Tuesday, February 26, 2013

What I’ve been up to lately in 3D printing

A question on my builder’s list list a few weeks back started me looking at the Prusa i3. It’s a good design though it’s still a bit immature (getting better daily). When I jumped in I had to look around a bit to find all the info I needed, and some of what I found was wrong.
I think it’s probably the way to go for future builds. You can’t just convert an i2 to an i3 – the X axis rods need to be significantly longer for one thing. I’m happy enough with it that I MIGHT convert my other i2 to an i3 as well, though really the i2 does well enough, and it’s more compact. The i3 is significantly larger. It does print up to about 230 mm high though, where the i2 only barely goes to 100. I have not yet tried printing anything very big.
I just installed my first magnetic “hall effect” sensor, purchased from RepRapDiscount. They work really well and are easy to install and adjust. I think mechanical is totally fine for X and Y, and that’s what I use there, but the hall effect is super accurate so for the Z it’s good. Optical is I think probably just as accurate, but it’s easier to get a magnet near a sensor than it is to make and mount a little flag and make it go through the slot on the optical sensor. Also the magnetic sensor has a sensitivity adjustment on it so you can adjust the height like that rather than having to physically more the sensor or flag.
I installed RAMPS 1.4 electronics on the i3. That was originally my really old printer and it had RAMPS 1.2 electronics back from before I discovered Sanguinololu. I upgraded the RAMPS because I am now 100% sold on having a control panel, and RepRapDiscount had RAMPS 1.4 boards and control panels all ready to rock. Also the 1.4 supports dual extruders, and I may be playing with that soon.
I had an exciting failure during the i3 build – I was debugging a problem with the electronics and inadvertently plugged a motor driver in to the board one row off. Turns out that this shorts the 12V supply to the 5V line. This makes things fail spectacularly. The electronics blew the centers out of the chips, actually threw sparks and caught fire. So yeah, do not do that. Carefully check the insertion of the driver boards.