Router Build number 2

[Boyan Silyavski]

Using extrusion will speed up the build immensely. if i am building a small multi function machine for me, thats exactly how i would do it, wider Y and shorter X, so i can use it for bigger jobs.

[JAZZCNC]

If your wanting high quality surface finish in aluminium then that setup is wrong way to go about it really. Unless the gantry is very heavily built it will vibrate along the long length and affect surface finish. Over building just costs more money so best avoided.

Would be much stronger traveling down the length with nice short stubby gantry.

[charlieuk]

How over built are we talking? the ability to take a full sheet of ply is worth something. If it wasn't the space restrictions I have I would be building a 8x4 machine in which case I guess I would be building the stronger gantry anyway.

I guess the only other way would be to have the gantry going down the length on the raised rails but have it only supported at ether end so a sheet can be passed under it?

[Boyan Silyavski]

Dean is right, if you expect perfect finish on aluminum you will have to overbuild like mine build. Ok maybe not so much but simplest will be 2x 100x100x3 box section welded together. Or something in the same range of strength at least. But also have to be fast so you can do HSM with light fast passes. But honestly i dont see how over that span you will go under 100kg gantry at least. My gantry is 180 kg for example with all mounted.

Dont you have now a large machine to do that stuff??

[charlieuk]

my large machine only has a width of 760 and was not really designed for much more than cutting foam fast.

[charlieuk]

something along these line but I guess the side rails would need to be more over built than this but I'm not sure it would be any better.

[JAZZCNC]

How over built are we talking? the ability to take a full sheet of ply is worth something. If it wasn't the space restrictions I have I would be building a 8x4 machine in which case I guess I would be building the stronger gantry anyway.

Charlie You said cutting Aluminium to high surface finish, ply is different thing altogether. Your first design will quite happily cut ply but aluminium is different matter. The Stiffness required goes up quite lot and to have high quality surface finish it goes to another level. Anything you can do to lessen resonance will help with surface finish so long hollow flexi beams are best avoided.
This means using thick walled heavily braced and stiffened design which opens up complete new set of issues regards ballscrews,servo, controllers etc which get expensive quickly.

If your spaced limited look at building vertical. You'll get 8x4 in the same space as your First machine. Something along the longs lines of this which I'm building at minute thou for high end aluminium I'd change the design slightly and do away with gantry sides.

[charlieuk]

I had wondered about vertical but it wont help much as I don't have much wall space spare to push up against, certainly for 8x4. I guess I will ether have to go for less quality on the aluminium or for go the ability for full sheets.

[charlieuk]

what would be the best I could hope for quality wise on aluminium for something bassed on the first design ether made from ali or a welded steel frame.

[Boyan Silyavski]

For cutting aluminum if gantry is from alu profile, then make your gantry as Dean makes his machines, L shaped. To simplify things for you, check data for 2x 100x100x4mm or 200x100x4mm on the span of your intended gantry and that should be your minimum, aluminum or not. I am talking about the moment of inertia of the beam.

I have a complete drawing of my machine in Sketchup which has 1300x2600x200 mm working area. Later i revised it again piece by piece as i sold plans to some interested people and reflected the changes and what i have learned from the build and even further simplified some stuff for easier experience of putting it all together. Also corrected some details for the cheaper Chinese servos to fit there. I believe $ per strength my machine is an incredible value, where 700kg of metal do what normally 3 tons of metal do. I was contemplating also to redesign all instead of Sketchup to make it in NX or other CAD. So its easier to visualize and make a manual with instructions how to put it together.

In other words i dont mind giving the CAD for free but in order to update it with variants like L style gantry, etc. its an enourmous work. So i have to be stimulated to develop all that further, as its absolute stupidity for people again and again to try to reinvent the wheel for months when i have spent half an year designing fast and strong CNC which i know every little detail about it. The fact that i could machine mild steel 1mm DOC with Z axis fully extended and have perfect finish should speak enough about the quality of all. I am not selling you sth here, but if you want to save time and effort and help further with the project, PM me and we can arrange sth.