Vacuum press Piano Veneer repair

[Steve Senseney]

I recent bought a used Steinway piano to repair. It was from 1896 or 1897. 45 inches in height.

I needed a lot of cleaning and mechanism work.

The case needed some help also. Some water damage had loosened the veneer completely on the top on one side. I figured the best repair would be a complete replacement of the veneer on the top of the piano.

The piano is finished in black paint/lacquer. I am not sure what was available when it was manufactured.

To do this repair, I decided to build a vacuum system to glue this down properly.

Randy Roberts gave some advice.

I read (several times) the Joe Woodworker site. It gave a lot of good help.

I won't detail the construction of the vacuum system, as the Joe Woodworker site does it very well.

I recommend that you buy the "kit" that has all of the controls and little pieces of hardware. I bought a cheap 2 stage Vacuum pump from Harbor Freight for the pump. This means I had to fiddle with the hardware a little and buy one or two additional connectors.

I was a little confused about the control unit that senses the pressure and turns it on and off. There are two ways to set this switch. OPEN when the pressure reaches a certain level or CLOSED when the pressure reaches that level. This had me confused for a while until I figured this out, but then the rest of the system worked well.

The connector system which they sell is odd, and I did not think it would work. Joe answered my email and assured me it would connect and hold vacuum and it does. I figured it would be a little different design.

Here are some pictures of my vacuum pump-

[Steve Senseney]

The system held vacuum very well, and was not too loud. If you wanted a quieter system, you could get a pump from an old refrigeration unit and it would be quieter. However, it will not pump as fast as this 2 stage pump if you are using a large bag.

It does put a mist of oil into the area where it is working.

To use the system, you need to connect it to the vacuum and have a bag of some sort.

I bought a bag and closures and connector system from Joe Woodworker and it worked well.

But of course, I could not vacuum bag the piano top which is attached to the frame on the piano.

Here are some connectors I made.

These have double sided foam tape on the surface to seal the vinyl, and they start out as a 3/8 inch bolt. I place a hole in the center to let the vacuum system suck air out of the bag, then chuck this into the drill press, and grind, file and work the end down to fit into the connector from the vacuum.

[Steve Senseney]

Of course this is a longer story.

Here is a picture of the piano top after the damaged veneer had been removed. I used a sharp well tuned hand plane, and the loose and still attached veneer came off easily.

It appears that it was placed with hide glue. The veneer is a 2 layered veneer. The under layer was probably mahogany, and the surface might have been the same, or something else. I really could not tell with all of the paint on it.

The wood underneath was a closed grain wood, which was a little soft. I suspect it was Gum wood (hackberry). It was 2 pieces which had no visible grain pattern, knots or defects.

The surface had marks showing a diagonal pattern. These were totally linear, and aligned and spaced evenly. Obviously a machine made these marks, but I am not sure what kind of machine did them.

There was a place where the water damage had caused the top to separate and there was a slight cupping in the boards. I filled the separation with a spline, and leveled the cupping so it would be flat when the veneer was applied.

[Steve Senseney]

I ordered veneer. I bought a 2 layer maple surface piece. I used Weldwood glue.

I got ready to use the vacuum press.

I bought one of the vinyl bagging systems from Joe Woodworker. The piano top folds in the center on a hinge. It was easily removed and glued in the bag with little problem.

I did not want to cut up the expensive bag for the piano top which could not be removed.

I bought a vinyl (the most expensive they had) shower curtain at Walmart. I had the glue that Joe Woodworker sells to put bags together.

I first used the double sided tape around the top of the piano and tried to simply pull the corners tight to seal the system.

To use the system, you need to make sure the vacuum will be able to suck air all of the way around. Randy recommended the use of the window screen.

Here is a picture of the "system" without the vinyl cover on.

[Steve Senseney]

Of course this did not work easily (actually at all) but here is what else I did.

The vinyl glue did not work on the vinyl shower curtain from Walmart!

I knew that they used heat to weld vinyl, so I got a Hair Straightener.

I bought this after I read online where piano people were using it to release the glue when they were taking hammer heads off. (it did not do this well, and I recommend using a hammer head puller device which has been the standard tool for a long time.)

It has a rheostat to adjust the temperature setting.

I tried using it to "weld" the plastic directly, and it was messy.

Then I tried something else. I marked with black marker where I wanted things welded, cut the material about 1/2 inch away from that spot, used the blue masking tape and taped these edges together, and used the hair straightener without difficulty.

Welding with the Hair Straightener

Finished welded edge

[Steve Senseney]

After making form fitting corners, I placed the vinyl bag on the piano. I used double sided sticky foam tape to seal the edges of the board.

I could not get an adequate seal. I placed some clamps on the edges and tried a few other things. Gave it a few days to think about it. I talked with Randy, and his comment was that it may be that the wood was porous enough that I could not keep the vacuum adequately with my system. Or, I had a leaky bag.

So, this is the final clamping system--

[Steve Senseney]

Randy asked that I go through some of the repair of the piano, as this does not get discussed much on the MIMF.

I plan on doing that in another discussion.

I now need to get another project for my Vacuum press.

[Steve Senseney]

One thing I forgot to include--

After I figured out that it was easy to weld the shower curtain, I made a bag out of the shower curtain that was about 2 ft x 4 ft in size.

To weld the longer distance--The hair straightener has about 4 inches of length where it has the heating element. There is an empty space below and beyond the heating elements. I was able to fold the vinyl at a 45 degree angle, and this allowed enough space to advance the heating element. I always let the vinyl cool before I heated the next section.

[David King]

Pretty darned clever all the way around Steve. I was able to buy proper vinyl sheeting and glue at my local TAP plastics for cheap enough for the last bag I made.

[Jason Rodgers]

Good work, Steve! Many of those joewoodworker parts are familiar, as I've built my own vacuum system (though haven't used it to its potential by far). I can't remember if I put it up on the mimf before or after the move to the new format, but it's here somewhere.

I ran into the wood porosity issue with this guitar I just finished. When I was carving the "original" of maple on alder, I sucked it up on a vacuum clamping plate and went to town with planes and chisels and it didn't budge. When I tried the same thing with the mystery mahogany, it wouldn't hold a seal. This might have been remedied with a splash-coat of shellac, but I didn't try it. Of course, that wouldn't have worked in your case. Sometimes, a seal just might not be possible.

[Jim Bonnell]

Great thread and well documented Steve. I built a vacuum system years back and like Jason have not made much use of it. I'm kicking around the idea of doing a laminated archtop so I might put it to use soon. I think Barry did a thread on that very process on the old website. I'll have to see if it's still around somewhere. I have to agree with you Steve, that pressure switch is a bit odd. Glad to know I'm not the only one that found it difficult.

[Jason Rodgers]

Found my thread http://www.mimf.com/phpbb/viewtopic.php ... son+vacuum

And down the page a little ways is you, Steve, saying you wanted to build one! I'm going to file away your experiments with vinyl sheet welding. You're basically doing a Food Saver suck n' seal maneuver.

[Steve Senseney]

I think it would be very easy to tool up to laminate archtop backs and tops.

I looked (a little) to find spruce veneer, and could not find any ready sources.

Another consideration is laminating fingerboards.

I will not copy Martin's laminated neck design.

[Randy Roberts]

Nice work Steve!
Boy does your pump kit look better than my Rube Goldberg outfit.
Thanks for detailing the misses as well as the hits. Sometimes you just can't get a seal to save your soul.
A coat of shellac on one side or the other of a porous board does usually do a good job of sealing a board that leaks, but leaks around your seals and edges can just drive you nuts.

I've always marveled at your tackling pianos in the past, and am really looking forward to your piano restoration thread.

[Bob Hammond]

Great info, Steve. (By the way, was it really you, who needed a lot of cleaning an mechanism work?

About the pump noise, maybe you could make a muffler for it. I have a hospital beside aspirator pump and it is very quiet. The muffler is a small device that screws into the exhaust port of the pump. I'll dig it out and take a pic for you, but it's basically like a silencer for a firearm.

About vacuum bag veneering, I've got an invitation to visit Bill Webster's shop. He's a harpmaker, who vacuum molds the sound chambers and soundboards of his harps. It should be an interesting visit, and if he agrees to let me take some pics, I'll post some info.

[Jason Rodgers]

As you can see in my link, I use a refrigerator compressor, which is super quiet, but still has the potential to spray oil mist. I made a "filter" out of a plastic takeout container filled with paper towels. One of these days I should probably take a look in there and see if the paper towels are at all saturated, but I don't use the pump very often. (In recent months, I've only turned it on to show the system off to visitors.)