I was searching for a thread for a clamp to glue re-sawn stock to a core, no luck. Anyway, after quite a lot of reading and discussions with very knowledgable people on knots I gave up my idea of using solid wood for the stiles, rails… for my new interior doors and am know going to use the stave core method instead (really, who am I to argue with those that build 1,000’s per year). I have found a good source of glulam stock for the cores and plan to re-saw the cherry I have for the skins (1/4″ planned). I do not want to invest the dollars on a vacuum press, and I know I can build a decent clamp with steel for very few dollars. I found some pics of a clamp built using channel iron and ready rod along the sides, but I think someone has done better. Any links or pics would be appreciated.
Thanks to all
Replies
If someone is advising you to veneer with 1/4" thickness, you should keep asking questions from others. That is too thick. No glue-line can overcome the stresses from normal seasonal changes.
I can tell you how to build wooden cauls, with camber in the middle, and using all-thread. In fact I could give you a box of them that I made before learning to vacuum-bag. But I would not be doing you any favor.
I would rather coach you in using your air-compressor along with about $10 worth of plumbing for a vacuum pump, but I have posted that here a dozen times, without ever getting any positive feedback, so I will leave you to search the past archives if you are interested.
Did a search for your article about a vacuum press. Found nothing. Could you help please.
Thanks .
I'd be interested in your shop-made veneer pump, too. I love a good contraption. Seriously. Two of the most inventive tools I've seen in recent years were a delicate bandsaw made with bicycle parts and a lathe regulated with a 1950's transmission. The bandsaw was really quite nice and performed well - the gent was using it for fine work, as you would a scrollsaw. The lathe was functional but had that '"Honey, grab the kids..." aura about it. And the idea of "shifting" speeds was odd. Anyways, I'd like to see your veneer set-up.Getting back to the original post and/or the subject of veneer thickness: Keep you veneers to 1/16th (or thereabouts) and your stay here on earth will be much more pleasurable.Regards.
Edited 2/3/2007 1:00 pm ET by beachfarm
If you have a little oil-less compressor, this may not work, however it is easy with any that I have tried that are normal piston with oil in the crank-case.All you need to do, is open the tank like you drain the water out, or just stick a male quick-couple in the line, so that the pump can not satisfy the pressure pump. Then on the intake side, if the air-filter screws on with 1/2" or 3/4" pipe thread, just take it off, and go to the hardware/plumbing store, and buy a bushing that fits your pump, on that side, and reduces down to something like 3/8" or whatever size hose you plan to use. and get a hose-barb to fit into the fitting, unless you already have some hose with a male thread on one end that will screw into that fitting.That is it, you don't have to have a vacuum switch, or venturi or anything else, just plug it in and let it run, however you can work in a switch if you want to, but a compressor that is accustom to compressing air to 130 psi will hardly know it is doing anything at minus 15 psi. After it has been running a while, I feel of the motor and pump for any heat build-up. While you are at the store, see if you can find a box of clear plastic drum liners. You can get a box of 80 for under $15, and they are about 32" by over 48", so they will handle lots of projects, easier than dealing with a big bag. Also get a box of rope-caulk, or whatever the caulk that comes on a roll is sold as.To use the drum-liner, I clip a small hole in the corner, and shove the end of the hose through, and wrap a strip of caulk around 5 - 6 times, then pull it back down to the entrance hole, and squeeze the plastic into it to seal that hole. I usually tape an old shirt-sleeve onto the end of the hose to keep the bag from sealing itself off at the end of the hose, and make an easy path for the air to get from the project over to the hose. You can seal the big end of the bag by rolling it around a thin strip of wood a few times then spring clamping another one down to it, thus pinching the bag wraps between.If you work a T into the line somewhere with a gauge in it. For each 2" of Hg that it pulls, you will get one psi of pressure on the outside of the bag. I normally get 28" with my pumps, or -14 inside the bag. This does not sound like a lot, but when you start multiplying that time the square inches of the face, it adds up in a hurry. 14 X 144" in a sq. ft. = 2016 pounds of perfectly even pressure. So if you were veneering a 2' x 4' panel, that is 16,128 psi.. If you tried to do that with cauls, it would take a closet full of them to do this small project.
I like your idea and will give it a go. There's a 5-gallon "portable" compressor in the back of the shop that hasn't seen battle in quite some time. It's a dust collector - soon to be vacuum accessory.Thanks...
Is the failer from using different types of wood? Could a cherry core be used and it all work together? Just wondering.
Thanks for the advice and idea. do you have a pic of the vacuum bag you describe? This is interesting. I attached a pic of a clamp device and veneer glue up I was reading about on the woodweb. I have read some discussions regarding the veneer thickness. I have owned the cherry stock for several months and am committed to using this for the doors. The veneer thickness was chosen based on machining (re-saw). I can easily plane to plane the thickness down, but am concerned about getting too thin given the possibility of destroying the stiles/rails in the process.
Thanks
I don't know what you were talked out of doing nor exactly what you plan to do, but go to your public library and search for veneer presses. There are probably many ideas in books there. Pay attention to KeithNewton, however, concerning thickness. Also check on veneering techniques and general practices. Wood can be very unforgiving of human error.
Cadiddlehopper
I second and third the reservations regarding veneer thickness. I was taught that you're asking for trouble with veneers over 1/28th thick (with most commercial veneers being 1/40th or thereabouts) With a rigid glue bond, thicker veneers WILL develop surface checking over time (DAMHIKT). With a flexible glue bond, joints will open up, bubbles will form, nightmares will plague you, your pets and loved ones will start to wither and die... (this applies to thinner non-paper-backed veneers too DAMHIKT either). I'd spend a bit more time reading up on the subject before committing yourself to 1/4" veneers.
Nat, for what it's worth.
Most commercial veneers are thin (1/28 and less) but one can still successfully use thicker. Certainly Wood is a source that has 1/16" veneer and it can be shop sawn up to 3/32 in my opinion and experience. Some say 1/8" is commonly used but I've had failures at that thickness. The 3/32" is my limit.
Brad
I would think you could use a bunch of sandbags as clamps for this application. Just cover the veneer with a sheet of plastic (paint dropcloth) then a sheet of 1/4" luan and pile on the sand bags starting from the center and working out. This would be more even pressure than cauls and clamps. The sand could even be piled on loose for more even pressure but would be messier that way.
Rich
The Professional Termite
That sound easier than it is. Dry sand only weighs 100 lbs per cu. ft. You would have to burry your work under 20 feet of sand to equal the pressure that you get from just drawing a vacuum inside the bag, and using the pressure of the air that is already piled into the sky several miles deep. It is there, ready to be used. All you need is knowledge.If you don't like the idea of dealing with all of those gravel trucks full of sand, I think it would be easier to just buy a swimming pool liner, and filling it with water on top of your work. However It would need to be over 30 feet deep to equal what you can get just using the air, and drawing a vacuum.Here is a link to specific gravity of just about anything you want to try.
http://www.reade.com/Particle_Briefings/spec_gra2.html
Keith
I realise you will get more pressure from a vacuum bag, however, The OP stated he did not want to invest in vacuum equiptment. I have glued up large panels this way using several 50lb weights rather than sandbags and have not had any problems with any of them to date. This is a very standard practice in many Pattern shops to use weights for clamps. Most people however do not have access to many weights so that is why the sandbag suggestion. One could also use springpoles, hydrualic jacks or any other number of items to create some pressure.
I really do not think it takes enormous pressure to do what he is trying to accomplish. I believe this would create a better final result than contact cement, yet many have used that for projects like this without any reservations about strength. There is an aweful lot of glue area to hold very little stress as compared to a leg to rail joint on a chair for example. More pressure can be created with cauls and clamps also but I question if that pressure is as even, and I know I can pile on several sandbags faster than I can apply cauls and clamps. Plus sandbags don't need anything to grip to on the other side like clamps do. The Professional Termite
What kind of glue do you use with this process?
Keith
I have used regular Elmers white glue for interier doors etc. but more recently have used high temp epoxy because of them being forms for vacuum forming plastic and the heat would have caused problems. I think the epoxy may be better for this application because it works better with less pressure causing a thicker glueline. A co-worker glued up some Mahogany panels out of three layers of 1/2 for an outdoor engraved sign using weldwood water resistant glue. I was dubious on that one but it has been seven years now of Western NY state weather and the sign is still holding up.
It's amazing what can be accomplished when one doesn't know what can't be done.
Rich The Professional Termite
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