Small Gantry Router

[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.

[mike os]

Hi Eddy

I thought if I used either of the others the ballscrew could go at the back? (behind the gantry beam...or should it be as close to y axis rails as possible?)

It is the dimensional accuracy that is tempting me with the aluminium section... one less thing to think/worry about, and a 15kg saving on weight cant hurt... or will the extra mass help with damping?

would a bolted aluminium gantry be stiff enough for light aluminium/brass work?