Best rails position on frame in a dusty workspace

Hello,

I am currently designing my first plasma table with a 2x1m cut area.

The thing that questions me the most is the problem of dust on rails, and more generally how to protect rails.
I plan to use Hiwin HG20 or 25 rails, but I worry that dust and cut projections can wear rails or carriage. I think about put rails on sides, or under sides (suspended gantry) but this only partially resolve the issue.
My workshop is very dusty (because of lot of different activities), and I do not want to clean my rails before each job.

What could be your advices / hints for this point ?

Precision : this table will not be used intensively. Only few times a month. And I have already made an investment on a Powermax 45xp with CPC port, a hand torch and a mechanic torch.
And I have already read those really nice posts :
forum.linuxcnc.org/plasma-laser/35349-cn...fo-and-guide?start=0
forum.linuxcnc.org/show-your-stuff/38547...plasma-build?start=0

Thanks in advance,
Have a good day.

I would recommend placing the rails as far away from the cutting area as possible. Mounting them on the side of the gantry will work but I would advise to cover the top of them with a section of flat bar.

On the large industrial machine I built, I mounted them on the side of the gantry but water and dust got onto the linear bearing and destroyed them. I ended up making a cover plate to stop dust and water getting on them and they have been going for a few years in a extremely dirty environment.

I am thinking to use something like that :

It has the advantage to serve as fairing in addition to dust protection. But I am afraid to have to use Hiwin dust accessories nevertheless. Those damn accessories that curb displacement...

What you have drawn should work well.

Ok, thanks for this reply

I think you need to improve the upright now. There are a lot of inertial  forces from movement on the gantry that will apply bending moments around your proposed gantry plate anchor points. You can't afford to have sideways movement on the gantry rail as accuracy will suffer.

Thanks, Rod.

The schematic is just a draft to show dust protection. A gantry designed like that would certainly have some lateral flexion. I will soon make some plans and post a subject on my project.

I try to treat on the forum the different part I am not able to resolve myself, mainly part that are non-intuitive to me, like drivers, encoders, dust, etc.
As a metal craftsman, the frame part is intuitive to me and should be a pleasure. As soon as I find the trick to be able to adjust rails parallelism (my next headache ).

To keep your frame parallel, weld it with a gantry in place. I made a simple one that ran on th eunderside for this purpose.
You can mount the rails oan a seperate plate bolted on and shim it if required to get parallel
For vertical alignment, you can sit each end of the plate on adjustemtn grub screws, then clamp the plate off when in position. A commercial manufacturer would likely mill the rail locations, maybe even when in position on the machine itself....

Thanks for these tricks Rod. I see how t o design my frame now

There are some interesting tricks used in this build:





He is making a router, based on a sturdy wooden base, so not a plasma, but some of the setup ideas might be useful for a plasma.