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Author Topic: festool vacuum clamping module leaves rings in finish  (Read 1538 times)

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Offline Cbrown154

  • Posts: 1
festool vacuum clamping module leaves rings in finish
« on: September 29, 2018, 07:09 AM »
I recently purchased the vacuum clamp to use for working on guitars and found an impression of the rubber vacuum ring embossed on my guitar finish that had cured for three days. The finish is water-borne lacquer. I had to re-level the finish on the back of the guitar and buff it all over again. I'm tempted to try again after 30 days of curing but am concerned about the risk of damage, again. Any thoughts or ideas?

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Offline Claimdude

  • Posts: 337
Re: festool vacuum clamping module leaves rings in finish
« Reply #1 on: September 29, 2018, 10:34 AM »
Short of finding someone with specific experience with the same brand and type of finish I recommend you ask the finish manufacturer when the finish with the thickness you have applied may be fully cured. Or better yet, take a piece of ply and finish it like you do the guitar then wait 30 days and test it on the vac sys.

Jack

I recently purchased the vacuum clamp to use for working on guitars and found an impression of the rubber vacuum ring embossed on my guitar finish that had cured for three days. The finish is water-borne lacquer. I had to re-level the finish on the back of the guitar and buff it all over again. I'm tempted to try again after 30 days of curing but am concerned about the risk of damage, again. Any thoughts or ideas?

Offline SRSemenza

  • Global Moderator
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  • Posts: 8614
  • Finger Lakes Region, NY State , USA
Re: festool vacuum clamping module leaves rings in finish
« Reply #2 on: September 29, 2018, 10:50 AM »
Hi,

  Welcome to the forum!  [smile]

      I think the vac clamp is a tool that does what it does. It's an on or off type of thing. I have no idea if a different sealing material, etc. might alleviate the issue. But I doubt it. There is simply a lot of force pulling the piece tight. I think that just about anything clamped tightly could cause the problem with the finish. I don't have the vacuum clamp nor have I used any other one to know if they act upon the work piece differently. The above are just my thoughts.

    I am not sure if this will work for you but maybe try using a porous material in between ....... such as MDF or something that will conform to the guitar shape?

     I think experimenting with cure time and type of finish is worth trying. I know there are other members of this forum that build guitars ...... maybe they have some advice?

Seth

Offline Michael Kellough

  • Posts: 3576
Re: festool vacuum clamping module leaves rings in finish
« Reply #3 on: September 29, 2018, 01:00 PM »
Seth is right. Vacuum clamping a lightweight finished piece like a string instrument will require some experimentation to find the right combination of surface area and pressure. The suggestion to use a leaky soft interface material is a good starting point.

Offline James Biddle

  • Posts: 141
Re: festool vacuum clamping module leaves rings in finish
« Reply #4 on: September 29, 2018, 05:20 PM »
Maybe try a sheet of butcher or parchment paper in between to determine whether the impression is caused by the suction itself or residue from the vacuum cup material. 

Offline JD2720

  • Posts: 1025
Re: festool vacuum clamping module leaves rings in finish
« Reply #5 on: September 29, 2018, 05:44 PM »
Maybe try a sheet of butcher or parchment paper in between to determine whether the impression is caused by the suction itself or residue from the vacuum cup material.

I do not see how that wound work with a vacuum clamp. The paper would stop the suction from getting to the wood.

Offline Michael Kellough

  • Posts: 3576
Re: festool vacuum clamping module leaves rings in finish
« Reply #6 on: September 29, 2018, 06:12 PM »
A water-borne finish should cure at least ten days before applying that much pressure.

A vacuum clamp with a suction area of 8 square inches will bring on atmospheric pressure of over 100 pounds. That seems like a lot more weight than should be applied to an instrument anyway but since the contact area between the suction cup and the finished surface is confined to the rim of the cup that 100 pounds is borne by only about 2 square inches of rubber so everywhere the cup is touching the finish the pressure is about 50 pounds. Bound to make an impression no matter how soft the rubber on uncured lacquer.

JD, the Festool vac clamp runs continuously so it depends on how leaky the interface material.

Offline Dick Mahany

  • Posts: 384
Re: festool vacuum clamping module leaves rings in finish
« Reply #7 on: September 29, 2018, 08:41 PM »
I vacuum clamp routinely on a lathe.  Surface area quickly adds up fast and can even implode a delicate thin piece of any appreciable surface area.  To that end, I simply put a bleeder valve in line and problem solved.  The vac pump does run more, but I can dial in the holding pressure to exactly what I need without damaging the part.  Can the Festool Vac chuck be set up this way?

Ignore the detail, but it is nothing more than a 1/4 turn valve inserted inline with one end open.  Instantly variable suction.

« Last Edit: September 29, 2018, 08:51 PM by Dick Mahany »

Offline Cheese

  • Posts: 5069
Re: festool vacuum clamping module leaves rings in finish
« Reply #8 on: September 30, 2018, 12:01 AM »
Can the Festool Vac chuck be set up this way?

Absolutely, the only thing I would change is to put a needle valve in series as opposed to the 1/4 turn valve. The needle valve will be infinitely more capable of dialing in fine vacuum leak adjustments. The pump will also probably run continuously...it’s just the price you pay.  [big grin]

Offline Cheese

  • Posts: 5069
Re: festool vacuum clamping module leaves rings in finish
« Reply #9 on: September 30, 2018, 12:04 AM »
I vacuum clamp routinely on a lathe.

Hey Dick, who makes the vacuum chuck or did you make it yourself?

Offline Dick Mahany

  • Posts: 384
Re: festool vacuum clamping module leaves rings in finish
« Reply #10 on: September 30, 2018, 09:25 AM »
I vacuum clamp routinely on a lathe.

Hey Dick, who makes the vacuum chuck or did you make it yourself?

Cheese, I've made all of my vacuum chucks although there are some inexpensive vacuum holding chucks starting to pop up on line.  I scored a Gast oilless vacuum pump for free when a piece of lab equipment was being discarded.  I've had my eye on the Festool vacuum chucks and foot pedal, but flat chucks are so easy to make and all that I really need is the adjustable swivel mount. ( I do like the needle valve idea for fine adjust )


Offline Dick Mahany

  • Posts: 384
Re: festool vacuum clamping module leaves rings in finish
« Reply #12 on: September 30, 2018, 11:09 AM »
An “adjustable swivel mount”

https://weldtables.com/collections/clamps-accessories/products/fabturn-diy-welding-positioner-kit-a-welding-turn-table-for-the-everyman

Michael, thank you for the link!  I see one of these made of Baltic Birch coming soon to a shop near me  [big grin]

Offline rst

  • Posts: 2011
Re: festool vacuum clamping module leaves rings in finish
« Reply #13 on: October 01, 2018, 07:00 PM »
When I bought my Virutex vac clamps I bought bar stool swivels to make the clamping units rotate horizontally , the units already had vertical motion. 

Offline Getmaverick

  • Posts: 124
Re: festool vacuum clamping module leaves rings in finish
« Reply #14 on: October 01, 2018, 10:20 PM »
I had the same problem with cabinet doors. I started using a used dryer sheet and it fixed the problem. I think the problem is the rubber that is used on the pads.