# Thread: Length of Ballscrew and Rails for 1000mm travel?

1. ## Length of Ballscrew and Rails for 1000mm travel?

Hi guys, i want to purchase the ballscrew machined for 1000mm travel but dont know how much need to be the length of the ballscrew and the rails.

I want to purchase
1 x THK Rails with SSR20 for 1000mm travel
2 x SFU1605 with signle nut for 1000mm travel

but have a priblem to calculate the final length and how calculate, i think that i need to extract for example from the THK rail the length of the SSR20 Block Bearing.

the drawing that i will use for machining the ballscrew are this http://www.slidesandballscrews.com/p...ng%20600mm.pdf

2. Hi,

If I read your post correctly I believe the minimum answer is the length of travel + the distance between the mounting blocks of your moving gantry. This assumes that your spindle is mounted in the center of the gantry. You should add something in rail length for error, over run, limit switches, etc.

Correction: + the width of the gantry, not one half.

Robert

3. thanks for your support, and yes the spindle will be in the center

4. Originally Posted by RTP_Burnsville
Hi,

If I read your post correctly I believe the minimum answer is the length of travel + one half the distance between the mounting blocks of your moving gantry. This assumes that your spindle is mounted in the center of the gantry. You should add something in rail length for error, over run, limit switches, etc.

Robert
Shouldn't it be full distance - you have one half overrun on each end which makes two halves.
As for the screw, it can be shorter than the rails depending whether it's possible to mount the supports under the table. but the threaded part must be at least the travel plus the length of the nut.
But is generally good to leave some spare length for later small modifications.

• Originally Posted by RTP_Burnsville
Hi,

If I read your post correctly I believe the minimum answer is the length of travel + the distance between the mounting blocks of your moving gantry. This assumes that your spindle is mounted in the center of the gantry. You should add something in rail length for error, over run, limit switches, etc.

Correction: + the width of the gantry, not one half.

Robert
Fixed Typo....

• well, for 1000mm length 16mm diameter ball screw are not enough? will be better if purchase 20mm?

is OK to mix ballscrew diameters in differents axis? later is possible to configure match or any other software to calculate the steps because that?

Regards