G0704 CNC Conversion

Ok, so being a person who has a small taste of LinuxCNC and seeing the power it has, I have come to the conclusion that I'm gonna retrofit my G0704 with some CNC parts. Problem I'm having (before I spend $$) is understanding why I need to convert the machine to a ball screw setup. LinuxCNC has some very robust backlash compensation in the .ini file and seeing some others videos it makes me question as to why people jumped so fast to changing out the manufacturer lead screw. Am I missing something here? Just seeing if anyone in the community has some light to shine, is it due to torque from the motors and it going to need more than a nema 23/34? And if that's the case just gear it? (Slower feed rate but that's fine, I'm cutting metal, nothing I cut goes super fast) so then my last natural thought is due to backlash, so why not use Linux CNC to compensate, and leave the option to still have a manual machine? Anyone do that? Or is everyone a ball screw fan and I just need to suck it up?

I think there are 2 issues. Life becomes easier without needing to worry about Backlash. Ball screws have less friction.

Re motor size, a friend has a Syil mill which is based on a Seig SX3 (about the same size as yours) It came with Nema 23's on X & Y and NEMA 34 on the Z (plus ballscrews)

It's not just the cutting speed that you'll want t consider but also the rapids. If the bit needs to move from one end of the table to the other without cuttings you won't want to do that to many times at cutting speeds. I have a Sieg X3 that I converted. I have Nema 23s on the X & Y and a Nema 34 on the Z. The Nema 34 is geared 1.23:1 via timing pullies. These are the steppers I used.
Nema 23
Nema 34
I have 5mm pitch ball screws all around.

John

I believe there are a couple ball screw kits with brackets out there

BD-Tools is one, that I use myself, 540oz/in on all 3 axis, with 5mm pitch ball screws. The kits are quality, it almost seems a shame to actually install them, they look and are that well built.

For the BF-20 that are sold in Aus the BD-Tools gear needed a bit of fettling. That's not fault of BD-Tools but differences between the G0704 & BF-20. The BF-20 has a thicker casting for the X and Z.

The original nuts will wear over time and you will need to constantly adjust them.
Ballscrews have way way less friction.

When I first started my journey I used Hoss's, from cnczone, recommendations for steppers, drivers and PSU, to tell the truth I'm really happy. I haven't seen any reason to use larger steppers. I keep the Rapids pretty conservative on the Z axis.

Compared to what they were years ago when I bought my ballscrews and nuts they are pretty well affordable now.

I think it is often forgoten that backslash gives something i would call sponginess in your axis. One side the cutter movement is in same direction, working against screw, and on the way back the cutter pulls away from the screw what sometimes gave me chatters.
It got much better when i changed my fm4, similar 20 year old Chinese mill to ball screws. Only on the z axis, still with the old gear and pinon solution, i have this effekt.
But not yet any idea how to change the mecanic...

I read somewhere that backlash comp only really works when you are moving along one axis, eg drilling a row of holes on the X axis....It may have been on the emc-user mailing list or the dev mailing list. The explanation given made sense, when I read it.....

Ok my mind went to sleep, this thread is a good reason the keep backlash down

sourceforge.net/p/emc/mailman/message/36908085/