Day: February 28, 2010

OverlapStrap progress and firmware modification

I have completed the Y and Z axes now of my OverlapStrap. I was originally planning to only use one Z axis motor and use one of the syncroflex belts that I bought for the Mendel to drive the two lead screws. But when I saw the price of the cheapest aluminium timing pulleys that I could find, I decided it was cheaper and simpler just to use two stepper motors for the Z axis instead

At this stage I also intend to drive the Y and X axis using lead screws. This required some modifications to the reprap firmware. Annoyingly there are preferences in the reprap software for features that don’t exist. I am a strong believer of YAGNI and also think that Green Code is a violation of this principle, so I was a bit annoyed to find both of these practices employed in the reprap code. Anyway, once I got over it and realised that the software preference for steps/mm had no effect on the hardcoded steps/mm defined in the configuration.h of the reprap firmware I was able to change it and upload the new firmware.

I have a feeling that such a low steps/mm setting will lead to printing problems when overlapstrap is complete, however I have a plan to mitigate these problems. I intend to bootstrap some basic parts using the leadscrews and then upgrade overlapstrap to a belt drive version using these parts. I will need to print a belt splitter jig, and some drive pulleys.

Advertisement

Green Code

Green code is code that has been commented out. Its usually green because the popular development environments I use syntax highlight the comments in green. In my personal opinion having large chunks of commented out code is a violation of YAGNI. A much better approach than commenting out the code is just to remove it, if you are using  source control, which surely you must be? a record of it will be stored in version control. Doing this has two advantages, firstly the current source code has less clutter, and secondly the source code is kept historically in version control along side the code that it was meant to work with. Keeping the code commented out along side the current code is daft, unless you think that un-commenting out the code six months later it will still work, which in most cases it probably won’t.