Small Gantry Router

[EddyCurrent]

thanks Eddy...more questions..

1, diagonals into corners why not?, ditto connecting 2 at the middle (sorry, I am one of those people that like to understand the why)

Jazzcnc
Be careful when welding the diagonals where they meet in the centre, don't weld both at same time has you'll be putting a lot of heat in one spot.

I assumed same might apply to diagonals in the corners, also it was suggested by silyavski to put the diagonals so they were about 1/3 way up the legs and also supported the upper rail at more places than just the centre point so I put them at 45 degrees which spread them across the upper rail but not at the same place as the short upright stubs supporting the linear rails beam.

[mike os]

Assuming that the base is basically OK.... will update drawings in final draft for asymmetric layout

What is a reasonable weight for a gantry given the OP? planning on steppers for drive, I guess 2 rather than 1 and belts.
ballscrews or rack for Z.... or does it make little difference at this size

been playing in steel, bolted/glued rather than welded as I don't want to have to take it to be machined & weight seems very excessive...

I am Aiming for about 240mm spacing on y rails and at least 150-200mm on z, does this seem about right?

[mike os]

playing with gantrys... please ignore drawing errors....just reused parts to get some ideas together

1, steel, with welded beam (100x50 box), 4/6mm brace. Ends & bearing carriage are 10mm bolted and tacked or TIG brazed if necessary and bolted to gantry beam. gantry approximately 930 wide, weight approx. Mass approx. 52kg

[mike os]

Gantry 2
Still all steel, this could be fully bolted, which eliminates any heat distortion issues, again can be TIG tacked or TIG brazed if necessary
A little heavier, but easier to ensure no distortion and should be a lot stiffer? however this weighs in at 66kg!!!
Cant help feel that is getting a bit much, but I really don't know

[mike os]

Gantry 3

Steel ends, aluminium box and plate gantry beam, all bolted
This checks in at a more reasonable 40kg

[mike os]

Am I worrying too much over the weight?
Which design is heading in the right direction? or am I going the wrong way?

on all the above the COG is low and just forward of the middle of the gantry beam

[EddyCurrent]

Only the first version has a space for the Y ball screw I think. One good thing about aluminium box section is that it's quite accurate dimension wise, I put my rails top and bottom and using a vernier the distance between them was the same right across the gantry.