Tuesday, March 16, 2010

Ruminations on a Heated Build Platform

In the early days of homebuilt rapid prototyping machines (that would be a year ago) there were constant problems with the parts warping due to cooling of the different layers of the object. Commercial machines have the whole build area heated in order to prevent this but that wasn't really possible given the RepRap's open grid design. Then someone had the brilliant idea of simply heating the build platform and a new era of predictably unwarped building was begun. Now anyone who is able to heat their platform can, with a bit of experimentation, produce good quality parts without throwing 50% of them in the trash.

It is fairly obvious that I will need to add a heated platform fairly soon after I complete the Mendel if I want it to actually be usable. I have investigated any number of designs on various blogs. Most of them look fairly simple but, being mechanicaly challenged, I want to take the absolute easiest path possible. I think that I have found that in Tim's design over at Bothacker.com. It is a bit more expensive than others I have seen but tons easier to implement. This guy is my hero, his repstrap design, using aluminum channel, is also extremely clean and elegant.

The following links and pictures have been shamelessy stolen from Tim's website.

The setup consists of the following:

I find this approach attractive because it is basically a buy it and install it solution. The pads even come with their own adhesive already applied. He has also posted a couple of pics of his control box which is exactly what I was planning on setting up. It seems logical to have everything neatly enclosed in a project box and, in addition to the heater, there will probably be a number of additional systems to build and control as things progress. The workbench could become a mess of loose switches, wiring, etc. without some advance planning and organizing. Below are a couple of pics of Bothacker's control box which includes the bed heater controls, power supply, fans, control board, stepper drivers and an emergency cutoff switch. Very slick, and he still has lots of room on the front panel to add things.

These project boxes are not expensive. I have been looking as a couple on this site but I will wait until I have gathered all my electronics before ordering one to ensure that I get the right size.

As a final note - A new set of Mendel RP parts has shown up on Ebay so I threw a bid in on it. Given that the set sold by Adrian Bowyer went for $647 Canadian, I don't hold out much hope but you never know.

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