Kinda surprised there's not a pattern making section on here. This isn't a real project, still in the testing phase of learning this process. I was trying to make a pattern for a simple straight tube. There were to be flanges with holes for tubes at both ends, similar to the one I made on my milling machine, although not angled sand much bigger I glued up a blank of poplar with a piece of cardboard in the middle and started turning it on my machinist lathe. I got the center section made okay so I stopped and put zip ties around it then started on the core prints. Then it exploded. Is there a good resource specifically for pattern making? I'm feeling like a book might be good for this one, although I'll take what I can get.
Hi Allen, I've found that layered MDF soaked in epoxy can be a useful material for making patterns as it doesn't really have a grain, just layers from the compression during manufacture. MDF will soak up epoxy resin like a sponge after rough machining and once cured it comes off the lathe tool in streamers like some plastics do, and it machines quite well. It also lends itself to CNC machining as there's no real grain to worry about, unlike wood that hasn't been carefully glued up in segments. I use machine screws to join the two halves of the impregnated pattern for machining and use wood screws to attach machined steel to the ends for the live center and chuck jaws to grip.
Thanks. I like the wood screws. Where are you getting enough epoxy so that you can soak MDF in it? I made the bore 1" so I could just make the core in a piece of pipe.
I make small batches of epoxy and brush it onto the MDF with a disposable brush. MDF soaks up epoxy rapidly almost as fast as you can brush it on and you will have an outer layer maybe 1/4" or more thick over the inner core with no epoxy. For that reason I rough machine the MDF before applying the epoxy. The wood fibres will get into all areas of a metal lathe so a vacuum cleaner sucking up the cut shavings will help keep things clean. I use boat builder's 5:1 fibreglassing epoxy resin with a slow cure, I use Allnex brand which apparently owns the West system brand. You may find the core hard to remove intact from a piece of pipe unless split: I use split PVC pipe with a few cable ties to keep it together and save the ties for reuse.
