Vacuum bagging question

[Joe Kieve]

I have been thinking about doing some veneering on a small table top, mainly to see if I can do it. I mentioned this to my son and he said he and my grandson had made some super small skateboards, I think they're called "thumbboards", about 1/4" X 3/4" X 3". They had used this vacuum bagging product with great results.

Here's a link to the company's website. Please let me know what you think. Will it work for veneering a small table top?

http://www.roarockit.com/rc_wood.php?cat=51

This is a great forum and I value your opinions.

Thanks,
joe

[Dan Mitchell]

I'd like to hear more about this as well. I've looked into vacuum bagging systems for veneering to a small degree, and they seem way more expensive than what you might anticipate for a bag and a vacuum pump. I see in the link Joe posted, a manual pump is used. I've often wondered if a cheap, AC servicing vacuum pump might not also work. One veneering pump http://www.veneersupplies.com/product_info.php?cPath=60_64&products_id=248 is said to pull 25" of mercury at sea level. It's $300. This AC evacuation pump from HF http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96677 is said to pull 28", and it's 17 bucks. Why are the "purpose built" systems so expensive? I imagine the HF pump is probably a bit slower, but is that really crucial?

[Chris Ricker]

Joe and Dan have some very good points, I hope others will chime in.

[Montgomery Scott]

I have six of their vacuum bags. It is an inexpensive way of doing veneering. I don't know how much vacuum it pulls but it's good enough for small panels. I used it to do these since trying to use normal clamping methods doesn't work well and it worked just fine.
http://c2.ac-images.myspacecdn.com/images02/127/l_389b4195581e4d8d8255121c705d8379.jpghttp://c1.ac-images.myspacecdn.com/images02/125/l_888bdda5b61545e189373463020685f0.jpghttp://c4.ac-images.myspacecdn.com/images02/137/l_8d2aba4bccc04e9ca3ddccfc30e3413f.jpg

[mreza Salav]

Interesting. I have been looking for something like that. I think I saw Norm used one very similar (or identical) to that one in a project for a bowed from chest of drawers and yes, it had a net and a hand pump.
Perhaps someone who has used it personally can add more to this.

[Frank Drew]

Getting set up to vacuum veneer doesn't have to bust the bank. For starters, never pass a used-equipment/motor dealer without stopping in to see if they have any used vacuum pumps; you might luck out. The good ones can last a long time, with maybe an occasional replacements of seals and/or gaskets, etc.

As for the bags, get a tube of vinyl glue and some sheet vinyl and make your own, it's really easy.

[Harvey Pascoe]

I'd like to hear more about this as well. I've looked into vacuum bagging systems for veneering to a small degree, and they seem way more expensive than what you might anticipate for a bag and a vacuum pump. I see in the link Joe posted, a manual pump is used. I've often wondered if a cheap, AC servicing vacuum pump might not also work. One veneering pump http://www.veneersupplies.com/product_info.php?cPath=60_64&products_id=248 is said to pull 25" of mercury at sea level. It's $300. This AC evacuation pump from HF http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96677 is said to pull 28", and it's 17 bucks. Why are the "purpose built" systems so expensive? I imagine the HF pump is probably a bit slower, but is that really crucial?

The question is not how many inches of mercury it will pull but but how many CFPM of air it can move. Sure, you can get a pump cheap but you probably won't like to wait all day for it to pull those 27 inches. I built my own system and bags using a Robinaire AC pump that cost under $200. It pulls a vacuum fast. A cheap diaphragm pump won't cut it. But unless you are going to use this frequently, its probably not worth the effort. It took several days to put it together with numerous trips to hardware stores to find the right parts. My total cost came to about $300 and a lot of hours. But then, I use it several times per week and it works like a charm.

Using reinforced gas hose, I attached it to the bag with a small, flanged plastic sink drain fitting into which I drilled and tapped a barbed hose fitting on the non flanged end. I cut my own neoprene washers for the flange attachments to the bag, but later discovered I could have used bag vinyl. For distribution screening, you don't need to buy the fancy stuff, plain old plastic window screen actually works better.

Making your own bags is fairly easy. Making one that doesn't leak is a different matter. Follow the instructions exactly, and pay special attention to the corners. I suggest glueing the two sides of the bag together at the edges at the corners BEFORE gluing on the overlapping tape. This way you get leak-proof corners. The material is pretty cheap so its a good idea to order more than you need and keep handy for another bag. You will find more and more uses for the system.

I don't have any fancy end clamps. I simply lay a 3/8" aluminum rod across the end, place a couple scraps of wood on that and with only two bar clamps lightly clamp it down. The vacuum does the rest as for sealing.

[Karl Card]

nice art in above post...

[Mike Henderson]

I'd like to hear more about this as well. I've looked into vacuum bagging systems for veneering to a small degree, and they seem way more expensive than what you might anticipate for a bag and a vacuum pump. I see in the link Joe posted, a manual pump is used. I've often wondered if a cheap, AC servicing vacuum pump might not also work. One veneering pump http://www.veneersupplies.com/product_info.php?cPath=60_64&products_id=248 is said to pull 25" of mercury at sea level. It's $300. This AC evacuation pump from HF http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96677 is said to pull 28", and it's 17 bucks. Why are the "purpose built" systems so expensive? I imagine the HF pump is probably a bit slower, but is that really crucial?
That Harbor Freight item is not a pump, it's a venturi. You need an air compressor to hook to it. That's why it's so cheap.

I agree with Harvey that there's a difference between making a vacuum bag and making a vacuum bag that doesn't leak. That's why many (most) people wind up buying a bag.

As far as sealing the end of the bag after you put the panel in, there's some special closures now that work really well. You can see the one Joe Woodworker sells here (http://www.veneersupplies.com/product_info.php?products_id=3484). They are worth every penny and then some.

Mike

[Mike Henderson]

If you just have a small table top, you can press it without a vacuum system. Get some plastic sheeting, some MDF, and some cauls. After you put glue on the substrate and lay your veneer in place, put the plastic down (this is to keep the MDF from getting glued to the veneer), then put the MDF over the top, and use the cauls to get pressure in the center of the table top. Works just fine. I did veneer for several years before I bought a vacuum system (the vacuum system is much nicer, however).

Some people will really object, but you can lay one side at a time. It's nicer to do both sides at the same time but I've done them one side at a time and didn't have any problems.

Mike

[Dan Mitchell]

That Harbor Freight item is not a pump, it's a venturi. You need an air compressor to hook to it. That's why it's so cheap.

Sure, but I think many of us DO have compressors. I know I do. In terms of how quickly it would do the job, for the occasional user, would it be slower than a hand pump? I guess you'd have to try the 2 & see. I still maintain for the price it may be worth looking into.

[Dan Mitchell]

I built my own system and bags using a Robinaire AC pump that cost under $200...

Sounds interesting Harvey. I'd love to see some pics of the system details and in action!

dan