Anti-wobble bed holders for Rapman

by chylld Dec 27, 2011
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To be honest, this has proved to be more difficult than it looks. I don't have a heated bed so I have serious warping issues when printing large parts like this, close together. I have tried to break apart the STL file into individual pieces, but that causes more headache than wasting time and ABS on trying out different build settings. Chylld, could you please post the individual pieces like you did with your corner parts? (which where brilliant btw!) That would be of great help,
Thank you!

Sorry to hear you're having trouble with warp. You can print the parts in PLA (like I did) but in the meantime I suggest you get a heated bed anyway as it's so simple.
I use a flat heating element (http://www.conrad.de/ce/de/product/532886/HEIZFOLIE-320-X-137-MM)http://www.conrad.de/ce/de/pro... sandwiched between a 5mm aluminium plate and a bamboo cutting board from the dollar shop. Runs off the 12V from a spare computer PSU (no other electronics). It gets to about 40-45C which is enough for my purposes but not hot enough to burn :)

We took your advice and ordered a heated bed, and a roll of PLA along with the extra ball bearings needed for the bed holders. I also managed to isolate the two larger parts (using blender,) so that we could print only the ones we needed. (They look terrible though; my brother decided to go for a 0.5 mm layer height, so we might be looking at a reprint with the heated bed)
Our next project is going to have to be a fan duct. I'm not sure that I can use yours though, since I need some of the air to blow on the aluminum piece on top of the heating element to keep my precious PTFE tube from melting... again...
quick question, if I may... Do you still use Axon? or is it just me that still uses it...?
Anyway, thanks a million for this, and for all your other stuff!

0.5mm layer height is extremely thick; I normally print at 0.18mm. I ditched Axon a long time ago for KISSlicer and Skeinforge, and now use just KISSlicer.
Especially with PLA I also have PTFE tube melting problems, so I made a small bracket to mount a 60x12mm fan at the rear of the extruder carriage/duct. It aims up into the top of the hot end and I haven't had a jam since! I also printed a deflector so that the main ducts didn't cool down the tip of the hot end directly (http://puu.sh/a36AI/8b6fc0cea3.jpg)http://puu.sh/a36AI/8b6fc0cea3.... I'll upload these 2 parts to the carriage thing (http://www.thingiverse.com/thing:15044)http://www.thingiverse.com/thi... tonight.

Ducted extruder carriage for Rapman
by chylld

Thanks a million, chylld, i just finished assembling my rig, and 80%(or more) of the wobble is gone! It's practically usable! :) I admit, it takes a few days to make and bake everything, but it's DAMN WORTH IT. You're a freaking genius and this is an amazing design!


Also used your corner threaded rods mounts (the ones at the bottom tightened with nuts, and loose ones at the top as well).


"no-wobble" bottom ball-bearing mount for RapMan 3.2
Anti-wobble bed holders for Rapman
by Daemon

Thanks Chylld, I just replaced my bed holders with your anti-wobble, and am in the middle of the first print. I can already tell that most of the z-wobble is gone. Everything fit great...I also printed all the parts without support because I was being lazy, but all seems to work.

Ohh... video finally highlights what everyone was talking about by wobble... I must be one of a very few people with straight z-axis threaded rods, or is that something that develops?

Unfortunately it does develop a bit by itself, but starting with straight rods is always advantageous.

Looking at this again and doing some shopping around, was there a reason you went with the ball bearings instead of LM5UU (or something) linear bearings? At least from my local suppliers the linear bearings look less expensive.

2 main reasons:

1) changing/installing linear bearings requires dismantling of the machine
2) the bars are 7.9mm not 8mm diameter - I was worried 8mm bearings would be loose. with my design, the corners need to have a very tight grip on the bars, and being able to clamp the bearings to the rod was my solution. th
at said there may be a sprung/tightenable linear bearing that achieves this?

Hm, hadn't actually measured the rods. Wonder if there's any reason why actual 8mm ones couldn't be substituted... though maybe I should stop reinventing the wheel.

So this is 8 bolts and 12 bearings per corner?

Total sorry... 2 bolts and 3 bearings per corner :)