Thank you John for those very nice words
in reality you only needed a tiny tiny nudge
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Thank you John for those very nice words
in reality you only needed a tiny tiny nudge
Thanks John
Sorry to be slow in responding but I have had a lurgy.
This is exactly the response that I was hoping for. Its targeted at those who have not tried vacuuming. No elaborate and expensive equipment required. No long learning curve. Virtually everyone I have spoken to who sees vacuuming for the first time is amazed as to how simple the equipment and technique is. Thanks for helping to demistify the process.
Fair Winds
Graeme
For those who are interested, a series of shots showing the process of laminating a pair of doors can be seen here. https://www.woodworkforums.com/f187/f...abinet-177684/
Here is a pic showing the inches of mercury pressure created by a hand pump in Toronto. (The Nitty Gritty Pressure | Ministry of Wood, Skateboard Builder Directory)
Attachment 297822
That's 26 inches of Hg ... or a little over 13 PSI. (Atmospheric pressure at sea level is 29.92" Hg or 14.7 PSI.) The doors on the Frilly Nickers Cabinet are about 8" X 60", or 480 sq in. At 13 PSI that's 6,240 pounds or 2.78 tons ... on each side.
These hand pumps appear to be better than originally imagined at extracting air and creating vacuum and pressure.
Someone asked for more detail on the fitting I used into which the Vacu Vin valve fits in my shop made vacuum press.
Here it is. I bought another to make one more press.
Attachment 307002
It is a water tank fitting, 3/4" or 20 mm (it is marked as both). I found it in the plumbing section of Bunnings (not the irrigation section).
I have been using the Titebond PU glue for veneering, and am very happy with it. It has an open time of about 30 minutes and a clamp time of about 45 minutes. The open time is plenty. Today I veneered 10 drawer fronts and got them all in the vacuum press together.
Have fun!
John
Someone further back in the thread suggested a vacuum cleaner for extracting most of the air. This is fine, but don't leave it connected for too long. I found this out the hard way.
Vacuum cleaners rely on large volumes of air coming through to cool the motor. If you run it against a vacuum, where little to no air is coming through, it will hold a half-decent pressure, but the motor will overheat and burn out in only a few minutes. I burnt out mine doing some fibreglass parts a couple of years back. Proper vacuum pumps are designed to work against a vacuum, and don't rely on the airstream for cooling, so you can use them properly for long setups, and for much better vacuum pressures.
Since this thread was started I have made a bunch of veneered panels and really like the look and strength that can be bachieved. The press works like a charm. However, I have made one small but important change.
The change I have made from the original bag is to use the 3M VHB tape on the sides. It does not let go when you fold up the bag the way the re-sealable tape can. Definitely use the VHB or similar tape to make permanent seals on the sides. I always clamp the mouth of the bag to guarantee an airtight seal. Be careful that the corners (where the sides meet the folded end) are sealed well. I pushed a little re-sealable tape into the corner and used a small clamp to guarantee an air-tight seal.
I strongly recommend you glue up with the Titebond PU glue, applied with a small roller (a cheapie because it is thrown away after use). An hour after you put the job into the press, it can come out. The Titebond PU is low foaming with 20-30 minutes of open time and 45 minutes of clamp time ... perfect for veneering.
Here is a recent job.
Attachment 364241Attachment 364242
A veneered MDF panel is cheaper to make than a solid wood panel, but it takes more time to make. It takes time to cut and sand the veneers and glue timber lips onto the panel which is sanded flat before applying the veneers. One big advantage of a veneered panel is that it is stable dimensionally, so there is no need to allow for wood movement.
This time the panel was veneered, trimmed to size and then the stiles and rails were glued on with biscuits. I was after a "frame and panel" look rather than the effect in the previous post where the veneer runs all the way to the edges of the lipped panel.
Attachment 364338
A trick I saw at Sturt to seal the long end of the bag was to get a 100mm PVC pipe the length of the bag and rip it into two halves. Place the edge to be sealed into the bottom half and invert the other half of the PVC and press it into the first piece of pipe trapping the bag between the two. I never heard anyone complain it did not work but I never used it myself only saw it used by others.
John,
Ive been reading with interest your development of the vacuum press. I intend to build one myself. What size vacuum pump would I need to power the press?
David,
I don't use a vacuum pump. Most of the air is evacuated using the shop vac, then a Vacu Vin hand pump is used to pull the vacuum. Dirt cheap and it works.
John, if I was to purchase a vacuum pump, what cfm pump would be ok for veneering?
David,
I'm afraid I don't know, as I have zero experience with such pumps. I did price a vacuum kit that came with an electric pump ... went into shock ... can't recall the price.
Can any woodie give me the info as to what cfm pump would be ok for veneering?