Wednesday, January 14, 2009

Quick update on the two RepStrap builds.

The DIY Repstrap started out using the pipe CNC idea using copper pipes and easy fit connections. Looking at it one day I just thought it would bee much cheaper in MDF with 2x1 and more robust.
Having already discovered the 13" long Y axis was not big enough I decided If I was to change the Y axis to 15" I might as well remove the copper hence we get the 2x1 and MDF low cost DIY repstrap.

Blogger Pictures



Using £12 stepper motors that seem quite happy with a 6 Kg load on the work table.

Problem with using the lower cost steppers motors they get very hot when powered continue sly. I had already bought a Maplin infra-red thermometer for checking the extruder temp.
pointing this at the itty bitty steppers showed me they were sitting at 70C burn your puddys hot.

Looked at the standard Arduino decided Pin 15 would do to switch all of enable pins on the RRRF stepper controllers.


Last weekend was spent playing getting the Arduino and Sanguino controllers working correctly with the RepStrap Machines now this appeared to be a bit of a black art at first getting a version of the firmware to run correctly there seem some serial coms race conditions, I must say seem as I have not bothered to investigate the actual problem. One set of documents have the data bits parity and stop parameters set labelled incorrectly.
Any way reading a Forum post by Chris Meighan I downloaded the zip file and ran the package Luckily Chris had chosen the same Arduino pin to enable the steppers.
All the problems were resolved by using the New, improved G-code firmware for RepRap the code is nicely commented and compact. I installed the latest Windows RepRap Host from Adrian the only problem seen using the Host software is some kind of resolution problem with the Z axis where instead of 400 steps per mm you need to set this to 200 don't know why yet. The firm ware from Chris seems to be correct in stand alone mode, not yet down loaded the source for the Host to investigate. Spent a lot of time playing with G code files and Windows RepRap host SW.

Next Job finish the extruder order ABS to play with not sure about using HDPE yet.
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