Focussed On The Future

I wasn't able to get back to the RepPresent last weekend but I was finally able to get to it today. I leveled the bed, twice because I did it wrong the first time, tested out the heaters, did some hand extrusion to make sure that was all okay, then I let it rip on its maiden print. There's video of it printing here.

When I was testing the print head heater it started to give off a bit of white smoke. The instructions said to turn off the heater if that happened, which I did. But the instructions never said what to do about it. So after a bit I turned the heater back on. This time it smoked less and eventually stopped smoking at all. I'm not sure what was being burnt off, but it appears to be gone now.

Here's the finished part:



It's one of the frame brackets for the printer itself. There are some obvious problems. Notice that lip around the bottom of it? That's not supposed to be there. I had the print head too close to the bed and it dragged a bit, leaving the first layer offset from the rest of the part. I moved it up a smidgen and the next part printed nicely.

You can also see some waviness along the lower right edge. I think that's due to the Y belt rubbing up against the motor sprocket. That will be tougher to fix, but I'm sure I'll manage. But compared to some of the first prints that I've seen out there this is pretty damned good and I'm quite pleased. Despite its flaws that part is actually usable.

While I was aligning the bed I over-tightened the clamp for the Z-axis limit switch and part of it broke off. Fortunately the screw I'd been tightening still had enough of a grip on the broken bit to wedge it in place. That left the limit switch a bit loose but still firmly enough mounted for the test build. The second part that I built was a replacement clamp. :-)

Before doing many more prints I need to come up with some kind of roller to allow the PLA filament to unspool without getting tangled. For these first few prints I've been unrolling the filament by hand and I can see that getting old fast. Once that's taken care of I want to try designing a mount for my Nexus tablet to go on the exercise cycle, so that I can use it to watch videos while I pedal.

Today I used a blowtorch for the first time. It did not go well.

The RepPresent has a small aluminium block which holds the print nozzle and the resistor which heats the nozzle up enough to melt the plastic being fed into it. Since the nozzle is made of brass it expands less than does the aluminium block when heated. So to make sure that the nozzle doesn't come loose when the block heats up, the build instructions say to heat the block up with a blowtorch and then tighten the nozzle with a wrench while everything is still hot.

I did this and ended up melting the block.

( Click to see an image of the devastation... )

In my defense, the instructions were frustratingly short on detail:


That's all it has to say about this particular step. No mention of the temperatures involved. No warnings about the possibility of destroying the heart of your machine.

It's a pretty weak defense on my part, though. I'd had some misgivings beforehand, but did I bother to follow up on them before ploughing ahead? Nooooo! Given that this was my first time using a blowtorch, did I think to perhaps experiment a bit first with less valuable scraps of material? Nooooo!

*sigh*

I don't have the tools necessary to build the block myself, but P may so I've sent him email. If that doesn't pan out then I'll just have to wait a week or so for a replacement to arrive.

Several years ago I got interested in 3D printers - machines which build physical objects by laying down thin layers of a material, like plastic or metal, and binding them together. In particular I was keen on the RepRap project as their machines were the cheapest to build and I liked their goal of trying to create a machine which was capable of duplicating itself. So I began salvaging stepper motors and other components from old floppy drives and 2D printers, with the idea of maybe, someday, getting around to building my own machine.

About a month ago the paramour caught the 3D printing bug. Having observed my glacial progress zie decided to speed things up by ordering a kit containing all the necessary parts. The kit arrived on the 14th. We're considering this to be our christmas present to each other and have tentatively named it the RepPresent.

The machine is currently a little over half complete, but the pace is picking up now that the holidays are here and I'm able to devote more time to it.

Behind the cut is a picture of the machine in its current state, with all the main bits labelled, and a description of how it will work.
( Read more... )