Vacum veneering on the cheap!

[sawdust maker]

Hi All

Thought you might be interested in this. For some time | have been thinking that you could use JML vacuum-seal storage bags to vacuum veneer.

Wish I had been quicker off the mark, two month ago someone sent it to a woodworking mag and won himself a rather nice plane. Anyway it made me go out and buy some. This is how I used them.

First I layed the ply to be veneered on a bin bag that I had cut open. My thought here was to protect the vacuum bag.

I then spread the glue, I used PVA, and placed the veneer on.

I then wrapped the plastic bin bag over the top and placed the whole lot into the vacuum-seal bag.

Then used my workshop vacuum cleaner to suck the air out.

I has to turn back some of the plastic bin bag because it stopped the air being taken out. The vacuum looks good, so all I have to do is wait a few hours and see if it works. If it does I have a vacuum veneering system that cost only a few pounds rather than hundreds!
Will let you know how it turns out.

Paul

 

[woodbloke]

A good idea and one that's occurred to me more than once. However the bags don't appear to be all that strong and may easily pierce. What's more certain is that you'll get nowhere near the vacuum using a hoover compared to a dedicated pump. On my AirPress it keeps on sucking well off the scale so I can be sure that it's giving me the full 14.7lbs/sq" which is what's needed to give a good pressing - Rob

 

[sawdust maker]

Yes Rob I see your point, and if I was doing a lot of veneering I am sure it would be worth investing in the real thing, however, I like a lot of others only need to veneer something once or twice a year. So £200+, as apposed to £30 is a lot of money. And yes you may have to give it a quick "zap" with the vacuum cleaned from time to time to maintain the pressure. I have just taken my wood out and it appears to be as good as a conventional veneer press and a lot quicker to use and store.

Paul

 

[Oryxdesign]

Can e se a picture of the finished item please, I have been thinking about trying this too.

 

[sawdust maker]

This is the finished veneer

Paul

 

[Steve Maskery]

so I can be sure that it's giving me the full 14.7lbs/sq" which is what's needed to give a good pressing

Rob, do you get a full vacuum? I have a new (ish) bag and I'm lucky if I get 90%. If you do curved laminate work, then yes, you do need as much suck as you can get, but for flat or nearly-flat pieces, I really don't think you need anywhere near a full pressing.

I've not done this, but I do suggest it in one of my video clips, as I'm sure that it is more than adequate for "tame" work. I'd certainly use it if I didn't have an Airpress.

Great idea Paul!

Cheers
Steve

 

[woodbloke]

so I can be sure that it's giving me the full 14.7lbs/sq" which is what's needed to give a good pressing

Rob, do you get a full vacuum? I have a new (ish) bag and I'm lucky if I get 90%. If you do curved laminate work, then yes, you do need as much suck as you can get, but for flat or nearly-flat pieces, I really don't think you need anywhere near a full pressing.

I've not done this, but I do suggest it in one of my video clips, as I'm sure that it is more than adequate for "tame" work. I'd certainly use it if I didn't have an Airpress.

Great idea Paul!

Cheers
Steve

Steve - yes, the whole 9 yards, in fact the needle is banging on the stop, takes about 5 or 6 mins to pull a full vacuum. If you don't pull a complete vacuum you may have a tiny leak somewhere which is stopping it, usually on the seam near the closer...a bit of duct tape does the trick - Rob

 

[ivan]

A "full" vacuum appears above a column of mercury of about 30 inches, or alternatively, 32 feet of water. Most (cleaner) vacs will pull about 6 ft of water column, about 15 x 6/32 = 2.8 psi. Better augment the cleaner vac with an old freezer compressor.

 

[Gill]

Better augment the cleaner vac with an old freezer compressor.

How would you do this? I've got an old chest freezer waiting to go to the dump.

Gill

 

[9fingers]

Better augment the cleaner vac with an old freezer compressor.

How would you do this? I've got an old chest freezer waiting to go to the dump.

Gill

If your freezer has lost its gas then this is ideal. Otherwise find a friendly refrigeration engineer who can empty the gas without letting it into the atmosphere.

Remove the compressor. keep it upright at all times as it is oil filled and needs to stay so!
Disconnect the themostat wires and wire the compressor with it's integral starter to a 13 lead & plug. Switch on and see which end blows. DONT put your finger over the other (inlet end) it will deliver a nasty suck/bruise.
Switch off and mark inlet and outlet. Connect inlet to your vacuum bag and bob's your uncle.

You may notice some oil coming out the outlet port. Note that if you loose a lot (cupful) then you will need to add some more from time to time down the suck (inlet) port. Ordinary clean engine oil will be fine.

HTH

Bob

PS fridge compressors will be just as good but a tad slower.

 

[Wanlock Dod]

Most (cleaner) vacs will ..... = 2.8 psi.

But I reckon that this measly 2.8 psi is nearly 2 tonnes per square metre, and arguably a good deal more evenly distributed than a pile of bricks stacked on a sheet of MDF over the veneering (and certainly lighter than the bricks).

If somebody told me that my vac would deliver 2 tonnes/m2 I'm not sure I'd see the need for much more powerful.

Just a thought.

Dod

 

[Digit]

But get ready to say goodbye to your vacuum cleaner. Using them in that manner means no cooling air to the motor. Best stick with the fridge compressor.

Roy.

 

[Gill]

Thanks Bob . I'll have to persuade His Lordship to get his spanners out!

Gill

 

[staffie]

thanks guy's. very informative. Great pictures too

 

[OPJ]

I guess you could also try glue which sets faster than PVA, so you don't have to wait as long for the glue to go off. Something like cascamite (urea formaldehyde) might do - although you'd have to go like stink when gluing up! :wink:

I'm sure it'd be fine on a smaller panel though.

Nice tip, by the way. Thanks.

 

[sawdust maker]

Roy (Digit) seems to think the vacuum cleaner is left on. This is not so, the bags have a valve that seals the bag as soon as the cleaner is removed. The load on the cleaner is very small.
By way of an update. Last night I saw an ad on TV for similar bags being sold by Woolworths. They are cheaper and look to have a better seal on the bag.

Paul