Month: April 2010

Stepper Motors

When I ordered my stepper motors sometime last year from motion control products I chose the cheapest model at £11.23 which was FL42STH38-1206A sometime afterwards I realised that these steppers have much lower holding torque than the recommended mendel FL42STH47-1684A-01 (25.5N-cm vs 43N-cm) however this was not a major problem since mendel requires that “Torque must be at least 0.13 Nm” which is 13N-cm, and well below the rated holding torque. It was only when I came to wiring the steppers up that I came across the next problem. The Generation 3 stepper drivers are for use with Bipolar steppers.

Wheras the steppers I had bought were Unipolar steppers.

Fortunately for me they were 6-wire Unipolar  steppers, and as you can see from the wiring digrams above you can just not connect the centre taps for the coils (labeled A and B above) and we have a bipolar stepper again.

More recently when I decided it was cheaper and simpler to use two steppers for my Z-Axis, I was a stepper short. This time I bought the SY42STH47-1684B compatible product from Zapp Automation for only £8.50 it has a holding torque of 43.15N-cm and is a 4-Wire Bipolar stepper. I am going to use this to drive the CrudeStruder, as I think it could benefit from the extra torque.

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Decking

My Dad kindly helped me build a nice decking area at the back of my house where we can have barbecues, and enjoy the sun. When I say he helped me, what I actually mean is that he did all the hard work.



I am really pleased with the results, Thank you Dad for being so kind and helpful.

Update: I created a panoramic view by stitching the above three images together in Hugin

OpenSCAD

I have been hacking around with OpenSCAD. First I added an exponent operator to the language because I felt that writing pow(x,2) was a bit more cumbersome than x^2 . Then I added a few more operators like a component-wise multiply and component-wise divide I wanted these to make it easier to translate points so I could use them as datums. I even implemented an experimental rotation operator. Then I decided to get a little bit more adventureous. What I wanted to do was make the OpenSCAD editor have syntax highlighting. Investigating doing this using qcodeedit is on the OpenSCAD todo list, so I thought I would give it a try

I was quite pleased with the results and it wasn’t to complex to implement, QCodeEdit’s QEditor is almost a drop in replacement for QTextEdit. I created a wrapper which allows somone compiling the source to choose which editor they want to use with compile time flags. In fact, to disable QCodeEdit support all one has to do is uncomment out the line with

CONFIG += qcodeedit

in openscad.pro

EDIT: All the changes have been merged into the main github repository which can be checked out using

git clone https://github.com/openscad/openscad.git