Length of ball screws vs axis travel

[Sup3rfly]

Hi everyone. I’m into my first diy cnc mill. I’m stuck however on how to go about picking ball screws when it comes to their actual physical length vs the travel distance of my x, y and axis’. All the ball screws I’ve come across seem to be too long or too short. Am I missing something here? Then I’m stuck at what driver I’ll need for the motors.

[peteeng]

Hi Sup - You 1) have to design the machine based on premade lengths 2) order the screws made to length 3) Buy premade lengths but machine the ends yourself to suit. I get screws made to length from BST Motion... Peter

https://bstmotion.aliexpress.com/store/314742

[pippin88]

Any decent seller will machine to length.

I wouldn't buy from a seller who won't machine to length as it means it is not their main business and they are probably just drop shipping.

[Sup3rfly]

You both have great points. I’ve picked the grizzly g0704 that being said do I go off of the travel distance measurements for the x y and z given in the specs of that machine or is something I’ll have to measure for myself once it arrives?

[rcheli]

When converting a mill you will likely have less travel than you get on the mill as delivered. That is because the ball nut or nuts are longer than the brass nut that the lead screw goes through. When the table or saddle travels to their limit the screw supports will eventually hit the nut and that is the max physical travel. When I converted my Sieg X3 I wanted to retain as much travel as I could so I ordered longer screws than would have otherwise come with the conversion kit. I added spacers at both ends of the table to allow the table get as much over hang as I dared. I ended up with a total of 2.7 inches of spacer split between the left and right ends. Roughly 1.93" on the left (motor end) and the rest on the other end. I was able to get travels of X =19.7 Y=6.92 and I could get another .5 in on the Y if I did some more work on it.

[Sup3rfly]

Sorry I’ve been away do to work.
So far from what you all have shared with me Its best if I buy the mill first before I order the ball screws. I don’t know why I thought I could go off the machines given specs on x, y and a travel.

[rcheli]

Sorry I’ve been away do to work.
So far from what you all have shared with me Its best if I buy the mill first before I order the ball screws. I don’t know why I thought I could go off the machines given specs on x, y and a travel.

That would be best. You can also check for ball nut clearance and figure how you are going to mount the screws and what style nut you want to use.

[catahoula]

Check out the kits available for G0704 conversions, probably save you a lot of hassle. I just found out the hard way that many pretty annoying details show up in selecting ballscrews

[rcheli]

Check out the kits available for G0704 conversions, probably save you a lot of hassle. I just found out the hard way that many pretty annoying details show up in selecting ballscrews

Yes, and it's really hard to make or modify conversion parts when your mill is all apart. I went the deluxe kit path with custom length screws.