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customcutter
09-01-2012, 04:02 PM
Looking for opinions on CNC Masters(sp) retro kits.

Possible lead on a Enco 3HP mill with tooling, extremely low hours. Seems like someone (not a machinist) bought the mill, bought a cncmasters kit and started to do the retro conversion. They lost interest, sold it to a friend. Now a few years later, that person (a machinist) still hasn't had time to do the conversion. He has 2 cnc mills so doesn't need it. Wants to unload it. Ball screws/nuts are installed. All the parts are there to either go back original, or finish the conversion.

Starting to do some research on cncmasters. Just looking for opinions/thoughts on cncmaster kits. It's steppers instead of servo's. What other "issues" should I be concerned with?

thanks again,
Ken

MaxHeadRoom
09-01-2012, 04:33 PM
I see from others on the Mach site and others, quite a few have converted to Mach due to software quirks etc.
Seeing as the B.S.'s are fitted, it may the way to go?
Max.

outback
09-01-2012, 04:38 PM
I would say there are no issues unless the steppers and the power supply to run them are undersize. If you can buy a mill
with ballscrews 90% of the battle is over. Even if the cncmaster kit is useless, stepper motors are readily available on Ebay.
Gecko driver boards can be bought for $135 each then you need a breakout board and a powersupply and you have a CNC controller.

Then sell the cncmaster kit on Ebay.

Stepper motors that have 1100 oz/in of power should run a full sized milling machine with no problem. This is the motor
Bridgeport used on my Series I CNC.

People start these projects all the time then never finish them. I have built 5 CNC contollers from scratch. It is all about
reading instructions then asking the right people the right questions. Jim

customcutter
09-01-2012, 05:39 PM
I see from others on the Mach site and others, quite a few have converted to Mach due to software quirks etc.
Seeing as the B.S.'s are fitted, it may the way to go?
Max.

Can the installation/fitment of the BS be screwed up (no pun intended). If so what do I look for? Can they be adjusted to work improperly/properly?

thanks,
Ken

customcutter
09-01-2012, 05:43 PM
I would say there are no issues unless the steppers and the power supply to run them are undersize. If you can buy a mill
with ballscrews 90% of the battle is over. Even if the cncmaster kit is useless, stepper motors are readily available on Ebay.
Gecko driver boards can be bought for $135 each then you need a breakout board and a powersupply and you have a CNC controller.

Then sell the cncmaster kit on Ebay.

Stepper motors that have 1100 oz/in of power should run a full sized milling machine with no problem. This is the motor
Bridgeport used on my Series I CNC.

People start these projects all the time then never finish them. I have built 5 CNC contollers from scratch. It is all about
reading instructions then asking the right people the right questions. Jim

I was thinking if there were problems with the steppers I would upgrade to servos. If I did that what else would I have to change out?

OOPS, looks like you may have already answered that question.

thanks,
Ken

MaxHeadRoom
09-01-2012, 06:01 PM
Can the installation/fitment of the BS be screwed up (no pun intended). If so what do I look for? Can they be adjusted to work improperly/properly?

thanks,
Ken

Not all Ballscrews are created equal, the ideal is precision ground with pre-loaded ball nut = close to zero backlash.
Some use rolled B.S.'s for economy, these are particularly susceptible to B.L. if pre-load is not used.
One other critical issue is the pitch, what resolution you will get for a particular lead.
Manually turning the screw, and then reversing with a dial gauge touching a part carried by the screw will show up if you have any B.L. issues.
Max.

PaulT
09-01-2012, 06:02 PM
Can the installation/fitment of the BS be screwed up (no pun intended). If so what do I look for? Can they be adjusted to work improperly/properly?

thanks,
Ken

I bought a BP clone knee mill that had a "semi-pro" CNC conversion done to it, it was being sold with the ballscrews, brackets and motors but without any controller.

The ballscrews were installed ok but all the motor mounts, thrust bearings, spacers etc. all needed to be redone somewhat but that actually wasn't too bad to pull off, I didn't have to buy any new parts but remade spacers, redrilled mounting holes, etc.

The quill drive is the touchiest on these knee type machines, particularly in how the ball screw nut is mounted to the quill. Fortunately on this machine that was done reasonably well.

Steppers will actually work pretty well on BP conversions as the machine really doesn't have the HP or rigidity to make good use of servos anyway, unless you are making small 3D parts or something like that where you need high acceleration.

If your steppers are a little undersize (I agree with the previous poster, for a BP a modern stepper with 1100 oz-in or so works fine) you can still use them, you just won't be able to set your rapids and accelleration as high but they will work fine at lower speeds. But as I already said, a BP is not really up to that much speed anyway, I'd try out the motors you have and how it works.

The Mach PC controller program works well for these kind of machines but it does have a stiff learning curve to get it up and running but once you make it through that maintaining the machine will be easy. Another nice thing about Mach is that its easy to add a 4th axis down the road if you like. On my machine I added power to the knee also under CNC control, which is nice for parts where the 5" quill travel isn't enough, plus I don't have to hand crank the knee anymore.

Paul T.
www.springtest.com (http://www.springtest.com)