All sorts of things work for the outer rollers, a single axis. The problems start when you get all three axis intersecting. On the middle assembly, if you did that slot method and did not have all 6 slots in the same exact spot your z axis would not be 90 degrees from the work surface. It might not be drastic, or it might not be that big of a deal but I would rather come up with a solution that does not need 6 bolts to be adjusted the same.
Ease of assembly I guess.
The first release of this machine it worked with several sizes. The center, tension bearing, stayed fixed and the wings, bearings without plastic on both sides, flexed open to accommodate EMT variances. This made for a weak machine, and I had to close the center parts to increase rigidity. I can redo it this way with 2 of the 3 bearings fixed and a movable 3rd, but every slightly different size will need a custom tool mount and z motor mount. Not too bad but I’m convinced there is a better way to keep it rigid.
Maybe I’m very far off base here, but you have made a cnc machine, so the version not to be called V2 could include a few CNC’ed aluminum parts. Or at least make them optional. Much smaller parts with more rigidity. I’m also wondering about the use of belts if you want to cut steel with a 2.2kw spindle. GT2 belts stretch!! For the value conscious all thread could replace acme leadscrews, or even ballscrews. China sells acceptable ballscrews with antibacklash nuts, and anti backlash blocks have been made for allthread. These are just a few random thoughts on a version that eats steel. 4th axis should be next, too…
I think steel is still out of reach for a while. We had large HASS mills at school and never saw them get used for steel. Steel is just a whole different animal everything has to be perfect, alignment, rigidity, gcode, bit, feeds, speeds, everything.
I found the corner blocks was to tight for my 25mm stainless tube so I had to scale the block by 1.01. Then they fit.
First I tried to use a heatgun to make them fit.
I’ve now built three of these machines and I am more impressed each time. While that’s partly because I do more things right the first time with each successive build, it’s mostly due to the excellent design (kudos Ryan!). While I’ve only used my machines for 3D printing so far, I can see the potential issues with large builds, heavy tools and a variety of conduit sizes. I think Ryan is trying to make a truly universal machine that’s rigid enough for big builds, easily scale-able (which this thing already is) and adaptable to round rail found nearly everywhere.
Here’s a thought to add rigidity and adaptability while maintaining scale-ability. It uses three lengths of conduit for each side of the axis (see attached image). As printed, it should support the largest diameter (25.4mm, from what I’m reading on here). Then, smaller diameter pipe could be used with printed spacers. The benefit of the spacers is they could be easily “customized” by each user. Simply print one as a test. If it doesn’t quite fit, scale up or down as needed. I envision these spacers placed every 10" (250mm) or so, but it would probably vary by application and amount of spare PLA on hand. For long spans or heavy-duty builds, the bottom leg of the spacer could be modified to accept a support member.
In essence, this works much like the “Vicious One” model. It still uses 608 bearings, 5/16" or 8mm bolts, PLA printed parts, etc. So, the assembly will be much like it is now, simple. Parts will still be readily available in imperial or metric sizes and the build will accommodate a variety of conduit/closet bar/pipe sizes. The increased weight of the additional material may require additional power to the steppers, but it should be negligible with these NEMA 17s.
As for names, we could skip the whole V2 thing and go right to “Vicious Three” or “Triple” or my personal favorite, the “Vicious Triad.”
Sorry just shooting these out as I think of them. Not censoring this.
I had though about using 3 before but it didn’t seem that elegant in my head! I kept coming up with a truss system, this is better
This would work in really large machines. For the highest rigidity the spacers would need to be screwed in (epoxy?). The outer plastic would need a different shape to hold more torque. I love this… This would really need something better than emt, I think this would exaggerate the surface flaws/imperfections. The spacer could extend out past the surface of the pipes to make the clamp so no holes needed to be drilled. This would not allow for one of the biggest upgrades I had planned for the “the next version”/improvements, not a big deal, this could be better.
So still looks like update the current version. (almost done with the corner, testing new center assemblies). This could legit be the model for all the guys that want an 4’x8’ machine!
Thanks @MJ Awesome idea I want to test it, but I have to at least finish this corner thing first.
Good idea! It might make the center assembly even more of a monster than it is now though. I agree with Vicious on the magnification of surface flaws. Right now it is no big deal to have slightly warped conduit, especially if it is only slight across the whole length before cutting, but with 3 stacked against each other they would have to be perfect or the fit would have to be intentionally a little more loose. Maybe a spring mechanism to push the bearing against the rail, but allow it to push back if something is warped or otherwise imperfect in an area. Kind of how an extruder could allow for an inconsistent diameter of material through it without a problem (physically speaking. There would be issues with too much or to little filament in a print).
First thank you Allted for your engenious design. After a long time of searching for a suitable design for my purpose I became all tingly inside after finding it.
I am able to source 25 mm chrome plated wardrobe rail easily where I live in Slovenia and not that expensive (under 10€/3m). I know other types exist, but this one has a wall thickness of only 0.7 mm.
Has anyone used this thin wall type successfully (I’m thinking 60x60 cm print surface - 90 cm tubes)? My fear is it would sag too much for printing.
I’m toying with the idea of filling the tubes with rigid lightweight (200kg/m3 @ open mold) 2k polymer foam to stiffen it (also reduce vibration?). Upfront I would insert a smaller dia. tube to allow for wiring.
Maybe this would bring the rigidity up a bit without affecting other aspects of the design.
This could even be applied to the “Vicious Triad” idea, which is so exciting, btw. (+1 for that)
I also wonder what would be a beter choice regarding long time wear: stainless (polished) or chrome plated?
Thank you All…
I’m using chrome plated wardrobe rail in mine as well (in the UK). Mine is around 1m x 0.8m, and it seems pretty solid (although it’s not comissioned yet – waiting for electronics). The chrome plating seems to be holding up well so far, considering all the manhandling it took to get it together.
I found some chrome plated closet rods at hd. sadly the only thing they have is 1 5/16" Which is like 35mm waaaay to big to try to force in the current design. i wish I could find something g closer to 3/4 emt around here
I found some 25mm stainless “shower rods” at Ace hardware, $14/6’. I did a test and at 6’ the conduit is a little better but this stuff is pretty thin walled.
I still have a few places to check. i do have a commercial account at the local big lumber company and they will special order whatever I want. they also deal with ace branded stuff, so if you have an item number or upc I can probably grab the exact brand you are using.
I think they told me 10% if I buy more than 5 or 10. I asked if that goes up if I buy more than 100! She didn’t know, I didn’t push it because I wanted to test it. The hard part is shipping it. The longest large flat rate box can fit 23.5" max. That is why I haven’t ever sold a “full” kit.
Hahahaha your killing me. I think I will have to try both of those with the mail guy just to see his reaction. slap a stamp and a label on a 6’ tube and try and hand it to him.
