# Bridgeport Resto



## N8TheGreat

After purchasing my new milling machine through an online auction I went and picked up yesterday 



Rented a tilting flat bed trailer from the local tool rental store for cheap cheap cheap. the tilting option was amazing for unloading since I have nothing heavy duty enough to pick it up but we were able to slide it off the trailer and onto some pipe and wheeled it into the garage  



It needs a little work before its ready for work...but once done I am sure it will provide many years of service for me.


----------



## JimDawson

Looks like a good start.  Nice job getting it off of the trailer!


----------



## brino

Hi N8,

First, welcome to the site.
Second, congratulations on the new hardware! 

There are many knowledgeable Bridgeport owners here, you've found a great place for Q&A and camaraderie.

-brino


----------



## N8TheGreat

Thanks @brino and @JimDawson for the replies and warm welcomes. snooping around on this site for a bit now and I know there are a lot of knowledgeable people on here with wisdom and experience to share   that's why i signed up!!

Couple questions to get me started....
1. mill did not come with a motor which is ok but i wish that is did even if it was in need of a rebuild...but that's besides the point. question is who has had good luck with substitutes? I plan on keeping it 3ph and it will be set up for VFD. even though this is a variable speed head originally. any one recommend a particular motor or even conversion to VFD if its out there for this. 

2. To fully dismantle or not ... I am going to be cleaning it up A LOT and repainting but I am hesitant to take everything apart. should I clean it the best that I can AS IS and make it look pretty and operational or completely dissemble and clean and inspect all parts? what is the generally consensus? problem is I am very ... well ... lets just say anal, and I know that if I fully dissemble it will be out of commission until I know everything is better then when it came out of the factory which I know will add to the cost and significantly lengthen it rebuild time.

Thanks for any and all input!!!


----------



## JimDawson

It's really too bad that you didn't get it with the motor.  The real problem is that there is a lot more hardware needed on the motor end for the vari-drive.  You can get an import motor/vari-drive pulley assembly from Jet complete for about $950.  It may not be a direct bolt on, but should be adaptable.  I have no idea what a true BP motor assembly would cost.  The motor is a special and has a long shaft for the vari-drive pulley assembly.

Another option might be to install a timing belt drive and eliminate the entire vari-drive system.  That's what I'm going to do if my vari-drive fails.  The VFD has enough range to cover the speeds needed.  If I were going to do that, then a sensorless vector drive and an inverter rated motor would be in order.  A 2 KW AC servo drive spindle system would be the top of the line.  

If the machine is in generally good shape and has been properly lubricated then I would not do a complete tear down.  Just clean things up a bit.  You won't know about the condition of the head and spindle before you are able to power it up.


----------



## alloy

I just did a quick search on eBay and found 3 vari speed motors with the pulleys for around $400. And new for about $1000.  I'd post links but I can't do that on my phone. 

Just search for Bridgeport Motor.  

Wish I could find one for my Kent mill for that price.


----------



## N8TheGreat

Thanks for the replies.
I do plan on running a VFD so I will need a motor that is inverter rated. I may be wrong but I don't believe stock motors will handle that.

So I will be disengaging the factory variable drive pulleys and running my own setup instead to work with new motor.
does anyone offer a pulley setup for this conversion? and what motor brand/size/mounting have people had good experience with?


----------



## JimDawson

You could run the stock motor on a VFD, but you won't have the speed/torque range that you would get with an inverter rated motor and a sensorless vector drive.  There are two types of VFD, most are V/Hz type, the other type is sensorless vector.  The latter is more expensive, but offer greater torque over a wider range.

I can't help with exactly what pulley arrangement to use.


----------



## countryguy

As an example, the Hitachi WJ300 is a sensorless vector VFD.   Cost me under $350 if I recall.  There is a WJ200 also.  I bought mine w/ a remote min-keypad.  then you can mount it all, wire it, and have a keypad w a flip up lid or panel etc...    On the low end, The ebay Hunyang's VFD for a  1 or 2 hP are something like 80-$100.     If it were my Mill, I would go w/ a Sensorless Vector style on the mill.    If it were a small grinder or something-  then I would go low end VFD.

I also have a Varispeed Mill setup w/ a VFD on CNC.  It does make a challange for setting the RPMs via software.   If you find a keen way to get this setup for the drive train I'm all ears!!

Welcome and post away- I know I have and they are awesome here!!!!

On the clean out/up-  Does it have a one-shot oil system?   Aluminum or plastic tubing?  Mine was all plugged w/ goo.  Had to remobe them all.  Soak and blow out w/ compressed air!    To me- Making sure I get oil in key places was an area we spend time upon.

the table will have the usual adjustments.  I likes this one as a Newb.





Electrical connections and disconnects.   On my hobby mill w/ VFD  I found wire post after wire terminal loose and barely screwed down.    Check it over there.

When my mini mill blew up after 1 week I determined someone had put the lollipop disconnect across 1 leg of the 220 into the VFD in order to turn the VFD based machine on/off.   Total no-no  That is what blew up the cheap VFD .  So I installed the WJ300 w/ the correct make/break setups to power that mill on/off.

Jim D. turned my onto Automation Direct.  LOVE those guys!  They also have a student discount typically!  find a way there if you can.  a .edu email if I recall.

there are a lot of motors out there.  I learned a ton about them from sites.  I liked this article.
http://ecmweb.com/design/mating-new-variable-frequency-drives-existing-motors

There is also a large motor reuse/New Old Stock up in Lansing or Saginaw if I recall.  Lots of good deals there.   I'll see if I can fine the URL.

btw/  I grew up in Westland.  Venoy and Warran rds.    long time ago!


----------



## JimDawson

There is a good chance that on Saturday I will have a timing belt drive in my hot little hand.  I'll post pictures if it happens.


----------



## alloy

If I have enough $$ in my pocket to win the bid on it yes you will have that drive in your hands    The Super E motor on that head is abut $900.  

I was doing a little research on the electronic head and found this.  Not much, but it shows the timing drive setup.


----------



## N8TheGreat

Thanks @countryguy for sharing that video! btw the machine does have a one shot oil system however the oiler has been removed but all of the plumbing remains and its plastic. I will definitely take that all apart and clean it out and maybe replace it with some nicely bent hardlines ....cause well I like the look of that  
what are you using for oil? way oil, motor oil or something else? 
small world you from westland I am not to far away from where you lived. Wayne and Cherry Hill

@JimDawson if you could post some pics of the timing belt drive that would be awesome! thank you! 

Thanks @alloy for posting up the diagram


----------



## N8TheGreat

I started the process of de-greasing and cleaning, still needs quite a bit more but definitely steps in the right direction. just from cleaning and not measuring the ways seem to look good and looks like it was well oiled in its life. I am going to pull the table this weekend to clean and inspect. 
Ill grab some new pics of the progress


----------



## alloy

The head with the timing belt setup is at an auction on Saturday.  I bought a Kent mill and the motor shaft is completely destroyed and Jim found the head at an auction site.  There are a few other things that  we are interested in also.  We will post our "scores" on here 

I'm looking to put the head on my Kent mill.  It's an electronic head, 3hp with a Baldor Super E motor.  I'm going to do my best to get it.  Willing to throw some bucks at it, but hopefully won't have too.  Jim said I'm up against scrappers and I should easily outbid them for it.    We should be able to gt it to Jim's on Saturday and take some pics of it.  Hopefully we can power it up also from the big VFD on my CNC mill.

For your lube lines I used 1/8" copper tubing and ferrules I got at an auto parts store to repair the ones on my Bridgeport.


----------



## alloy

I just dug this up. It' my Bridgeport build.  Might be of some help to you. 

http://www.hobby-machinist.com/threads/just-picked-up-a-bp.24097/


----------



## alloy

Jim and I just went to preview the  auction and he looked inside the head and it has a V belt setup in it.   

I'm pretty sure I'll end up owning it.  If you want we can post pics of the belt setup.


----------



## N8TheGreat

alloy said:


> Jim and I just went to preview the  auction and he looked inside the head and it has a V belt setup in it.
> 
> I'm pretty sure I'll end up owning it.  If you want we can post pics of the belt setup.



If you would please that would be awesome. thank you!


----------



## alloy

I got the head for $200.  Was pretty late when we got out of the auction, so I'll go out to Jim's tomorrow and put some power to it and get you some pics.


----------



## N8TheGreat

alloy said:


> I got the head for $200.  Was pretty late when we got out of the auction, so I'll go out to Jim's tomorrow and put some power to it and get you some pics.


That will be awesome, thanks! 
I pulled the top of the head off yesterday day to take some measurements and see what I am working with to timing belt pulley sizes and locations.


----------



## N8TheGreat

Still cleaning but its definitely getting there 
the automatic feed for the spindle may need some work seems to be very tough to engage/disengage and feels a little tough using the handle to drop the quill, maybe its just the old sticky oil but seems to be tougher then should be to move all that.

I also haven't removed the table yet, am I supposed to remove the gib or just loosen it before sliding the table off? I have read it being done both ways?


----------



## JimDawson

N8TheGreat said:


> I also haven't removed the table yet, am I supposed to remove the gib or just loosen it before sliding the table off? I have read it being done both ways?



You might want to remove it.  If you don't, it will just fall out when the table comes off and it could be damaged.  Only takes a couple of minutes to pull it out.


----------



## alloy

Looks like your having the same problem with pics that I have.  The show up rotated.  The only way I've found to fix that is to open them, rotate them 90 deg, save it, and then  rotate back and save again. Then I can upload them.

It works, not sure why I have to do that though.


----------



## N8TheGreat

JimDawson said:


> You might want to remove it.  If you don't, it will just fall out when the table comes off and it could be damaged.  Only takes a couple of minutes to pull it out.



Thanks Jim I figured as much, I will remove it first


----------



## N8TheGreat

alloy said:


> Looks like your having the same problem with pics that I have.  The show up rotated.  The only way I've found to fix that is to open them, rotate them 90 deg, save it, and then  rotate back and save again. Then I can upload them.
> 
> It works, not sure why I have to do that though.



Yea I don't know why it was doing that, I rotated like you said and it seemed to work now so I was able to fix the images.


----------



## alloy

Here are a couple of pics of the belt drive.  We decided to tear the head completely apart.  The head was full of grease and every time we moved it water poured out of it.

If you need more pics Jim can get them for you.  It was late last night when we got it apart and I had to head home.  I get up pretty early for work.


----------



## N8TheGreat

Thanks for sharing @alloy, I had something similar pictured in my head.
is there any kind of belt tensioner?
Interest the head was full of water  thats a little strange. ha maybe it was water cooled lol


----------



## alloy

No tensioner, just the slotted base on the motor. Uses an AX31 belt.  

Then head was under a canopy at the auction when we saw it, but it must have been out somewhere before that.  Guess it needed cooling off because it was such a hot deal for me


----------



## N8TheGreat

Got the table off the mill last night, pretty easy to do however I knew it was going to be heavy but it was even heavier then I thought it would be. I removed the gib and slid the table onto some milk crates and 6x6s that were at the same height, that wasn't too bad but then I flipped it over and that's when I found out just how heavy that sucker was lol.


----------



## alloy

You might want to take a look at the casting around the Y axis table lock on the saddle. It's pretty thin there. On mine there were several cracks where someone over tightened it.  I thought about trying to get it welded, but came up with a repair that didn't require any welding.


----------



## 4GSR

Your table ways look good, but the saddle ways are heavily worn.  Looks likes some scraping work ahead of you there.

BTW-Can't help but notice the lawn mower in the back ground in your picture.  You mow your yard with that?


----------



## N8TheGreat

yea that one way on the saddle is the worst looking out of all of them. This is getting beyond my knowledge/terminology but do I just need to do frosting to help with oil retention? if so how can I do this on the cheap, I'm not afraid  and learning/attempting new things however I just don't have any tools to do the job. Is there any homemade or backyard engineered tools that could do the job.

About that lawnmower though, I don't mow with it but I have a little helper who loves to mow with it when I do


----------



## countryguy

Here are are few threads from the "similar threads" section that show up on our posts.  I really like that feature.   There is a great close up of a before and after.  The user is also noted as active.   Give him a shout out. 
http://www.hobby-machinist.com/threads/bridgeport-rescraping.39115/

I know it seems to go on and ....  And the tooling and skills you learn and need never end.   Best of all .. it's just plain fun!    Keep the updates coming.   you're doing great! 
Jeff


----------



## countryguy

PS-  I left it w/ just the one post as several of the other posts said to get in touch w/ Sidecar who is the BP resto king.      

Also-  For heavy lifting and before you hurt something - There are a few posts on a 2 ton crane/engine lifts... I got mine off Amazon. I see the same import model all over now.  HF too.      Tractor Supply had the best value chain-fall hoist w/ 8ft of travel!    And of course - the HF 1ton Gantry (grey one) w/ 20% coupon to lift & set the rest of your gear off the hauler and into the bay.     You know it will not stop w/ the 1 Mill.  What's next?  The Lathe right?        PS-  the cars go outside here. I sent my beloved 99 Tahoe to the lot and took the bay for my shop!   
http://www.hobby-machinist.com/threads/very-good-shop-hoist-2ton-cinnci-2-in-the-air-photo.25184/


----------



## N8TheGreat

Thanks Jeff for the replies, I'll have to do some more digging into scraping/flaking ways.

Got a quick question, took the table bearing assemblies apart and noticed on 1 side there were 2 bearings and the other there was only 1 and it was a different bearing then the other 2. whats up with that? 
btw the numbers I got were 1 - FAFNIR 204KTT and 2 - FAFNIR RM204KT4

I wanted to replace the bearings but not sure how many to get ... 3 or 4?


----------



## 4GSR

N8TheGreat said:


> ..........table bearing assemblies apart and noticed on 1 side there were 2 bearings and the other there was only 1 and it was a different bearing then the other 2. whats up with that?
> btw the numbers I got were 1 - FAFNIR 204KTT and 2 - FAFNIR RM204KT4
> 
> I wanted to replace the bearings but not sure how many to get ... 3 or 4?
> 
> View attachment 113307



The 204KTT  and 204KT4 are common bearing numbers.  Not sure what RM204KT4 is about.   The RM designation is odd to me.  I'll have to get my bearing book out and see what is specific about each of the numbers.  I don't recall them as being any fancy bearing per say.  They are "shielded both sides" type of bearing.  Your local bearing house should have them.

EDIT:

My bearing book says the 204KTT wider than normal width (.625") bearing with felt or labyrinth seals on both ends.  Both inner and outer race are the same length.
The 204KT4 again is a wider than normal width bearing, but the inner race is .600" wide and the outer race is .625" wide or very close to this.  Standard 204 bearing width is .5512".

The thing that bugs me is the Bridgeport manual I have says 770200 in the parts list and XF-12 on one of the assembly drawings.  The 770200 I assume matches up to a 7020 BCA bearing or a Fafnir 204KT bearing, bot have a single felt or labyrinth seal. It also matches up with Norma FAG 77000 series bearings as 77020 size, which has felt or labyrinth  seal.


----------



## N8TheGreat

Picked up my end mills yesterday that I bought from auction 



I have a serious auction addiction lol ... so much stuff so cheap


----------



## N8TheGreat

Update:
Ordered my new motor and VFD for the machine 

and currently cleaning and sanding and preparing the machine for paint

Sorry no pictures of the progress :-(


----------



## N8TheGreat

New motor and VFD showed up!!!  
VFD - Huan Yang 220V 2.2KW 3HP
Motor - Inverter Duty 2HP 208/230/460Volt 3Phase 3510RPM


----------



## N8TheGreat

Got the first coat of paint on last night, it will need one more before I call it good. 
I rolled and tipped the paint and it seemed to cover and flow out nicely even in the cooler weather, using Rustoleum Oil based Enamel. Its amazing what a little paint will do


----------



## JimDawson

N8TheGreat said:


> New motor and VFD showed up!!!
> VFD - Huan Yang 220V 2.2KW 3HP
> Motor - Inverter Duty 2HP 208/230/460Volt 3Phase 3510RPM
> View attachment 114423
> View attachment 114424



The mill is looking good!

One problem I see is the motor RPM.  Mills normally use a 1725 RPM (1800 RPM nominal , 4 pole) motor, as opposed to a 3510 (3600 RPM nominal, 2 pole).  The torque from the 2 pole motor is going to be 1/2 at the same HP rating of a 4 pole motor.  Normal spindle speed range is about 500 to 4000 when in direct drive on that mill.  A 2:1 belt reduction in the drive would fix the problem on the low end of the range, but you can not spin that motor up to 8000 RPM to get the max speed.  The 3 HP Baldor SuperE inverter motors are rated for 6000 RPM max, I don't know about yours.

Also the VFD you chose is not quite correct for a non vari-drive mill.  That VFD is a volts/Hz type VFD, where you should be using a Sensorless Vector type VFD for full speed/torque control over the needed range.

At the very least, I would see if you can send that motor back and get a 4 pole (1800 RPM) motor.


----------



## N8TheGreat

JimDawson said:


> The mill is looking good!
> 
> One problem I see is the motor RPM.  Mills normally use a 1725 RPM (1800 RPM nominal , 4 pole) motor, as opposed to a 3510 (3600 RPM nominal, 2 pole).  The torque from the 2 pole motor is going to be 1/2 at the same HP rating of a 4 pole motor.  Normal spindle speed range is about 500 to 4000 when in direct drive on that mill.  A 2:1 belt reduction in the drive would fix the problem on the low end of the range, but you can not spin that motor up to 8000 RPM to get the max speed.  The 3 HP Baldor SuperE inverter motors are rated for 6000 RPM max, I don't know about yours.
> 
> Also the VFD you chose is not quite correct for a non vari-drive mill.  That VFD is a volts/Hz type VFD, where you should be using a Sensorless Vector type VFD for full speed/torque control over the needed range.
> 
> At the very least, I would see if you can send that motor back and get a 4 pole (1800 RPM) motor.



Hey Jim, these aspects were already thought of and pros/cons weighted. This mill came with a 1.5hp motor and others came with 1hp, I stepped up to the 2hp to help compensate for the torque that will be lost at lower RPMs but for the planned uses of the mill it will be more than enough for me. I am going to use a 1:1 pulley ratio and spindle speed will be controlled via motor’s RPM that is why I went with the 3600RPM motor instead of the 1800RPM motors that would have come with the machine originally.

The sensorless vector drives are better however the benefit per cost just does not make sense for my application. Budget had a large impact on parts chosen and is the reason I went with the equipment I did. I got the NEW motor and drive for under $400 delivered and they both carry a 2-year warranty!!

Btw not sure what the motor’s maximum RPM is but the bearings inside are rated to 17,000RPM!! lol


----------



## countryguy

Glad to see everything is looking on the upswing.   Some things on the Huanyang - Several typos exist in the manuals.  I documented a few of them at 1 point.  If something's just not working right in there.....  Check for the same setting in another spot in  guide.  I found 2 settings like this on mine.    But Very inexpensive seemingly solid in my Mill so far! 

Keep the posts coming.


----------



## JimDawson

N8TheGreat said:


> Hey Jim, these aspects were already thought of and pros/cons weighted. This mill came with a 1.5hp motor and others came with 1hp, I stepped up to the 2hp to help compensate for the torque that will be lost at lower RPMs but for the planned uses of the mill it will be more than enough for me. I am going to use a 1:1 pulley ratio and spindle speed will be controlled via motor’s RPM that is why I went with the 3600RPM motor instead of the 1800RPM motors that would have come with the machine originally.
> 
> The sensorless vector drives are better however the benefit per cost just does not make sense for my application. Budget had a large impact on parts chosen and is the reason I went with the equipment I did. I got the NEW motor and drive for under $400 delivered and they both carry a 2-year warranty!!
> 
> Btw not sure what the motor’s maximum RPM is but the bearings inside are rated to 17,000RPM!! lol



I well understand budget constraints, at least you went into it with your eyes open.  17 grand might be a wee bit much


----------



## N8TheGreat

Finally have some new updates! 
Been slowly collecting parts and finally have all the pieces for my one shot oilier  Thank you eBay, Amazon, Enco and H&W Machine Repair.



Got everything plumb in yesterday and only a few things I need to tweak in the future is the flex line going to the saddle, just setup temporarily now but it works. Also one of the line going to the ways on the saddle is horrible pinched and will need replacing, this is what caused the badly worn way on the saddle...it wasnt getting any oil


----------



## N8TheGreat

Finally got the table on last night 



Ran into a couple issues .... The dial holder for the for the table are both different and either of them match the y axis


the one on the left is from the y axis and the other 2 were from the table. the two mismatched will not work on the table because they are either too short or not enough back clearance.

also when I tighten down BOTH table bearing bracket to the table, when cranking the table it is very difficult and not smooth?  but if i loosen one side and free it up about 1/4", it frees it up some and much easier to crank. however still feels gritty when cranking the handle. I assume this is due to the bearings since when I had them out they spun freely but I could feel some dirt in there.
Are these symptoms due to the fact that I may need new bearings? 
or is it the feed nut? when I am just spinning the lead screw through the nut by itself it fells nice and smooth.


----------



## JimDawson

It sounds like it's time to stop, take a deep breath, and review the work you have done so far.  I'm not sure I can help with the specific problem, but it sounds like something is not assembled correctly.  What you have there is a giant 3-D jigsaw puzzle, and it's possible to put some of the pieces in the wrong location.  I'm assuming here that it was working more or less correctly when you took it apart, so it should work the same when reassembled.


----------



## chips&more

Those bearings are not going to be worn from any high speed use. More than likely got some dirt in them or old hard dried grease. Before you replace them. I would remove a shield/seal from the side that is NOT exposed the elements. And carefully clean the bearing(s) and re-grease it. Sometimes you can even put the old shield/seal back if you removed it without any damage. And those dial holder things typically have spacer washers so you can set the proper spacing from dial to bracket…Good Luck, Dave.


----------



## N8TheGreat

When I first picked up the machine it wasn't fully put together one of side brackets wasn't put on all the way so the table would still move back and forth. I assumed this machine once had a powerfeed and when I picked it up they pulled all the good stuff off, thats why I got is so cheap. I believe they took off the oil pump from the lube system, motor, drawbar and even the powerfeed or this is what i speculate. 

Prior to install I have blown those brackets completely apart and cleaned all of it and soaked the bearings and clean them and then cleaned them again and grease/lubed them up the best that I could. They were better then before but still not that smooth new bearing feel. 

I made sure to put everything back together to match this view... and according to this, all of the dial holders should be the same part number, whereas I have three different one.


----------



## JimDawson

I guess I would start by assembling it without the dials on the holders.  That will tell you if the dials are rubbing.  You may need to do some shimming.  The axial preload is set by the the nuts (item 1).  It's just a matter of taking it one step at a time until you find the problem.  It could be rough bearings.


----------



## N8TheGreat

The problem with the dials is yes they rub and also the holders are to short to still be keyed on the screw so they just free wheel when on there making them pretty much useless for trying to lock them in.


----------



## JimDawson

If you have a lathe, making proper spacers would be a good project!


----------



## N8TheGreat

lol unfortunately I don't ... yet  
Looks like a stack a washer will have to do


----------



## N8TheGreat

Well its been a while but I finally got the mill running!! 
Ill share some pictures of the progress


----------



## N8TheGreat

Got the drive mounted and wired up with my controls panel. 
Even have a RPM meter where the sensor is mounted to the spindle so I am able to get very accurate RPM readings at the spindle


----------



## N8TheGreat

Got the table and vice trammed in and made some test cuts on some T-nuts I had lying around to fit my table


----------



## N8TheGreat

I must say I am liking it so far, runs great! very smooth and noise or vibrations whatsoever and everything works like the power feed  
Drive still needs to be dialed in still like ramp up and down times and etc... but they will come in time. 
Also I very happy with the 2-pole motor choice with the pulley configuration and the High/Low gearing on the mill I have a huge RPM range to work with even at motors full torque. 
I have a RPM chart I could share if anyone is curious or would like to do something similar.


----------



## JimDawson

Nice job!  I would be interested in learning more about how you did the spindle speed sensor.  Would you post the details?  I'm most interested in where and how you located the pickup and what it is actually ''seeing''.


----------



## FOMOGO

The Bridgeport is looking great. Were you able to get the table issues worked out? Would definitely like to see your rpm chart. Hoping to get a little time to work on mine soon. Mike


----------



## N8TheGreat

Here is my RPM chart, because I dont have what you may call a fancy motor($$$) I will only have full torque to around 15hz which is perfectly fine for me with my pulley's and gearing gets me down to around 70RPM at full torque I could always go slower to get the RPMs even lower as shown on the table.


----------



## N8TheGreat

JimDawson said:


> Nice job!  I would be interested in learning more about how you did the spindle speed sensor.  Would you post the details?  I'm most interested in where and how you located the pickup and what it is actually ''seeing''.



As for the sensor, its a hall sensor and I located the magnet on the pulley mounted to the spindle that way it is picking up the RPM of the spindle not the motor
I wish I would have gotten better pictures but you can just barely see the sensor here.





Because there is a 8:1 reduction in the High to Low gear selector on the mill I am working on a logic board that will do the division and then display to correct RPM at the tool when the machine is in low gear. so for now the RPM meter is only really relevant when in high gear but I am working on that. but that's another project


----------



## JimDawson

Thank you.  I understand.  I was hoping you would have found a sensor location that would actually measure the spindle speed as opposed to the driven pulley.  The actual spindle is really hard to get to with a sensor.  I want mine to read correctly in both high and low range and also read direction without the software gymnastics.  I know how to do it, but I was hoping you had found a better way.


----------



## N8TheGreat

JimDawson said:


> Thank you.  I understand.  I was hoping you would have found a sensor location that would actually measure the spindle speed as opposed to the driven pulley.  The actual spindle is really hard to get to with a sensor.  I want mine to read correctly in both high and low range and also read direction without the software gymnastics.  I know how to do it, but I was hoping you had found a better way.



What's a way to do it? 
Do you have to pull the head apart?
Easiest must be the handheld tachs and you just put the markings on the spindle.


----------



## JimDawson

Yes, the drive portion of the head would have to be disassembled to install.  There are only two parts that always turn at spindle speed;  

The low speed bull gear,




and the quill power down feed worm gear.  The spindle is directly driven by the internal spline on these two gears.  There is nowhere that you can access the spindle spline.



The bull gear is pretty easy to access, but it has too many teeth to be sensed at greater than about 3200 RPM with a 5 KHz sensor.

The only really viable option is the quill feed gear.  It does move up and down as the low/high range is selected, but it remains in a range that is accessible to the sensors.  In the case of my mill, I am not using the quill feed hardware so it is pretty easy to access through the quill feed selector hole.  It is possible to put the sensors in there with the quill feed selector in place.  There is just enough room on the back side.




I have a spare head that I can use as a fixture to build the sensor bracket so I can build it without disabling my mill.  A project I'll get to one of these days.   I'll post a thread when I do that build.

I will be using these 4mm prox sensors to form a two channel encoder by spacing them to sense the gear teeth with a 90° phase offset. 



The bracket will be something like this.  I built this one for Alloy's Shizuoka, but was able to use the bull gear in that case because it has about 1/2 the teeth of the BP style bull gear.  (there is about 0.015 clearance between the sensor and the gear teeth)




And the outside view.  It works very well through the entire speed range and also gives rotation direction information.  I was nice of Shizuoka to provide a perfect mounting port for this install.


----------

