My BLV MGN cube build/upgrade saga (ongoing)
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Three Z axes complete!
The motor mounts are probably a little over-engineered. I have the weight of the lead screw being taken up by a thrust washer that rests on the top, and there's a pillow block bearing underneath that to center it axially, and then a spider coupling to the motor. Haven't wired it up yet, but by hand it feels really good, with no visible wobble in the leadscrews.
I aligned everything using a central extrusion common reference and a dial indicator.
I first trued up the reference extrusion in X and Y against the left rail (unmoved from initial build) to within about 0.001" over the majority of travel.
I then aligned the two right rails against that. If (and most likely, when) I need to do this again I'm going to get a better piece of extrusion for it, or borrow someone's mill to face a piece -- the stuff I have is beadblasted and makes the indicator jump around.
The bed went on really well. I'm so pleased with how it feels—I was mentally prepared for my magnetic mount system to have slop or wiggle to it, but it feels solid. Grabbing the edge of the bed and shaking it moves the whole (heavy) machine!
Proof is in the pudding, though. My Keenovo heater finally made it over the pond from China, so on to the fun parts of hooking up the Duet 3...
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I got sidetracked designing an experimental toolchanger system...
I made a separate thread for that if anyone is interested!
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Those small extrusion pieces you used to attach the bed will transfer heat quickly to the plastic mounts you have them in. Unless you are planning on keeping the bed temps down I would either add something to thermally insulate them from the bed or make those mounts out of something like Polymax Polymide CoPA which is rated to 140c without annealing and higher if you anneal it.
I used railcore beds on both of my BLV printers and initially had extrusion mounted right to the tabs on the bed and they got real hot. I then just made a 3mm thick spacer from that CoPa filament between the extrusions and the bed and it helped tremendously.
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@JamesM Thanks for the tip! I've got some Nylon foam sheets in my McMaster shopping cart for just this purpose.
I'm also rethinking the way I have the kinematic mount designed. The current layout is nice in that it allow minor misalignment of the rails without causing them to bind, but will transfer that misalignment to the bed as rotation around the primary constraint (left center). I'll be doing a bunch of testing once I get it back up and printing to see how much that ends up impacting the dimensions on the print.
If it's bad, I will instead create a rigid extrusion 'T' and mount it directly to the Z carriages, and have my magnetic V blocks at the three ends of the T. The magballs will then be attached upside-down directly to the Railcore bed tabs. This also will have the advantage of limiting thermal conductance to the printed parts given the very small contact area. But it means I'd have to get out the dial indicators again... 🤪
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Are you putting any updates on the Facebook page? I've had my triple Z with railcore bed done for about a year but I'm not gonna lie your setup has my quite intrigued
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@dhusolo I'm not on Facebook, unfortunately -- definitely bums me out that the BLV community nexus seems to be there!
I would love to see your build! Any links? Also, how has it worked out for you? Would love to know more!
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ben is working on all metal parts for the blv.
https://www.blvprojects.com/post/the-metal-parts-are-finally-here
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I'm actually re-doing my bed mounts after seeing you using the extrusion pieces. It gave me an idea and I'll see how it works. Have to design and print a few things first
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@JamesM Sweet, I look forward to seeing the result!
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@whopping-pochard No links. I just swapped to a Duet 3 but I haven't published my parts. As far as the bed leveling has been once I got the offsets right it's been awesome. My biggest thing was bed stability so I redid my bed carriage. Now mine has 3x 331mm on Y (with one in the middle for extra stability and reduce possibility of twisting) and 2x 400mm on the X. With those dimensions the bed mounts are directly in the center of the 2020 channel so less printed parts needed to mount it.
It's not the current setup but it's my most current picture I have
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@dhusolo Looks great!
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If you are willing to beta test.
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@Veti said in My BLV MGN cube build/upgrade saga (ongoing):
If you are willing to beta test.
https://www.aliexpress.com/item/1005001323175853.htmlI just placed my order. Incredible price
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Wow, that is indeed amazing! I'm tempted to order one myself, even though I'm not sure how many components I could use from it at this point...
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Word of warning those metal parts are still in the beta phase. It's entirely possible those parts might need revisions. Personally I won't upgrade to the metal parts until Ben and I work out the details of an official triple or even a quad Z axis with independent leveling.
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@dhusolo
i would really like to take part in the beta, but i am not on facebook (and i wont get an account) -
You don't need to have Facebook for it and it's not really an "official" beta. The parts have been released to only one specific supplier on Aliexpress. Anyone can order them. There's no signup to get them. You just buy them
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@dhusolo
can you answer some questions?where do the endstops on the x carriage go now? the bottom seems to be different and no space to mount the endstop.
are the mounting holes on the x carriage compatible with the hemera?
does the original hotend cooling fan cover fit?
does the original part cooling fan duct fit? -
@Veti I'm not entirely sure. I haven't seen any of the cad drawings to see how it's assembled. I won't purchase the metal parts until a suitable triple/quad independent Z axis is developed.
However I was mistaken. You do need to be on the Facebook group to have access to the beta metal parts
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I used blind joints with my Misumi extrusions and it was worth every penny! Misumi's cuts were spot on and when done, no angle was off my more than .3 degrees using my digital square. And SOLID as a rock to! Thanks to @Nuramori for the suggestion!
