Well here goes... Aluminium frame router design

[Boyan Silyavski]

Yes,about the epoxy, the 10mm at each side is ok, given that you weld to the mm the frame.

i also am wondering about that diagonals and at the same time big holes in the middle. I don't know the top you are planning on but generally i wouldn't have a hole in my table bigger than 300mm, otherwise you will need 50-70mm top if made from ply or similar. even alu top would benefit from such maximum distance.


IMHO you are mistaken about the ball screw end mounts. Do yourself a favor and design it similar like i did them from 10mm plate and additional plates that screw to that perpendicular reinforced with ribs plate.
Or you could find your self in a scenario that you have to file shims or even worse, what you will do if the ball screw has to go inside direction?
I believe the way i did it was simpler especially for precise alignment of the ball screws. Meaning that when gantry is mounted and squared, i just screw the nut to the nut plate and moved the gantry one side by hand. Screwed the ball screw mounts, then repeated at the other side. Then tightened. So no fiddling with alignment and so.


About the welding i also have not welded before. Played around a bit , watched some videos on YouTube and was good to go. Just remember- if arc or mig welding the most important thing is to keep the arc at the same distance and watch the pool and spread it, not think about quality, instead think about welding strong with good penetration. just zigzag to ensure penetration.

[CharlieRam]

i also am wondering about that diagonals and at the same time big holes in the middle. I don't know the top you are planning on but generally i wouldn't have a hole in my table bigger than 300mm, otherwise you will need 50-70mm top if made from ply or similar. even alu top would benefit from such maximum distance.

I will add another cross beam, maybe 2 then if I have enough material, as I mentioned earlier the plan is to put 4" x 1" 3mm alu box section over the length of the bed and then 10mm alu plate on top of that drilled and tapped.

IMHO you are mistaken about the ball screw end mounts. Do yourself a favor and design it similar like i did them from 10mm plate and additional plates that screw to that perpendicular reinforced with ribs plate.
Or you could find your self in a scenario that you have to file shims or even worse, what you will do if the ball screw has to go inside direction?

I understand what you are saying but so long as the rail seating faces are parallel to the bearing block seating faces and the bearing blocks are machined correctly then I will only have to adjust the distance to the Z plate which I am hoping to adjust with the ballnut housing bracket, out of interest how accurate are the ballscrew end blocks from base to centre height? If the heights are out I can always grind them at work while no one is looking!
Cheers, Charlie

[CharlieRam]

Does this bed design look better? It is still made using 1 off 80x40x4mm 7.5mm long and 2 off 50x50x3 7.5m long steel.

[Boyan Silyavski]

I see it better.

I measured the ball screw mounts i use/chinese/ . They are 0.01mm precise.

[CharlieRam]

Does this bed design look better? It is still made using 1 off 80x40x4mm 7.5mm long and 2 off 50x50x3 7.5m long steel.

I keep going back to my bed design and I'm wondering, for a novice welder (zero experience!) will I need to add adjust-ability into the X rail supports, I have allowed for 5mm thick epoxy but I am just a bit concerned about welding the frame only to find it is twisted or out of square?? If I were to make the X box section bolt on to the bed frame rather than welded would it be strong enough and would I be able to skim the 80x40 seating face acurately enough to bolt the rail directly without the need for epoxy.....I think what I am asking is 'how flat does the seating face need to be? less than 0,01 or is it more forgiving than that?
Also if I go the epoxy route I have read people say drill and tap after applying the epoxy, could I do that with a standard drill or would I need something like a magnetic drill press? I was thinking to drill and tap the holes and coat some bolts with molten wax and then fix them in place before pouring the epoxy, would that work or not?
Cheers, Charlie

[IanS1]

You want to try to avoid welding directly to the X axis box section. You can weld a 10mm plate to the top of each upright along the X axis then bolt through that plate into the X axis box section.

[CharlieRam]

This is what I had in mind, There will be aluminium blocks in each end of the X box section tapped to accept the the two bolts through the legs?

[Boyan Silyavski]

Nothing will happen if you weld carefully, tack everything together, don't make stitches bigger than 5cm, use your brain to figure what to tack before so it would not twist and most of all be patient. It really takes a lot of time welding a CNC frame.
What you suggest is alternative but people go further this way and don't use epoxy at all / only at the shims/

Anyway, most of all you should care for your top 2 rails to be more or less in the same plane. On paper the epoxy to spread the force needs to be minimum 3mm thick, so basically that's your limit. You can pour more than 5mm if needed.

[IanS1]

This is what I had in mind, There will be aluminium blocks in each end of the X box section tapped to accept the the two bolts through the legs?

As Jazz as pointed out, the more adjustability you have, the better. Cutting and fixing the ends of the X box section the way you have drawn could make the adjustability more restrictive. Also, bolting through the end uprights may cause the frame to warp as you tighten the bolts.