Building of Mini Kossel 3D Printer

2014/09/16

Things to change when you use 2020 aluminum extrusion instead the 1515 one on the bill of materials.

Misumi HFS3-1515

DF2020
DF2020_alusys

According to Kossel_Mini_Assembly_Guide_V1.0.pdf,
One bottom vertex frame requires:
M3 Allen key
M3x8 cap screw x10
M3 nut x10

Three of the bottom vertex frames needs total 60 M3x8 screws and M3 nuts.
One top vertex frame requires:
M3x8 cap screw x5
M3 nut x5

Three of the top vertex frames needs 15 M3x8 crews and M3 nuts.

The total number of M3x8 screw is 45, and M3 nut is 45.

However M3x8 screw and nut dimension is too small to attach the vertex frames.
Slot width of DF2020 is 5.4 mm on top, 8.3 mm in the middle.

Let’s calculate dimension of M3 nut.

D is 3 mm.
Length of s is 4.8 mm (1.6 x 3.0).
Length of e is 5.4 mm (1.8 x 3.0).
Outer diameter of washer is 6.0 mm (2.0 x 3.0).
Well, the slot width of DF2020 is 5.4 mm which makes M3 nut useless without washer.

The wall thickness of vertex frame is around 4.1 mm plus 2 mm of the DF2020’s edge gives 2 mm clearance.
So if I gonna use M3 screw and nut for mounting the 2020 aluminum extrusions on the frames, I’ll need to buy 45 pairs of M3x10 screw and M3 nut or simply uses M4 screws and nuts.

Second thing you have to consider is that extra cost of six vertex frames or labor time to make the square holes bigger.

When you buy the printed parts kit, make sure what linear mechanism it uses. Original Kossel Mini uses steel rails to handle vertical movement of the push rods. Price of one steel rail is over $34 with shipping and handling fee, buying a set of three rails probably increases the total cost 1/3.

At the moment I have to deal with these two problems.

About janpenguin

Email: janpenguin [at] riseup [dot] net Every content on the blog is made by Free and Open Source Software in GNU/Linux.
This entry was posted in DIY, Reprap 3D Printer, Science and technologies and tagged , , . Bookmark the permalink.

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