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Discussion in 'CNC Mills/Routers' started by RogueGeek, Oct 28, 2014.
This build log will chronicle the construction of my oversize (1000mm X 1500mm) OX router.
RogueGeek published a new build:
Read more about this build...
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 ...
I've not considered filling the aluminium either. Taking additional weight into consideration, as Serge says, I guess even a dense expanding foam could add strength to some degree, providing there was no where for it to be squeezed out.
It'll be interesting to watch your build!
Good Luck and keep us informed please.
Thanks for the comments...
I'm not too worried about weight. If my calculations are correct, and they often aren't, the volume of the space to be filled is around 0.52 liters or approx 17.5 fl oz. The resin has a specific gravity of 1.05 so it is just barely heavier than water. Giving me a resin weight of 18.3 oz to fill a 1000mm beam.
Since the X axis beam is driven by the dual motor Y axis gantry. I don't think it will overload the motors.
Due to some issues beyond my control, after Sunday I will not be able to work on the Ox again until Nov 15 or 16. So this mod may take a while to complete.
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.
It looks like I screwed up something when I was calculating the surface area of the voids to be filled and as a result my volume calculation were wrong.
This time I brought the VSlot drawing into AutoCad and used the "area" command to calculate the area and thus the volume.
So the total volume of the voids created by the dual beam X axis is 924 cubic cm. or approx. 32 fluid oz. This will bring my resin weight up to 2 pounds.
Still not too much, but a bit more than I was hoping for. I may do some experimenting (using one of my other molds) with adding a light weight filler like perlite to the resin and see how much it effects its strength and weight.
I'll post results once I get time to experiment.
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.
Sorry for the long delay in updating my build. I had to unexpectedly make a trip to Florida for two weeks due to an illness in the family.
Now that everyone is recovering and I'm once again home. I'll be resuming work on my OX.
I finally received the pc boards for my custom GRBL breakout while I was away. I'll be assembling those this weekend.
Before I left on my trip I tested my resin to make sure it was still good after setting on the shelf for almost a year. As luck would have it, it had went bad. So my resin filled gantry rails are on a temporary hold until I make it down to the hobby shop and pickup more resin.
I'll be updating the build log this weekend to reflect all of the changes and upgrades.
thats all for now...
Construction of my OX is 99.5% complete and it has had its first taste of wood.
I only have a little bit is clean up of the wiring left to do and I need to add limit switches and a dust shoe.
Here is a quick video of the first cut.
Warning the audio is very loud.
Brian, what are your GRBL settings for speed/acceleration?
did you build a bigger bench? LOL
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.
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.