Imran's personal blog

January 10, 2012

Imran’s Better Bot Try 3

Filed under: Uncategorized — ipeerbhai @ 12:17 am

Hi All,

Just a quick update on my better bot. I’ve rev’d to v3, abandoning v2. I’m now deciding which way to go:

Just to Recap:
V1 — This version used 80/20 1515 ul extrusions and printed linear motion carriages from my RepRap. I completed the linear motion portion of this design, and decided to stop. The printed carriages were too big, and I felt that they were too inefficient. It also took a long time to print the parts, and I felt it would be too hard a build for most folks. Lots of bearings, long build time, low linear efficiency made me kill this version.  I still have the design files if someone wants them, please email me.

V2 — This version used my home-made linear motion system.  I got a few prototypes put together, and got stuck on 2-dimensional motion.  The problem being that my linear carriages needed greater precision to manufacture than I could achieve with a drill press.  I was going to continue this version, but then I went to China and MakerSlide started shipping, causing me to reconsider what this should be.  I was able to buy SCS12uu carriages and polished chrome rod really cheap there, and it made less sense to design a linear motion system when I could buy them for so little.  I also bought some MakeSlide and had a chance to experiment with it.  I must say, it’s growing on me.  Originally, I felt that MakerSlide couldn’t handle routing loads.  But as I experiment with it, it impresses me. It’s much more stable and sturdier in use than I expected it to be, the linear carriages are much smoother than I expected them to be, and it’s surprisingly tolerant of contamination.  If you have a CNC bot, I can give you my carriage design.  I’ve tested it, and it does work fairly well — though I don’t know for how long.  It uses a hybrid bearing of my own design — one part rolling bearing, one part plain bearing.  I don’t know how the two bearing systems will interact with the track.  I already notice witness marks forming in the track from the steel rolling bearings on Aluminum track.   I suspect the plain bearings will wear as well, and that dimensional stability will reduce with wear.

V3 — This is in concept stage.  I’m deciding between a MakerSlide based system and a steel rod system.  I have concept drawings of a makerslide system.  I suspect this will be a major direction change for my design — Focusing more in filament printing and weight reduction than on CNC routing for this revision.  I actually have 3 different designs in mind for this system — one like my V2, but with MakerSlide, one that is frameless using MakerSlide, and one that is using 12mm rods, sk12 supports, scs12uu bearings, and a mix of CNC – milled plates and printed connectors.  When my mind settles on one of these, I’ll push that design further.

On a side note — I bought a ShapeOko.  I think this may be the end of my CNC design, if the ShapeOko works out as well as I hope it will.  As I wrote about earlier, it’s a design very similar to my V2, but with the linear motion system problem solved with MakerSlide.  I didn’t expect ShapeOko to be available generally until 2012, and thought I would be done before 2012 rolled around.  Now it is 2012, and ShapeOko is beginning to have  availability.  Coupled with PrntrBot, and I have less impetus for completing my own designs.  I may abandon this project and move to my next project — I’m not sure yet.

Thanks for reading, and keep your stick on the ice!

Imran

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