jonh's 25x30 build

Thanks for the advice over in the help forum! It’s been a big weekend for my MPCNC build: I’m most of the way through printing my parts; I ran through 2kg of PLA and now I’m dry, with some feet and the tool mounts still in the queue. (Weird, because the parts sheet estimates 1.6kg; my parts have been running 30% more massive, despite trying to follow the infill fraction recommendations.) My vitamin kit came on Saturday (thanks, Vicous1!), and my router came on Sunday. I settled on a 25x30 addressable area because I didn’t really want to have to move around and store a bigger table, and because I’m interpreting that suggestion in the build guide as good starting advice. Can’t wait to cut some conduit and start putting pieces together this week!

Do others have a recommendation for a fast way to clean up the flash on the bottom edge of the parts? I’m filing them tediously right now. Maybe some dremel attachment or some oscillating powered hand tool?

Here’s what I used

So is that a 220V model, or one of those underpowered 110V models? :v)

Nice! I noticed your Delta printer in the background. Looks like we will have similar setups. I’m actually building a kossel at the same time as the mp CNC. Good luck on your build.

After spending the weekend repairing the garage door while printing parts (and wishing I was assembling all these great parts), I managed to get my conduit cut this morning before work, and then when I got home, I finally got to start putting together my built parts with parts from my vitamin box.

I’m popping bearings out of sleeves like some sort of Life Saver junkie. Oh, wow, is it ever satisfying. What a fantastically well-designed machine! Dropping the stepper into the mount was both aesthetically pleasing and also nice because now I’ve already got something with electrical wires attached to my parts. :v) The roller assemblies slide so gorgeously on the conduit, it’s hard to believe that the precision rods are $4 hardware store materials. Very nice!

A couple quick notes I made along the way:

  • the assembly/roller page mentions 1/2" screws for the roller clamps, but the engineering diagram says 3/4", which is strongly supported by the fact that my vitamin kit only had two 1/2" screws in it (for the rigid coupler).
  • The 2.5" bolts for the rollers don't quite bite into the nylon in the lock nuts. They might if they can stand really being cinched down later, but I wonder if a 2.75" bolt wouldn't be better (albeit with some ugly thread sticking out beyond).
  • The only tedious thing about this was digging the support material out of the bottom nut trap on my corner blocks. I probably should have built that part with support disabled, since nothing else needed it, and surely it would have bridged the nut traps easily.

Anyway, kid in a candy store. Next step is the middle assembly, which looks sufficiently complex that I should really take this opportunity to go to bed. It’s like trying not to start the next chapter of Harry Potter at three A.M. :v)

Looking good, smooth sailing so far. As for the center…keep everything super loose, only tighten it when you have it on the machine and the cross bars are snugged up in place. seems to keep things a bit more, square.

I’ll check the assembly page now. Sorry about the 2.5’s, sound like crappy engineering…I made so many version of that part with the bearings in different configurations I got tired of waiting for it to print so it never really got any finalizations.

Yup no support on anything other than the rigid middle z. Although I get as good of support with cura now as I do with simplify 3D. I always set a 1layer gap, and the support density plays a big part 2mm apart seems good usually, and about .7-1mm from the x and y.

keep everything super loose, only tighten it when you have it on the machine and the cross bars are snugged up in place. seems to keep things a bit more, square

Got it.

Sorry about the 2.5’s, sound like crappy engineering

Oh, yeah. “Crappy engineering,” that’s definitely the phrase that’s been running through my mind. Are you joking? This design is phenomenally cool.

  • a surprisingly minimal design that makes good use of ordinary, inexpensive materials. It’s just amazing that conduit can be “good enough”. The design uses surprisingly few bearings to stabilize against so many degrees of freedom. The paired belt-stepper assemblies are a simple solution to providing squareness and avoiding torque. It even reuses bolts to simultaneously be a bearing axle and to join two printed parts. So elegant!
  • parts are really well-designed for easy printability. They exploit the “material properties” -- one flat side, good vertical cross sections -- while avoiding difficult build features (support, sharp corners that like to peel, small details that build poorly).
  • parts are aesthetically elegant, with organic curves
  • assemble-ability is very good: it’s easy to understand how the parts fit, and easy to ensure the critical dimensions (parallel sides, square corners). I haven't gotten to that step, but I can already see from the assembly instructions how straightforward it should be.
  • So. No. You may try to be humble, but this design is quite impressive.

    As for the specific 2.5" bolts: I think it would probably be fine to just ship the next size up and have 1/2" stick out the end. A little dorky looking, but would save a part redesign. I guess the alternative would be to sink a hexagon 1/16" into the head side of the roller-F, but that’s just one more concave spot to clean crud out of, and one of the things I’ve enjoyed about this design is how close the parts build to ready-to-use.

    Yup no support on anything other than the rigid middle z.

    I think I may have come across that tip, but only after I started printing parts, and the corner blocks were the first thing I built.

    Although I get as good of support with cura now as I do with simplify 3D. I always set a 1layer gap, and the support density plays a big part 2mm apart seems good usually, and about .7-1mm from the x and y.

    Good to know. I’ve noticed your enthusiasm for cura elsewhere in the forums, so it’s on my list to play with it. I’m still using the copy of slic3r I installed when I got my printer last year, because inertia. :v) I will totally try cura really soon now.

^ completely agree with this. Clearly a lot of thought and analysis has gone into each part. And… it’s great fun to build.

Jeez…Should have put a haha behind that statement!
Thanks you so much for noticing all that. I was just being lazy when it came to that part. I have noticed it and a super quick part edit could fix it but things have taken off so fast I barely get to touch CAD anymore. While I am typing this I am on hold with the post office and flashing/running the next batch of boards.

Hurry up and get That thing put together. Sounds like I am going to like having you around here!

Hurry up and get That thing put together.

Okay, twist my arm!

I put the Z components together, and then set up the outer rails tonight. I’m short three feet, with two of those coming out on the printer right now. I also hadn’t yet cut my leg conduit (we should add that to the calculator – I had to dig around to find advice on conduit length of “z travel + 10-20mm”), so I took care of that tonight. Should be able to get the legs on and screwed down tomorrow.

PS starting to regret my arbitrary choice of colors on my PLA orders; this machine is shaping up to look disturbingly Christmas-themed…

I totally forgot to think about the colors when I started printing mine too. Hopefully the blue and black is somewhat organized on my machine. Or a total mess.

Not much progress tonight. The last foot came off the printer today, so the next step was to glue the feet to the corner blocks. Strangely, red and green PLA glue together with cyanoacrylate, but white and red don’t. I’m guessing the white (Hatchbox) stuff has too much baby seal in it or something, and isn’t super-gluable. Weird. As good fortune would have it, I had a container of plastic-specific epoxy in my glue bin, so now the feet are clamped up and hardening. But not much for me to do until it’s solid tomorrow.

Lol. I started printing mine with filament i had on hand and it turned out my corner blocks and roller parts ended up red and green too.

Tonight I got the rails “square” (measured out precisely, clamped, marked holes, center-punched, drilled, reassembled, and now the diagonals are off by 1/16" – ah well; the holes are there now. There’s no going back. :v), and set the height (with a block, so they should be pretty good).

My z axis is mostly together. The four towers of the z motor mount were a little delicate, because they broke when I dropped it. (cough cough maybe that’s not what they were designed to endure.) I’m waiting on a print of the Hicwic universal tool mount to use to square up the z conduit. Unfortunately, the only PLA I have right now is Hatchbox, and it has been pretty weak. (The rest of the spool is going back to Amazon tomorrow.) Even after I get the universal mount printed in good plastic, I’ll eventually try to redraw it to make it a little beefier.

Trouble with the z nut lock. Assembly guide says:

Put the z nut lock on smaller end towards the stepper.
Tighten up the Z nut lock with a screw driver and needle nosed pliers. The screw closest to the stepper motor does all the holding.

First, is it weird that, with the nut lock arranged as described, it’s friction that holds the z assembly from falling towards the table? I mean, I guess that’s cool, because the rest of the parts on the system are clamp-fit, too.

But the problem is that I can’t tighten up the Z nut lock enough to grab the coupler nut – the gap in the plastic is closed, but the coupler happily slips through. Did I miss a step?

Looking from the bottom end – is there a chance that I printed a z-nut-lock designed for a bigger nut:? The hexagonal slot seems way too big.

There are 2 different sized z nut holders, 1mm and 13mm. Looks like you might have the 13 and need the 11.

And the bottom of both are larger because the small nut is designed to float, but not spin.

Just realized I had the wrong Z nut holder, printing the 11mm now.

Yup, there’s yer problem, mister! Looks like yer bearings are square, and ya need an 11mm nut lock, not this 13mm. I dunno what mechanic put this 13mm on here, but that was never the right part. We’ll get you fixed up right quick!

Thanks for the tip-off – I had manually grabbed a bunch of STLs, and until you pointed this out, I didn’t go back to the original list and see that there’s another part there. Gantry’s mounted! Woo!