Securing the material

[darkling27]

I just got my new cnc machine and i have noticed that there is no way to secure the piece of wood to the bed..... actualy there is no bed at all! Lol. So i was just wondering how you lot have got around this. Atm i have a sheet of MDF placed there to act as a bed, but obviously that isnt going to stop the piece of light material being worked on from sliding around.
I know i could screw the piece down, but i think it would be far more practical to have some sort of clamps in place? What are your thoughts on what i should do?

[CarveOne]

I just got my new cnc machine and i have noticed that there is no way to secure the piece of wood to the bed..... actualy there is no bed at all! Lol. So i was just wondering how you lot have got around this. Atm i have a sheet of MDF placed there to act as a bed, but obviously that isnt going to stop the piece of light material being worked on from sliding around.
I know i could screw the piece down, but i think it would be far more practical to have some sort of clamps in place? What are your thoughts on what i should do?

I drill 1/16" holes in the material to be cut at appropriate places that are out of the cutting area and then drive 5/8" long wire nails through the holes into the MDF with a small hammer. The wire nails will hold it down flat and will only leave small holes that won't hurt the MDF. The material you are cutting can easily be pried up with a wood chisel used like a pry bar. The wire nails can be reused until you bend them too much. Also, side cutter pliers will be useful for pulling up the wire nails after you loosen them with the chisel. Try to avoid running the cutter into a wire nail of course.

Sometimes I use double side carpet tape under the material and then butt small pieces of scrap wood snuggly against the material and then wire nail them in place. Until you get good at knowing where the cutter is going to go, give yourself plenty of room to avoid the wire nails. The one or two times I've hit a nail with a 1/4" cutter there was no damage. Smaller cutters may not deal with the nails so well.

CarveOne

[dlwoodworks]

I've attached some photos of ways I do hold downs ranging anywhere from vacuum to clamps to screws. Each method has its place.

[ger21]

I have threaded inserts in my table. I typically bolt the parts down into the inserts. I also have an X and Y fence, and use cam clamps to hold the parts tight to the fence. I bolt the CAM clamps into the threaded inserts. I'm also getting ready to make some vacuum hold down jigs.

[electronicwood]

I also have threaded inserts and an x-axis fence on my table. I find this very useful for aligning fixtures to the x direction on my machine. I made the fence by gluing a set of blocks just inside the y=0 edge of my table, then machining them so they are perfectly aligned along the x-axis.

I find this edge very useful for aligning fixtures. One I made that you may find helpful mounts a drill press vise to my table. I simply took a piece of MDF (although I would use plywood if I did it again) and machined one edge straight and machined in features to locate the vise on the MDF. I drilled and tapped threaded holes in the bottom of the vise. When I want to attach the vise to the router, I screw the vise and MDF plate together, then set it against the x-axis fence on the router and screw it to the table with the threaded inserts.

One lesson I learned the hard way about cam clamps is that they don't always hold the material down very well. One of the first projects I did was a small box. The sides and lid nested in a fixture and were held in with cams. Unfortunately, I used an upcut spiral flute tool, which lifted the parts out of the fixture. For the first several boxes, this problem looked like a programing error because the boxes did not fit together quite right. On about the third box the router lifted on of the parts completely out of the fixture - then I knew what the problem was. In the future, I will use a downcut spiral flute tool.