Fix it! (Moving to fixed gantry)

[pippin88]

Hi all. I built a moving gantry router primarily out of MDF over the past 6 months. My own design, which was probably a bit ambitious. Now I am left with a machine that works... but is not square, nor rigid.

Parts I have:
16mm supported rails: 1100mm, 600mm, 300mm
1605 Ballscrews: 1100mm, 600mm, 300mm
Chinese 1.5kw spindle + VFD
Gantry bridge: 80x80mm aluminium extrusion 610mm long.


My concept is fairly simple:


The 1100mm rails bolt straight on to 30x60mm extrusion with 2 (or 3) cross beams.
Then some short length of 30x60 stick out. On to these bolt 60x60mm gantry uprights.
The extrusion will be joined by bolt in slot into tapped end + some corner brackets.
The gantry beam is then attached these with a bracket (not pictured) - this is the main problem with the design, obviously not as strong as gantry beam sitting directly on the uprights. However, unless I want to get rid the $50 piece of metal I have all set up with rails and replace it with a longer piece (which I'd do from 60x60, therefore need nuts etc adding to the $$$) then I'm stuck with this.
Also not pictured is bracing for the uprights in the X axis plane. I picture that this can be done very cheaply with sheet bolted to the outside of the uprights (triangle shape) with a free edge 'resting' on the table holding the machine.

Thoughts?
Load of crap?

[louieatienza]

Hi all. I built a moving gantry router primarily out of MDF over the past 6 months. My own design, which was probably a bit ambitious. Now I am left with a machine that works... but is not square, nor rigid.

Parts I have:
16mm supported rails: 1100mm, 600mm, 300mm
1605 Ballscrews: 1100mm, 600mm, 300mm
Chinese 1.5kw spindle + VFD
Gantry bridge: 80x80mm aluminium extrusion 610mm long.


My concept is fairly simple:


The 1100mm rails bolt straight on to 30x60mm extrusion with 2 (or 3) cross beams.
Then some short length of 30x60 stick out. On to these bolt 60x60mm gantry uprights.
The extrusion will be joined by bolt in slot into tapped end + some corner brackets.
The gantry beam is then attached these with a bracket (not pictured) - this is the main problem with the design, obviously not as strong as gantry beam sitting directly on the uprights. However, unless I want to get rid the $50 piece of metal I have all set up with rails and replace it with a longer piece (which I'd do from 60x60, therefore need nuts etc adding to the $$$) then I'm stuck with this.
Also not pictured is bracing for the uprights in the X axis plane. I picture that this can be done very cheaply with sheet bolted to the outside of the uprights (triangle shape) with a free edge 'resting' on the table holding the machine.

Thoughts?
Load of crap?

Seems like you can make your table a lot narrower, since your gantry travel would be the length of the rail minus the width of your carriage? Would make you gantry stronger.

[ger21]

Also not pictured is bracing for the uprights in the X axis plane. I picture that this can be done very cheaply with sheet bolted to the outside of the uprights (triangle shape) with a free edge 'resting' on the table holding the machine.

Thoughts?
Load of crap?

I don't think that the triangles resting on the table will increase rigidity at all. They need to be fastened to the tubes under the table.

[pippin88]

Seems like you can make your table a lot narrower, since your gantry travel would be the length of the rail minus the width of your carriage? Would make you gantry stronger.

louie: My lower Y rail runs on the underneath of the gantry beam. This means I can't get the uprights under the (current) beam. Changing the work table size won't change that unfortunately.

I don't think that the triangles resting on the table will increase rigidity at all. They need to be fastened to the tubes under the table.

Gerry: I should have been clearer, the braces would rest on the benchtop, not the work table. I'll CAD it up tonight.