[awe1au]

Hi All,
I have been lurking around the zone for many months gathering many ideas on my own build and now I have some time to contribute something back, better late than never.
Being both time poor and on a limited budget my machine was built using a cheap and simple design. The SX3 is my one and only milling machine/drill press so all the parts had to be machined using it. I wanted to retain manual control and the standard leadscrews in the initial build, with the view to convert to ballscrews at a later date. The design was completely ad-hoc (sorry no plans) with the main disadvantage that quite a few holes are drilled in the original castings. It has been built from pieces of scrap aluminum; this explains the black paint on most of the pieces. The stepper motors (387oz all axis), gecko G540, power supply and timing belts/pulleys were all purchased from AusXmods - Modify Your World.
As a picture is worth a thousand words, I have included a few photos of the build and will be happy to describe in detail where necessary. The X axis is a direct drive, the y axis is 1:1 belt drive and the z axis is 1:2 belt drive. The pulleys and cable on the top are a simple counterweight system which was necessary using the standard leadscrew.
The machine is working but still needs a bit more work and I look forward to your comments.

[slashmaster]

Nice! I've never seen anyone put the motor for the Y axis in that spot before, did you have to sacrifice some of the Y axis to get it there? Looks like it would touch the column. Are you still using the Z axis crank?

[slashmaster]

Ah oh, I just realized you def had to have sacrificed a couple of inches of X axis to do that, you've got to make yourself a longer bracket and get a longer belt so your Y motor won't hit the column like that!

[cjdavis618]

Looks good and you should be able to make some nice parts with it.

One thing I do want to warn you about though is the small Z axis stepper. I also did the same in the beginning and had a nema 23 motor (425 oz) with a counterweight system. I took all of the components apart and measured them so I would know what the weight should be. The counter weight did work well for a few months, but one day the 1/4" shaft of the Nema 23 snapped and I lost that axis. I now use that motor backwards on my 4th axis.

But I would highly recommend that you get a Nema 34 motor for that G540. You can leave the counterweight, but I found that it made getting backlash adjustements almost pointless. Sometimes the cable would have a slight bit more tension in certain places along the counterwieght travel and caused some bad finishing ops.

[awe1au]

Nice! I've never seen anyone put the motor for the Y axis in that spot before, did you have to sacrifice some of the Y axis to get it there? Looks like it would touch the column. Are you still using the Z axis crank?

Hi
I can see why you may think I lose Y travel from the photo, but the everything clears the column (pulleys and stepper) and travel is the same as standard. I did remove the z crank and shaft, before I fitted the counterwieght to reduce the drag. The 387oz stepper still stalled ocassionally so fitted the counterweight and eliminated this problem. Maybe the z crank could be refitted, but for manual jobs (usually drilling/tapping) I prefer to use the z stepper as a rapid and the quill for down feed.

[awe1au]

Looks good and you should be able to make some nice parts with it.

One thing I do want to warn you about though is the small Z axis stepper. I also did the same in the beginning and had a nema 23 motor (425 oz) with a counterweight system. I took all of the components apart and measured them so I would know what the weight should be. The counter weight did work well for a few months, but one day the 1/4" shaft of the Nema 23 snapped and I lost that axis. I now use that motor backwards on my 4th axis.

But I would highly recommend that you get a Nema 34 motor for that G540. You can leave the counterweight, but I found that it made getting backlash adjustements almost pointless. Sometimes the cable would have a slight bit more tension in certain places along the counterwieght travel and caused some bad finishing ops.

Hi thanks for the advice
Were you using a reduction drive belt or a direct drive on the z. I have a 1/4" shaft at the end of the leadscrew so with the torque multiplication it will probably break that one before the stepper shaft, here's hoping. I haven't had the backlash & finish issues yet. I think my counterbalance may be a bit lighter than yours,not be a true counterbalance but just helps the z up travel. I wasn't very scientific about how much wieght I put on, I just kept adding until the stalling stopped.

[SCzEngrgGroup]

The counter weight did work well for a few months, but one day the 1/4" shaft of the Nema 23 snapped and I lost that axis.

Did you perhaps have a rigid coupling between the motor and screw on that axis? I don't see how a 425 oz-in motor could snap a 1/4" shaft due to excessive torque. But a rigid coupling, if the shaft alignment is not absolutely PERFECT in all three planes, WILL fatigue the shaft, eventually causing it to snap.

Regards,
Ray L.

[cjdavis618]

Did you perhaps have a rigid coupling between the motor and screw on that axis? I don't see how a 425 oz-in motor could snap a 1/4" shaft due to excessive torque. But a rigid coupling, if the shaft alignment is not absolutely PERFECT in all three planes, WILL fatigue the shaft, eventually causing it to snap.

Regards,
Ray L.

I used the CNC fusion kit and the pulley was alliged with the shaft of the leadscrew. There was no torqing involved that was off center. The CNC fusion pulley is set screwed into place and I used blue loctite on the threads to make sure the pulley didn't come loose.

I was in the middle of a finishing operation at about 30ipm on a 10/22 receiver block test out of wood when it snapped. I assure you it can happen, because it did. Right at the base of the pulley. It is possible that I had the delay of the counterweight that amplified the problem, but it snapped none the less.

[rwskinner]

Do you remember what the weight was on that head CJ?

I took all of the components apart and measured them so I would know what the weight should be.

[cjdavis618]

Mine weighed 104lbs with all equipment on the head. I'm sure the castings could vary a small bit, but if your counter weighting, it shouldn't matter that much if you have a larger stepper.

[awe1au]

I weighed my counterwieght today, just for comparison and it is 30kg (66lbs). Quite a bit less than 104lbs but it does work well. I dont have any stalling problems now I have fitted it and I rapid at 750mm/min.

[LeeWay]

I use a gas strut on my mill and it is rated at about half of what the Z axis weighs.
It simply assists the motor with lifting and is strong enough to stay in place when powered down.
If you use the full weight of the Z, then the motor will have to work just as hard lowering it as it would raising it without any weights.
I did add a second to strut to test my theory and that was my conclusion.

The conversion looks good. Lets see some machined goodies.