Bridge Vacuum Clamp

[johnc.marple]

I am thinking of buying a Bridge Vacuum Clamp from a supplier in Germany

https://shop.gitabou.de/product/bridge-vacuum-clamp/?lang=en

I have a Festool vacuum clamp that I will need to adjust to make the connection or alternatively this supplier has a vacuum generator that connect to a compressor. 

Is anyone using a Vacuum Clamp with a compressor and what specification of compressor would  be required? 

Thanks

[Dick Fulco]

Hi John,

I don’t know about the tools, but I do know the website/shop.

No problems there:)

Met vriendelijke groet, Dick

Op di 4 jun 2024 om 17:53 schreef johnc.marple <johnc....@gmail.com>

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[johnc.marple]

Thanks, I have sent them an email

[Charles Tauber]

John,

I purchased the LMI bridge vacuum clamp shortly before LMI closed. It came with remarkably little practical information on pressure or air flow requirements. I had hoped that it would seal sufficiently well that once vacuum was developed it wouldn't need a constant-running vacuum source to operate the clamp. Unfortunately, it leaks considerably, loosing vacuum immediately once the vacuum source is turned off. (Translated: it needs a constant source of vacuum to work.)

It appears that Festool has discontinued its VAC SYS and I could find little technical information on the flow rate and vacuum it can achieve. At one point, I considered buying one and decided against it because the flow rate and vacuum was sufficiently low that it could not realistically be used for, for example, a CNC hold-down table. In the absence of technical information, it isn't clear if the Festool would provide what is needed for the bridge vacuum clamp: it might, it might not, making planning difficult. It probably does.

Aside from a dedicated vacuum pump, one can also generate a vacuum by attaching a Venturi "pump" - referred to as a vacuum generator, on the German website you referenced - to a compressor. This website provides some practical data on their Venturi pump/generator: https://infinitytools.com/blogs/blog/inexpensive-vacuum-clamping-made-easy. Specifically, when used with a small compressor producing 2.3 CFM, or less, at 70 psi, the Venturi can produce -26 inHg (vacuum). The German Venturi might have different specs. I don't know how much the bridge vacuum clamp needs, but that is probably enough and then some. That should give you some indication of the minimum compressor requirements for use with the Venturi/generator and bridge clamp.

Charles

[Robbie O'Brien]

John,

Greg Porter of Skyscraper guitars is going to be making a bridge vacuum clamp. It should be out soon.

https://skyscraperguitars.com/

Robbie

Lutherie Academy by O'Brien Guitars lutherieacademy.com Keep track of the changes going on now at O'Brien Guitars by signing up for my newsletter

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From: 'Charles Tauber' via Robert O'Brien Guitar Building Forum <obrien...@googlegroups.com>
Sent: Tuesday, June 4, 2024 13:34
To: Robert O'Brien Guitar Building Forum <obrien...@googlegroups.com>
Subject: Re: Bridge Vacuum Clamp

 

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[Robert Gibfried]

Allied Luther three now has a new vacuum clamp for bridges in their inventory.

Bob

Sent from my iPhone

On Jun 4, 2024, at 8:06 PM, Robbie O'Brien <robi...@hotmail.com> wrote:



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[johnc.marple]

Hi Charles

I think that is the nature of vacuum clamps, they need a constant connection to a running pump.  

I bought the Festool ex demo a few years ago, and it does cot get used as much as I hoped, using it for bridge clamping would justify the space it currently takes up. I have no concerns about its power, when an item is clamped it's rock solid; however that does not give any indication to its suitability for bridge clamping.  

The Venturi Pump option is appealing, the supplier said it works with a regular “hobby” type compressor, but it's an extra 90 euros and a compressor takes up more space + cost.

I am thinking I'll give it a try with the Festool, I can but a spare hose and connector for £60.00 which is less than the cost of a compressor and a Venturi Pump

Regards

John

[JohnParchem]

A bridge vacuum clamp needs constant vacuum as the wood itself will not hold a vacuum. I have a dedicated vacuum pump. For a bridge clamp a small vacuum pump is OK not need to move a lot of air. 

[Charles Tauber]

I'm new to vacuum clamping guitar bridges. I have experience with vacuum clamping laminated sides.   For laminating sides, I use the Roarockit system, https://www.roarockit.ca/luthier-tap-kits-bags-and-parts/,  that consists of a simple hand-pump and a one-way valve and a vacuum bag. So long as the bag fully seals, once one has drawn a vacuum, the vacuum source can be disconnected. No noise, no fuss, fast, inexpensive. It would be ideal to have a similar system in a vacuum bridge clamp: the clamp, a small hand pump, a one-way valve and some tubing: simple technology matched to a simple job. I've tried using that setup with the LMI vacuum clamp. It fails because of the loss of vacuum - leakage. I know the "system" doesn't leak, which leaves leakage of the clamp.

I've tried drawing a vacuum with LMI's bridge clamp against a variety of surfaces, including glass, acrylic and melamine, which should be impervious to air leakage. Regardless, the clamp loses all vacuum immediately once the vacuum source is discontinued or removed. Ideally, the clamp, itself, should not leak, allowing one to turn off or remove the vacuum source and still have the clamp retain its vacuum. That it does not suggests that the leakage is likely through one of three sources: the sealing gasket, the bolt holes used hold the two halves of the clamp together or through the membrane itself. 

To determine which of these is the primary source of leakage would take considerable effort. It might well be that even if one did come up with a leak-proof clamp that the finished top wood would allow air leakage through it and leakage through the clamp, itself, would be irrelevant. I've yet to decide how much I want to pursue the idea versus just going with the status quo of constantly supplying a vacuum - buying a Venturi and running a compressor or buying a vacuum pump.  

Charles

[John Charnock]

I’ll give it a try with my Festool and report back

 

That is once I can get I into the UK, the German supplier ships all over the world, including Mongolia, Iran, Kazakhstan and Kyrgyzstan but NOT THE UK because of BREXIT !

 

I’ll keep you posted

 

Regards

 

John

 

From: 'Charles Tauber' via Robert O'Brien Guitar Building Forum <obrien...@googlegroups.com>
Date: Wednesday, 5 June 2024 at 19:29
To: Robert O'Brien Guitar Building Forum <obrien...@googlegroups.com>
Subject: Re: Bridge Vacuum Clamp

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[Kris Young]

I use my Festool vacuum pump for bridge and cnc vacuum jigs.  No problems but I needed to replace the filter last summer. 

- Kris

On Jun 5, 2024, at 3:51 PM, John Charnock <jo...@marple.co.uk> wrote:



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[Ray Cutler]

Hi John.  I have the same Festool vacuum and I just use a 3/8 ID piece of hose over the pump fitting and a short 1/4" ID hose into the other end if the 3/8" hose.  From there I coupled it to the 1/4" from the clamp.  It doesn't look as bad as it sounds and it doesn't leak.  Clamps well

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[John Charnock]

Hi Ray

 

To avoid cutting the hose I purchased a spare Festool hose, and I am waiting for an adapter for the 6mm to 8.9mm internal diameter of the Festool hose.

 

It will be next week before I get a chance to assemble it and try it out. 

 

I’ll probably looking for some guidance which I’ll post in another thread

 

Regards

 

John

 

From: obrien...@googlegroups.com <obrien...@googlegroups.com> on behalf of Ray Cutler <rcutl...@gmail.com>
Date: Friday, 7 June 2024 at 18:31
To: obrien...@googlegroups.com <obrien...@googlegroups.com>
Subject: Re: Bridge Vacuum Clamp

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[Ray Cutler]

John I didn't explain myself very well.  The hose I used to connect to the European fitting on the Festool pump was just hardware store tubing, pushed on tight even to not need a clamp.  I didn't cut any Festool hoses

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[John Charnock]

Hi Ray

 

My Festool hose is connected to vacuum clamp with a festool adapter, and the other end is a permanent jubilee type connection. 

 

I’ll share what I have ordered when it arrives

 

Regards

 

John

 

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[johnc.marple]

This is the new hose I bought for my Festool Vacuum clamp with the reducer from the 16mm OD Festool tube to the 6mm clamp hose 

I didn't have to cut my current festool tubing

[Murray Francis]

Hi John 

Could you tell me the Festool part number.  I am contemplating the same setup over here in the colonies.  I was not even aware that this hose was available.

Thank you,

Murray Francis

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[John Charnock]

Festool Vacuum hose D 16 x 5m VAC SYS 

Code: 495293

Its 5mt long, which I think is longer than the original, so it gives you a bit more flexibility  

I got mine discounted, still expensive at £70.00 UKP   

 

Regards

 

John

 

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[larryathaluthier]

FWIW:

for those not already invested in a system - but interested in investigating vacuum clamping and seeking less expensive sources and reference info - to know what performance a given size Air compressor  will create with a venturi valve or desiring to get a lower cost vacuum pump...

I saw that Marc Adams School of Woodworking is offering a course to "Make Your Own Vacuum Pump & Pressing Table with Mark Osgood" The course is next weekend (june 22-23, $715 = $415 fee and $290 materials) .

here is a link: 

https://www.marcadams.com/workshop/make-your-own-vacuum-pump-pressing-table-mark-osgood/

 From the photos and cost and some searching, I see the instructor for the course  is using vacuum kits from "Joe Woodworker."  I think - based on price - they are using the "V4 Kit" which is a venturi valve, fittings, plumbing, and some other stuff for employing  reservoirs. This is $290. 

 https://www.veneersupplies.com/products/Project-V4-Auto-Cycling-Venturi-Vacuum-Press-Kit.html

They have other kits with an auto-cycling pump and some kits with continuous pumps too.

 
There is a lot of free info on this site about employing and sizing vacuum systems (both for pumps and flow requirements for venturi valves) on this site. but if you have an reasonable sized air compressor capable of doing hobby spraying - it looks like you could get started with this kit for around $290.00

https://www.joewoodworker.com/veneering/choosingavacuumpress.htm

I would also point readers of the Guild of American Luthier's journal "American Lutherie" to some republished articles on vacuum clamp stations from Charles Fox, in "the tools and jigs anthology" book. 

https://luth.org/books/american-lutherie-anthology-series/tools-and-jigs-an-american-lutherie-anthology/

 

I hope this post doesn't divert the topic .I feel like I drafted this post before, but was afraid to share as it was slightly off topic and I don't mean to change topics, if you think it does,  my deepest apologies. Maybe this will permit someone to learn about vacuum clamping at a price point they can manage.  

sincerely,

Larry Atha

Huntsville, Alabama