Steel/Aluminium design/build, sorta smallish, cuts ali hopefully

[mart154]

Been busy with other things recently and finally decided to have another crack on the design.

The work area has increased a bit and gone a bit beefier.

The work area is now 890x1000
The cutting area should be about 670x780 now.

Main frame is now 50x50x3 box. The rails bolt on to 60x60x5 (blue)
The green bits are 30x30x2 box to support the baseplate.
The gantry is still 120x120x5 ali box.

So any feedback is greatly appreciated before I start cutting the steel :)

[JAZZCNC]

Looks ok to me but I'd change the way the bed is constructed to help keep side frames from being pushed while welding and cut down on steel.

You won't need mesh that tight so I'd drop 2 of the long rails and flip other around and take rail across machine from each side in centre, this will hold sides together better and lessen chance of welds pushing/bending side rails. I'd then run the others up the machine and space outer ones so they land on the edge of the planned cutting area, they will support whole cutting area better. You will probably have a lower bed that goes right up to the sides but you'll also have a spoil board that is the size of your cutting area so ideally you want the edges of this to land on the supports and not rely on the bed underneath which isn't supported.
This also means you could drop the green bits because the bed will be supported where it matters, in the cutting area, and the small overhang which is a cantilever won't matter has it has no forces acting on it.

Other than that then fire up the saw. .

[JAZZCNC]

Oh forgot to spot this but was more looking at the frame than the gantry.! . . . . Mentioned this before many times .!! Wouldn't have the Y axis like that with a rear piece so basicly creating a box with no sides. It's just adding weight and costing money it gives very little strength. Get your self a card box and cut sides out and see what it does.?? . . .Same principle.

It also adds other complications in the build because if the edges are not machined perfectly 90deg it skews the box making it parallelogram which will cause bearings to bind and stick when bolted together.

[mart154]

Thanks! Got it on the frame. Makes absolute sense! :) I was already designing some jigs in my head to keep weld distortion under control. Now I can probably ditch those.

But with the Y. I basically just copied some designs I found here and there and I don't really have any more ideas. :(

[JAZZCNC]

I was already designing some jigs in my head to keep weld distortion under control. Now I can probably ditch those.

Jigs to stop distortion are not practical really.? Heat cause's distortion and stress so to restrain these forces would need massively strong Jigs which for a one time machine just isn't worth the trouble. If you stitch weld in short runs and spread welding around so not to create heat build, Take your time and don't try to weld frame in one go let it rest and come back to it then you won't have much trouble.

Tips to help with stress relieving are Stitch weld and balance the welds IE: If you weld for half inch on outside face of steel box then immediately weld half inch on inside face opposite to keep balanced stress's. Don't weld all of one side up then turn over and do other, Also Don't weld in one spot for long but Move around and try to weld with minimum heat.

But with the Y. I basically just copied some designs I found here and there and I don't really have any more ideas. :(

I'd just move the rails on Gantry closer towards front and just have narrowest top and bottom brackets possible you won't need any thing more than that and they will be more than strong enough. Edit: When I say narrow I mean looking from side not narrow bearing spacing.!!

I noticed your Z axis plates look on the thin side what thickness did you have in mind.? For the front and rear Z axis plates I wouldn't go less than 15mm and 20mm is best balance of strength and cost.

[mart154]

I make my living with welding and have big strong (200ton tested) jigs I could use and know how to hold weld distortion to minimum :)
But still I like your idea for the bed more. The massive amount of steel I designed there was in a hope that I could maybe use 15mm ali bed and stop excessive movements with the frame underneath.

So with the Y you basically suggest a structure shaped like a PFC?

Z axis plates? You mean the plate where the spindle and Z axis rails mount to? It is intended to be 20mm. At least in my head, have to check the drawing tho :)

[JAZZCNC]

I make my living with welding and have big strong (200ton tested) jigs I could use and know how to hold weld distortion to minimum :)

Well your sorted then and you'll understand why I said what I did thinking your DIY welder with minimal resources.

But still I like your idea for the bed more. The massive amount of steel I designed there was in a hope that I could maybe use 15mm ali bed and stop excessive movements with the frame underneath.

Yep it would have been but personally I'd only buy enough to cover the cutting area has Ali plates expensive and even with ali plate you'll want the edges supported. My steel Bed frame is larger than yours with less supports than you first drew and with 16mm ali bed and I don't have any probs with movement. Unless your throwing engine blocks on it then there's very little forces acting in a downward direction while cutting and you really want to limit plunge cutting to a minimum for spindle and machines sake has it knocks shit out of them.!!

So with the Y you basically suggest a structure shaped like a PFC?

Yep just like a PFC ( Parallel Flange channel for those wondering.!!)