Friday, 21 September 2018

DIY - Laminating Hot Box / Layup Table / Cutting Table

Making a board in winter can be a frustrating exercise with many epoxies requiring minimum temperatures of around 20 degrees Celsius to cure correctly.  Up until recently I have only built boards in the summer months as I didn't want to risk burning the shed down with any of the usual methods such as heat lamps or domestic fan heaters.  The other problems with lights are a huge delta-T over the surface of the board and most of the heat generated is lost.  Of course you can enclose the board with the lights but then have an even greater risk of overheating near the lights and a possible fire!  I also began to laminate on a table and found it was hard to get a large enough workspace to laminate the cloth in one flat section.  The solution was a Hot Box!

The Hot Box allows you to: 
  • gently warm your laminating resin
  • warm the board to be laminated
  • warm the cloth to be laminated
  • cut cloth without repositioning
  • maintain resin temperature during laminating
  • maintain precise curing temperature of the laminate
  • store blank foam when not in use
Heating is provided by 2 x 400W fan forced block heaters with a digital temperature controller with temperature ramping.  These allow gentle heating of the air with continual circulation; it really is a big fan forced oven.  

There is a slot near the edge of the door to clear a vacuum tube and I have added wheels to stand up the box when not in use.  I recommend you have someone help you lift it onto its wheels though as it can be dangerous if you slip and flatten yourself!  

I tied to save a few $ on insulation and use sisalation as the coldest nights in the shed would be about 5 degrees celsius.  Also the plywood insulates fairly well on its own.  If you were wanting to minimise operating costs or work in consistently low temperatures I would insulate all of the inner surfaces except the top and bottom.  On the bottom I would place the insulation underneath to maintain the hard wearing floor. On the top I would place insulation on top once the board is inside as you need the lid to conduct heat for laminating and pre warming the cloth.

So far I have utilised the Hot Box to make 2 boards and have had no problems running it all night.  

I will do a drawing if there is any interest in the comments!

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