Thursday, 14 April 2011

Bodge It Quick

Having spent nearly all the funds I have til my last student loan payment on this kit, and finding the local hardware stores without a countersink bit, I went through various forms of 'ingenuity' so far this week in my quest to get this printer up and running.

For starters, I really wanted those bolt holes counter-sunk, at least the ones that held the bed onto the Y-axis assembly, anyway. So what does a man do when he has a drill bit big enough to counter-sink the hole, but no drill big enough to hold it, nor cash to get one?

What to do, I ask you?

Of course, I still had spare bar clamps from nophead, since I wasn't using any lower circuitboards, so I have an instant 8mm hand-drill. :) It worked a treat, and only needed a little bit of tightening up during the drilling.

After this, I ran into all kinds of trouble with not understanding the software typically used to control this printer - RepSnapper and SkeinForge. The former didn't seem to produce useful gcode for my hardware, and the latter required a lot of tweaking to work. This eventually got sorted out with the aid of reprappers on IRC and a handy hacker friend, who know a little more about software and firmware interfaces than I do with my mechanical background.

Now, I can mount a printbed, but I don't want to be printing straight onto an aluminium plate, especially with those holes there that I didn't take the time to countersink to mount the heating resistors, so I covered it with some Kapton tape. Unfortunately, this stuff is very slippery and doesn't like PLA much, and my first print tests result in the extruded filament simply hugging the extruder, and not sticking to the bed at all.
My first reference for solving this problem of course was the ever-curious nophead with his tests for PLA on Kapton tape.
So he reccomended to get the bed up to 55 Celcius, but my bed isn't heated yet, so what to do? What to do???

That'll do.
Now with clothes-iron pre-heating, some of the filament would stick in some places, but in others it just slipped right over the surface and went back to hugging the nozzle:

So I consider something that I'd heard about before when Adrian was describing printing on glass - that the oils from fingerprints can stop the plastic from sticking to the surface. Apparently acetone is ideal for cleaning the surface off, I'd say I 'need' some acetone then, but for one thing it seems our only bottle of nail polish remover was miles away in another flat, and I hate to use absolutes, as they are so restrictive. So no, acetone is an optional, what could I possibly use instead?
The shops are shut and I don't have any masking tape, so...

Yo Ho Ho.
Hunt around, find some cheap supermarket rum with flamboyant label, wipe bed clean.

Next I try another test, this is what I'm trying to produce as a test by the way:
A simple box, 60mm x 30mm, could be a handy bolt-holder.
This test starts with more success than the last, starting to lay down a perimeter of plastic and working into the first layer, before the temperature possibly gets too low, and the filament starts dragging up again:

This was the rather messy result, just after I stopped the machine:
At least the blob on the end isn't the size of a citrus fruit, like this unfortunate incident.
I'd like to get a glass plate to print on, and I found some glass panes chucked out on my street as part of some broken up cabinets to be picked up by the bin men, however the first pane that I tried my hand at cutting seemed very tough, and after lots of tapping and eventually putting my full weight on the plate, my first ever attempt at glass cutting was... less than successful.
Things are looking up though, as I just heard that a very nice friend should be able to lend me their drill tomorrow, so I may be able to get a proper heated bed going.

Til next time, I leave you with the wise words of Adrian Bowyer, founder of the RepRap project at University of Bath:
Wealth Without Money

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