What is a proper way to raise rail (NOT table!)

[Wojciech Szul]

Hello,
First have to say - I'm not talking about laser table, but exactly about rail. I have HiWin MGN12C in my cheap Chinese machine and looks like one from rails is a slightly lower on one end - so optical plane is not perfectly flat but looks like a propeller. I can compensate it by dropping one side of the table, but this will have influence on verticality of cut - and I don't like it.

So I need a advice what is a proper way to raise one side of the rail. It is very slight - hard to estimate, but will say 2mm on 70cm. Can I use just standard round washers directly under rail, or I have to raise whole profile which is under rail? I have hard access to bolts, so I'm bit afraid to touch it.

375797

[Dave Sheldrake]

Raise the entire profile or the rail will bend

[Wojciech Szul]

Rail will bend Thanks Dave. I was afraid of that, and thought is a any "_magical_ washer set" to do this job. I will wait till summer.

[Gary Hair]

I don't know that machine, but wouldn't it be better to swap out the part of the machine that's bent, causing the rail to be out of parallel? I'm afraid raising the rail is just a band-aid and there are likely other defects that you will fight with to get/keep things aligned.

[Kev Williams]

If the right right rail is lower at the Y low point, then wouldn't NOT straightening put stress on the X rail, possibly causing IT to bend?

I would just figure out how much shim you exactly need at the end to get it parallel to the left rail, then make it, plus one or two proportionally thinner shims to fill the gap(s) between the 2 ends...

[Bill George]

Is this what it is? https://www.ebay.com/i/142642044982?chn=ps

Rail and linear bearing and the rail is bent??? Replace it.

[Wojciech Szul]

Is this what it is? https://www.ebay.com/i/142642044982?chn=ps
Rail and linear bearing and the rail is bent??? Replace it. Rail itself and profile underneath is a straight, machine quality is poor and looks like frame itself is a NOT perfectly flat - so have to raise profile with rail slightly to acquire "optical flatness". Tomorrow I will go back to check it again. Is not very bad, I was cutting products from 9mm ply (non-laser grade water resistant BWR) 80W CO2 DC, but want set machine really good.

[Dave Sheldrake]

Not unusual on some Chinese makes to be honest, all the bolt on's are straight but the machine frame is all shot to hell and on the pee

[Ian Stewart-Koster]

Put a coin on the floor under that corner leg...

[Rich Harman]

I would use shims like Kev said. I had to do the same on mine, I used one shim (piece of plastic from some packaging) to raise the back end of one rail. From your picture it looks like the rail is mounted to a section of square tubing. If you can shim up that square tubing (profile) it would be better.

[Mark Canada]

Shim the hollow section it's sitting on, only secure the hollow section at either end with 1 bolt - that way the rail and hollow section will remain flat.
My laser's frame was bent during shipping - one wheel went through the pallet... so it's not alway poor contruction, but poor packing. Thankfully on my laser it didn't affect the optical path/flatness like yours!

[Wojciech Szul]

It's NOT very bad, I have this laser over 1.5 year and have done serious number of test. I estimate this displacement to at most 2mm - maybe less, as is a hard to measure. Definitely laser is still "workable", but I love tools which are working very well, not just "OK".

376583
This is picture of paper fitted to front of the head. Two shoots - on top right and bottom right positions of the table. And this slight "blur" is difference. Best visible when firing second shoot. Not a big displacement. On left top/bottom shoots they cover each other perfectly. Actually at this moment I have idea how to measure it better, but first have to check it.
Thanks all :)