View Full Version : y clamping method for smaller parts with lots of one off's

Steve knight
06-17-2008, 12:43 AM
I seem to do lots of one off's and oddball things and solid wood. so vacuum clamping can be a pain unless I am doing several.
I have modified this method quite a few times. The last one was a pegboard type setup with threaded inserts and big wooden cams.
This works well but for the threaded inserts. They do not hold great in mdf and I need to use the cheap soft ones so if I hit one it is not a big deal.
Another issue was keeping thins flat. I had solved that issue with the treaded inserts mostly.
So I finally broke down and bought some t track and shofox cam levers. I debated on just cutting t track into the mdf but I think ĺĒ mdf may be too thin for strong enough slots. Though feedback on that would be good.
The advantages to this are that the cams put downwards pressure on the piece so it should stay flat. Plus I donít have to hunt for chunks of wood when the cams are not close enough on their own to reach and thatís most of the time it seems.

Michael Kowalczyk
06-17-2008, 8:00 PM
Cool idea Steve.

So do you use bridges/tabs to cut small parts since you are not using vacuum?

I just started doing two up prototypes on the big twin table cnc using a 1/4" mdf as a spoil board and the 5hp bush vac pumps, one for each table, drop down to 8-10 inches very quick so I had to add bridges so the parts would not fly. The 5's work great when I make a dedicated spoilboard out of PVC, HDPE or lately I have been using 18mm Russian birch. I can maintain 23-25 inches easily and still cut around 600 to 800 IPM without parts moving and no bridges. But I have to get the order first in order to make a dedicated one. So for now the 1/4" MDF works OK.

It still amazes me how some of you guys create fixtures for one ups or non vacuum jigs for multiple hold downs of solid blanks.

I am working on a jig/spoilboard to cut a two 3D parts out of hickory plank and then flip it over do the exact same thing on the back side so I have to create a mold with excellent vacuum holding power because the part has rounded over edges and they are from a fingernail bit (whiteside 3294 with bearing ground off if you want to see what I am talking about) not a standard 1/2" roundover bit and I have not found any software yet that can have this kind of tool in the tool library. Otherwise I could just create the mold in ArtcamPro and be done. So for now I have to fake it out to get anywhere with it. Still working on it and hopefully I can get it going this week.

Thanks again for sharing. What kind of CNC is that? Looks a bit like an old Digital tool 904.

Steve knight
06-18-2008, 1:19 AM
Don't get me wrong I like vacuum but my setup is not powerful enough if I don't have great seals. with solid woods that can be problematic. I have two fien vacs for my main vac through the spoilboard.
I would need a whole new electrical panel to get much more power into my shop so till I can really justify the expense it won't happen soon.
this setup lets me slap odd and normal shapes on fast so I can do prototyping.
if I cut through then I would use tabs but another trick has been to use a down cut bit and that will keep sawdust in there and keep the pieces in place. a lot of times I am not cutting though so it's not an issue.
the machine is a shopbot prt alpha.