MPCNC Version 2 -opinions-

New Home Forum Updates MPCNC Version 2 -opinions-

Viewing 30 posts - 31 through 60 (of 442 total)
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  • #8036
    Ryan
    Keymaster

    That way works fine, until you get to the center assembly, that throws off the z axis. That means all 4 would have to be adjusted very well to get a 90 (normal) z axis. Then that changes the tool holder dimensions, the motor mount dimensions, and the z nut lock dimensions. Meaning everyone’s machine would require custom z axis parts.

    #8043
    F
    Participant

    Interesting…. as if i don’t use the ‘fix’ there is a bit of space (the single bearing on the roller not touching the tube) which means, that one way or another it will never properly fit…. until i find 25.4’s (as i presume the issue is, 25mm vs 25.4mm) ?
    let me print the international version first…. and struggle 🙂

    #8044
    Ryan
    Keymaster

    Not sure what you are asking there.

    There is not a 25.4 version yet. 25mm should work.

    #8046
    F
    Participant

    let me first finish the printing :), and try to make some pictures of what i mean

    #8079
    John Wells
    Participant

    Just finishing my build, and it all went together almost perfectly — with the exception of the corner blocks (and roller locks), which were very tight. I’m using 25mm tube (chrome-plated wardrobe/closet rail), and while it fits perfectly into the roller assemblies, the corner blocks were a very tight fit. I did file down the holes a bit, but still ended up banging in the tubes into the corner blocks with a hammer.

    It’s all snug, but the bottom of the blocks now sit at an angle. I only noticed this after gluing on the feet of course — which now aren’t vertical.

    I guess I can fix my corner blocks without taking everything apart with a bit of a blast from a heat gun — but to deal with cases like mine (where the rail seems to be the right size, but the printed holes a re a bit tight, it might be a good idea to either make it clear in the instructions that it is worth spending more time filing…. or provide a parametric shim (e.g. in openscad) that can be glued onto the bottom of the corner blocks.

    #8084
    Walter
    Participant

    Sounds like you could use something like the taller corner block I’m designing.

    I’ve only made a 23.5 version for now but I guess anyone could jump into tinkercad and bring over the 25mm version.

    Attachments:
    #8146
    John Wells
    Participant

    Impressive stuff — although that looks like a lot of PLA… are they hollow?

    #8149
    Walter
    Participant

    There’s a 25mm hole going up the inside for support and for to reduce the amount of material. 4 Posts will most likely need one fresh roll of filament to be on the safe side, and about 30 hours per leg. which is why I havent actually made any yet

    #8153
    Atomist
    Participant

    Couldn’t you do something like this, slot one or both sides of the bearing bolts and have a set screw on the outside to adjust/lock them in place? Why would something akin to this not work for different size rails? We are talking a couple mm different between what’s available in the US and other places around the world. Is this a bad way to accomplish this?

    #8156
    Atomist
    Participant

    I’m looking over the other pieces to the MPCNC, I don’t see any reason why there couldn’t be a slotted version with lock screws. I’m mainly just interested in the possibility of there being a single design that can accommodate a variety of rails/pipes/stock.

    #8183
    Ryan
    Keymaster

    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.

    #8344
    David Posea
    Participant

    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..

    #8363
    Ryan
    Keymaster

    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.

    #8388
    Göran Blom
    Participant

    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.

    #8390
    MJ
    Participant

    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.”

    Thoughts??

    Vicious Triad

    #8393
    Ryan
    Keymaster

    Dang!!!!!!

    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.

    #8397
    nerdyrcdriver
    Participant

    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).

    #8436
    Andrej
    Participant

    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 60×60 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…

    #8517
    John Wells
    Participant

    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.

    #8715
    Walter
    Participant

    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

    #8716
    Ryan
    Keymaster

    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.

    #8717
    Atomist
    Participant

    Walter, where are you located in the world?

    #8718
    Walter
    Participant

    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.

    #8719
    Walter
    Participant

    Murica

    #8720
    Ryan
    Keymaster

    They told me they can order as much as I want but the bulk discount is small.

    #8730
    Walter
    Participant

    I will see what they will do for me. we’ve had an account at this store for 40 years 😉

    I may be doing a group buy if anyone in the us wants to go in…

    #8731
    Ryan
    Keymaster

    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.

    #8732
    Walter
    Participant

    Chop em up to 30″ put a stamp on em…

    #8750
    Walter
    Participant

    You take 2 flat rate boxes and slip them over one another…

    #8753
    Ryan
    Keymaster

    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.

Viewing 30 posts - 31 through 60 (of 442 total)
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