Tuesday, December 22, 2015

This is Why You Need a Starter 3D Printer

For the last week off and on in between a bunch of other stuff here, I have been thinking about how to make these linear guides for CNC machines.

 I have a whole boatload of different designs to use, from expensive commercial stuff, to cheap and everything in between. However, due to a few self imposed limitations for my designs, I was looking for something that is cheap, like super cheap.

When I started building my latest 3D printer, (Of which I probably will have 3-5 identical units by the time i am done) I dug into my big box of bearings ordered last year from China. I printed parts and bolted the China bearings to them. Only to find that the China stuff I paid a lot of cash for, had a large quantity of crap parts. Gritty bearings, loose tolerances, and the mounting holes are all off. Nothing was the same.

So I started looking at how I can make my own. I came across a old article from the reprap guys describing how they were making 3D printed PLA bushings and were getting well over a year of use out of them.
So my interest piqued, I started researching and yesterday bought a kilo of Esun natural color PLA filament along with a can of silicone lube spray. I designed and printed all day today to come up with this:

Now you are asking yourself what is that?

It is a 3D printed linear guide.  This is the part that makes your machine move up down, left, right and mattached to a mechanism like a belt, chain, ball screw, or threaded rod, will let you make real stuff.

Every milling machine, and lathe has one form or another of a linear guide in it. 

The machine shop seed will give you the tools and parts to build bigger and better machines.

For example the China linear guides come in metric sizes, but polished stainless steel pipe comes in english sizes.

Now if you cherry pick thru the stock of a stainless supplier, you should be able to find enough straight material to make your own guides in english measurements.

For this particular design here are the tech specs:

Black block is ABS+ plastic printed at 230C and 0.3mm layer height

The white bushing is Esun PLA printed at 0.3mm layer height, at 207C and was hand fitted by using a 12mm drill bit clamped into the bench vice to hand ream it to fit.
The bushing was printed with 2 perimeter, 50% infill 3 solid bottom layers and zero top layers cause that part is hidden and being open allows the silicone to soak all thru the piece.

To do the same with 1 inch stainless steel mirror finish pipe, you draw the same shape black part in CAD but larger (obviously) and you then draw a smaller bushing insert for it.  The bushing contacts the rod only at the ends and for only 6mm on this particular design.

You will have to make several test prints to make it fit properly.  I print mine just a tiny bit tight then hand ream it out with a drill bit.

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