X3 conversion - ballscrew mounting question

[Neil_J]

I'm buying 3x Roton ballscrews and ballnuts this week for my Grizzly X3. For the conversion, I'm machining all the aluminum pieces myself rather than buying a kit. I'm also bribing a machinist friend to turn the ends down on a lathe and do the threading on the ends.

My question is, should I secure the ballscrew from both ends, or just a single side like the CNCfusion kit? (see link below)

http://www.roton.com/application_engineering.aspx#16

The link above shows four styles of mounting a ballscrew (fixed/free, supported/supported, free/supported, and fixed/fixed). The CNCfusion kit seems to be fixed/free. Would a fixed/supported or fixed/fixed system be overkill?

[DonF]

There have been a few people complaining about roton here. For my conversion I was going to research it further....
Homeshop cnc used to offer good ballscrews but it looks like they are switching over to another brand????

[philbur]

How you fix it depends on how fast you intended to run it. Is there some reason to doubt the procedure for determining the mounting layout given in the Roton link you posted.

Phil

Originally Posted by Neil_J I'm buying 3x Roton ballscrews and ballnuts this week for my Grizzly X3. For the conversion, I'm machining all the aluminum pieces myself rather than buying a kit. I'm also bribing a machinist friend to turn the ends down on a lathe and do the threading on the ends. My question is, should I secure the ballscrew from both ends, or just a single side like the CNCfusion kit? (see link below) http://www.roton.com/application_engineering.aspx#16 The link above shows four styles of mounting a ballscrew (fixed/free, supported/supported, free/supported, and fixed/fixed). The CNCfusion kit seems to be fixed/free. Would a fixed/supported or fixed/fixed system be overkill?

[tauntdesigns]

I like fixed/supported for X and Z and fixed/free for the Y. If using direct drive on the motor mounting I'd put the motor on the fixed end.

[Neil_J]

Originally Posted by philbur How you fix it depends on how fast you intended to run it. Is there some reason to doubt the procedure for determining the mounting layout given in the Roton link you posted. Phil

I won't be running super-fast rapids or anything. No reason not to use their procedure, I just like to get rules-of-thumb and personal accounts from people before starting an important project.

[Neil_J]

Originally Posted by DonF There have been a few people complaining about roton here. For my conversion I was going to research it further.... Homeshop cnc used to offer good ballscrews but it looks like they are switching over to another brand????

So I should stay away from Roton?? What exactly were they complaining about.. Accuracy? Overall quality? I did a lot of searching but didn't see anything that bad about them (probably looking in the wrong place).. They are pretty cheap so I guess it doesn't surprise me.

I don't need a super-accurate machine, but it does need to be usable. If I were to map out any linear error in the screws, and use oversize balls to reduce backlash (hopefuly to ~0.001) .. Maybe even a double-nut on the Z axis.. what kind of accuracy can I expect?

[Neil_J]

Originally Posted by tauntdesigns I like fixed/supported for X and Z and fixed/free for the Y. If using direct drive on the motor mounting I'd put the motor on the fixed end.

Seems a great way to go. I'll more than likely be going that route.

[phantomcow2]

Fixed/Supported will be fine for the X axis. I am getting 400IPM on my X3 with a .2" lead, fixed/supported X and Z, and never a problem. My ballscrews are 20mm diameter though.

[phantomcow2]

Oh, what kind of ballscrews are these? I used ground ones on my X3, so the diameter was maybe a micron over 20mm. Instead of trying to turn down these beasts, I simply used a 20mm ID radial bearing and had it lightly press onto the end of the ballscrew. Check eBay for ballscrews with at least one end already turned and journaled.

[DonF]

Originally Posted by Neil_J So I should stay away from Roton?? What exactly were they complaining about.. Accuracy? Overall quality? I did a lot of searching but didn't see anything that bad about them (probably looking in the wrong place).. They are pretty cheap so I guess it doesn't surprise me. I don't need a super-accurate machine, but it does need to be usable. If I were to map out any linear error in the screws, and use oversize balls to reduce backlash (hopefuly to ~0.001) .. Maybe even a double-nut on the Z axis.. what kind of accuracy can I expect?

They were complaining about accuracy. I couldnt find where Roton listed it? So that probably means they arent proud of it either.

[Neil_J]

Originally Posted by DonF They were complaining about accuracy. I couldnt find where Roton listed it? So that probably means they arent proud of it either.

Yep, Roton doesn't publish specs on their site.. I guess their targeted niche is linear positioning for factory automation.. think machines that cap bottles or ones that move car bumpers around. 6 thou of backlash wouldn't matter there.

As far as using them for hobby CNC use, I'm still really interested in them because they're about 1/3 as cheap as the other guys. I've read a few places that the linearity over the entire screw isn't great, but I can map that out in Mach3. What worries me is any irregularity in the ball grooves, especially since I'll be using over-sized balls. I just wish someone knew what the repeatability was...

[BZER1]

I've had my X3 for about a year now am I'm about to embark on a conversion myself. My issue is that I don't have alot of time to make the parts myself and getting the missus to part with the cash for the cncfusion kit is like pulling teeth...your own teeth. Is there another outlet for the items needed to make the conversion or are my choices limited to cncfusion or make it yourself? I would prefer to buy the ballscrews premade and make the rest myself. Buying a lathe is definately in the plans, but not for a while so for now I would have to pay someone to turn them down for me. I like the cncfusion delux kit but it's a bit expensive for me right now, and I never think that buying the cheaper kit and upgrading later is a good idea. Wow this is frustrating.

Now that I think about it maybe if someone out there would like to do some trading of services, I have a small powder coating/ceramic coating shop, I could do some coating for you and you could turn down my ballscrews for me. I'm sure we could come to some sort of agreement. I do work mostly for local Hot Rod shops and my quality is very high. I stock a few colors but would be willing to do the work and provide the powder at cost for a trade. Anyone? Anyone?