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View Full Version : Something Old, Something New..Upgrading An Old CNC Millrite



Too_Many_Tools
05-20-2006, 11:28 AM
Sometimes the Gods smile upon a person...I was just given a old CNC
Millrite. ;<)

So now I (or perhaps I should say my son) has a summer "project" to
upgrade this Millrite from its old numerical controls to use the
current technology.


The mill has Acme screws on the X and Y axises.


The X and Y axises and the quill are equipped with servo motors that I
will want to reuse in the updated electronics conversion.


I do have the old numerical control electronics that were used to
originally power the servos but will likely not reuse it except for the


cabinet.


The spindle is powered by a three phase 1Hp motor.


So if this was YOUR machine, how would you go about updating it?


What hardware, software, what companies would you go with?


I will also add that I searched the entire archives without finding
anything like this that has been done before so any contributions that
you might add will provide guidance for those who are looking for
insight in the future....and help me alot. ;<)


Thanks for any contributions that you can add.


TMT

NC Cams
05-20-2006, 11:49 AM
Looked at a bunch of them for by Bridgeport.

Ultimately, you have a choice of engineering your own retrofit (not for the uninformed/uneducated) or buying a kit and bolting it on.

I'd be inclinded to buy the pre-engineered kit which may or may not interface with your old servo's - check closely before you commit.

Mach has charm BUT it can't interface EASILY with servo feedback (long complicated story - in short, I wouldn't bother but surely someone with take exception to this).

Looked at Anilam but the cost got prohibitive due to downturn in business (proprietary system that supposedly uses a DOS backplane - I"m not a fan of ANYTHING Windows based for CNC).

Cost/benefit wise, I became fond of the AjaxCNC concept. Ajax is the DIY version of Centroid. Linux based and quite affordable at a reasonable price. Self tuning and seems to be reasonably "plug and play" if you use their "kit". They do a BOSS retofit which may be close enough to P&P (paraphrase and plagiarize).

FYI: the former Bridgeport engineers who helped design/build the early Bridgeport CNC stuff (IE: ExTrak, etc) now run their own CNC service/integration business. Interestingly, they sell, distribute and service Centroid. Says a lot about the product if you ask me....

You should/must also do a google for "cnc retrofit" and go deep into the pages that will turn up.

Al_The_Man
05-20-2006, 12:21 PM
If you want any kind of accuracy and lack of backlash, I would replace the Acme with ball screw, if you go with rolled BS, it is cheaper but I would pay extra for the pre-loaded ball nut, especially for rolled BS.
If it is similar to the Bridgport, Nook Industries used to supply a BS conversion in different lengths , complete with cross over DogBone.
If you do not have three phase for the spindle motor, get a VFD, 1ph in-3ph out.
This can be controlled under CNC spindle command.
Al.

Too_Many_Tools
05-24-2006, 06:24 PM
If you want any kind of accuracy and lack of backlash, I would replace the Acme with ball screw, if you go with rolled BS, it is cheaper but I would pay extra for the pre-loaded ball nut, especially for rolled BS.
If it is similar to the Bridgport, Nook Industries used to supply a BS conversion in different lengths , complete with cross over DogBone.
If you do not have three phase for the spindle motor, get a VFD, 1ph in-3ph out.
This can be controlled under CNC spindle command.
Al.


Has anyone converted a Millrite from Acme to ball screws?

What suggestions do you have?

Thanks


TMT

balsaman
05-25-2006, 08:52 AM
Servos are no problem with Mach software combined with Gecko 320 drives.

Eric

Too_Many_Tools
07-24-2006, 02:27 PM
Could I get some comments about the software that others use for CNC?

I have a number of older computers that I would like to use for the shop.

They are rack mounts and built like a tank.

Also, how good are old servos versus the newer ones available today?

Thanks

TMT

NC Cams
07-24-2006, 06:46 PM
Re: old servos = good if you can find drives that will handle the voltage and current. Some retrofit houses won't touch old motors (Ajax/Centroid for one). Much easier to interface if encoder fitted as oppose to resolvers.

I suspect the lack of desire to fit new amps with old servos has more to do with "self tuning" of the new brushless stuff - the older brushed stuff doesn't interface with Windoes very well if at all.

Too_Many_Tools
07-29-2006, 02:28 AM
Re: old servos = good if you can find drives that will handle the voltage and current. Some retrofit houses won't touch old motors (Ajax/Centroid for one). Much easier to interface if encoder fitted as oppose to resolvers.

I suspect the lack of desire to fit new amps with old servos has more to do with "self tuning" of the new brushless stuff - the older brushed stuff doesn't interface with Windoes very well if at all.

Could you explain the "brushed versus brushless" interface with Windoes issue?

Does anyone have any info on this Millrite setup?

TMT

Too_Many_Tools
07-31-2006, 01:02 PM
Sometimes the Gods smile upon a person...I was just given a old CNC
Millrite. ;<)

So now I (or perhaps I should say my son) has a summer "project" to
upgrade this Millrite from its old numerical controls to use the
current technology.


The mill has Acme screws on the X and Y axises.


The X and Y axises and the quill are equipped with servo motors that I
will want to reuse in the updated electronics conversion.


I do have the old numerical control electronics that were used to
originally power the servos but will likely not reuse it except for the


cabinet.


The spindle is powered by a three phase 1Hp motor.


So if this was YOUR machine, how would you go about updating it?


What hardware, software, what companies would you go with?


I will also add that I searched the entire archives without finding
anything like this that has been done before so any contributions that
you might add will provide guidance for those who are looking for
insight in the future....and help me alot. ;<)


Thanks for any contributions that you can add.


TMT


An update....after doing some digging I find that this CNC Millrite
has 1200 oz/in STEPPERS...not servos like I thought...and they are
wired for an open loop system,

The feed rates for the machine were 0.75" to 24"/min.

The 5 pitch ACME screws are speced at 0.001".

The electronics are probably early to mid 70's.

Now if you were going to update this machine (that has had only a few
hours of usage), how would you go about it?

Would you replace the steppers? If so, what size servos and where
would you buy them?

How about the ACME screws? If so, where would you go to buy the ball
screws?

I think the electronics except for the power supplies are well worth
a replacement...any suggestions?

Any other suggestions that apply to a small knee mill update?

Thanks

TMT

Too_Many_Tools
08-01-2007, 07:53 PM
An update....after doing some digging I find that this CNC Millrite
has 1200 oz/in STEPPERS...not servos like I thought...and they are
wired for an open loop system,

The feed rates for the machine were 0.75" to 24"/min.

The 5 pitch ACME screws are speced at 0.001".

The electronics are probably early to mid 70's.

Now if you were going to update this machine (that has had only a few
hours of usage), how would you go about it?

Would you replace the steppers? If so, what size servos and where
would you buy them?

How about the ACME screws? If so, where would you go to buy the ball
screws?

I think the electronics except for the power supplies are well worth
a replacement...any suggestions?

Any other suggestions that apply to a small knee mill update?

Thanks

TMT

Still looking for anyone who has converted or updated a Millrite to CNC.

Any information is appreciated.

TMT

cjmerlincnc
08-07-2007, 06:57 PM
Hi, Do a search on this site for Hafco mill. Theres alot of info on retro-ing a medium sized mill with servo's. I have a similar mill and doing the same. Have a look at the Mach3 site and it's forum, alot of info there as well. Gecko do servo drives and stepper drives. The stepper drives I've used on a lathe and cannot fault them, I've yet to test the servo drives but i'm told that they are the best on the market for low voltage servo's.

Regards

Too_Many_Tools
08-09-2007, 08:23 PM
Hi, Do a search on this site for Hafco mill. Theres alot of info on retro-ing a medium sized mill with servo's. I have a similar mill and doing the same. Have a look at the Mach3 site and it's forum, alot of info there as well. Gecko do servo drives and stepper drives. The stepper drives I've used on a lathe and cannot fault them, I've yet to test the servo drives but i'm told that they are the best on the market for low voltage servo's.

Regards

Thanks for the response.

I am a bit surprised that no one has done a Millrite....they are a common 3/4 sized mill which are a good candidate for a CNC conversion.

TMT

Karl_T
08-09-2007, 10:38 PM
Hey TMT,

Same guy as on RCM?


You certainly want to go Mach with steppers. Gecko should have dirves you need. As Al said, VFD to drive your spindle.

Karl

cjmerlincnc
08-11-2007, 02:42 PM
Hi, I've not seen one. It would be great for others if you post some pics as you are doing the retro-fit. When I was looking for my mill (Ebay!!) the problem I had was you only see Bridgeports (too big for a small machineshop/garage/shed) or benchtop mills which are ok for hobby use but maybe not for manufacturing parts everyday. The other problem was that Bridgeports come up cheap on Ebay and hobby mills tend to go for high rediculous prices, lucky for me I got a 3/4 sized knee mill + tooling which was only a few months old for about a third of the price from new.
Now the long slog to find the time between work and converting it to CNC.

Can't wait...

Good luck with your project.

Cyclotronguy
04-01-2008, 03:10 PM
Just a personal opine. I've rebuilt a couple of the Millrite / Powermatic vertical mills. Like the spindle's with their tapered Timken bearings.. they are really nice.

Hate the gibs on the saddle and table. They are not tapered and are difficult to adjust just right. The crossfeed screw sets outside the ways, given any play in the saddle gibs the saddle fishtails it's way across the knee.

The crossfeed screw (0.200 inch / Rev) does have a backlash adjustment via split nut, if the long axis on yours also has backlash adjustment then you may be able to keep the acme screws.

Cyclotronguy

hybidder
04-02-2008, 12:45 AM
Well since you asked,

Leave the acme screws for now, hold off on the VFD. I have seen several posts mentioning interference from VFDs with breakout boards and drivers- I didn't say ALL but some. Leave the screws as they are, you can always upgrade later to ballscrews if you're seriously in trouble accuracy-wise. I'm a firm believer in taking things one step at a time instead of trying to throw everything including the kitchen sink into a retro. Get the basics down pat and operating reliably then add the bells and whistles later- one at a time.

If your motors spec's match up, get the Gecko 203v drives and a good breakout board. I'm using three 203v's and a CNC4PC C11 breakout board running Mach3 on my converted Bridgeport II copy and they work flawlessly together. I kept my old CNC controller but use it only as a DRO and comparing the Mach3 output position to the actual position on the DRO my 20+ yearold machine (with original ballscrews) will usually hold .001" and often better.

voltsandbolts
04-10-2010, 11:48 AM
How did your Millrite turn out?