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Flip Top Vacuum Press
http://www-.luthiersforum.com/forum/viewtopic.php?f=10102&t=4967		 Page 1 of 1
Author:  Tom Armstrong [ Wed Feb 08, 2006 2:39 am ]
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I'd like to build a flip top type press for bracing tops. Anyone have plans or tips they could share?
I already have a bag type system but I'm assuming a flip top would be a bit easier to manipulate.
Author:  PaddyD [ Wed Feb 08, 2006 4:08 am ]
Post subject: 
hi there,
welcome to the Official Lunatic Forum!!

i am just about to build a frame press also, there isnt a lot in the way of plans, so i have just kind of pieced it together from picture and articles,

you need a 40"x40" piece of melamine faced board or corian to act as a base which the frame can seal onto,

the frame itself can be made of aluminium or birch play or mdf, i'm using aluminium as i can have a friend weld it for me and then i will tap a hole in the side for the push fit connector, birch or mdf works fine, but you need to seal them with something to make them airtight, i guess a coat or two of Zpoxy would work, then you could thread a small piece of brass expoxy that into a hole in the frame, then screw in the push fit, or you can just epoxy the push fit straight into a hole.

you need some 1/16 silicone rubber sheeting, there is a guy on ebay who sells it cheap, but its not transparent, i think mcmastercarr has transparent, or natural sheeting... you just lay the sheeting over the top of the frame then put a sheet of 1/8 plexi over the top of the rubber, then screw/bolt throught the plexi into the frame....

then you want a piano hinge or something similar along the rear or the frame, a couple of catches or some sort of fixing to lock the frame down, and some 1/2" closed cell foam strip, again from mcmastercarr, to seal the frame to the corian/melamine,

then as for fittings, PISCO and FESTO seem to be the main guys for push fit connectors, i went with the 10mm pushfits with g 1/4 thread, and some 10mm nylon tubing that wont crush under the sort of vacuum we are using....


thats about as far as i have got... hope this info is helpful and not just teaching you to suck eggs,

paddy,


p.s the inside dimensions of the press frame should be at least 32"x32"

Author:  Bruce Dickey [ Wed Feb 08, 2006 4:18 am ]
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Check the Collings Site. Maybe a visit from Frank Ford off Frets.com Don't remember. But they use a combo of gobars, then flip top vacuum.
Author:  Bruce Dickey [ Wed Feb 08, 2006 4:23 am ]
Post subject: 
I heard one guy used a shower curtain.   
Author:  Daniel M [ Wed Feb 08, 2006 4:36 am ]
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I have only used my vac press a few times, but i found the hinges were holding the lid up & creating a slow leak. To fix it, I elongated the hinge screw holes & left the screws a bit loose, so the seal can compress unimpeded once the vac is turned on.

I didn't bother putting the plexiglass sheet over the frame. It doesn't seem necessary to me.
An old 20 Lb. propane tank (free from the junk yard) works great for a resevoir. It stinks bad for a while if you don't clean it out first.

A brass "3 way" fuel valve works great as a selector valve. It has one position which will vent the press without venting the resevoir.

Make sure the bottom section of the lid is thick enough that you can close the lid without having the rubber sheet hit the braces. I found that a bit of tape over the ends of the X braces stops things from slipping around while the suction is applied.

I used MDF for the base & the hinged frame. A couple of coats of Varathane, sand it smooth & it's a good sealing surface.

While you're at it, consider building a bridge press. I love not having to risk denting the soundhole edge with clamps. Its also really quick... if you use hot hide glue, it's no sweat getting everything together in jig time.

Author:  Rod True [ Wed Feb 08, 2006 5:46 am ]
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Hey Daniel, Thanks for the pics the other day on the power feed system.

don't suppose you have any pics of your vac press set up do you? Also, do you have a rough schematic of the vacuum system?

Jee, what an idea hog I am.
Author:  Brock Poling [ Wed Feb 08, 2006 6:03 am ]
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I am in the same spot, and here is what I am thinking of doing. I am going to build a set of full extension shelves that will fit between a double layered top on my work bench.

Then you would be able to pull out the drawer, flip open the top, do your bracing, turn on the vac, and slide the whole thing back

That will give you nice convienent storage that is out of the way.

I got the idea from one of the Taylor Factory Friday videos.

It might be worth checking out.

Author:  Pwoolson [ Wed Feb 08, 2006 6:14 am ]
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Brock, that's exactly what I did. I'd take pics but there are so many darn clamps in my shop I can't open anything. Remind me next week and I'll send you some.
Author:  Daniel M [ Wed Feb 08, 2006 7:11 am ]
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When I figger out how to easily shrink pics down to 150 KB, I'll post some. I can't help it... I'm from Ludite stock.
Author:  Rod True [ Wed Feb 08, 2006 7:12 am ]
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Oh, Paul would you mind posting the pics here for us all to see. Pleeeeeeaaaaaaassssssssseeeeeeeee.
Author:  klhoush [ Wed Feb 08, 2006 7:33 am ]
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[QUOTE=Daniel M] When I figger out how to easily shrink pics down to 150 KB, I'll post some. I can't help it... I'm from Ludite stock.
[/QUOTE]

The easy way to shrink a photo in windows is to right click/ send to/ email recipiant/ and then drag the image from the email to your desktop where you can find it. It makes them about 30k which is good for hiding glue mess and chisel marks!

Kurt
Author:  Steve Spodaryk [ Wed Feb 08, 2006 11:03 am ]
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I made a nice compact one last year - similar to Don W's. I demoed it at a NEL meeting and have enjoyed using it. It's a fair amount of work to build and there is some cost involved (materials, pump, etc). Go-bars worked just fine for many years and are far less complicated.



My frame is poplar with black enamel paint. Plywood & MDF will definitely leak air if not coated with something. I found I needed the maple strips and plenty of clamping (from the screws) to get a good seal. I drive the jig with a small Gast pump getting 23-25" of Hg.

While not completely necessary - you'll want the plexiglass the first time you drop something on the top of your jig. Drill the evacuation holes before assembling.

Piano hinge on the back and sturdy sash lock on the front. 1/4" x 3/4" closed cell foam insulation.

I have three workboards (25', 15' and flat) that I can swap in/out for different plates. Size the height of the frame so that the membrane sits a little bit above your tallest brace.

My inner dimensions are no more than 18x24". I tuck it away when I'm done and it takes very little space. That is a parlor top not more than 18" long, but it will easily take a dread. Not sure why PaddyD is suggesting 40x40" & 32x32" - that would be a seriously large guitar top! Two plates at once, maybe?

SteveSteve Spodaryk38756.8075694444
Author:  PaddyD [ Wed Feb 08, 2006 11:11 am ]
Post subject: 
hi steve,

like i said i'm no expert, and i have had no help with this, i do acoustic basses from time to time so i made the jig bigger, i guess its easier to make it bigger and not have to use the space rather than going, "gee i wish i had a little more room"

ciao

paddy
Author:  LanceK [ Wed Feb 08, 2006 11:20 am ]
Post subject: 
Steve, I fixed your link
Author:  Steve Spodaryk [ Wed Feb 08, 2006 11:36 am ]
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Lance, thanks!

Paddy, I agree - if you have the bench/storage space, why not go for it.

My own space is pretty limited and I figured I'd never need wider than 18". This size also makes it quite a bit lighter, although it's still pretty heavy. The handle on the side is pretty useful. The bottom is 3/4" particle board covered in melamine (from some old shelf or tabletop).

Again, it depends on what your needs are - but if I was starting out, or only building a few a year, I'd probably devote my energy to other things (like guitars) and not this kind of rig. I kind of miss my go-bars and cursed almost continuously while putting it together!

BTW, I really like Brock's idea. Once I get a new bench setup, I may just mount that underneath.

Steve
Author:  Tom Armstrong [ Wed Feb 08, 2006 11:40 am ]
Post subject: 
I'll steal Paddy's idea on a closed aluminum frame...no vacuum leakage there if welded properly. What did you use to seal the bladder between the fliptop and the plexiglass?
The picture seems to show a fair amount of screws with rubber o rings but I'm not sure. Could you explain this a little futher please?
By the way, thanks to everyone who responded. I'm a visual type person, so pictures work greatfor me.
Author:  Tom Armstrong [ Wed Feb 08, 2006 11:43 am ]
Post subject: 
oops....that last post was a question to Steve. Sorry, I'm new at this.
Author:  John Mayes [ Wed Feb 08, 2006 12:01 pm ]
Post subject: 
I've used both Vac Press systems a bunch as well as Go -Bars. The
advantage I see with vac press systems are two fold. First the dry time is
much less than go bars. You can take the stuff out of the press in 10
minutes with no fear of damaging the glue joint. Second it allows you
pre-profile a lot of the braces as you do not have to worry about denting
the braces with go-bars (although I saw Mario has a cool triangular thing
that fits offer his braces...cool) That being said I much prefer the tactile
feel of the go bars. I've built (and currently have one I built) a few va-
press systems. They are not very hard to build. Rather simple actually
and work fine, but I prefer the Go bars greatly for overall experience.
Author:  Jim Watts [ Wed Feb 08, 2006 12:17 pm ]
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I have one thats almost identical to the one steve posted a picture of and it works well.
Author:  Steve Spodaryk [ Wed Feb 08, 2006 4:07 pm ]
Post subject: 
I'm sure there are a lot of ways to do this, but I used basic 1/4" x 3/4" self-adhesive weatherstripping (closed cell foam) between the base and the flip top frame.

The silicon rubber membrane sits on the (wood or AL) frame. The plexiglass sits on the membrane and then the maple slats and screws pull everything tight. The rubber forms it's own gasket. Drill a few small holes in the plexi to help evacuate the air under the rubber.

The "o-rings" are just washers - probably not necessary, but didn't hurt. I initially tried to screw the 1/8" plexiglass directly to the frame, but 1/8" pg wasn't stiff enough to get a good seal - even with closely spaced holes. That's the reason for the maple strips. 1/4" plexi could probably serve double duty.

Part of my frustration was ordering a bunch of wrong material and redoing things until I got them right. I found that .020" siliconized rubber will leak air. The .040" I had was marginal. I found I needed the .060" for the system to work well.

It's not a hard project and you can get most of what you need with one order to MSC or McMaster-Carr - but if you don't know exactly what you need - it gets tiresome, and expensive.

Steve

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