy a computer for $100 that worked perfect.  Anyway, I shoved the computer back in the same cabinet near the mill.





Here is a list of the parts I used:

Meanwell 5v power supply

Shielded ethernet bulkhead connector

Shielded ethernet cable

PZ


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## phazertwo (Apr 5, 2018)

Wiring the Acorn is a pretty simple thing.  I think I re-used all the wiring from the nMotion, however you do need to add the 5v power supply.  Acorn provides great schematics specifically tailored to different drives, so I just picked the Leadshine schematic and went for it.  I didn’t make any changes to the VFD wiring or settings, just simply tied it into the analog output terminal of the Acorn and it worked flawlessly.


With the nMotion I could never really get my limits to work, and they needed to be switched form NO to NC.  So I tore into that next, and it turns out that there were a few broken wires, and most of the terminals were loose.  So I went through the entire machine and found that a fair number of the wires were loose.  I would suggest to anyone who has a 940 CNC to check all your terminal connections to make sure they’re gooten-tight.  After that the limits started behaving correctly.

This is how the limits need to be wires for Acorn:





Last thing  had to do was change the settings in the Acorn to work with the normally open (NO) e-stop.  An NO e-stop is quite dangerous, so I ordered up a new e-stop from the goold ol’ amazon and swapped it out two days later.  All the wiring in the PM was quite nice, the loose connections could easily be from transport from China.  The ONLY thing that I really didn’t like was the NO e-stop.  I’ve been witness to a pretty bad industrial accident, and several smaller ones… don’t mess with e-stops and safeties.  They are normally closed (NC) for a good reason.


After all the wiring was complete the Acorn fired right to life and connected to CNC12 no problem.  I was up and running!

Parts used:
New E-stop

PZ


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## phazertwo (Apr 5, 2018)

And I apologize, I didn't realize there was a time limit on editing posts... so the thread index in post one is dead.  Unless there is a super nice/awesome/cool Mod out there that can either bestow upon me the access to keep editing, or just toss some links in there to keep up!

PZ


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## phazertwo (Apr 7, 2018)

The Acorn was very easy to setup and tune.  It still took me a night of dinking with it, but after setting up and tuning M3 it was no big deal.  I wouldn't say it easier or harder, just different.

After all the tuning was done it was time to make some chips.  I found myself at a loss of what to build, so I just made a gizmo in Fusion and had at it.  I had some blocks of UHMW laying around, which I hate machining, but I figured what the hell, good for a test.  I used all brand new HSS tools, so it worked out okay, but not perfect.






I ran most of it with a 4 flute 0.5" end mill at 3200 RPM and about 0.004 IPT with a 0.35" step over.  It was a little nerve racking to watch this setup that I had done nothing but basic tests on run at 51IPM just chewing thru material....  Worked perfect, no hick-ups.

So I made a mating part, they fit super tight...















With just this one run under my belt, my confidenice was already higher than it ever was with the nMotion and M3!

PZ


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## phazertwo (Apr 7, 2018)

After the plastic went so well, I setup to make and aluminum test part.  I was worried about speeds and feeds for this, so I kept it simple.  Just grabbed a scarp block of aluminum, faced it and put a slot in it.






Worked out perfect, and I was pretty happy with the surface finish of the walls of the slot.  Next I flipped the block over and made something more complicated.  Something that had some different features I could measure, and push my S&F's a little bit further.






Everything seemed to come out with in 0.002" or so, I'm thinking I measured the end mill wrong.  It was the first time I programmed the fly cutter and it did great.... Except I didn't deck the scrap far enough, you can still see a little bit of the slot that was running through the center of it.  This was also the first time I used the chamfer tool to deburr the part, if you haven't tried this I strongly suggest it, I do it on every part now.  All and all for a test part I was very pleased.

PZ


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## phazertwo (Apr 15, 2018)

From the factory PM states that the 940 is capable of 100 ipm in the x and y, and 75 ipm in the z.  However I was never able to get the z to 75ipm.  Sure it would run 75 ipm, but it would miss steps regularly.... and it ALWAYS misses them moving in the positive direction, which means your tool always ends up lower than it should be.  NO GOOD.  So one day, I was cranking the manual z crank and was thinking "damn this is tough, no wonder the motor misses steps" then I realized that the motor is turning this 90° gear and it really doesn't need too...  So I tore into it, and I removed all the guts for the z manual (sorry I didn't take any pics of this).  Then I built an actual real FUNCTIONAL part to block off the opening.

I had an awkward shaped piece of 0.5" black anodized aluminum that had a spot in the middle of it just perfect for the cover plate.  I drilled the three holes with the closes drill bit I could find to the actual OD of the bolts, and punched the pattern in the plate, including the counter sinks.  Then I was able to cut the rough shape on the band saw and bolt it to a fixture plate.  Quick program to clean out the outside and it was done.






Surface finish was pretty good, though no picture ever really shows it right.  Defiantly getting better at this!





After I pulled it off the fixture plate I used the pistol drill to drill the holes out to the proper clearance size and everything fit perfect.  Installed in it's new home:





All and all I highly suggest this mod.  It made the whole z move smoother, and MUCH quieter.  Not to mention I can run 75 ipm now, without worrying about it.  The only down side is that you CANNOT move the z unless you power up the machine.  I make sure I always leave it in a good spot when I power down, and a few times I have had to power it up just to move the z up or down while working on the mill.  Not really a big deal to me.

PZ


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## phazertwo (Apr 15, 2018)

So, as it turns out, as a hobby machinist I'm on a budget.  I consistently scour Amazon for tooling, and have some favorite tools I found there... here they are:

My number one go to tool for roughing... I beat the crap out of this thing, and it just keeps begging for more.  I CANNOT believe I'm still using my first one, even though I have had to use a punch to remove aluminum from the flutes at least three times.
https://www.amazon.com/gp/product/B01AOE7DBU/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Same thing in 0.5" and I haven't actually taken it out of its package yet... the 3/8" just works so good.
https://www.amazon.com/gp/product/B00VGR6EVK/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

For finishing I've been using this carbide set, mostly the 6mm, but the 8mm works great too.  For the price, this kit is unbeatable.  They are 4 flute, I know a 3 flute would be better for aluminum, but they are cheap and work good, so screw it.
https://www.amazon.com/gp/product/B01M0W9XON/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Last is this ball endmill set.  I haven't done much profiling, but what I have done worked great with these:
https://www.amazon.com/gp/product/B0117A6R5S/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

You might notice that all of these tools are 4 flute, which I like because I can move faster with the same IPT, however they tend to gum up with aluminum and I have to hit them with WD-40 a lot, or just take very fine cuts.  I decided to start looking into mist coolant.

This is the the story of that.

First off, I ordered a solenoid from Amazon.  The Acorn’s output wasn’t rated for enough go juice to run it so a new relay needed to be installed.  I had some very small relays left over from some industrial gear I de-commissioned, so I removed the fwd and rev relays that were much larger than they needed to be and replaced the with these tiny guys.
Before:





And with the new, smaller relays:





Next I got a simple mist coolant nozzle from Amazon… it’s cheap.  We’ll see.  I removed the factory bracket for flood coolant and built a nifty replacement out of the same 0.5” black anodized aluminum as the z cover plate.  Again, it turned out awesome, and mounted right up.

The bracket:





Mounted in place:





And with the nozzle base attached:





After the nozzle was mounted, it was time to mount electronics and pneumatics.  I decided that I want a regulator on this setup, so I used an old filter/regulator setup and just mounted it to the side of the machine.  I also bolted the solenoid and a manifold to the machine.  The manifold gives me some ports to grow into for some other cool things…






I had some water bottle sized/shaped tanks that were used to collect waste ink, and they even come with a mount!  I pulled them out of the scrap pile when the company went under and have been holding onto them for 10 yrs… glad I didn’t pitch them.  A simple 0.5” spacer and some 1/8NPT holes to allow air in/out and it was good to go.






The idea here is that I can control air pressure from the regulator, and coolant with the ball valve that lets air back into the coolant tank… I was worried that it would siphon coolant when the head is lower than the tank (it did), and that the ball valve would not be able to control the flow of make up air coming into the tank (it couldn't).  I figured I needed to start somewhere, so I let if fly just to see what happens.

Ran the lines along with the z home switch wires, the ¼” pex tubing helped stiffen up the whole bundle which helps keep it from getting snagged on stuff… just an added bonous.


Then it was time for a test part...

Parts used:
Solenoid
Nozzle and base
Coolant

PZ


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## phazertwo (Apr 15, 2018)

I had two big steel parts that a friend had given me over a year ago to fix, and I was feeling bad about still having them and having done nothing to fix 'em!  So I decided that this would be a good test for the coolant, because I would need to build an aluminum fixture that would need a fair bit of material removed. 

I programmed it a little more aggressively than any cut I had run so far.  I used my favorite roughing end mill, and I knew for a fact that the flutes would gum up far before this with out constant WD-40 spritzing... Game on!

Tool path:






And the details:





That's 0.003 ipt, at 38.4 ipm, with all the RPMs the 940 can muster.  0.1125 step over (30% of cutter Ø) and I'm leaving 0.020" to clean up with a 6mm carbide, but I'm bringing it right down to the deck.  Fixtures don't need to be pretty.

Finished fixture:





I like to pretend I'm a tough guy, but let me tell you... I giggled like a 3rd grade school girl at a sleep over... for the ENTIRE TIME it was cutting.  Watching the mill chew up that material with out me needing to do ANYTHING but watch, freakin' amazing.  Mist coolant is THE BOMB!

However... the setup needs work to be perfect.  When the head is down it siphons pretty bad, and the ball valve on the tank cannot meter the coolant at all.  I was putting out way too much coolant with the thing barely cracked.  On the next few parts I manually opened and closed the valve to conserve coolant.

Fixture worked perfect.  Look close at the closest hole, it's an oval, that's one of the things I needed to correct.  One of the parts that needs fixed:










Here is the other plate... the water jet that cut the part crapped out before finishing:





After machining:










Again I pushed the mill pretty hard one this one.  0.002 ipt 0.075" WOC, 0.500" DOC.  Everything seems to work really well... until the tool started pulling out.  Backed it off to 0.250" DOC and it cut just fine, next time I will likely bump the WOC.

That pretty much brings us up to date, which means things will slow down a little bit, and I will include far more of my research planning, and questions.

My next step will be spindle upgrades...

PZ


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## phazertwo (Apr 16, 2018)

After months of going back and forth and back and forth... I finally decided on AC bearings for the spindle.  I was looking at P5 tapered roller bearings, but wasn't real excited about the limiting RPM and that P5 is about the highest grade you can ever get...

I ended up going with some NSK AC bearings:
7206CTRSUMP3 - NSK Precision Angular Contact - 30x62x16mm
7207CTRSUMP3 - NSK Precision Angular Contact - 35x72x17mm

It was about $240 for the two.  These should be very high precision bearings, and are rated to 18k RPMs greased.  I don't intend to get anywhere near that kinda of speed, but it will at least allow me to hit my goal spindle speed range of 100 - 7500 RPM with two speeds.

I have not yet figured out exactly what I'm going to do for "gears" besides that I want to use J profile ribbed belt/pulleys.  I would REALLY like to come up with a nifty way to change pulleys automatically, so if you've seen anything cool feel free to drop a line or a link here so I can take a look.  To start I am just going to make a sliding motor plate and run just the high set of pulleys, as I will need to get the mill back up and running to make what ever parts I will need for an automatic gear changer... thingy...

PZ


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## WyoGreen (Apr 17, 2018)

My wood lathe uses varible pitch pulleys (with a V belt) to vary the speed with the twist of a lever. My wifes hybrid uses the same setup for it's transmission, using a metal belt. The same setup is used in Snowmobiles, again with a heavy rubber V belt. So the setup can take considerable torque.

It might be something to check into, Steve


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## phazertwo (Apr 17, 2018)

I'm actually well versed in the world of snowmobile clutches, and the idea of a change on the fly infinitely variable setup sounds awesome.  Due to the nature of my controller, I would have to know the gear ratio that it's operating at, and have a way to change it to pre-set "gears" if that makes any sense.  I know the CVT's used in cars these days are computer controlled, unlike a snowmobile/4wheeler that uses springs and weights to actuate the clutch as it spins up.  If I could figure out how to control one like a car does... that It would be the ticket...  Honestly though, it sounds like a whole bunch of parts and complexity.

Good idea though!  Keep em coming!

PZ


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## phazertwo (Apr 20, 2018)

The head of the mill is torn down, and cleaned.  The oil that came out of the head looked/smelled/felt just like the stuff in the automatic oiler.  It was full of grime and crap, after I got the top popped off I found that the gear case was full of gunck including metal shavings and other small particles.  It could be sand from the casting process, but I doubt it because the rest of the casting is free of sand.  Anyway, the top bearing on the spindle was in really rough shape for a bearing that has >20hrs on it (almost all of those hrs at max speed).  Here are some pics.
Here you can see the rings of "stuff" on the edges of the oil:





Under the cap:





A look at the "stuff" left over in the bottom:










Another look at the "stuff" and the weird grease that was in the bearings, and here you can see that the rollers actually don't have much grease packed around them... turns out when I got them out the bearings didn't have any grease "packed" into them:






And the bottom bearing, again you can see not much grease "packed" in the rollers:





Upper race, you can see serious scaring near the middle of it... If I had to guess I would say the pre-load was too loose:





And the upper bearing itself, scared to match the race:





Lower race and bearing looked perfect, so I didn't take any pics.  Also didn't take any pics of it clean, but you should be able to see it in the re-assembly pics.

All and all, the fit and finish on all of the machined parts in the head were quite nice.  The spindle and quill fit together nicely and the press fit on the bearings and races were good.  A little more cleaning before oil, some better bearing packing, a touch more pre-load on the bearings and it would be about perfect...  I still think that bang for buck you couldn't beat this mill with a club, considering that all of the heavy metal (un-replaceable parts) seems to be good quality.

I've also started getting the head in Fusion... it's a bear of a job trying to get everything dimensioned properly, but it's coming along nice.

PZ


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## phazertwo (Apr 20, 2018)

Brown Santa left me a nice little gift this afternoon.





I never would have guessed that I would think bearings are sexy... I was wrong.  These are marked to show the max run out with an o, and the outer race has a V that tells you which way to install it, and where the max run out is.  SUPER cool, though I'm not sure it's going to help me because I don't know where the max run out is on the spindle and quill.  Also the -2 indicates the deviation in bore size in microns... that 0.002mm... or 0.000079" freaking cool!





Getting excited to put this thing back together.

PZ


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## navav2002 (Apr 21, 2018)

I am replacing the bearings in my PM932m mill. I'm interested in what grease you are intending to use on the roller bearings??


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## TomS (Apr 21, 2018)

navav2002 said:


> I am replacing the bearings in my PM932m mill. I'm interested in what grease you are intending to use on the roller bearings??



When I converted my PM-932 to AC bearings I used Kluber Isoflex NBU 15.  Not cheap but highly rated.  My mill has 8800 rpm capability and I've run at that speed for more than an hour on numerous occasions with no problems.


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## phazertwo (Apr 21, 2018)

navav2002 said:


> I am replacing the bearings in my PM932m mill. I'm interested in what grease you are intending to use on the roller bearings??



Like Tom did, I'm going to use Kluber Isoflex NBU 15.  It certainly is expensive, however the precision AC bearings were a lot more so it's not worth it to cut corners IMO.  I was able to by a small amount of it from The CNC Specialty Store so it wasn't too bad.

https://cnc-specialty-store.com/gre...m-tube?zenid=c288e5e92d51aa4139e3195aff46151a

PZ


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## phazertwo (Apr 22, 2018)

Well I chickened out big time today.  I was going to install my new bearings, but realized a few things that held me up.  First was that the upper bearing will just be open to the world, anything can fall down in to it.





Even if I put the seals back in, the seals are a Ø35mm ID and the spindle is only a Ø28mm, not only that, there will still be an opening at the splines that will allow crud through.

Second, I was looking through all the gizmos I keep around the press for tooling, and I have nothing that will work well to pushing these things in.  I'm sure I can get them in there, but I don't want to push on these beautiful bearings anything but the right way...

Unfortunately I need the mill to make the proper press tooling and a new seal adapter to plug the opening on the top... Kind of a catch 22.  So I ordered a set of VXB ABEC-5 AC bearings to run in the mean time.  They were about $90 for the set instead of $240, so I figure these can be a practice run, and buy me some time to get other parts made...

Today wasn't a total loss though!  When I first started this, I ran the motor while it was chucked in the vice to figure out how many poles the motor has.  It didn't sound so good, and was actually vibrating, so I ordered new bearings for it at the same time I ordered the spindle bearings.  I DID have all the press tolling I needed to get that done (pretty easy).  Now she sings, and is smooth all the way up to 150hz.  And in case anyone was wondering, it's a 4 pole motor (1800RPM at 60Hz).  before I put the motor back together, I took the time to tap the holes on the cap that hold the fan assembly to 10-32.





I had tightened these screws so many times trying to keep the thing from rattling that they were all stripped out.  With the larger threads, and some blue Loctite I don't think I will have to listen to it rattle ever again... but only time will tell.

PZ


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## phazertwo (May 3, 2018)

Well... I've been busying doing everything BUT working on the mill.  We had a knarly wind storm two weeks ago and it put the finishing touches on my crappy fence. 2 days 9 posts, 30 stringers, 240 pickets, 1600lbs of concrete, one earth auger, and two DAMN good friends later, I have a fence again.









It's much improved, not only because it's not falling over anymore, but it also has a gate.  That means I can put MORE **** in the backyard!


I also had to do a fire drill re-gear of the front and rear differential of one of those buddies Land Cruiser...

While all that was going on some parts did come in.  The new VXB bearings (I just noticed that for some reason the pictures of the NSK super precision bearings are gone..) and they are going to work perfect for a "test" run.  The quality is surprising, however they are no match for the NSK bearings.
Left is the upper NSK, right is the upper VXB:





Also, the pulleys for the "test" belt drive showed up:





They are sitting on some 0.5" aluminum plate that I will use to build a "test" motor mount, and the rod to the side is to make a new quill lock.  My plan is to get the mill up and running again with minimal machining, since I will have to borrow a friends manual machine to make parts while it's out of action.  Once it's back in action, I will re make a lot of these parts, and add a power draw bar, and a two speed system.  I will also make special press tooling to allow me to push the NSK bearings in with out messing them up.

Unfortunately progress will likely be slow for a while.  We're coming up on our annual trip to Moab UT, and I have to get the truck ready to go.  Hopefully I can get some time here and there to work on it, but most likely nothing significant until June...

PZ


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## TomS (May 4, 2018)

Do you ever slow down?  I'm getting tired just reading through your post!  LOL.

I had the same issue with the upper bearing on my PM-932.  After thinking a while the light went on and I realized that the spindle drive pulley acts like a slinger and prevents most anything from getting past the splines during operation.  This proved to be true because about six months after I did my conversion I opened up the gear head and the interior was as clean as when I assembled it.  

I don't remember reading what your upper RPM goal is but seals have a RPM limitation.  My upper limit is 8800 rpm.  I didn't find any seals that would live at that speed.

Hope this is useful information.


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## phazertwo (May 4, 2018)

I try to keep busy...

It is very useful information!  I did consider that the pulley would be protection, but my spindle pulley is so small (67mm) that I figured it would still be a problem.  What size is your spindle pulley?

Here is the seal I plan to use, should be good over 10k rpm:
https://www.mcmaster.com/#5154t122/=1cp1m10

My goal is 7500rpm on the top end, and I should be able to hit that at 120hz.  Theoretical top speed should be 9000rpm at 150hz, but there is no torque up there.

PZ


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## TomS (May 4, 2018)

phazertwo said:


> I try to keep busy...
> 
> It is very useful information!  I did consider that the pulley would be protection, but my spindle pulley is so small (67mm) that I figured it would still be a problem.  What size is your spindle pulley?
> 
> ...



My setup uses a two step pulley.  The large pulley is 5"diameter.

16,300 rpm, Wow!  When I was looking for a seal the highest rpm rating I could find was about 5,000 rpm.  Thought about using a labyrinth style seal but the price was a bit much.

Lack of torque at the upper rpm range hasn't been a problem for me.  Usually I'm running end mills 3/16" and smaller in aluminum so no need for much torque.

Good luck with your retrofit project.  Your thread has been a good read.


----------



## COMachinist (Jun 3, 2018)

Hi PZ 
Could post the numbers and the place where you bought the NGK bearings I want put ne bearings in and up grade to  2hp 3ph moto for better control on my rpm. I like to run a faster on the aluminum parts I make.
Thanks 
CH


----------



## phazertwo (Jun 4, 2018)

I ordered them for qualitybearingonline.com.  7206CTRSUMP3-NSK, and 7207CTRSUMP3-NSK.  They are out of the UK, so I had to pay in lbs, but paypal handled the conversion for cheap.

I decided to go with them even thought there is probably someone closer that deals in good ol' $$$, but they were quite helpful while trying to find precision tapper roller bearings.

PZ


----------



## phazertwo (Jun 5, 2018)

Well I got back from Moab Saturday afternoon and was back working on the mill last night!

First I got the VXB bearings out of there packaging and cleaned up.  They are nicer than I first thought, which is fantastic.





Then it was time to load them up with the ISOFLEX.  I'm pretty particular about the way that I pack bearings.  I pack them from one side until the grease comes out the other side.  Then I just smear it all over.











The 50g tube is just the right amount for the two bearings.

Then came the hard part.  How to press them in with out pushing on them wrong.  I found some press adapters from another project that worked just right.  It's like $15 bucks on the Amazon.






The larger of the adapters worked great for the big bearing and the smaller for the smaller bearing.






Then I ground down the old cone race so it slipped in and out of the quill.  






Coupled with my Harbor Freight 3/4" press adapter... I mean 3/4" drive socket set, it worked like a champ.






Don't forget to put the set screw /  collet key in before you put it all together... It's a pain in the ass to do afterwords, ask me how I know...






For the smaller bearing I had to rely on the angular contact.  I had to push on the inner race even though it was pressing against both races.  Seemed to go just fine.











After that I set it up so I could tighten the spindle nut.  It also allowed me to spin the whole setup, and man is it just SMOOTH!






None of the fingers on the spindle nut keeper were even close to lined up... of course.  So I found this on the ol' Amazon, think it should keep the spindle nut tight.

https://www.amazon.com/gp/product/B00UHE3DHG/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Feels real good to have some progress after working on other stuff for the last few weeks.  Next step is to try to get some mill time on my friends mill so I can make the motor plate.  That's the last piece I need before I can get it choochin' again.

PZ


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## phazertwo (Jul 5, 2018)

Well a month later and I finally have a very small update.

I ended up at my parents house for Independence Day, and was looking at my dads home brew CNC router and thought, why don't I make a temporary motor mount plate out of wood... Maybe it will work, maybe not, but hey it's what is holding me up at the moment and it' something to do.










My plan it to use this to make an identical motor plate out of 0.5" aluminum.  I'm hoping it will last long enough to get it done... or maybe the motor will fall off... I guess we'll find out.

PZ


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## phazertwo (Aug 1, 2018)

Got an incredibly small amount done yesterday.  I mounted the motor to the wooden motor mount, and got it all attached to the mill.  I will defiantly need to trim the casting, which I knew I was going to need to do.  Unfourtunatly I ordered the largest pulley that I could fit in the head, which was 140mm...  With the belt on it only gives me ~2mm/side of clearance.  I am going to have to step that down to a 132mm pulley to feel comfortable running it...
















I'm very glad that I made the first motor mount out of wood.  We'll call this one REV p1, the aluminum REV A will rotate the motor a bit to help get the electrical connections in a better spot, along with have some large holes to help get the belt on the back side of the pulley.

In case anyone was wondering why my progress has been slowed to a crawling pace... we are expecting our first kid at the end of October and I have been spending most of my time with house stuff getting ready for a half pint.  That along with some crazy weather (wind/hail) that has caused damage to our house/vehicles I've been very tied up.  *HOPEFULLY *I can get the mill back together and making parts before half pint shows up and my time in the shop takes a digger!

PZ


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## phazertwo (Oct 27, 2018)

*OH MAN!*

Guess who showed up early!





Born 10/21/18 at 1:10am.  Mom and baby both did great, and everyone is now home trying to figure out how this all works!

In preparation for the little man showing up, I cut down a big cottonwood tree that was dying in my front yard.  We had to rig most of it out so we didn't hit the house, it was a ton of fun.




















Those are just a few pictures of the 6hr time lapse we took... maybe some day I'll turn it into a vid.

Then I had to build a shed, which was much less fun, but it's done none the less.  The shed is a big deal because it will allow more space in the garage, which hopefully will make it easier to work out there when I do actually get some time!!






In the mean time, I've been working in Fusion trying to get the new belt drive system finalized... Hoping to have that done soon so I can order parts and get the mill running again.  We'll see how it goes.

PZ


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## Rickwjenn (Oct 28, 2018)

Congrats!  Nice update and pix!   You should be very proud and you are a fine american taking such good care of your family and property.   That tree is one amazing job.  Bet you notice "big sky" for the next few weeks!

The shed looks great.  What all is going in it?

Fusion360 is great and I am just scratching surface of learning it.


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## phazertwo (Oct 30, 2018)

Rickwjenn said:


> Congrats!  Nice update and pix!   You should be very proud and you are a fine american taking such good care of your family and property.   That tree is one amazing job.  Bet you notice "big sky" for the next few weeks!
> 
> The shed looks great.  What all is going in it?
> 
> Fusion360 is great and I am just scratching surface of learning it.



Wow, thanks!

Well I had a shed that I tore down the same day we removed the tree.  It was junk, the floor was collapsing and there was only a small man door to get into it.  This one is double the size, and has the double door at the front (I increased the door height from what the plans called for).  This one fits our small side x side (pioneer 500) all our camping gear, all the outdoor power equipment and some other odds and ends, and its all locked up!

PZ


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## phazertwo (Nov 5, 2018)

Slight update... I had some friends come over Friday night to help me move some heavy stuff around in the garage.  Not sure if I ever mentioned that I have a bulldozer project in my garage, but I do... and all of the parts that come off of it are too heavy for me to move by myself, which is why I needed all the friends.  We got done moving dozer parts faster than I thought we would, so we took some time to get the mill on it's new feet!

These are just the feet you can buy from PM.  They are nicer than I expected, and the mill is now level and all 4 feet are firmly planted.  Before it was not level and I had some scrap metal wedged under one corner to keep it from "floating."  With out having any machine time on them, I highly recommend them.  I couldn't find anything I liked for nearly the cost of these, so they seem to be a great value.  They have a fair bit of rubber on them, so I think they will dampen quite well... I'll try to remember to post more comments when I run the machine again.






Parts used:
PM Leveling Pad

PZ


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## bretthl (Nov 6, 2018)

Anyone know why PM stopped selling the CNC version of the 940?


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## phazertwo (Nov 6, 2018)

bretthl said:


> Anyone know why PM stopped selling the CNC version of the 940?



I didn't know that they had?  It was never advertised on their site, you had to call.  Don't be afraid to give them a call or drop them an email, SUPER nice people, ready and willing to help!

PZ


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## smartin733 (Nov 12, 2018)

I decided to go with them even thought there is probably someone closer that deals in good ol' $$$, but they were quite helpful while trying to find precision tapper roller bearings.

PZ[/QUOTE]

Just curious about the precision tapered roller bearings...  How much were those going to cost compared to the angular contact bearings?  I've been thinking about purchasing the PM-940 or the 833T and doing a cnc upgrade.  I can't seem to find much (at least easily) about precision tapered roller bearings.

Thanks,
Shane


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## TomS (Nov 12, 2018)

smartin733 said:


> I decided to go with them even thought there is probably someone closer that deals in good ol' $$$, but they were quite helpful while trying to find precision tapper roller bearings.
> 
> PZ



Just curious about the precision tapered roller bearings...  How much were those going to cost compared to the angular contact bearings?  I've been thinking about purchasing the PM-940 or the 833T and doing a cnc upgrade.  I can't seem to find much (at least easily) about precision tapered roller bearings.

Thanks,
Shane[/QUOTE]

Here's some tapered roller bearing info to get you started.  https://www.timken.com/pdf/5722_Precision Tapered Roller Bearings.pdf


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## phazertwo (Nov 12, 2018)

smartin733 said:


> Just curious about the precision tapered roller bearings...  How much were those going to cost compared to the angular contact bearings?  I've been thinking about purchasing the PM-940 or the 833T and doing a cnc upgrade.  I can't seem to find much (at least easily) about precision tapered roller bearings.
> 
> Thanks,
> Shane



The link provided by TomS has some great information, and is pretty much where I started when researching taper roller bearings.  Timken has some great information on them, and I was even able to find the part numbers that I needed... however NO ONE can get them.  Which is really unfortunate because a precision taper roller bearing would be better than AC bearings just because they have a much higher load capacity...

Anyway, I'm pretty good at the ol' internetz, and I used some of my contacts from my industrial maintenance days to find some.  The only thing I could come up with are off brand C3 precision (just "3" in the table in that link TomS provided), in my opinion, you need "0" precision or better.  The factory spindle bearings are taper roller bearings rated at C3, but you have to take that with a big shot of Chinese salt.  Mine were not packed with grease properly, and the bearings met an early end.  If you do get a 940 (I would check an 833-T as well) pull the spindle apart before you fire it up and pack those bearings properly.

If you happen to find some taper roller bearings "0" or "00" precision let us know.  Some of the places I went had them in their system, but a week after I ordered they canceled the order saying the couldn't actually get them.

PZ


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## phazertwo (Dec 20, 2018)

Alright, I'm tired of dealing with pics with broken links, especially here on Hobby Machinist since you cannot edit old posts...  So I'm giving a new hosting service a try (Flickr).

This week I received new pulleys for the belt drive.  Motor pulley will be 132mm and spindle will be a 90mm.  This gives me 1.466:1 ratio, so I should get about 5000 rpm out of the original motor, and 10250rpm with my new motor... but more to come on that later.

I ordered the pulleys from Ametric again, except that I ordered the wrong bushing for the spindle (ordered a 24mm bore instead of a 28mm) lucky for me Whistler Bearing had one in stock, so I took a long lunch and grabbed it yesterday.




Also had a friend with a lathe turn out a quick spacer so I can ensure proper preload on the spindle bearings.





Hoping that I get some time this weekend and next week to get everything assembled *correctly*, tram, and fire it up!  Then I can start some fun with the new motor!

PZ


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## phazertwo (Jan 8, 2019)

Well, I've got a fair bit of work done on the mill that last few weeks.  I have only been working in hour long chunks here and there, but it's something.  I got the whole thing assembled, trammed and and tested... I didn't take my normal number of pics because of time constraints... but I did get a shot of how ghetto this thing is.  The temporary motor mount didn't work out as well as expected, so I had to clamp it down.  It still has bolts on the back side of the motor, and I had to hit it pretty hard with a dead blow to make it move.



IMG_20181226_221207 by Phazer Two, on Flickr

It's UGLY and I'm not proud of it... but it works, and it's pretty dang quite (click for vid).



VID_20181227_184401 by Phazer Two, on Flickr

Anyway, I have to make one part to mount the new motor with a legit motor mount, and I think I've decided I'm going to do it with this wood pile of crap.  Even if the motor mount slips, I just loose tension on the belt which means I break a tool... Nothing catastrophic.  I took the time to tram the machine to the best of my measuring abilities.  To get it right I had to shim the head. Using the table to remove the head works fantastic, especially if you set your zero right before you unbolt the head!



IMG_20190101_133439 by Phazer Two, on Flickr

I've been watching Ebay close for deals on upgrade parts, I scored a few things, one of which is this massive air cylinder.  Its a 5" bore x 4" stroke two stage.  I think I'm going to disassemble it and try to get it down to 2" stroke so it's not so dang tall.  $120.  It's next to my new compressor for size reference.  The new compressor is a 150psi unit, compared to my current worn out 120psi comp... so I should be able to get well over 5k lbs out of this cylinder.



IMG_20190107_175651 by Phazer Two, on Flickr

I changed the stepper drives from 1600 steps/rev to 2000 steps/rev but have not had time to tune it.  I have a small list of things I need to do before building the motor mount:

Load the latest flavor of Centroid software
Tune for 2k steps/rev
Install mist coolant Rev B. (not necessary, but I would like to test it out.  More on this later)
Exciting stuff...
PZ


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## phazertwo (Jan 14, 2019)

I missed one thing that I needed to get done... I need some kind of containment.  Since we had the kiddo, we decided that my wife should park inside, so she doesn't have to walk out on our steep(ish) driveway when it snows.  Also, she doesn't have to scrap windows, which saves her some time in the AM and you need every second you can get trying to get this fat baby out the door.  Anyway, can't be shooting chips all over her car, and need to try to keep them from getting into the house.

So, I summoned my inner Martha Stewart and made it happen...



IMG_20190113_150342 by Phazer Two, on Flickr

I have been thinking about doing this for a while, but couldn't decided if it was going to be too hodge podge.  Turned out to be fantastic!  It contained chips so they are only on the floor below the mill, so no more mess all over the garage.  Another big plus is that it makes cleaning up much faster.  The curtain rings are snap on things that I can get on and off pretty quick, so I can move it all out of the way pretty fast if I need too.   When it's closed the two shower curtains meet right in the middle in front.  Super happy with it.  If you're looking for budget containment, I think this cost me $45-$50 all said and done.

I also got Centroid CNC12 updated, and tuned in for 2k steps/rev.  I was able to tune it pretty well, I think it's actually better than last time, however it makes me want to go to 4000 steps/rev.  I feel like that would make it even better/smoother.

After the curtain was up and the machine was tuned, it was time to make a simple test part.  I just grabbed some scrap I had laying around and modeled up some features to measure.



IMG_20190113_171937 by Phazer Two, on Flickr

Everything came out great.  I was taking it very easy because of the wood motor mount and all, so I ran it at about 50% speed to start.  However halfway though it was doing so well I bumped it back to 100% and it just sang.  Everything is really working well together, which feels really good.  Now I just need to get my dang mist coolant running more consistently.... that should be next!  Soon I will be cutting my new motor mount!

Parts used:

Shower curtain (2x)
Curtain rings (2x)
PZ


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## Firstgear (Jan 16, 2019)

Why is this unit or any other unit for CNC not offered anymore by PM?


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## phazertwo (Jan 17, 2019)

I don't think they ever offered any CNC units on their new site, and their old site didn't offer the 940CNC. You have to call or email them (I emailed).

If you have not contacted PM, I highly suggest you do.  Matt is fantastic to deal with, and responds very fast.  If I hadn't emailed him I would have ordered the wrong machine for sure.

PZ


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## Firstgear (Jan 17, 2019)

Sorry, duplicate post


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## fritts (Jan 27, 2019)

I actually just ordered and received one of the last two 940 CNC's they have.  Also got a good deal on it as well.  If you are still looking I would suggest calling them.  I think the problems with Mach3 and the nmotion card pushed the cnc version out.  Based on what he said it sounds like they may be looking at bringing it back later with a different control.


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## Firstgear (Feb 1, 2019)

makes sense...I sent an email inquiring.....


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## phazertwo (Feb 20, 2019)

Well, I got what feels like a fair bit done in the last two weeks...  In an effort to make things faster I didn't take many pics and just trucked though what I could.  Turns out the wooden motor mount was just fine, never once ran into a problem.  It cut the new motor mount with zero issues, and being able to run at 6k RPM is VERY NICE!

My friend made this tensioner shaft for me on his lathe.  He's an excellent hobby machinist and he turned it out in no time, and it's dead nuts.



IMG_20190213_192209 by Phazer Two, on Flickr

The motor plate took me two nights to run.  I used some slotting, which I normally try to avoid, and it didn't go very well. Slotting is defiantly on my list of things to work on.  I also had some serious chatter on with the Superfly, I think I need to pony up and get some of the Al specific inserts as the general use inserts seem to cause problems.  All and all it came out okay, even with all the stoopid mistakes I made.



IMG_20190213_192119 by Phazer Two, on Flickr

Yes, that is a massive air cylinder in the background... no idea what it could be for...

Here is what it looks like all assembled.



IMG_20190213_200210 by Phazer Two, on Flickr

And a quick vid of how the tensioner works (click to see vid).



VID_20190213_200523 by Phazer Two, on Flickr

Should make tensioning the belt a breeze.  Finally, it installed on the machine.



IMG_20190213_201543 by Phazer Two, on Flickr

I've been working on wiring ever since.  I got the servo drive mounted in the cabinet, and the cables run though cable glands out of the cabinet.  I stated mounting some cable chain, and that's where it sits.  Hoping to get the cable chain finished up this weekend, and start testing out this servo!

PZ


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## phazertwo (Feb 23, 2020)

Well it has been a long time since I updated this... but here we go!  Keep in mind that all of these updates happened in the last year, not yesterday... so I may be forgetting somethings.

The spindle servo has been on for a year... and the jury is still out.  Not sure if I like it.  I had problems stalling it using a 1/2" EM in steel.  I ended up running the EM way to fast (to much surface speed for HSS) to get the job done.  With the pulleys I have, it just doesn't have any low end grunt.  The larger issue is that it vibrates for some reason.  I have pulled the motor out and ran JUST the motor and tuned JUST the motor twice now, and it just vibrates above 5k RPM.  I also had my friend build a roller to go over the tensioner bearings to slow them down a bit, they were getting pretty hot.  At this rate, I really think one of the Marathon 1000:1 torque ratio motors is a better bet.

Next it was time to tear the mill apart and make sure everything was tight and had the proper bearings.  My X axis backlash was creeping up and I wanted to make sure everything was as it should be... Cut2Cut pulled his X axis apart and found regular deep groove ball bearings holding the ball screw in place and that is what I expected to find... I was in for a very pleasant surprise.




IMG_20200201_165641 by Phazer Two, on Flickr




IMG_20200201_165710 by Phazer Two, on Flickr

That's right, matched, serialized AC bearings.  Notice the serial number is the same except for the -1 and -2?  These even have the "V" on the OD to show which way they go, and the run out is marked (that's the -2 in the face).  Very nice bearings... never heard of the manufacture, but they seem very nice.  The only issues was that the bearing retainer bolts were loose, on all three axis.

The rest of the ball screw mount left a little to be desired...



IMG_20200201_165741 by Phazer Two, on Flickr

That is the surface that the head of the bolts that hold the mount to the table sit... not so good.  These screws were also quite loose.  A quick trip to a friends house and it was all fixed up.



IMG_20200222_192001 by Phazer Two, on Flickr

I also pulled the table and saddle off, the bolts that hold the ball nuts to the ball nut mounts were also lose.  I tightened the X and Y, Z will have to wait a bit.  In case anyone was wondering, or can read Chinese, these are the markings on the ball nut:



IMG_20200217_202334 by Phazer Two, on Flickr

Note that the ball screws don't look rolled, but does have a grease groove in the base of the ball track...  Again, didn't expect that kind of quality.

Re-assembly was not bad, except there was a lot of paint on mounting surfaces, so I did lots of scraping and stoning to get them clean again.  I was very careful when pressing the bearings back into the mounts, making sure the "V"s were aligned, and lining up the run out (not pictured).



IMG_20200222_213553 by Phazer Two, on Flickr

Next I got after the Y axis.  The mount didn't have the same issues with the bolt head surface as the X, but there was plenty of other bad news in the ball screw mount.



IMG_20200222_210426 by Phazer Two, on Flickr

You can see that they didn't get full clean up on the bearing bore for those beautiful bearings... shame.  Also, you can see that the bore is WAY off center, so much so that the bearing retainer is actually missing a screw, and was ground to clear.



IMG_20200222_213039 by Phazer Two, on Flickr

Not much to do besides put it together...
LOTS of scraping on the Y axis re-assembly...  The mount bolts to the nice clean machined surface... that was painted.  They also had to grind a bunch out of the column to get the mount in there.  Again not the best.



IMG_20200222_214142 by Phazer Two, on Flickr

I must have forgot to snap a picture of the mounting surface all cleaned up...

Up next, new motors for X, Y and Z.  I bought a 1700oz-in leadshine motor off ebay.  The motor is the same series as the motors that came with the machine, just bigger.  No need for new drives.  I will use this to replace the Z motor, and use the 1200oz-in off the Z  on the Y.  Cut2Cut was nice enough to sell me his old motors, so I will use his 1200oz-in on my X.

PZ


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## phazertwo (Mar 22, 2020)

What better time to work on the mill than when we are "social distancing"?

From the factory the axis motors are wired in series, which gives you similar HOLDING torque as wiring them in parallel.  The difference between series and parallel is in the torque the motor can supply while it's actually moving.  If you look at the graph below right from Leadshine (1200oz-in motors), wiring in parallel will net me more torque after 150 RPM's which is about 30IPM for me.  I choose to wire the motors in parallel for now.






I had to bore out one coupler from 14mm to 16mm for the 1700 oz-in, but on my friends lathe that was no big deal.  The motors look good in place, the X cover almost looks like it was made to cover the longer 1200oz-in motor!



IMG_20200229_200353 by Phazer Two, on Flickr




IMG_20200321_151624 by Phazer Two, on Flickr

Z axis wires were long enough, but the flex conduit is a bit tight.  I might try to find a different conduit to cover these better, but for now they are covered.



IMG_20200229_200343 by Phazer Two, on Flickr

With all the motors fired up and tuned, I was able to get 250IPM out of the X and Y, and 175IPM out of the Z!  This is SCREAMING fast compared to the old motors where which were 100IPM in X and Y and 65IPM in the Z.  However after lots of testing, I decided to set everything at 150IPM.  Things seem smoother limiting the machine to this speed, and I think that is because of the accelerations of the motors not being fast enough to get to 250IPM fast enough.  Anyway, I really like everything moving 150IPM, it's much faster than it was and is running great.

My thoughts on the motor upgrade... don't waste your time/money.  While this did work great, and I'm happy with it, I wish I would have just put the money towards servos.  Considering the machine ran reliably before I upgraded, the only thing I gained was speed.

You may notice in some of the pics above that the cable/hose management to the head is poor at best.  In reality its embarrassing.  I set the thing up to test the new spindle motor, added some mist coolant, and just ran with it.  Well, I couldn't take it any more!  I took a few nights and cleaned everything up.  I used some Amazon cable chain, and had work laser me out some stainless panels and brackets.  I added bulk head fittings for everything, which really made things look nice.  I am also trying out a new logo (no idea why I have, or need a logo).



IMG_20200321_151608 by Phazer Two, on Flickr




IMG_20200321_151614 by Phazer Two, on Flickr

It's still not perfect, but I'm not embarrassed by it anymore.  The button on the front cover will be for a power draw bar when I get there, the extra holes were for things that I decided went better on the side cover.

Last, you might have noticed a probe in the spindle...  I bought a DrewTronics S5000LED with TTS, it was about $260 to get it to my door and let me tell you... WORTH EVERY PENNY! I am repeatedly getting better results than they have listed, so I can't complain at all.  I still have some figuring out to do with the Acorn.  I have some issues stemming from the probe being a normally closed probe and Acorn is really designed to work with a normally open probe.  Hopefully I can get some resolution on it soon, as I am not the only one with this issue.

Until next time,
PZ


Parts used:
Cable Chain:





						Cable Drag Chain, URBEST 18mm x 50mm Wire Carrier 1 M/ 3.3Ft Plastic Black Towline Machine Tool: Amazon.com: Industrial & Scientific
					

Cable Drag Chain, URBEST 18mm x 50mm Wire Carrier 1 M/ 3.3Ft Plastic Black Towline Machine Tool: Amazon.com: Industrial & Scientific



					www.amazon.com
				



DrewTronics S5000LED TTS:


			https://drewtronics.org/s5000led-tts-1


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## phazertwo (Mar 22, 2020)

In case you want to follow along with the issue with Acorn and my NC probe.



			NC Probe and MPG Issues - Centroid Community CNC Support Forum
		


PZ


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## phazertwo (May 2, 2020)

The guys on the Centroid board got me sorted out in short order.  Turns out that the way I had it set, it was looking for a tool height setter on the same input... Changed the input for the tool height setter (which doesn't exist) to a open input, and we're rocking.

I've been probing, and it's freaking life changing.  Setup takes about half the time... Centroid provides some free probing routines with my Pro license, and with the next update of the software they are giving the Pro license access to all probing routines, so it should get even faster when I have those!

The fun was short lived though, as during a spring pass on the first part I made after getting everything running again, the spindle dropped to 500 RPM, even though the control was still calling for 6k RPM.  Opened up the cabinet and the spindle servo drive was flashing an error code that turned out to be "hall sensor error."  While this servo motor *was* very nice, it was a pain to setup.  Even running on the table I couldn't get it to run super smooth at higher RPMs, and since it had no auto tuning it was a long process to get it to where it was okay.  I decided to go back to the original 2hp motor and Delta VFD that came with the machine.  If anyone remember the wood motor mount, well it saved the day again.  I was able to machine the new motor mount for the original motor with it, and it worked great.  Unfortunately I was working fast because I had a paying job that needed to get out the door, so no pics.  I dumbed the new motor mount down quite a bit, and got it to work well enough with my existing PDB design.  After all that, I actually like this setup much better.  It hums at 5k RPM max, and is MUCH smoother than the old servo motor.  Makes me wonder if that hall sensor was bad all along?  Also, a note for the other 940CNC-VS guys out there, I changed the Delta VFD to sensorless vector control.  It seems to make a nice difference down low, time will tell how the motor likes it, but it's running nice and cool.  I actually disconnected the electric fan on top because I was sick of listening to it.  Even after 20 min straight of spindle time, running a 3/8 EM hard, it was only warm to the touch.

I got the paying job off the mill and started the stand-offs for the PDB.  They came out quite nice, I've been running the machine hard and it really seems to be doing a good job.  I cut the 3/4" 6061 place at full depth, 0.075" step over and 0.004 IPT.  At 5K rpm I think that was 60IPM.  Spindle didn't even slow down, and she just ate it.  Did a 0.010" finish pass at 0.001IPT with a repeat pass, and the parts came out about the best I've seen off this machine!  You can also see the motor mount in the background.




IMG_20200501_194355 by Phazer Two, on Flickr




IMG_20200501_194400 by Phazer Two, on Flickr




IMG_20200501_194437 by Phazer Two, on Flickr

Next up, I bought a 3" 3 Jaw chuck off Amazon.  I'm going to make mounts to bolt it to the table.  Should make Round parts much easier!



IMG_20200430_120731 by Phazer Two, on Flickr




IMG_20200430_121053 by Phazer Two, on Flickr

For $88, with Prime shipping, I couldn't say no.  It also came with a set of OD jaws, which look like they would clamp on ~3" stock.  Hoping it will let me knock out the round parts I need to make for the PDB faster than working in the vice.

PZ

Parts used:





						Accusize Industrial Tools 3''/80 mm 3-Jaw Chuck, Plain Back, 0.630'' Center Hole, 0559-0110 - - Amazon.com
					

Accusize Industrial Tools 3''/80 mm 3-Jaw Chuck, Plain Back, 0.630'' Center Hole, 0559-0110 - - Amazon.com



					www.amazon.com


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## phazertwo (May 10, 2020)

Last week I made the sub plate and standoff for the 3 jaw chuck.

The sub plate was easy, a few though holes and a few counterbored through holes on the back side.  I wish I would have used something more robust than 0.5" MIC 6 plate.  You'll see why a bit later.

Milling the stand off was a little more interesting.  I made it out of a 3x4 piece of scrap alluminum I picked up at the scarp yard years ago.  No idea what flavor it is, but I would guess it's 6061 T6, since that is what most aluminum is.  It cut great.  I forgot to take a pic of side one, which would be the side that is bolted down to the subplate.  I than flipped it and bolted it to the sub plate and finished the top while it was assembled.  Originally I had it at ~3" tall, but decided that was too tall, and made it 2".  In the end, I think it will be getting even shorter to maximize rigidity.  Here is a video that shows the roughing cut that reduced it from 3" to 2".  0.990"DOC x 0.04" WOC at 60ipm for a total of dang closet to 2.37 cubes/min.

Click link for vid...



VID_20200508_205355 by Phazer Two, on Flickr

Notice that I have some chatter in the X axis.  When I made this same cut on side one, in the vice, I had no chatter at all.  I am going to say that is the fault of the sub plate being too thin, and the bolts being too far away from the chuck itself.  I will just have to baby parts in it for now, as PDB is absolute top priority right now.

And the finished assembly.



IMG_20200510_090423 by Phazer Two, on Flickr

The whole point of this, is to make it easier to make the round parts I need for my PDB, since I don't have a lathe.  I have a chunk of 1045 I found in a scrap bin that I was hoping to turn into the top hat, so I decided to chuck it up and see how she goes... Didn't go awesome.  I was using a 0.5" 4 flute carbide end mill.  I would much rather use a 0.375" 5FL EM for this, but beggars can''t be choosers.  I had to go VERY slow, and while it wasn't chattering it didn't sound great.  I also got some interesting vertical facets, which I believe are due to the 4 flute end mill noting having more than one flute engaged causing a vibration/resonance in the system.  If anyone has a good line on 0.375" 5FL EM's let me know!  In the mean time, I think I am going to double the LOC and half the WOC to see if I can get more than one flute engaged...

FYI, this was 20 min worth of milling to get to this point, and while the 0.5" 4FL is not chipped, it's now very dull.



IMG_20200510_090441 by Phazer Two, on Flickr


Till next time,
PZ


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