[giannifp]

Hello,
I'm working on upgrading a custom machine. Currently I have an issue with the Y axis. Axis is moved by a ballscrew, in the normal fashion, I have mounted a NEMA34 motor at the end of the shaft with a Ruland coupler. The problem I have is the motor which is a Clearpath Servo (CPM-SDSK-3441P-RLN) is sticking out too much past the end of the axis. The motor is close to 6 inches long, plus the 2 and change inches in the coupling, I have a protrusion of 8+ inches on the side of the axis. I'm looking for alternatives to mount the motor (a) with a right angle 1:1 gearbox or (b) use a pulley for which I could maintain the 1:1 ratio.

My issues are as follow: (a) is massively expensive (TrueNEMA by Thomson is about 1100 dollars) and (b) I can't seem to find a set of pulleys for the 0.5 inch shaft of the motor and 10mm for the ballscrew, something mix and match.

Any help or experience would be appreciated.

Thanks!

[Jim Dawson]

The 0.5'' bore is readily available, but the 10mm seems to be a bit hard to find. I would make a bushing that is 10mm ID x 0.5 OD and use a 0.5 bore pulley.

[giannifp]

Excellent... Thanks so much!!!

Any detriment or performance issues using the belt vs direct drive?

[Jim Dawson]

Excellent... Thanks so much!!!

Any detriment or performance issues using the belt vs direct drive?

You're welcome

None at all.

[cncuser1]

What is your reason to look for alternatives to the 8" protrusion? Is there a technical reason like no space in the surrounding environment? Or is the reason just a preference?

I have seen designs of CNC mill conversions where the motor is flipped 180 degrees and tucked under the axis, connected by timing pulleys. Also on my X2 mill the Nema 23 motors plus couplersd and mounting plates are about 6" all together, I suspect most other X2 conversions are in the same ballpark.

It is fairly common practice to buy pulleys and couplers with undersized bores and open them up to the desired diameter in a lathe or mill. Also it is not unheard of to make custom pulleys from scratch. I did it for the spindle of my X2 mill.

[giannifp]

It's more of a space constraint where the mill is located. It could be easily bumped. I have sourced the pulleys, but I'm still a bit worried about the effects of adding it with respect to backslash or even added vibration due to elasticity of the belt. I have never used them. I'll give them a try and see if it works.

Thanks!

[cncuser1]

There was post here a few years ago where the increase in backlash due to belt slack was calculated. The upshot was probably not significant for the home hobbyist.