I still have to figure out how to hold on the workpiece a little bit better. The final layer becomes a bit of a problem when it cuts through. The Proxxon tool is nice and quiet — but Im beginning to want more power. EPVC ( Expanded PVC ) is super easy to mill — I run at the speed I do because the proxxon begins to complain at higher speeds. at 16mm/s, the tool is noticeably loaded. A little faster, and the tool stalls. I think EPVC can mill at a much faster speed than I’ve done it at. And it’s super cheap! I always find scrap pieces at my local TAP plastics — I bought a bunch of different plastics for experimentation. So far, I like EPVC and HDPE — they mill wonderfully. I hear Delrin mills well, but there’s no local supplier that can sell me the small sheets I want. Getting a large sheet and cutting it down is a pain — though I may do it as an experiment in the future.
I’ve ordered a remanufactured ER11 spindle, complete with motor, from China. I don’t think I’ll make that a standard part for EasyMaker — it’s just too expensive to get them new.
The part above is a design change for the printing mode of EM. The final part will be made of HDPE and much thinner. This part was a test of holding down the workpiece with two pieces of carpet tape. I have to find a better way to hold down a work-piece when milling all the way through. When the final layer gets cut, there’s no support anymore.
Oh well, off to work. Thanks all!
One of the core problems with CNC milling is workpiece holding. EasyMaker can do it 3 different ways.
- Use screws into the T-Slot. Although right now I have an MDF spoilboard mounted, EasyMaker supports using T-Slot extrusions as a mounting system for the workpiece. You can see it in some of the other videos.
- Screw down a piece of MDF, then attach your workpiece with carpet tape of woof screws. I’ve sized EasyMaker to accept a 12″x16″x1/2″ MDF spoilboard. I chose this size because it’s super cheap. Go down to your local lumber store (I used Dunn lumber, because they’re right next door to the Grocery store ), have them take a 2’x4′ sized board, and cut it into 6 equal pieces. Viola — 6 spoilboards! Super cheap — less than 10 bucks for all 6 of them combined, so around $1 and change per board.
- Use a vise. I’ve tried this out a few times, and dislike it. You lose a lot of Z room to the vise, and you need to position the X beams pretty high with a vise. I get paranoid about accidents — the tool could run into the vise, and that would be bad. It’s also heavy/inconvenient to carry a vise around.
All of these methods have their ups and downs. I like the wooden spoilboard best right now, because I don’t worry about the tool running into it. I milled the mounting screws for the spoilboard on EasyMaker itself. One cool thing is that the tool aligns with the T-Slot when in the home position. This makes aligning everything for milling in mounting holes easy. I just mounted a 5/32 drill bit, and jog it like a drill press. Very easy. The downside of CNC milling is workpiece holding. Some times, you spend as much time designing your supports as you do your product…