A couple of vacuum veneer questions

[Alan Tolchinsky]

Hi All, I'm just getting into veneering with a home made vacuum press. So far it's working great! I'm using tape to seal the bag end. Anybody have a better idea to seal the bag. My pump pulls 25Hg by itself and 23Hg attached to the bag. My main leakage is the taped end.

Also can somebody describe how to sharpen a veneer saw? Or is it better to just use a router with straight edge to cut veneers. Thanks Alan in Md.

[Chris Padilla]

Bob Smalser in the Neanderthal section posted a little ditty about sharpening handsaws...check it out and post there, too.

[Alan Tolchinsky]

Bob Smalser in the Neanderthal section posted a little ditty about sharpening handsaws...check it out and post there, too.

Chris, Thanks I'll check it out. Alan

[Dave Ramer]

Alan,

I too just completed my own vacuum press. Joe Gorleski, at Joewoodworker.com, has an excellent DIY Vacuum Press section. It it you will find a great bag clamp system you can make in a very short period of time and for little cost.

In addition to veneer, he also has parts available including 30 Mil bag material for making your own bags. If you contact him, tell him his friend Dave sent you.... ;)

This is the link to the clamp making page on his website.
http://www.joewoodworker.com/veneering/connectbags.htm

Good luck,
Dave



Hi All, I'm just getting into veneering with a home made vacuum press. So far it's working great! I'm using tape to seal the bag end. Anybody have a better idea to seal the bag. My pump pulls 25Hg by itself and 23Hg attached to the bag. My main leakage is the taped end.

Also can somebody describe how to sharpen a veneer saw? Or is it better to just use a router with straight edge to cut veneers. Thanks Alan in Md.

[Dave Ramer]

Alan,

sorry... I added the incorrect link... my bad! Try this one:
http://www.joewoodworker.com/veneering/clamps.htm
Dave



Hi All, I'm just getting into veneering with a home made vacuum press. So far it's working great! I'm using tape to seal the bag end. Anybody have a better idea to seal the bag. My pump pulls 25Hg by itself and 23Hg attached to the bag. My main leakage is the taped end.

Also can somebody describe how to sharpen a veneer saw? Or is it better to just use a router with straight edge to cut veneers. Thanks Alan in Md.

[Alan Tolchinsky]

Alan,

sorry... I added the incorrect link... my bad! Try this one:
http://www.joewoodworker.com/veneering/clamps.htm
Dave
Thanks Dave, That's where I got my bag material from. Have you made a bag closure using Joe's method yet? Thanks Alan

[Steve Ulrich]

Hey Alan,
The JoeWW site is full of lots of great info. I picked up a cheap pump on EBay (shipping was more that the price of the pump). I ended up making a small reservoir using 4" PVC and connected a pressure switch to it. The 27 x 36" bag was sealed so well that it would only cycle once every few hours.

I made a bag clamp using PVC pipe. I had two pieces of 3/4" PVC that were the same length which were slightly wider than the opening of the bag. I cut a slot in one pipe lengthwise using the tablesaw. The cross section is now a "C" instead of "O". I slowly widened the slot until ia could get the C piece to snap around the other unmodified piece which is wrapped with the end of the bag. I works fairly well and is quick to use.

I, too, bought my material from JoeWW and it worked great. Using this type of clamp, I had a small leak at the seam. The overlapping of the material made a slight bump which kept it from sealing tightly. It didn't take much to seal it, I believe I put a dot of caulk or some H66 glue right at the bump to seal it (sorry I can't remember, it has been over a year since I used it). The vacuum will pull a little into the seam to plug the hole without gluing shut the bag.

Hope this helps.

steve

[Jamie Buxton]

Alan --

I used a veneer saw for maybe a decade, but I gave up on it many years ago. A sharp knife works much better. I use a standard utlity knife -- the kind with the replaceable blades. I guide it with a straightedge for either crosscuts or rips. For crosscuts in anything except cantankerous burls, I don't bother even cutting all the way through the veneer. I score it with the knife, and while holding the straightedge still in place, just flex the veneer to snap it -- the technique is almost like drywall. For rips, I do have to cut all the way through, and it does pay to make several passes with the knife. Otherwise the cut may wander off to follow a grain line, not the straightedge.

In contrast, the veneer saw requires you to remove lots more wood, so there's more work involved. The effort required to push or pull it has a nasty habit of moving the straightedge. The saw leaves little frayed edges, and at least in my hands tends to rip out the edges of the veneer sheet. The knife has none of those issues, and is just easier to use.

After ripping with the knife, I edgejoint the veneer with a jointer plane. I put the veneer stack on a board to get it up off the bench, then put another board on top, and pile weights on top. I happen to have a bunch of lead bricks which work well for this. The veneer edges to be planed stick just a little beyond the edges of the boards, so the plane can hit them without hitting the boards. The two boards clamp the veneers flat, and hold them while you run the plane along the veneer edge. If the veneer sticks out too far, it may bend up or down while you're planing, and give you an edge that is not straight. Just look out for it and you'll be okay.

After you edgejoint the veneer, tape it together with veneer tape and then glue it to the substrate in the veneer press. I always make the veneer sheet larger than I need, and trim the veneer+substrate panel to finished size.

Jamie

[Alan Tolchinsky]

Alan --

I used a veneer saw for maybe a decade, but I gave up on it many years ago. A sharp knife works much better. I use a standard utlity knife -- the kind with the replaceable blades. I guide it with a straightedge for either crosscuts or rips. For crosscuts in anything except cantankerous burls, I don't bother even cutting all the way through the veneer. I score it with the knife, and while holding the straightedge still in place, just flex the veneer to snap it -- the technique is almost like drywall. For rips, I do have to cut all the way through, and it does pay to make several passes with the knife. Otherwise the cut may wander off to follow a grain line, not the straightedge.

In contrast, the veneer saw requires you to remove lots more wood, so there's more work involved. The effort required to push or pull it has a nasty habit of moving the straightedge. The saw leaves little frayed edges, and at least in my hands tends to rip out the edges of the veneer sheet. The knife has none of those issues, and is just easier to use.

After ripping with the knife, I edgejoint the veneer with a jointer plane. I put the veneer stack on a board to get it up off the bench, then put another board on top, and pile weights on top. I happen to have a bunch of lead bricks which work well for this. The veneer edges to be planed stick just a little beyond the edges of the boards, so the plane can hit them without hitting the boards. The two boards clamp the veneers flat, and hold them while you run the plane along the veneer edge. If the veneer sticks out too far, it may bend up or down while you're planing, and give you an edge that is not straight. Just look out for it and you'll be okay.

After you edgejoint the veneer, tape it together with veneer tape and then glue it to the substrate in the veneer press. I always make the veneer sheet larger than I need, and trim the veneer+substrate panel to finished size.

Jamie
Jamie,

Thanks for that detailed description. That sounds like a neat trick with the jointer plane. I'll have to try that. Thanks again. Alan

[Alan Tolchinsky]

Hey Alan,
The JoeWW site is full of lots of great info. I picked up a cheap pump on EBay (shipping was more that the price of the pump). I ended up making a small reservoir using 4" PVC and connected a pressure switch to it. The 27 x 36" bag was sealed so well that it would only cycle once every few hours.

I made a bag clamp using PVC pipe. I had two pieces of 3/4" PVC that were the same length which were slightly wider than the opening of the bag. I cut a slot in one pipe lengthwise using the tablesaw. The cross section is now a "C" instead of "O". I slowly widened the slot until ia could get the C piece to snap around the other unmodified piece which is wrapped with the end of the bag. I works fairly well and is quick to use.

I, too, bought my material from JoeWW and it worked great. Using this type of clamp, I had a small leak at the seam. The overlapping of the material made a slight bump which kept it from sealing tightly. It didn't take much to seal it, I believe I put a dot of caulk or some H66 glue right at the bump to seal it (sorry I can't remember, it has been over a year since I used it). The vacuum will pull a little into the seam to plug the hole without gluing shut the bag.

Hope this helps.

steve


Hi Steve,
I tried the "pipe clamp" method using 1/2 and 3/4" CPVC and so far can't get the bag into the clamp. The bag is just too thick. I'll try it again but so far I've been taping the end closed which works but takes a lot of time and tape. I can get the vacuum down to 23Hg with this method. I may try the clamp on Joewoodworker if I can't get this to work. Alan in Md.

[Scott Post]

Paul Schurch has an excellent picture of how to sharpen a veneer saw on his website:

http://www.schurchwoodwork.com/tools/index.html#nine

Basically, you file it like you would a rip saw then file across the teeth to form very sharp points.

[Jamie Buxton]

Hi Steve,
I tried the "pipe clamp" method using 1/2 and 3/4" CPVC and so far can't get the bag into the clamp. The bag is just too thick. I'll try it again but so far I've been taping the end closed which works but takes a lot of time and tape. I can get the vacuum down to 23Hg with this method. I may try the clamp on Joewoodworker if I can't get this to work. Alan in Md.

For me, the trick was to buy two different diameters of plastic pipe. The inside diameter of the outside pipe should be larger than the outside diameter of the inside pipe by a little less than four thicknesses of the bag material. (Don't pay much attention to the label on the pipe. In plastic pipe, neither the inside diameter nor the outer diameter is what the label would lead you to believe.) For 30-mil bag thickness, 3/4" schedule 40 pipe works as the inner pipe, and 1" schedule 21 works as the outer pipe. (Schedule 21 is the really thin floppy pipe often used for buried lawn sprinklers.)

[Chris Padilla]

Jamie,

I always thought schedule 120 was the really thin stuff...the sprinkler guys call it eggshell. It is a pain to cut with normal PVC cutting shears since it is so flexible and it sure doesn't take a whack from a shovel or landscaper's axe!! DAMHIKT!! :rolleyes: I replace all the 120 with 40 where I can.

Edit:

Okay, found this: http://www.ppfahome.org/pdf/pvcpipewaterspec.pdf (http://www.ppfahome.org/pdf/pvcpipewaterspec.pdf)

Not to blow this completely off-topic like I am so famous for doing but apparently there is a whole bunch of SDR and DR # for PVC pipes. There is an SDR 21 so my apologies! :D

[Dave Avery]

Alan,

Power tool variant to Jamie's jointer plane idea..... I clamp the veneer stack between 2 MDF sheets, aligning the MDF sheets parallel to each other and with the veneer sticking out about 1/32". I run the entire stack through the jointer. Proceed with joining the edges with veneer tape (really terrible stuff to work with, particularly if you have negative manual dexterity) as described by Jamie. Good luck. Dave.

[Dave Ramer]

Thanks Dave, That's where I got my bag material from. Have you made a bag closure using Joe's method yet? Thanks Alan

Alan,
I have not used his clamp yet. Just got the system up and pulling 27Hg... cut the recycle back to 20Hg. Bag and clamp are next on the list. However, having talked with Joe and over the course of 50+ messages exchanged, that is the clamp he uses and has had exceptional results... so I am expecting the same. So far, everything I have done/bought has been as advertised and more. No reason to suspect otherwise with the clamp.
Let me know how it works for you and I will do the same.

Dave

[Alan Tolchinsky]

Alan,
I have not used his clamp yet. Just got the system up and pulling 27Hg... cut the recycle back to 20Hg. Bag and clamp are next on the list. However, having talked with Joe and over the course of 50+ messages exchanged, that is the clamp he uses and has had exceptional results... so I am expecting the same. So far, everything I have done/bought has been as advertised and more. No reason to suspect otherwise with the clamp.
Let me know how it works for you and I will do the same.

Dave

I can't believe I finally did it. It was getting very old using tape to seal the bag so I kept working on the pipe clamp. It works using 3/4" CPVC and 1/2" CPVC. I cut a slot into the larger pipe and this was the critical part. You have to remove about 1/3 of the diameter to from a pretty open "C" in the 3/4" pipe. With this opening you can get the edge of the bag into the "C" and then push in the 1/2" pipe.

The other thing I learned was not to put too much of the bag into the "C" channel. Just insert the end of the bag and then push in the smaller pipe. This closes the end of the bag sealing it very well. I was able to pull 24Hg with no clamps on the pipe. Normally my vacumm will pull a max of 25 so I considered this good enough for pressing.

No if I can learn how to cut veneer more cleanly I'll be all set. I'm experimenting with the veneer saw and so far it ain't easy. :) Let me know how you're doing. Alan in Md.

[Greg Wease]

Hi All, I'm just getting into veneering with a home made vacuum press. So far it's working great! I'm using tape to seal the bag end. Anybody have a better idea to seal the bag. My pump pulls 25Hg by itself and 23Hg attached to the bag. My main leakage is the taped end.

Also can somebody describe how to sharpen a veneer saw? Or is it better to just use a router with straight edge to cut veneers. Thanks Alan in Md.

Alan, I use the two pipe method. If this doesn't work for you a simple method is to use two thin (~ 1/4") battens to sandwich the end of the bag. Fold this sandwich over and hold together with spring clamps.

To sharpen the veneer saw you need a small triangular file and a single cut mill file. Make one or two passes on each tooth with the blade in a saw vise with the triangular file. Then assemble the saw and flatten the back of the blade. Finally, use the mill file to bring the teeth to a sharp point with no edge showing. It is helpful to use a magic marker to darken the teeth first so it is easier to see where you are as you sharpen.

OR, try an Xacto knife with a #2 blade. The #2 is longer and stiffer than the "standard" #11 and fits the larger size handle.

The shooting board is a good tool for squaring the edges. You can use a handplane or a router with pattern bit. Work on your cutting technique a bit and try to avoid the need to shoot the edges. Sometimes I think I'm doing more harm than good by shooting.

Good luck,
Greg