Monday, March 05, 2007


Darwin makes a move

I tested a bit of Darwin today. I asked the Z to go up and down 20 times, putting the motor through 1000 steps for each stroke. This, in theory, would only move the bed up and down by 3 mm, but there was some timeout error going on in my code, so that's as far as I could push it today. Testing over a big range is on the list, but it's repeatability I'm interested in, so 3 mm will do for now.

The motor torque was at 100%, speed 200 (see exerciser scale - approx 80%), and the results on the caliper bolted to the bed were... well... the graph can do the talking:

Happy days! I guess that puts the resolution at ±0.01 mm. There's still the X&Y to get moving yet, but it's good to know they're on solid foundations ;-)

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fantastic! that looks really good, and is also some really good news. its hard to gauge how progress is coming along on darwin some times because you spend more time in the lab than on the web =) (a good thing)
What? If you only have the z-axis going on Darwin, not that that isn't great news, mind, what did you use to print out that shot glass? I'm confused.
> hard to gauge how progress is coming along on Darwin

Yeah, I should post more - appologies. I'll break the milestones down a bit...

> what did you use to print out that shot glass?

Ah, Adrian did that on ARNIE. Also while I'm mentioning it, I re-read the entry and realised I'd completely omitted to mention Adrian's huge part in the results. He knows it already, but everything electronic hardware is his doing, not to mention most of the coding!

It's really a culmination of everything team RepRap has done - I was following the wiki for most of the setup and it's a marvel to plug the thing in and watch it go.

Made all the sweeter by drinking tea from the RepRap mug!! Nice one everybody...
Now let me sure I've got this right. There's Arnie and there's Darwin? Are they the same or two different 3D printers?
They're different. Arnie is one of the early prototypes originally designed to test Ed's string-powered Z axis. It was retrofitted with a screw-based Z axis.

They do look a lot alike.

Vik :v)
Okay, so it sounds like Bath has Arnie more or less working and Darwin still abuilding. Cool. I was vastly confused with the situation.
Yup - that's it. ARNIE's been fully working for a month and a bit - we're using it as a test bed. Darwin is being built as the first release design. It's a lot simpler, smoother, more successful with members of its gender orientation of choice etc.
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