Hmmm... that filling idea of yours sounds quite interesting. Maybe just fill the space between the two 20x60 to keep them together and leave the other spaces empty to minimize weight (and cost) ? Although it might add stiffness to the whole structure ...

 

Doesn't sound that bad of a weight gain, especially if you have a lighter spindle/router to move around.

As you seem to be into molding as well, you probably did as they often do : fill the space with some fine dry sand (or whatever they use, some do use water) and then pour whatever filled the form into a container which is easier on the calculation of volume (ex: cube). The trick being not to compact the filler material during the process (water thus being a good choice).

GrayUK's suggestion of dense expandable foam could work, without any leaks, in the enclosed opening/spaces of the extrusions. Might be tricky to get an even density as the foam needs an escape route, if that could affect inertia and such as the tool end zooms around the work area (?) Would filling those extra openings add enough stiffness to be worth the extra cost/effort/weight ?

I do like the 'fusing' of two lengths approach though... It could be a lot cleaner (if no leaks during the process) and fit the gap like a pair of skin tight jeans The clamping of the two lengths would have to keep the lengths nice and straight until fusing agent is fully cured.

On myOX, with full 1500mm lengths, I can see the two lengths somewhat parting. They just share the load, none of the other forces like twisting and such. Bolting and glueing them together seemed to be the only practical way ... until now.

 

Suggestion: 3D Print 9 of the pieces in the resource file to hold the 2 beams together. Drive 3 to the middle mark, holding the centers of the 2 X beams together. Turn up on one end and fill one half of the center with alunilite resin, leaving room at the top for the 2nd printed "caps". When resin is firmed up enough, turn the beam ove and repeat for the 2nd half. The other holes not used to connect the beam will not need to be filled. Should be easy and very solid.

 

Might also want to add some of that 'micro bead' filler used by those molding their own fishing lures. The stuff, if well mixed, appears to remain suspended and allow the resulting part to "float". It might help shave a few oz off without reducing too much the strength - especially with the imbedded 3D printed parts to help keep the beams tight together and plugged during the curing of the alumilite.

This is getting very interesting ... Can't wait to see where RogueGeek takes it.

 

Brian, what are your GRBL settings for speed/acceleration?

-- JohnM

 

did you build a bigger bench? LOL
looks great!
Bob

 

I am looking to build my first cnc router soon. I would like to see how you replace the belts with the lead screws. This is what I would to do. Lead screws instead of belts.
Thanks,
Phil

 

Phil take a look at Neil's Frog build. His final build uses lead screws and looks to be running nice. McMaster Carr has six foot 5 start 1/2" lead screws for less than $20 right now which is a great price. I purchased 3 6 foot 5 start rods in October and they were $63.00 each.

http://www.openbuilds.com/threads/the-frog-not-an-acrynym-cnc-router.233/

http://www.mcmaster.com/#99030a704/=vbp3w8