Vacuum Clamping

Ian Barley

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Despite recent PC problems I have actually been active in the shop in the last few days as well. I have finally got round to implementing a vacuum clamping system for the templates I use with my Onsrud pin router.

I always had a vague distrust of vaccum clamping. I guess for two reasons - firstly because I had a bad experience with a cheap system but mainly because - heck - its only a bit of air pressure - how is that gonna hold my workpiece firmly.

Well - I recently got to experience a real vacuum system at W6 - the main woodworking exhibition in the UK - and bought an Onsrud add on kit. When this thing grabs hold it does not let go! It has languished in my shop for the last 3 weeks waiting for me to put a plug on it and set up some new templates. Today I finally got round to it and it is fantastic.

Basically it saves me having to screw through the template into my workpiece and therefore saves time and also reduces manufacturing artefacts in my finished product. I reckon it will save me at least 30 seconds a piece which sound like nothing untill you consider that I cut about 5000 components a year - thats about 42 hours a year saved - nearly half a weeks holiday!

I will try and take some pics tomorrow and expand a bit on this - I just wanted to post something about woodworking for a change!
 
Skin of Your Teeth

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I will try and take some pics tomorrow and expand a bit on this - I just wanted to post something about woodworking for a change!
Ian, here I was preparing to get all over your case for not showing any pics of this new clamping system, and you sneak this in at the very end. It might buy you a little time, but you're by no means off the hook. We need pics! :p
 
Simple, it sucks :D
Reminds me of a time years ago when I was a construction inspector, and I was chatting with a couple of plumbers installing a big vacuum pump on the HVAC system at an airport. Pointing to the pump, I said something like "so that's the Suckutron, huh?" In a deep southern drawl, one of the guys reached over, patted the top of the pump a few times, and said "We just call her Darlin'" :p
 
ian, i`ve been using vacuum for years, both as a fixture clamp and bags, all i can say is welcome to the modern world! your product will be cleaner with less work and as you get used to having a vacuum system you`ll think of lots more uses for it.......enjoy! tod
 
ian, i`ve been using vacuum for years, both as a fixture clamp and bags, all i can say is welcome to the modern world! your product will be cleaner with less work and as you get used to having a vacuum system you`ll think of lots more uses for it.......enjoy! tod

tod

I already am thinking of new uses. So many jigs - so little time!!! When I bought the Onsrud router which was the main driver to this purchase the vacuum setup was a little bit more money than I was able (willing) to spend. The other problem was that it just seems too good to be true. "No way can a bit of foam tape and a little pump hold that workpiece". And then you try, as hard as you like to tear it off and it won't come.

I have just cut a small batch of one of my components and I am saving more like a minute a piece with better quality. I wish i'd spent the little bit of dough 2 years ago - no where have I heard that before?? Oh yeah - me!
 
ian, one of the handiest non-pinrouter jigs i`ve done is a 90 degree hold down that i can use on the saws or shapers sliding tables.......food for thought...tod
 
My first exposure to vacuum cups was at the IWF show from these guys.

http://www.bettervacuumcups.com/

I thought there could be some good applications for the home woodworker but the prices are too high IMO. The holding power of these this is pretty incredible. I guess if a veneer vacuum press can give you 1200 pounds of force, these can hold well too.
 
brian, cups are cool.......but they require a substantial amount of vacuum, generally provided by a screw type pump........not exactally hobbiest or even small shop type of equipment. the onsrud pump i think ian`s talking about looks like a 20 gal. compressor only instead of a compressor head attached a gast vacuum pump is used. the system i use uses venturi generators but any small to medium piston type pump will do well for template holding and the smaller diaphram pumps will work is a storage tank is employed so the pump isn`t under so much load all at once.....food for thought....tod
 
Ok - here goes with some pictures and some extra explanation of what I have been doing with my new found friend atmospheric pressure.

First pic is the pump. This is a dry running pump - absolute minimum maintenance. It has no reservoir but I may look to add a seperate one and am also going to build a wheel around cart for this as I am gonna find uses for this all over the shop but will not have the time/money to plumb vacuum around like I do compressed air.

Next Pic shows the valve/guage qizmo that is attached to the top of the router. Basically it is a push pull pneumatic (5/2) control that diverts the vacuum "pull" either down the tube to the fixture or to a silenced exhaust at the back of the setup. There is also a filter (clear drum on the back) and a pressure guage which reads from 0 - normal atmospheric pressure - down to -1bar which would be a perfect vacuum which, while theoretically possible, is almost impossible to achieve in practice. I am getting readings of -0.8 to -0.9 in oak. That is more than enough to do the job. Interestingly MDF runs at about -0.5 because it is more porous. Even at the lower value I cannot remove the workpiece by hand.

The template is attached using a removable connector so that switching templates is a matter of seconds. The metal part is a kind of latching plate that acts to keep the connector mechanically locked to prevent sudden loss of vacuum. One of the great things about vacuum is that the basic physics help to keep the whole system together. Any loose joint in compressed air tends to get blown apart but with vacuum it just gets sucked back together. So even my sloppy engineering gets a result :D

And this is what it all does. This is a template that I use to cut a footrest side. I use clear acrylic so that I can position the template to avoid faults in the timber finding their way into the product. The black tape is the foam that creates the vacuum reservoir and you can see at the top of the template the hole which is drilled to get the air through. There is another hole which intercepts this one at right angles creating a path from inside the resrvoir to the connector on teh back edge of the template. The connector is located on teh back edge of the template so that the vacuum tube does not interfere with the template guide pin on the router.

This is a closer pic of the template showing the air hole a bit more clearly and also showing the holes drilled through the guide path of the template. Basically because the extraction has to pull chips down through the template and teh workpiece these holes increase the airflow and improve the chip extraction.

Last two pics are another jig I have just "updated". Basically rebuilding a very flimsy one that I have used for the last 3 years. This is made in HDPE plastic and is used to align two compnents in the front leg of my chairs. I was going to use a pneumatic clamping system but vacuum has advantages of simplicity and also ensures that nothing is held tight until evrything is in the right place. Basically just three blocks carefully lined up with 3 holes and some tape but it does the job. Why HDPE? I wanted something that was a lot less susceptible to moisture, would enable me to wipe (or peel) off any glue squeeze out and which was not the colour of wood - my workshop is just too brown!

In the background of the second pic is another top tip. I always lose stanley knives - just too small and non-descrip in colour. So I tie lengths of coloured tape to the which not only helps from the colour point of view but also makes them visually much bigger and easier to spot. I do the same thing with a number of things like small hammers etc - using different colour tapes. Helps to break up the visual "brownness" of a shop full of wood.
 

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I have been using vacuum clamping for many years. But I have made my own clamps--- of many sizes--- almost always use the system for bench top routing,sanding etc.
the holding power amazes me each time.
 
RE: price----purchase vacuum pump-----need not be exotic or overpriced----make your own clamps ---if you go for commercial you will need more money. Quick connect hardware,plastic hose available on amazon-------once you go there you will never go back----enjoy.
 
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