I have started to build the new larger Mantis CNC inspired repstrap. The plywood i’m using for its construction is, oddly enough, from 8mm rifle ammunition boxes previously used by the Australian navy.
Lids and bases of the ammunition boxes.
Its 16mm thick, easy to work with and best of all, free. Hence I have called this new repstrap the “Gunstrap”…
I have made a reprap wiki page with a few details of the build, including all the dimensions which I have been using to cut out the required parts.
An exploded view of the 'gunstrap'.
After a few hours with the jig saw I ended up with most of the required parts.
Plywood parts for the gunstrap.
You could use a hand saw in theory, but it would take considerably longer.
A few notes on the construction; by drilling through both sides that hold the stainless steel rods at once, you can ensure a perfect alignment. This, in combination with the gluing of parts onto the hollow sliders means even someone as care free with measurements as my self can end up with a smooth sliding repstrap. Both of these ideas I greatfuly borrowed from David Carr and his construction guide for the Mantis CNC.
Drilling through both parts at once ensures perfect alignment.
After another few hours of drilling, gluing and screwing together its about half done.
The Y axis (print bed) is mounted and ready for the belt to be attached. I had planed on imitating Nophead’s heated bed design which uses 240V AC. However I’m now having second thoughts due to safety concerns and so will instead look into the 12V computer power supply option.
One key lesson from all of this is that Sketchup is indeed very useful for designing new things. Its easy to learn, very easy to use and you have a large collection of parts to source designs from on the 3D warehouse.
Lastly, I’m still unsure if I should commit to the Peltier idea for the extruder stepper motor as mentioned in the previous post. A lot of people commented saying that 100 degrees C is too hot and that the commercial printers only run at around 70C. Even at this reduced temperature the stepper motor would still benefit from some form of cooling. However other options such as a Bowden extruder or ducted cooling (used by commercial printers!) for the extruder motor were suggested which could be possible options.
Before I move on to all that though I want to just start printing first. If my wades extruder arrives some time this week then then my first prints should be before the end of the year.
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