I seem to remember a FWW article about a home-made vacuum clamping system that had an “off the shelf” shop-vac as the heart of the system. Anyone remember seeing it? (Might have been from another mag, as searching shows nothing on FWW)
I want to give vac-clamping a try, but I don’t want to invest much money or time in the experimentation. I read everything on www.joewoodworker.com, and like what I’m reading. However, it looks like about $400-$500 to build their system, which I may very well do in the long run. In the shorter term, I want to experiment first, and be up and running very quickly.
Any help would be appreciated.
Lon
Replies
Do you own an air compressor. If yes, tell me what you have, and I can give you some instructions to try.
Keith,
Thanks, but no...I don't have a compressor. In fact....I don't even have my shop...yet. It's been a long time coming, but we close on a new house next week, and it has a garage. Yipeee....at last...a little shop space.
I'm only a "weekend sawduster", but I've got an eye on some wood art ideas, and the vacuum clamping looked like something I might need. So, I wanted to give it a try, but do it as cheaply as possible in the beginning, just in case it doesn't turn out as expected.
Lon
You might be able to rent a compressor from your friendly neighborhood equipment rental place.
-Steve
If you get an air-compressor which has pistons with oil in the crank-case, you can remove the air-filter, and replace it with plumbing that adapts to a hose-barb. When you open the tank drain, this will allow the air on that end to escape, so the pressure switch won't shut the motor off. I found clear 55 gallon drum liners at Lows for about $12 for a box of 80. They are about' x 5', and while thin are quite tough. Let me repeat CLEAR. you want to be able to see through the bag. While you are at the store, getting the plumbing, and bags, get a roll of rope caulk. This is caulk which is slow drying , and rolled around a cardboard core tube. Take one of the bags, and cut a bottom corner off, making a smaller hole than the hose, and force it through making it stretch. Wrap a string of the caulk around the hose 4 - 5 times about a foot from the end, then pull it back down to the corner, and squeeze the bag down on it smooshing it onto the hose tighter, and making a seal with the bag. I usually tape an old shirt-sleeve onto the end of the hose which provides an air-path which overlaps, or just touches the fabric which is laid on top of the part. The other end of the bag can be sealed just by rolling a few turns around a piece of lath or scrap ripped from the edge of a board, with another one clamp to to that with spring clamps. When you first try this with your compressor, check your oil beforehand, and after it has run a while, I feel of the motor, and the pump regularly, for heat. A bad ring, and an unsealed crankcase could send all of the oil down into the tank, and burn up the pump. I have only tried one oil-less compressor, but it would not work. Vacuum bagging is a great way to clamp large areas just using the weight of the air from where-ever you are, all of the way up to the stratosphere to press perfectly against the outside of the bag. I usually draw 28" hg with my pumps, which is ~= to -14# psi., times 144 is 2016 per sq. ft.I have some vinyl bags that I have made up, but I have also made up bags using heaver plastic sheeting, with carpet tape between the top and bottom layers. I have done this when the work gets too large for several people to pick up and slip into ####prefabricated bag. With a good imagination, there is no limit to the size of part that you can press with this method. I prefer epoxy for my adhesive, especially for curved work. It lubricates the parts, allowing them to slide easier, and I have control of the open time. If I need an hour for rolling glue with a paint-roller, I can do it, or even take longer in the cool months. THe cure needs heat so I can tent the work and use space heaters blowing under it to warm things up after the vacuum is drawn. I contacted FWW with and proposed doing an article back in the mid eighties showing some of my tricks. For some reason we have never been able to link and make that happen. I guess, either I can't write well enough, or they think you guys wouldn't get it. Well you only needed the first five sentences to get you started, so print this and save the rest for later. Good luck Lon, and don't try this while you are up in your plane, if you are that kind of pilot. I think you loose about one psi for each of the first thousand feet of elevation, but the scale starts widening as the elevation increases.
Couldn't you use one of those Spacebags they sell on TV and use a shop vacuum to evacuate the bag? Has anyone tried that?
http://cgi.ebay.com/NEW-4-Space-Saver-Storage-Bags-28-x-20-and-20-x-16_W0QQitemZ230177974683QQihZ013QQcategoryZ43504QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
I have and it worked for me. But I just did a few small thing that fit the bag. NO it was not a 20 foot long table top!I have no idea how long it will stay nice!
Keith (and all)
Bag Sizes: Thanks for the various inputs. I want to try some more sizeable projects, so the smaller bags won't do what I want.
Home Vacuum: I have yet to be convinced that these will provide enough suction. Also, I don't want to run the home vacuum continuously, and they have no automatic shutdown capability. Plus, pretty noisy. (...no, I'm talking about the yelling from my wife when she finds that her vacuum cleaner is in the garage sucking air out of a plastic bag)
I have a contact in the med field, and I may be able to get my hands on one of the Invacare pumps for under $50. It will be used but in good working condition. But, my limited knowledge of how to go about setting one of these bag clamping systems up makes me reluctant to spend even that much. Here's the pump I'm looking at. Can anyone tell me if this can be adapted for the use I'm intending? http://www.home-med-equip.com/nebulizer/irc1135.html
Lon
Edited 10/3/2007 11:13 pm ET by pilotlon
Forget the home vacuum cleaner. While if sucks air, it won't even move the needle on a vacuum gauge, and as you said, it will drive you mad. As for the medical unit. Yes it will work, but for the same money, I think you should re-read what I suggested above. You may find that having a compressor is more valuable than having a vac. pump, yet having one pump which moves air, and does both, to my way of thinking, is like getting the second tool free.That medical unit looks t have a 1/4" or less intake or less. Since vacuum is limited to less than 15 psi, this will take a while to get the air out, which may lead to problems if you run past your open time for the adhesive. An air compressor that is set to compress air to say 120 psi, will only be doing about 1/8 of the work when pulling a vacuum. You can NOT pull more than one atmosphere, which will be less than -15 psi.
Keep looking on Ebay and you will find a good vacume pump for under $100.
Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
Mudman,
Yeah, I've been looking on Ebay already, but I'm such a noob at this, and with very limited mechanical experience, so I'm still trying to sort out one pump from the other and make some sense of what would work.
There is an Ebay seller who has a store in the Pasadena, CA area. That might help, as I can go in there and actually look at what they have available.
Thanks for the input.
Lon
If just a test try the Spacebags .. All you need is a vacuum cleaner. If you do not have one find a woman that will show you how to use it. May be more fun than you expected! OR some wax paper and some thick plywood and park your car tire on top of it over night!
Edited 10/3/2007 8:27 pm by WillGeorge
The specs you are looking for are a CFM of 1.8 or better, 3 CFMs is nice, and a max pressure of 28 Hg. 25 Hg is enough for bagging.
Veneer Supplies sells rebuilt Thomas pumps that are hard to beat. Very good price for a very good pump. Here is his Ebay store link. His veneer supplies website is full of great info and specialty supplies.
http://cgi.ebay.com/Rietschle-Thomas-Vacuum-Press-Pump-3-15-CFM-120VAC_W0QQitemZ220130732504QQihZ012QQcategoryZ46548QQcmdZViewItemPardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
Mike,
Thanks. Pretty good prices, too. I'll order one of those.
Lon
Try this skateboard bag; only $50 and it'll do the job. Norm used it on a recent show:
http://www.woodcraft.com/family.aspx?familyid=5200
Yep I saw somethin' like that at my local Rockler for about $40.00.No I do not have one,,EDIT: As I remember there were two different sizes to pick from.
Edited 10/3/2007 8:25 pm by WillGeorge
Depending on the 'footprint' the workpiece presents, a shop vac can handle small to medium workpieces Trouble is, most vacuum systems have many many ports (Usually not needed and bleeding vacuum )
My son does plenty of CNC machining using only a shop vac.
Any un needed holes are taped up. Have you entertained the thought of using TWO shop vacs?
Edited 10/4/2007 12:07 am ET by Steinmetz
I'm getting very confused.... There seem to be two discussions going on at the same time here. One is about vacuum clamping--using vacuum to hold down workpieces so that they can be carved, machined, etc. The other is about vacuum pressing--using vacuum and a bag to clamp glued-up veneers, laminations, etc.
I can't tell from the original message which one of these is the intended subject.
-Steve
Steve,
It's Vacuum Pressing that I'm interested in. Got lots of input here, but much of it obviously comes from people more experienced than I am. Guess I'm just going to order the entire kit from JWW and go that route. That way, I'm not fumbling around with some unknown motor entity. With my luck, I'd get something a bit out of whack and suck her car into the bag and laminate it to a slab of Cherry. That would take more explaining that I'm capable of.
Lon
A waterbed mattress makes a good vacuum bag. You need one of the old style that is just one big vinyl sleeve, and preferably clear. There is a "super single" one on ebay now with a "buy it now" of $25.
I used the shop vac on the original fill/drain fitting, to get most of the air out, and then used a hand vacuum pump to finish it.
Go to an appliance shop and get ask then for a compressor out of a refrigerator they are fixing to throw in the land fill. Aircondition shop will have some too. Either one will pull all the vacuum you will ever need.
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