I would like to play with vacuum holding. Looking at Amazon.ca, there is a plethora of materials and diameters. I am a bit (well a lot actually) miffed at the cost of this stuff. I realize that I probably have lost touch with reality and the cost of things but paying almost a dollar per foot seems pretty darn expensive.
I would like to hear opinions on several things:
Have you found sealing material that works and is noticeable cheaper?
Should the material be made of foam or can solid rubber be used (the rubber cord that is used to hold bug screen material in frames is dirt cheap but it doesn’t have much give)
What cross section are you using (round/rectangular/other)
What thickness or diameter are you using? I was thinking 7 mm diameter round material to use in 6.35mm channels.
Any other thoughts?
I was playing around with this concept for sanding or for holding stuff down on a work bench. Found a nice neoprene rubber sheet that works well, then just cut out the middle.
Neoprene I find works well, not too spongy but still rubbery enough to seal well.
Also tried a rounded bit to make the channel, but found square worked better as it held the cord in better.
Again - i was just horsing around, not sure how it would hold up with a cnc.
Hey Jens,
If I start to play around, it will mostly involve materials that are lying around my shop. In fact, the only sport I like is to make something for the shop purely sourced from it and will see going to a hardware store as a point lost.
The other day the misses asked for the third time -3 strikes is out- to fix that leaky outdoor water crane that got frozen last winter. It was a soldered connection. I do not have the right tools for that. No burner (only a weed burner.) No silver/lead solder, only lead/tin and no flux paste, only flux for pcba rework. I however had pinch connectors and a wall plate for a crane that would fit the pipe. I however did not have teflon tape to seal the connection between the plate and the crane. So it was time to come up with a shopsolution.
It turns out that loctite 243, a glue to prevent bolts and nuts from shaking lose can resists water and petro-chemicals. Since I have a skitload of that everywhere in the shop, I simply took the gamble and used it as replacement for teflon tape. Works like a charm. No idea for how long, but that is the gamble to take if you want to score shoppoints. The only thing I am worried about it it’s holding strength when force is applied on the seal. It’s designed to crack at 20ish Nm force. So I intructed the misses to hold onto the crane while opening and closing in order to be able to shift the blame when things go fountain.
The thing is, if it didn’t work, I would have learned a thing, lose a point and bought that tape. It costs a buck or two but that is no longer the point. I am hellishly fanatic when it comes to shop sports.
So yes, I think those door seals will do for a proof of consept, as will tape, hotglue and anything that looks like it will come close to be able to create some kind of under presure strong enough to hold something down. (hint)shopvac(/hint)
I bet you have all the components to create something that works, just so you can see if it will be usefull or not. You will learn a ton about vacuum table setups and find out if you need the expensive stuff or not. (Not.)
If it sucks, its good enough, right?
LOL .. shopvacs are for sissies. My source of vacuum is a 5hp variable speed 3 phase chip collector that, at least in theory, should be able to collect chips AND provide enough negative pressure for vacuum holding.
… at least that is my theory at the moment.
Sounds like you might be able to just hold your hose somewhere aproximating the underside of your mdf wasteboard and call it a working vacuum table.
Done, next project!
@Jens I used the dollar a foot stuff when I did my vacuum pucks. IMHO, you do not want foam. It will leak. I used 1/4" round. That made it easy to route the grooves to hold the gasketing material. I already had a vacuum pump that I’ve used for the vacuum chuck on my lathe.
I tried and failed with a larger version, using both a shop vac and my dust collector. I fried the shop vac. The dust collector, while not frying, was definitely not the right machine for the job. It depends on being able to suck air through the machine dust boots. When it can’t do that it does not do anything remotely ressembling a vacuum pump.
The shopvac needs the incoming air to cool the motor. Without that the motor fries. There are exceptions. Fien and Festool come to mind. Both are out of my snack bracket.
For most of my projects, the pieces are too small to make vacuum an effective hold down. But, the pucks work well for pocketing projects.