Worn leadscrew?

[Husky1]

Doddy: rails had 0.03mm error on 700mm

[JAZZCNC]

i am using 15mm tbi motion linear rails on the gantry. I have changed my setup 6 months ago, moved leadscrew too high above the linear rails. I am always pushing my machine to the limits of the spindle (3000mm/min, 2mm wall, 15mm deep, 10mm endmill). I think this was the cause to wear them. I didnt have any issue before the change.

I am changing gantry rails now with 25mm, and putting leadscrew between the linear rails. Considering buying 6.6kw hsk63 spindle.

TBI are decent enough linear rails and I still wouldn't expect them to wear out like this, also those cutting parameters while at the limit of the spindle shouldn't be anywhere near affecting the linear rails.
If the machine cannot handle 2.2Kw or 3Kw spindle then it certainly won't handle a 6.6Kw HSK63 spindle and just fitting larger rails may not be enough. I would look carefully at the machine to see if can find any other cause for the rails wearing out in that manner because I'm pretty sure it's not just because you have moved the ball-screw position. That large spindle will quickly find any weak areas and you could be back to square one chasing issues.

[m_c]

TBI are decent enough linear rails and I still wouldn't expect them to wear out like this, also those cutting parameters while at the limit of the spindle shouldn't be anywhere near affecting the linear rails.
If the machine cannot handle 2.2Kw or 3Kw spindle then it certainly won't handle a 6.6Kw HSK63 spindle and just fitting larger rails may not be enough. I would look carefully at the machine to see if can find any other cause for the rails wearing out in that manner because I'm pretty sure it's not just because you have moved the ball-screw position. That large spindle will quickly find any weak areas and you could be back to square one chasing issues.

If the machine is using this design - http://www.mycncuk.com/threads/10118...2769#post82769 I'd say it'll be putting quite a lot of leverage on the rails through cutting forces.
Looking at the diagrams, it must be verging on a 2:1 leverage between the lower trucks and the upper trucks, which I'd guess will be pushing 15mm rail to their limits.
However I'd probably look at doubling up the 15mm rails, rather upsizing given the design.

[JAZZCNC]

If the machine is using this design - http://www.mycncuk.com/threads/10118...2769#post82769 I'd say it'll be putting quite a lot of leverage on the rails through cutting forces.
Looking at the diagrams, it must be verging on a 2:1 leverage between the lower trucks and the upper trucks, which I'd guess will be pushing 15mm rail to their limits.
However I'd probably look at doubling up the 15mm rails, rather upsizing given the design.

If I remember right there are 3 rails on this Y-axis design with 2 bearings on each rail so I wouldn't expect them to wear out the rails in just over 3yrs. Even the bearings should last that long and they would wear long before the rails.? . . . But you could be right because the Z-axis is a long lever.?.

Matt which rail is worn out and how many does it use.? . . . Also how many hours does the machine have on it.? (mach3 will tell total operating time)

[m_c]

I had just assumed it was the Z-rails...

Y the load should be spread over a larger pivot, however it'll do far more movement than the Z, so any dirt ingress/lubrication issues could wear it out quicker.

[JAZZCNC]

I had just assumed it was the Z-rails...

Y the load should be spread over a larger pivot, however, it'll do far more movement than the Z, so any dirt ingress/lubrication issues could wear it out quicker.

No, I'm pretty sure Matt had 15mm rails on the Y-axis and 20mm on X & Z. This is why I'm surprised they have worn.
I've got a machine with 20mm Hi-win rails that I bought second-hand 15yrs ago so could be the best part of 20yrs old which have been completely utterly abused and neglected with hardly any maintenance on a machine that solely cuts Aluminium and still the rails are not excessively worn.

It takes a lot of abuse to wear these rails and even thou 15mm I'd still expect them to last 4yrs on a machine which I'm sure isn't working in a production environment.

[Husky1]

Sorry for late reply.

To explain: My first y axis setup did have 3x 15mm rails and the leadscrew in the middle of the rails. No issues. Then i redesigned the z axis so i could fit my bt30 spindle there. Two 15mm rails stayed there and i removed the third rail and in addition i relocated the leadscrew. Now the leadscrew is not in the middle of the rails but on top. This 2 modifications caused the rails to wear faster since only 2 rails left and the leadscrew on top made additional leverage on z axis. Machine works 8h/day all week, half of the time the 2.2kw spindle is on the limit. After changing top rail with the spare one, the error was gone.

I am changing the design again. I am getting 2x rexroth 25mm rails for y-axis and placing leadscrew in the middle and hope there is enough room left for the big hsk63 servospindle.