Virutex SVN 460

[barry...@gmail.com]

I stumbled across this product on youtube and Chris from Driftwood Guitars was extolling its virtues.

In the video he mentions modifying it to use a vacuum pump rather than driving it with a compressor.

The vacuum pump is much quieter - does anyone know how to make this modification and can you suggest a vacuum pump to use?

Thanks!

In His Name -
Barry

[Neill S Morgan]

Barry, I have one of these that was delivered a few minutes before I left for ten days. When I get back home I plan to figure out the pump and will let you know if nobody else has chimed in here.

Neill

> On Aug 22, 2025, at 4:37 AM, barry...@gmail.com wrote:
>
> I stumbled across this product on youtube and Chris from Driftwood Guitars was extolling its virtues.

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[Barry Oren]

Thanks Neill -

In His Name -

Barry 

To view this discussion visit https://groups.google.com/d/msgid/obrien-forum/C6A2ADF5-7A43-43F3-9E35-DAB476265D87%40gmail.com.

[Charles Tauber]

Not sure I have an answer to your question. However, I have an identical basic vacuum unit, without the rotatable base, that I purchased a decade or so ago. I haven't really used it as having a compressor constantly running doesn't work well in my small shop. Likely the Australian company Vac-Clamp that patented the basic unit has sold the company or rights and it seems to now be sold as the Virutex, with or without the rotating base. 

Earlier this year, I purchased a Joe Woodworker vacuum pump kit. It works very well. So, when I saw your question, I remembered that I had the V-Clamp and spent an hour investigating its use with a vacuum pump rather than a compressor. My conclusion was that the integral Venturi unit isn't really removable or bypass-able. It isn't a standard Venturi arrangement, though it seems like a clever implementation. If one simply attaches a vacuum pump to the inlet port of the V-Clamp and plugs the small exhaust hole, one is drawing a vacuum directly - rather than blowing compressed air out the outlet past the Venturi/vacuum port. It does draw a vacuum on the surface of the V-Clamp. However, I didn't find it to be a very strong clamping force. If in the video, https://www.youtube.com/watch?v=j0R9dMkwy7s, the unit has in some way been altered, it isn't obvious to me. I'll write to Chris and ask him what modification he has made. 

Being new to vacuum clamping, I was expecting the same solidity of the workpiece as one obtains with more traditional clamping. That is, a completely rigid, non-moving workpiece. Instead, apparently due to the rubber seals against which the workpiece is clamped, there is a certain amount of seemingly inherent movement.  (I note in the Driftwood video, that he dismisses the amount of play in the rotating base. I think I'd find the play irritating.) My question for those experienced in using vacuum work holding for guitars is, is this typical of vacuum clamping of guitars, that there is a certain amount of "play" in the clamped workpiece?

Charles  

[Barry Oren]

Thank you Charles.

In His Name -

Barry 

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[Paul McEvoy]

I'm confused.  What are you using this for?

Paul McEvoy
207-699-9526

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[Barry Oren]

Paul, I’ll be using it as a clamping device to hold the guitar (or parts) while I’m working on it. 

This is a good video of it:

 https://www.youtube.com/watch?v=j0R9dMkwy7s

In His Name -

Barry 

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[Charles Tauber]

A follow-up...

I did write to Driftwood guitars asking what modifications they made to the clamp so that it would work with a vacuum pump rather than a compressor, as stated in their video. I received no response. 

I modified the clamp that I have so that it now works with a vacuum pump. It is a simple, three-minute alteration to the clamp. Cast/molded into the body of the clamp is a hollow reinforcement for the passage of air.  All that is necessary to use the clamp with a vacuum pump is to bypass the integral Venturi that is set into the hollow reinforcement. To so so, drill a single diagonal auxiliary hole into the reinforcement from the clamping face, creating a channel through which to draw a vacuum. Place tape, such as electrical tape, over the original exhaust port and the original vacuum port to eliminate any air flow through those ports. Attach your vacuum pump line directly to the existing/original port on the side of the clamp body. Air is drawn from the face of the clamp through the auxiliary hole you drilled into the reinforcement, bypassing the Venturi and its exhaust. 

To use the clamp with a compressor, one needs only to remove the tape and seal the auxiliary hole with a piece of tape.

Charles

[barry...@gmail.com]

Charles - you’re awesome! Thank you for this info. 

Much appreciated!

In His Name - 

Barry

On Sep 4, 2025, at 9:18 PM, 'Charles Tauber' via Robert O'Brien Guitar Building Forum <obrien...@googlegroups.com> wrote:

A follow-up...

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[Gill Brewster]

Thank you for work on how to modify to use with a vacuum pump. I’m not picturing about where the hole is drilled for the modification.  Any chance you could show a picture.

Thanks, Gill

Gill Brewster Sent from my iPhone

On Sep 4, 2025, at 21:36, barry...@gmail.com wrote:

Charles - you’re awesome! Thank you for this info. 

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[Charles Tauber]

I have created a short instructional on how I modified the clamp. I've attached a PDF version of it. 

[Charles Tauber]

I had intended to mention that I purchased the vacuum pad about a decade ago along with a Veritas Carver's Vice, https://www.leevalley.com/en-ca/shop/tools/workshop/workbenches/vises/31172-veritas-carvers-vise. The Carver's Vice  allows 360 degree rotation of the platen and tilting of up to 90 degrees, much like the motion with a variety of vacuum clamps.

Having finally set the thing up, I find that the Carver's Vice with vacuum pad adds a minimum of 8" to the working height of my bench. My bench is 38" tall. The combined height puts anything I clamp to the non-tilted vice at about the middle of my chest height, too high for a lot of activities. (I'm 5' 9".)

Virutex's website, https://www.virutextools.com/products/multiple-fastening-fystem-tilting-swivelling-svn460, does not seem to provide a total height of their clamping system but it appears to be of similar height, 8" or so. For me, to attach that to the top of my usual workbench would put many tasks for which I might use it too high. Despite Driftwood's endorsement of it, something for perspective buyers to keep in mind. 

[Neill S Morgan]

Thank you, Charles, that made it so easy!

Neill

On Sep 6, 2025, at 6:43 PM, 'Charles Tauber' via Robert O'Brien Guitar Building Forum <obrien...@googlegroups.com> wrote:

I have created a short instructional on how I modified the clamp. I've attached a PDF version of it. 

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<Conversion of Virutex Vacuum Pad.pdf>

[LesPauloholic]

This is very interesting, as I just bought one of these units and one of my friends has been using one for a while in his guitar builds.

How much additional vacuum pull do you get by drilling this hole?  I have a friend who uses one of these for guitar work, and he's just been blocking off the port, which is referred to as "C" in the modification instructions.  He's been very happy with the results and says that the unit holds his guitar bodies very securely.  If there is an advantage to adding an additional hole, that must mean that the venturi is very flow restrictive and that by allowing more flow than that port would allow is giving a stronger vacuum.

Greg

[Neill S Morgan]

If you’re using an air compressor with the venturi, using it stock is the way to go. If you want to use a quiet small pump, making the alteration Charles describes seems like a necessity. It reverses the air flow direction.

Neill

On Sep 9, 2025, at 8:11 PM, LesPauloholic <gr...@tonedog.com> wrote:



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[Charles Tauber]

Greg,

As I noted in my "instructions", I did try simply plugging port "C", the exhaust port, when using it with a vacuum pump. I found that it did not hold workpieces well enough for my comfort level. I could, for example, take a 2' square piece of plywood and with out too much effort pry it from the clamp, mostly levering it off the clamp.  I assumed that that was due to the very small orifice in the Venturi - if you look into port B with a good light, you can see the parts of the Venturi arrangement, with its very small orifice. 

Bypassing the Venturi by drilling an auxiliary hole, "D" in my instructions, I obtained considerably more clamping force, enough that there was no way I could pry the plywood from the clamp. I didn't gather any objective (numeric) data of how much the clamping force increased.

In both cases, the gauge on my vacuum pump setup read 23 mm of vacuum: both situations had the same amount of vacuum drawn, but one develops considerably more clamping force than the other. I attribute that to the difference in air flow. Regardless, the pump does cycle every minute or so, indicating there is air leakage somewhere in the clamp. A water/soap test suggests that it is leaking at the glued seam of the rubber seal. (I've tested my vacuum pump setup and there is no leakage in it.)

I'm assuming your friend is using the clamp with a vacuum pump rather than a compressor: you won't get any vacuum if using a compressor with the exhaust port blocked. Doing so negates the Venturi. I'm paranoid about having a finished - or nearly finished - guitar hit the floor because the clamp let go while I was working on the guitar. If using the clamp as-is with a vacuum pump gives your friend clamping force that he is comfortable with, there is no need for your friend to modify the clamp. If, after testing your own rig with your own guitars you are happy with the clamping force it provides, again, there's no need for you to modify it.  In my tests, there is considerably more clamping force with the Venturi bypassed. 

Charles

[Charles Tauber]

For those who might be interested....

The manufacturer states that the clamp should be used with an air compressor delivering between 80 and 100 psi. At that pressure range, the clamp needs about 1 CFM of air flow. In general, the higher the pressure and higher the air flow, the greater the vacuum it can draw. The manufacturer states that the operating air pressure should not exceed 120 psi. The manufacturer states that at 85 psi, the clamp produces about 12 lb/in^2 (psi). With a total clamping area of 150 mm x 150 mm, the total clamping force it can achieve, at 85 psi, is 466 lb. That's using the entire clamping area of the pad. 

My calculations show that if using the same clamp with a vacuum pump obtaining 23 mm Hg, without restricted air flow, the clamp is capable of achieving 394 lb of total clamping force. Again, that is using the entire clamping area. (I don't know what it would be if using the Venturi with a vacuum pump.)

Since the holding force the clamp develops is directly proportional to the area being clamped, keep in mind that if one arranges the clamp's seal to use a smaller clamping area - for example, to hold smaller/narrower workpieces -, one gets less clamping force. Half the clamping area, for example, produces only half the holding force. Also, the clamping force is proportional to the supplied pressure/vacuum. Less air pressure, or less vacuum, reduces the holding force. If one uses only the smallest of the clamp's grid areas, about 1-5/8" x 1-5/8", one is down to about 30 lb of holding force.

Charles