building a new 3D printer

after working with the MakiBox 3D printer for 8 months, I think I’ve learned enough about its failings to start building my own.

I’ve started building a 3D printer of my own, based on the SmartCore idea, but with enough changes that this will be my own design.

Makibox (on the right) printing out pieces for the new KVPrinter version 1. The wood on the left is for the walls and base of KV Printer 1
Makibox (on the right) printing out pieces for the new KVPrinter version 1. The wood on the left is for the walls and base of KV Printer 1

The MakiBox printer’s major failing (as far as I’m concerned) is in how it controls the X/Y position of the hot-end.

To do this, it has two long horizontal threaded rods, against the back wall and the left wall. These rods have long arms positioned on the threads, extending out above the print bed. Where the arms cross each other, the hot-end hangs down. Thus, the position of the hot-end can be adjusted by turning the rods.

The problem with this method is easy to see when you consider an analogy. Hold a pencil normally, and draw a 1mm line. Now, hold the pencil by the eraser end and try draw a 1mm line. The precision is just not there. The further away from the fingers the pencil lead gets, the harder it is to control it precisely.

One solution to this which I thought of, is to use a Bowden cable (bicycle brake cables, for example) to fix the position of the arms at the screw side to the position of the arms at their opposite sides. This would work, and would increase the precision of prints drastically, but it’s a lot of work and would look ugly.

After seeing the SmartCore printer, I decided that instead of fixing what I have, I would use what I have to make a new printer. In a way, I am printing a new printer. At least, parts of one.

The SmartCore printer is based on the CoreXY positioning technology, which is similar to the Bowden solution I came up with. Here is a video showing CoreXY in motion

In CoreXY, the hot-end (or drawing thing in the video) is positioned on a moving platform. It can move in X along the platform, and the platform itself moves in Y along rods in the sides of the frame.

To reduce cost in my own printer, I will replace the Y and Z rods with ledges that the platform will slide along.

My calculations suggest that the material cost of my printer will end up being below €150. If this ends up being correct, and the printer is as good as I hope it to be, then I will sell kit packages of the printer for €200.

Bill of Materials:

item amt cost per piece total
nema 17 motors 2 €18.61 €37.22
nema 17 motors 2 €12.675 €25.35
rods, 8x500mm 2 €4.58 €9.16
lm8uu bearings 12 €0.5075 €6.09
608 bearings 10 €0.237 €2.37
timing belts (meters) 5 €1.004 €5.02
controller board 1 €25.71 €25.71
pfte bowden tube 1 €7.97 7.97
hot end 1 €8.53 €8.53
psu, 12v 20a 1 €21.29 €21.29
wood
Total €148.71

I’m working on construction at the moment. I’ll write more articles as I go.

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