[snapman]

Hi there,

I am converting a Light Machines Prolight series mill back to mill form- it was modified for use manufacturing stents and the original motion control system and motors, motor mounts, axis end covers, etc...were removed.

My question is this- (and I apologize for its simplicity, but I wanted expert opinions because I have found simplicity in CNC to be deceptive)-

Is there an advantage to using a bigger size motor of similar holding torque? Specifically, my options are:

- Order some components from Intelitek for the original NEMA 23 configurataion and use the current system and motors we have- Flashcut with 3.5 amp microstepping drive and 250oz steppers.

Or

-Use the NEMA 34 motor mounts that are on the machine now- and order new steppers from Flashcut in NEMA 34.

Both options cost about the same. And if we wanted to step up (pun intended ) to the more powerful 425oz NEMA 23s on our current system, the cost of similar power NEMA 34s from Flashcut are still about the same.

Is there an advantage to a larger physical size motor? Both choices have other advantages and disadvantages- 34 size mounts are installed in such a way to allow a large variety of gearing options while the NEMA 23 mounts look to be rather a tight fit and gear down 2:1. I would really like to use a 1:1 with the 5tpi ballscrews which should give me around 75-100 ipm which is plenty for me and most of the stuff I cut for us is in the under 40ipm range so I would be in the lower rpm area of the steppers.

On the other hand, the NEMA 23 mounts are what would come stock and allow the use of the stock swarf guards, belts, and also do not get in the way of longer pieces of material on the table like the mount on X does at the moment.

If you cannot tell this yet- I ramble once I get going. I just would like to hear any input from you guys either way so I can make the best decision or discover what I have overlooked

I have also attached pictures of the current motor mounts. Another post on this forum in the project log section, retrofitting another prolight, shows a picture of the original setup on a TMC 1000 which would be the same.

Thanks for reading and I look forward to hearing your thoughts.

Ryan

[NC Cams]

You might want to check here for a starter:

http://www.cnczone.com/forums/showthread.php?t=17707

[snapman]

Cool, thanks for the link- I will check it out.

I just don't want to assume that a NEMA 34 at 424oz is the same as a NEMA 23 at 425oz (besides the one oz difference and the different size bolt circle)

Logically, to me, it seems they would be the same...but my logic also told me to slow the feed down when I experienced chatter...and that 4 flutes would be better than 2 when making deep cuts, etc..etc.. I have not been right to many times when I have assumed stuff dealing with CNC...

I am gonna go download that software now though. Looks cool.