An experiment in using vinyl templates for mandolin parts.

[Pete Jenner]

After three weeks of head scratching, research and learning some very basic programming, I have at last, managed to get my old vinyl cutter to behave itself via usb/parallel connection under Linux. (Fedora 20 for any geek types interested.)

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The idea is to create vinyl templates for mandolin parts to replace the normal paper ones ones I print out and stick together. The parts are taken from my mandolin designs produced in Rhino (windows) -> saved as dxf files -> imported into Librecad (Linux) -> exported again as dxf files that can be; -> read and imported by Inkscape and; ->exported as hpgl files to be concatenated directly to; -> the usb parallel port (/dev/usb/lp0).

Here, I am cutting out three mandolin necks and a mandola neck but I see the real potential for these vinyl templates in cutting more complex parts e.g. tops and peghead overlays. Vinyl templates allow view ports and alignment holes in the template to be cut with precision The use of transfer tape allows for multi part templates. (Handy for setting out oval sound hole rosettes.)



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Some Blackheath rough necks. It would have been funnier if I'd used red vinyl.
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I'm sure some people are wondering how much these templates will stretch. The answer is not at all. This stuff has good memory too, so if it does get stretched by use of force, it shrinks back to it's original shape.

I'll be interested to see if it's possible to make a good computer cut fretboard mask when the time comes for fret work. However I suspect that may require the use of spray mask vinyl. (It's thicker than sign vinyl.)

If anyone is interested, I'll post more vinyl template work as it happens.

[Nevin]

This looks like a great idea. I have heard of guitar makes using vinyl templates. I like the idea of the fretboard masking. You could probably sell those.

[Paul Hostetter]

Ordinarily, vinyl and nitrocellulose lacquers are arch-enemies. Once wood is contaminated with vinyl (thinking of vinyl straps, stands, polishes, etc.), the finishing options go way down. Can you cut any safer materials, such as Lexan or whatever its generic name is?

[Pete Jenner]

Hi Paul,
I'd never heard of Lexan so I looked it up. I don't think the cutter would handle it unless it was quite thin.
There is a rubber mask material for sandblasting which can be cut. It's about 1 mm thick apparently. The down force of the blade can be adjusted according to the material.

Are you saying that something in the vinyl will penetrate the wood? What if most of the area in contact is to be cut or sanded away? Is shellac affected by it?

[Marty Jacobson]

Pete, I don't think you need to worry about the vinyl thing. The adhesive is rubber-based. Wipe your parts down with mineral spirits and move on with life. Awesome work!

[Turtle]

After three weeks of head scratching, research and learning some very basic programming, I have at last, managed to get my old vinyl cutter to behave itself via usb/parallel connection under Linux. (Fedora 20 for any geek types interested.)
I don't know much about making instruments but I'm always glad to meet another Linux user. I've been primarily using Slackware at home for 10 years or so now. It sounds like you've found a good use for some older hardware.

[Paul Hostetter]

Hi Paul,
I'd never heard of Lexan so I looked it up. I don't think the cutter would handle it unless it was quite thin.

It comes in 1/32" 1/16" and so on. At least the Bayer polycarbonate does. Very flexible, not prone to shattering, etc.


Are you saying that something in the vinyl will penetrate the wood? What if most of the area in contact is to be cut or sanded away? Is shellac affected by it?

If most is sanded away, I guess it'll probably be OK, but I still worry about it. You can't bury it in shellac, it gets through a shellac coat and still wreaks havoc with nitro. If you even use polishes containing vinyl compounds on an existing finish, the reactive component penetrates through the finish and really messes up subsequent refinishing. I wish I understood this well enough to explain it, but anyone in the guitar world, particularly the finish part of it, knows from simple experience what can happen. But when you try and wrap your head around language such as "Allylic nucleophiles often react by vinylogous nucleophilic addition instead of direct addition; these are termed allylic rearrangements," you tend to simply observe results and heed them, and save your head. In any case, what you're proposing doesn't sound so scary, but I wish it could be anything but vinyl.

[Jim Adwell]

The vinyl would have to be in contact with a dried and cured nitro finish for quite a while before any problems would develop, if then.

Vinyl sealers work very well under nitro.

[Paul Hostetter]

Can you explain a bit more about the chemistry, and why some vinyl reacts, and why others don't?

[belbein]

Great work, Peter. I have to think that your time with Marty and his computer rubbed off on you. You can sell these things, I'll bet. And I might just be willing to buy a set.

[Nevin]

I know some plastics used on instruments stands can damage lacquer but the templates would be removed before finishing, no?

[BlueMt.]

I'm not a builder but I have used a lot of sign vinyl (which I assume this is) over the years. This is a thin vinyl with a sticky back much like shelf liner and I don't see where there would be much contact with the vinyl layer. Whether or not the adhesive layer could cause problems I don't know but I have used the stencil variety and then lacquered over the finished product with no problems.

[sunburst]

It's not so much the vinyl, as I understand it, it is the plasticizer in the vinyl that causes damage to lacquer. I would have to assume that vinyl sealer doesn't have the same plasticizers as vinyl plastic. It is more similar to Titebond, or other polyvinyl acetate adhesives.

I've worked with the masking material for sandblasting, many years ago when I worked for a sign maker briefly. I think it would work well for this, but I think I'll still be using my Plexiqlass templates and a pencil.

[delsbrother]

Just to answer Paul H's question, you can easily cut thin plastics with a laser cutter, which are fairly inexpensive and/or available in "Maker" hives.

[Marty Jacobson]

Laser cutters are over $25k if you want one big enough to be useful for mandolin work. I've bought two in the last year for the educational shops I manage. They're OK... I'd rather have a HAAS TM-1, for my money...
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What about cutting mylar?

[delsbrother]

We're talking about templates here, right? I have three laser cutters in my school's model shop, none of which cost $25K, and I can't imagine needing a bigger one to make mandolin timeplates. But YMMV. Sorry for the hijack.

[Pete Jenner]

Time to cut the master jig in vinyl.

Here's the theory.
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On the third attempt (don't ask), here's the practice.
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There's a week's work for you. Now to commit it to the bandsaw.

[sunburst]

Just a thought...
One of the reasons I use plexiglass for templates is because it is a clear material and I can see the wood through it. Sometimes there are "things" to avoid in the wood (sap pockets, grain deviations, etc.) and when I can see the wood through my templates I can see exactly where everything is (until carving commences, that is). In other words, with an opaque template you can see the wood that you're going to cut away but you can't see the wood you're going to use. I wonder if there is a clear vinyl or other material you could use for cutting templates, or if it matters to you at all.

[Pete Jenner]

Good point John. Yes I'm pretty sure there is clear or at least translucent vinyl available. Vehicle window tinting vinyl can be cut on these machines and that may be a good substitute.

EDIT:I often use Avery 700 vinyl and just discovered that the Avery 700-103-O is clear.

[delsbrother]

Is it important for the template to be flexible? Or non-flexible? How thick is your vinyl, and does it stretch at all?

All the templates I have used for other projects have been plexi cut on a laser cutter, and they've been completely rigid. Was there a reason you chose vinyl, other than you already had a cutter (which I would admit is a good reason)?

[Pete Jenner]

Is it important for the template to be flexible? Or non-flexible? How thick is your vinyl, and does it stretch at all?

All the templates I have used for other projects have been plexi cut on a laser cutter, and they've been completely rigid. Was there a reason you chose vinyl, other than you already had a cutter (which I would admit is a good reason)?

No it's not important for the medium to be flexible although that can have it's advantages. For instance, when making top and back templates, I can calculate the cosine error for individual sets of wedges and adjust the template width accordingly.

The vinyl will stretch if you pull it hard enough but for normal use it doesn't distort and the system is extremely accurate. It allows me far more flexibility and accuracy than the paper and cardboard templates I was using. I believe it's about 70 microns thick.

I don't use acrylic (perspex or plexiglass) because I haven't got access to it or the funds to have acrylic templates cut.

This is just another solution to a problem and one that works exceptionally well for me. Having said that, it is still an experiment and may prove impractical down the track.

Of course the main reason for choosing this system was a desire to make full use of the resources I had available i.e. the cutter.

[delsbrother]

For instance, when making top and back templates, I can calculate the cosine error for individual sets of wedges and adjust the template width accordingly.

Wow. Hard core, man. :)

[Pete Jenner]

It just needs bolting to the base.

Oh... and I have to rob a bank to buy the toggle clamps.

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[Steve Ostrander]

I'm sure some people are wondering how much these templates will stretch. The answer is not at all. This stuff has good memory too, so if it does get stretched by use of force, it shrinks back to it's original shape.

There should be no reason to stretch the vinyl if it is applied correctly. The preferred method is to use a low-tack transfer tape that lifts the cut vinyl off of the backing paper, then you apply to the final surface and lift the tape off, leaving the high-tack vinyl in place.

I have applied hundreds of cut vinyl letters and graphics. The release tape is absolutely the way to go. I wouldn't even attempt to apply vinyl without it.

[Pete Jenner]

Yep I agree. I used application/transfer tape.