All steel, no welding, 2000x1300x250mm

[eurikain]

Hi Wal, and thanks for the input :)

I appreciate the advice ! Though I think I won't worry much about this as this is my first build and as I don't intend to machine things that often (I'm still a student and the machine will only be accessible on weekends). I went with SBR rails because in my humble opinion replacing a $5 SBR block every so often is not such a problem :) The machine design is done so that you can take it easily apart whenever you want and put it back together without loosing starigthness, rigidity or anything, as steel won't move when mounting / unmounting.

May be in a later version of this machine I will switch to profile rails and HWIN blocks though :)

[Wal]

That's fair enough. Just thought I'd give you a heads up. Best of luck with the build!

Wal.

[eurikain]

That's fair enough. Just thought I'd give you a heads up. Best of luck with the build!

Wal.

Very nice of you, that's what this forum is for and I'm looking forward to reading all you guys' caution advices and design improvement comments !

[eurikain]

Hey mates ! (hahahahaha for those of you who will get it)

I spent yesterday modeling the Y axis. Today I will make the gantry sides to fix the Y axis, fix its motor, and connect Y and Z if I have the time.

Here is a render of the Y axis with a section view (calculated weight is 28kg):

[Wal]

Looking at your renders - in reality, your rails will be supported along their entire length, won't they? Not at intervals, like you've got them in the images..?

Wal.

[Clive S]

Looking at your renders - in reality, your rails will be supported along their entire length, won't they? Not at intervals, like you've got them in the images..?

Wal.

Wal according to his first post he intends to weld them to the supports so not using conventional rails. ..Clive

[eurikain]

Wal according to his first post he intends to weld them to the supports so not using conventional rails. ..Clive

That's right :) They will be supported at intervals. That's because they are integrated in the design. There is no efficient way to plasma cut full support profiles. Or you would need to cut the profile from lets say 20mm steel and stack all the supports next to each other, but that's just too much of a pain and would lead to alignment inaccuracy.

Supporting them at intervals won't cause binding of the 20mm plain stainless steel shaft, considering that the interval length stays reasonable. Current interval is 220mm on Y axis and 240mm on Z axis.

[toomast]

Something fresh and new!

Your calculated weight numbers seems to be very low! 10mm and 15mm steel is heavy stuff...

My experience with laser and plasma cutting tells me that positional accuracy is always good but edge is never 90 degrees. Plasma is worse than laser. It also gets worse with thicker materials. Most certainly you will have to use straightening tools since sheets are not flat. But good rubber hammer will get it fixed :D
You have to somehow make the openings for M10 nut pressfitted otherwise the nuts will fall out. That especially when you assemble the gantry...or you have another solution for it?

As for the rails...somehow I have a feeling that you will end up with HIWIN stuff.

[Sven]

Okay, allow me to state it again:

Using unsupported shaft in this machine will be a waste of money and effort!
Building this thing in steel allows it to be a good performer, using unsupported shafts will allow flex, making the results no better then the same thing built of plywood.

Then two general remarks on the design:

1: It seems to me that you will not be able to assemble this thing, as the nuts will be falling out all the time.
2: If you add tabs+rectangular holes here and there to position parts, you can probably glue the thing together, if you choose the right kind of epoxy.
If not using epoxy you can still use an occasional spot weld to fix a tab in its hole.