Friday, December 4, 2009

Ok, things got pretty hectic around here, but we finished building our plywood Mendel. We stopped using drawings and went for a more hack it together approach. We ended up abandoning the Z Axis support bars and only using the screw drives with a bearing on top and bottom for sway control. This worked well, but we do have about .5mm of wobble from a slightly bent screw drive.

Tuesday, October 27, 2009

Ok, we got the Y-Axis bearings made up and the Stepper driver boards are in. Too bad I forgot most of the drawings in Ontario. I do have two photos with me (don't ask why, thats all thats on my memory card).

I've attached a couple pictures, including a couple screen shots of the bearing supports in AutoCAD (If anyone wants the CAD files let me know and I will email them out). The bearing supports are made out of 5/8" plywood, and if you print the CAD file in 1:1 ratio you can just stencil them on. Disregard the "mm" after the angle measurements, AutoCAD Overrides and I weren't getting along that day.

Mounting the bearings on the print surface was a little rough (as you can see in the photo its a little crooked) but it works really well, and moves full range smoothly. Adding the Stepper Motor and belts should be a snap. Make sure you cut the top of the bearing mount in the right spot, or you'll have to use washers to level the print surface.

The original design was a failure, they were too hard to make up, and impossible to tune. This new design is easy (as long as you are precise with your cuts) and takes about 15 minutes per bearing mount.

When I get home I will post the photos that show the bearings better.

Wednesday, October 14, 2009

While talking about the rest of the Y Axis we realized that the Mendel print tray parts are too complicated to make from Plywood (not to mention pulling part dimensions out of Art of Illusion seems to be impossible), so we are re-engineering the bearing system for the print tray (I'll be nice to get a plastic version printed off when this is all over, but hey it's going to be one hell of an adventure). I've included the drawing we are looking at for the bearing plates and the bearings I picked up today. The dotted lines in the drawings are the angles for the bolts we're using.

This whole blog thing may work out for the best as it keeps me from talking off my girlfriends ear with things that she neither understands or cares about :).

The trend around here seems to be to blog your build-up for others to use as guidance and drooling, so here it is.

My buddy and I have been looking into building a RepRap for a month or so now, and we've finally decided to get started. We were originally going to start with a McWire bot and use that to build a Darwin, but got distracted by the new shiny Mendel build last minute. With the years of backyard mechanics, basement electronics, and twin electronic engineering technologist degrees, we decided the fact that we have no way of printing Mendel parts and no real clue of how to start was of little discouragement and that we'd give it a go anyways.

Our "Mendel" (in spirit mostly) won't be made out of precisely printed plastic parts, but rather cobbled bits of 5/8" plywood custom engineered to work as close to the original plans as possible (Did I mention we have no access to a wood/machine shop, and do most of the work on my apartment balcony with an old school drill and jigsaw?). Let this be a lesson to anyone who is ambitious enough to give it a try, with enough stubbornness you can accomplish anything ;).

OK, enough babbling, on with the build. We have completed our first night of building (last Friday after work) and I think it went pretty well; we got the main support structure and the Y Axis rail system in place (Pics attached).

We already have the Arduino Dev Kit this project uses, and a slew of stepper motors and other fun bits; we did however have a hard time finding the stepper motor driver boards (the ones specifically for this kit are sold out in kit form and pre-assembled), and digikey seems to be sold out of all the useful bits we needed. We ended up finding driver boards from Sparkfun, we'll let you know how they work out.