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In the beginning...

Posted by MasterUWA 
In the beginning...
March 04, 2013 08:58PM
Hey everyone,

I'm only just starting this whole 3D printer thing but I'm studying Mechatronics Engineering and this is right up my alley. Only problem is, with all the different iterations (and the fact that I live in Western Australia) I'm having the hard time of finding an accurate BOM and Australian Suppliers for a Prusa Mendel. Most of it I have sort of worked out from multiple BOM's that I have found but I'm stuck on how many bearings to order, I want to use the LM8UU linear bearings and the Wiki page's BOM states that I need 48 624ZZ bearings but I'm not sure if i do. So far my BOM is:

- 1x Printed Part Set (Need to choose which type of extruder to get printed with this)
- 1x Steel Rod Set
- Hardware (nuts, bolts, washers etc and I can get these from work)
- 5x NEMA 17 Stepper Motors
- 1x RAMPS/Pololu/Endstop Kit
- 1x Hot End
- 1x Heated Print Bed
- 2-3m Belt (Unsure about which size to go for)
- ?x Bearings
- ?x Linear Bearings

I'm sure i'll find other things that I need as well. Also does anyone have any opinions on these vendors: BilbyCNC.com, Create3D.com.au, OzRepRap.com and 3d-industries.myshopify.com?

Cheers,
Matt
Re: In the beginning...
March 06, 2013 04:43AM
The Prusa Mendel uses 608 bearings for the extruder and belt idlers- 6 of them I beleive. Also for the axes, 11 or 12 LM8UU's
Re: In the beginning...
March 06, 2013 09:30AM
(2) 608 bearings is the bare minimum. X-Idler and Y-Idler. You could use two on each Z-drive rods, but many people don't recommend it anymore as they over constrain the rods and help induce Z-wobble. But to be honest I'd order at least 10 as you'll want some once you start making things (filament holders, etc).


- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]
Re: In the beginning...
March 21, 2013 09:22AM
lm8uu
3 or 4 for each carriage, depending on how the carriage is made.
I had 3 for my x-carriage, which I think is the most common.
and 4 for the y-carriage, but there might be iteration with only three here.
two each for z-rods.

608zz skateboard
1 for x-belt, 2 for y-belt.
two for the extruder
I have seen a version where the z-rods is resting on top of two bearings, but I don't use them and have no wobble problem. So it might be correct.
However it was hard to get the zords to stay in the z-couplings, since I didn't have the correct tubing for the z-motor shafts. I solved that with a couple of shrinktubes instead.

that's it.
I used flanged 608zz for the extruder which I bought on ebay by accident.
Luckily I found regular ones in a sports shop locally that was meant for skateboards, an 8-pack so I had plenty left over.
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