Inspired by Nophead’s excellent work, I decided to do my own testing. I had the folks up at Najet make me a prototype and pitted it against the existing timing belt pulley from SDP-SI. As with Nophead, I found the worm-gear style pulley to be much superior.
My process was pretty simple. We’re testing the pull strength of the extruder only here, so it involved hooking up the filament drive portion to a force meter (fish scale) and running it until it either stopped or failed. Here’s my setup.
Force Meter
A fish scale 50lbs / 23 kg. I couldn’t figure out how to make it do metric. FAIL! It still worked reliably, and I got a rough sense of what forces were involved. Now that I know my range, I am purchasing a much nicer digital force meter. (Its held down by capa / shapelock… I know, I should really have printed that part)
Filament Harness
Since we’re measuring how hard the extruder pulls on the filament, we need a way to hook up the filament to the force meter. I ended up bolting the filament between two washers and then looping that over the hook. I only rarely had problems after that.
Extruder Drive System
No need for the hot end or anything like that for this test. I laid the electronics to the side. Then I just clamped it to the wood, making sure to clamp in the middle of the dinos and not too hard. The bolts dug into the wood after a bit and made it snap right into place.
Then I just did a bunch of test and measurements. The fish scale did not have a very fast update rate at all (5 seconds?) It also did not have a peak weight or anything like that. I just watched it and tried to remember the highest number. This was a big deal because sometimes the filament itself would either break or elongate and deform. There readings could be slightly low because of that. It was also a bit chilly in the Botcave (its late december but I’m not going to go that deep on ya.
Here are the results as a google doc:
As for the extruder pulley, yes we will have these eventually. No idea on the timeframe, but having to wait is the price we pay for being as open as possible. I also made the silly mistake of making the diameter of the threaded parts different from the diameter of the current pinch wheel teeth. Its not much of a difference, but I’d like it to be a drop-in replacement. Its a really daunting thing to go into production on a part without a prototype, so it means I’ll probably need to get a new one made. I might have a few other variants made and see how they match up with the results from this one.
CrashSpace (the new Los Angeles hackerspace) is hosting a Makerbot Make-In starting noon Sunday Dec 27th and continuing on a few of the following days. This is our first event. We will be building several Makerbots from early mechanical up through first prints (hopefully!!)
If you have a bot (finished or unfinished), come on by and build!
Exact continuance days and times depends on response. Notices will be posted to http://groups.google.com/group/crashspace and http://groups.google.com/group/lamakerbot
Crash Space wiki
10526 Venice Blvd, Culver City CA 90232
(see wiki for map links, etc)
If you’re interested in laser scanning you’re going to need a laser level. Recently I got some laser levels from DealExtreme. It’s a bit touch and go, I got 4 lasers and 2 of them have good lines, so if you get some, get a few!
If you’ve got a hookup on galvanometers, drop a note in the comments!
Ok, it only works on windows at the moment and it only works with OBJ files, but Meshmixer looks AWESOME! Get over to Thingiverse, grab two open objects, export them as OBJ files in Blender and MASH THEM UP!
I saw this photo in the MakerBot photo pool. Bas Piljs used the scrap lasercut part that holds the brackets as a sorting tray to keep the nuts and bolts for assembly separate. So elegant! I’m definitely using this idea in the future.
We’re very excited to announce that we have custom-designed hand-made 1AEON t-shirts in the MakerBot Store. They are printed on American Apparel tshirts and are awesome.
I’ve been friends with 1AEON since I saw his work over at Etsy and worked with Tara Young to make this video about him. Besides making shirts for sale on Etsy, he is a designer for hire who has made the NYCResistor t-shirts and Things t-shirts.
Here’s a picture that shows you a bit of the process. Everything is handmade. 1AEON builds and burns the screens and then prints them.
Robert Bowdidge discovered a cool way to make model train buildings!
I wondered if I could break up the long side pieces so that the top layer couldn’t pull across the piece to cause the warp. Back in SketchUp, I made the piece twice as deep, and cut some wedges out of the thickened back side perpendicular to the warping.
but I’m not going to go that deep on ya.
