www.TK560.com

[jdougn]

[kayaker43]

Thanks to everyone who reccomended my plans. I try not to discourage experimentation, I've done plenty of that. I do cringe sometimes though whenever I see someone heading down a road that sacrifices performance for no good reason.

Mark, feel free to improvise but call if you want to make big changes, I don't have enough time to monitor forums but if you call I can at least explain the consequences and thought process behind the plans so you can better consider the effect of changes.

A few comments,.. The general rule is that the plastic should be spaced away at least 2X the distance between heating elements. Too close and you heat stripes, too far and you lose efficiency. The clamp frame doesn't close off the oven, we're not heating air, the infra red is doing the work.

Vacuum forming ovens are all about juggling the variables to get a specific kind of IR output in a range best absorbed by plastic. Other materials want something different. Hot air ovens are a completely different challenge. The Hobby-Vac and Thurston james ovens heat from below so even though its still primarily IR output, you also have to consider how airflow affects it, and it sure does.

While all nichrome ovens seem the same, they all perform differently. Something as simple as changing the thermal mass with different materials for the housing or insulation boards will alter the output. So will adding insulation or changing the venting of the oven. Of course any changes to the coils and you start all over with different watt density and IR output. Even the same coils with different spacing or stretch ratio alters the temperature and output.

The Proto-Form oven is a result of research, guessing, luck and years of tweaking. Honestly, mostly guessing and tweaking, now that it works well I'm starting to understand why! People ask me why I can't just whip out a custom sized oven design for them? I have enough experience now to get close, but I would still have to build and test many versions before I'm willing to sell the information.

Platen, tank and pump sizes are also related, but like ovens you can be way off and they still work to a lesser degree. If you want to enlarge the Proto-Form without risking performance loss, simply scale up the vacuum system proportionately. If you want to enlarge the oven, use the 6 x 24 oven tiles I sell and copy all aspects of the mounting and installation as closely as possible.

I encourage anyone who has the time and desire to experiment and invent, that's the most satisfying part of any project. My plans just give you a place to start.
_________________
Doug Walsh
www.build-stuff.com
Hobby-Vac and Proto-Form machine plans

Also other plans books and videos for people who like to build things