Something Old, Something New..Upgrading An Old CNC Millrite

[Too_Many_Tools]

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]

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]

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]

Originally Posted by Al_The_Man 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]

Servos are no problem with Mach software combined with Gecko 320 drives.

Eric

[Too_Many_Tools]

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]

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]

Originally Posted by NC Cams 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]

Originally Posted by Too_Many_Tools 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]

Originally Posted by Too_Many_Tools 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]

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]

Originally Posted by cjmerlincnc 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