Veneering

[gasman]

Afternoon all
I need to veneer a table top and having done small boxes etc before I think that the size of these panels means I am going to have to get a pump
So Ive been doing some reading (and also placed an advert in case anyone is selling their vaccuum kit) Am I right that an ordinary compressor like the sort that powers air tools, combined with this kind of thing Bagpress BPPN21 Vacuum Kit will sort me out?? Otherwise it looks like the big vacuum presses are very pricy
Thanks anyone for their advice
Regards from oxford
Mark

 

[Droogs]

It's not a compressor you need but a vacuum pump, which works the opposite way to a compressor. If youu can't afford one it is possible to use a compressor but have it running in reverse and many people use the ones from fridges for this purpose and get good enough results. these though are only really good enough for small things. If youwant to do table tops etc of a decent size 1m2 or above in area you need a decent pump.
There's various types and price points. A good point to start is at an american site called joewoodworker. Lots of info there on the principles and techniques in a plain english way to get your head around. Once you've had a good read there youwill be in a better position to decide which way you want to go in terms of kit and techniques. The gwinnet woodworking club on youtube have a couple of good intro videos as well.
I'd be happy to advise where I can if you have any other ques that pop up - just gimme a pm any time i use both the vac press and traditional hide glue and hammer hth

 

[ColeyS1]

Afternoon all
I need to veneer a table top and having done small boxes etc before I think that the size of these panels means I am going to have to get a pump
So Ive been doing some reading (and also placed an advert in case anyone is selling their vaccuum kit) Am I right that an ordinary compressor like the sort that powers air tools, combined with this kind of thing Bagpress BPPN21 Vacuum Kit will sort me out?? Otherwise it looks like the big vacuum presses are very pricy
Thanks anyone for their advice
Regards from oxford
Mark

Yeah that's all you'd need. Just a compressor running continuously connected up to the venturi valve.

Sent from my SM-G900F using Tapatalk

 

[ED65]

How big is the table?

You don't need to use a vacuum bag for veneering, with PVA (the white type) being thermoplastic you can iron veneer down after coating both surfaces with glue. I expect someone will be along to shoot this idea down very shortly but it does work.

Or you could use hide glue with a veneering hammer of course

 

[custard]

You don't need to use a vacuum bag for veneering, with PVA (the white type) being thermoplastic you can iron veneer down after coating both surfaces with glue. I expect someone will be along to shoot this idea down very shortly but it does work.

Yes, it does work. But it works best on fairly small stuff like edging or small boxes. The problem with the iron-on PVA technique applied to larger pieces is that PVA contains a lot of moisture, especially as it's best to add about 10% water to make it easier to get a thin, consistent layer. So when all that moisture gets soaked up by the veneer any reasonably sized piece will warp and cockle, often to the point where it becomes unusable, especially for the beginner who is the one most likely to be using this technique.

 

[gasman]

Interesting thoughts gents many thanks
I will try the PVA technique on some less vital practice pieces. I think my eventual panels will only be 400x240mm and will be floating panels within the frame of the table top - with a chessboard in the middle - maybe like this sketchup image but still under review. The whole thing is a coffee table along the lines of a Linley Classic with inlaid burr walnut on legs, rails and top, dentil mouldings, etc etc. If possible I want to end up with the table top absolutely flat but I'm struggling a bit to see how I can do this using 0.6mm veneer....
More thought needed - cheers again
Kind regards Mark

 

[custard]

I will try the PVA technique on some less vital practice pieces.

Another option is glue film, which is this stuff,

It's a layer of hot melt EVA glue laid on a silicone proofed backing sheet. You can either peel off the glue film and lay it on the ground, or a better method is to tack it to the ground through the backing sheet with a few dabs from a hot iron, and only then remove the backing sheet.

Like all these things it looks easy, but there's a still a few things to watch out for. There's a fairly narrow temperature window at around 100 degrees C, and you don't want to overwork it. The ideal is to get it quickly up to temperature and then apply heavy pressure with a veneer hammer or something similar, I use the backing sheet to keep the veneer clean. It's exactly the same with the painted on PVA method, going back and forth with a hot iron will just leave a weak bond.

I don't know how much veneering experience you have, so apologies if I'm teaching granny to suck eggs, but veneering burrs is a lot trickier than veneering straight grained stuff. You need strategies for flattening the veneers, jointing the veneers, and for filling the inevitable voids.

If you want to try glue film PM with your address and I'll send you some pieces to experiment with.

Good luck!

 

[Mr T]

I have always found ironing down veneer on larger panels rather problematic. If you have loads’a clamps I reckon you could do it between boards.

Sandwich the panel between 18mm mdf boards then have 2x3 cross bearers at about 250mm intervals and clamp the ends (you would probably need an assistant). The cross bearers need to be slightly curved in length (you could buy them from B&Q!)

Actually, rereading your posts, I think on a 400 x 250 panel you could get away without the cross bearers just G clamps round the outside and a couple of big F clamps for the middle.
If you plan to do more larger panel veneering a vacuum press may be a good investment but you don’t need one for this job.
I have an article which covers this on my web site.

Chris

 

[mbartlett99]

I've pretty limited experience in veneering but have recently knocked up a stack of 600mm x 720mm panels.

The iron on PVA method was quick, cheap and easy but all my joints opened up by about 1mm.

Using a cold press worked well but was slow as hell and tied up all my clamps/table for ages and deep throat clamps aren't cheap.

Thought about the iron on glue but didn't for reasons given by Custard.

You could buy a vacuum pump used for refrigeration 2nd hand quite cheaply on ebay etc and easily fit a gauge or switch.