Wednesday, February 12, 2014

Building a 3D Printer: Part IV

If you've been reading my previous posts, then this image will be familiar to you:


This was the final design we ended up using on the MSE Printer. It's pretty elegant, actually... The pieces that hold the frame also act as bar mounts and motor mounts. The glaring issue with this:

It's hard to put together!

Because the mounting features of this frame are composed mainly of blind holes, the only way to have everything fit is by assembling everything all at once. For example, if we push all the aluminum angles into their respective holes, there's no way to insert the linear rods.

This lead to an awkward dance of sandwiching the printer together, and brought about what is most likely the biggest failure of this printer.

Everything. Is. Glued. Together.

We had always planned on gluing things in place -- it's a cheap, easy way to secure things! The problem is that now the frame and rods are permanently affixed... and if one of our axes needs to be replaced, the printer will likely have to be broken apart.

Unfortunately, we were late. This was a school project, and we had deadlines to hit. So, we did what any student would do:

We said "Fuck it", and glued it anyway.

Sunday, February 9, 2014

Building a 3D Printer: Part III

Continuing my last post...

So now we had the right aluminum angles. Everything was peachy-keen from here on out, right?

WRONG.

Turns out, neither Ryan, Jacob, nor I are fantastic fabricators. We're not robots. Robots are perfect. We're not perfect.

We drilled some holes, and tried to fit things together. They didn't fit. The holes were off by millimeters, but that was enough to screw everything up.

I like to think that if something needs to be *perfect* to work well, it must be very poorly designed. So we revisited our model. We ended up with something like the following:


We printed off brackets that the angles all slid into. We also integrated the smooth rod clamps and the belts pulleys into these brackets. All in all, a pretty elegant solution! Not perfect, as we'll see later, but definitely workable.

This part also popularized the "45 degree print" orientation that is very popular among one specific WOOF member... It's able to be printed without any support. I personally think that it's pretty darned slick.

Of course, these parts weren't perfect either. That would be way too easy! Stay tuned to hear the biggest problem with this printer design...