Help with purfling?

[donbarzino]

2 mm thick maple will be difficult to bend. 

Have you thought of using 2 parallel rows of violin purfling ?

[Crimson0087]

So tell me what you guys think of this. My purfling channel is almost 2 mm wide which is even too wide for cello purfling...I was thinking about ripping some 2 mm think maple on band saw dying it black and gluing it in place...not perfect but then again this is my "learning" violin. Thoughts? Maybe next time I'll use a Dremel...

[Crimson0087]

I could try that

[chiaroscuro_violins]

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[Davide Sora]

 I use this, the blades are 0.6mm thick and 3.7mm wide, with double bevel. The spacer is a strip of metal (steel), to prevent it from compressing.

 

Here in action:

https://youtu.be/2d2rsgOeWeM?t=134

 

[nathan slobodkin]

Once again suggest the trois Brins style purfling which requires no prebending of anything and tends to swell and conform to the vagaries of a variable width channel. Karen Rost in Germany (Austria?) has whatever thickness veneers you might need or for that matter could probably make up preglued purfling in whatever thickness you want.

[uguntde]

I wonder why violin makers insist on using antique tools and refuse to use modern equipment like that below. This can be made better so the rotor is fixed and the plate is moved. The goal is to cut a nicely round prufling channel - does it matter how? In either case the accuracy of the outline will be crucial to avoid kinks.

[Marty Kasprzyk]

  If you are using power tools it is important to use a solid support.

[Davide Sora]

41 minutes ago, uguntde said:

I wonder why violin makers insist on using antique tools and refuse to use modern equipment like that below. This can be made better so the rotor is fixed and the plate is moved. The goal is to cut a nicely round prufling channel - does it matter how? In either case the accuracy of the outline will be crucial to avoid kinks.

For some it still matters, for others it doesn't. The same goes for buyers, to each his own.

[Dennis J]

The obvious reason is that losing control would be disastrous. Of course that can be a problem with other methods, especially when channeling spruce, so you need the right tools and methodology anyway.

I've made a little tool that is quite efficient at levelling the bottom of the channel. It's made from a rotary tool twist drill squared off at the end.

 

[jezzupe]

23 hours ago, Crimson0087 said:

So tell me what you guys think of this. My purfling channel is almost 2 mm wide which is even too wide for cello purfling...I was thinking about ripping some 2 mm think maple on band saw dying it black and gluing it in place...not perfect but then again this is my "learning" violin. Thoughts?

Your original insight is correct, and that once varnished and perhaps with some extra attention with a filling varnish it should look ok enough. So before you go and try to do something like dutch on a piece of wood to make it bigger and fill the gap, I will simply say that a "modified" version of the Hargrave method will save you or at least make the job manageable.

The Hargrave method, which I named after Roger Hargrave, involves pre-painting or coating the purling to be used , installing it, then brushing on hot water to activate the glue, this give one all the time to get it right and does not make a glue ghost nightmare....so in most cases under normal circumstances we would want to apply the glue so it it is very thin{but adequate} so it will be a snug fit in the groove

{ I always suggest making pre glued {swelled} pieces to use as a gauge for sizing the channel, just as much a pain when it's the other way around being to small.

But in your case instead of laying the glue up thin, you will be laying it up thick and may even do 2 coats.

I suggest wax paper, with plastic pens for stickers and to simply dip three fingers into the glue {if you can handle the heat} and extrude the purfling through your fingers with a little twirling in order to coat all the surfaces.

By building up a couple of layers of glue on the material you will greatly increase the dimension and make it so it will stay put when you are trying to fit and cut it, pre clamp strategically, then apply water and let it dry.

All the low spots will sink down where there are gaps and it will return to looking small in the groove, but it will stay put, and then as you progress with the varnish it will smooth out enough and if you need to toothpick in some filling varnish before final coats  it should work well enough to be good enough to move on to the next one and get it better next time...

Always use just one side of the cutter and the do the other, don't try to get two channel walls in one cut, and don't use that tool for anything but shallow scribing of the line, they call it a cutter, but it should not be used for that, just a shallow cut that THE SHARP ASS FLAT SHOULDER KNIFE YOU USE WILL FOLLOW...You will have more success using a good knife freehand once the initial cut has been made with the tool, than using the tool to try to do the cutting, which is what it looks like you did.

To see if this will work simply coat 1 piece before you commit to it all and see if the extra glue makes it fit snug enough for it to work 

[chiaroscuro_violins]

/

[David Burgess]

On 1/17/2022 at 7:03 AM, Davide Sora said:

 I use this, the blades are 0.6mm thick and 3.7mm wide, with double bevel. The spacer is a strip of metal (steel), to prevent it from compressing.

 

Here in action:

https://youtu.be/2d2rsgOeWeM?t=134

 

I have used something like that with reasonable success for marking, but my preference is to use only one blade in the marker, enabling it to cut to the full depth of the purfling. Then, one can reposition the blade to cut the other side of the purfling channel, or keep a separate marker/cutter, also with a single blade, which is already set up to do that. The one I have found most useful only costs about 85  bucks, so about 170 bucks for two, if that's preferable to dinking around a lot between inside and outside cuts.

I also prefer a marker/cutter which is gripped below the plate (as Davide's appears to be), so that a big-ol' hand gripping the marker/cutter from above the plate doesn't impede the view of what's going on.

[jezzupe]

10 hours ago, chiaroscuro_violins said:

If you can't hold your fingers in the glue, doesn't that mean it's too hot?

I think what I was getting at is that if you dip your middle index and thumb into the glue very shallow, like a 1/2 " for a half second ,  that most people can handle that and then simply extrude the purfling thru the fingers. You do not need to be speedy because your not trying to glue the purling to anything , just coat it with glue, as if it were paint....you can use a brush, but I find it wasteful and potentially messy on the wax paper  , and well just applying with fingers uses the least amount and seems to apply it the most evenly, then obviously clean your hands when done ....I mentioned the heat thing because some people are way more sensitive to heat that others, I suppose dependent on how calloused ones hands are 

[uncle duke]

I'm still using my hardware store circle cutter with the cutter turned backwards and following with an x-acto knife.

[Michael Darnton]

Blow up of OP's purfling cutter blades. He's  not cutting; He's plowing. Gotta sharpen those things!

 

 

[MikeC]

Here's mine.  I had to reshape the blades.  They were pointy like a needle and that doesn't work.  It came with four and I lost one.  Where can I get more blades?  

[uncle duke]

1 hour ago, MikeC said:

 

You wore those out on just one violin?

[MikeC]

1 hour ago, uncle duke said:

You wore those out on just one violin?

LOL  I'm pretty rough on blades!   You should have seen them when I got them.  Looked like sewing needles.  

[Marty Kasprzyk]

  

Does an audience really care what the violin's purfling looks like?

 

[David Rosales]

1 hour ago, Marty Kasprzyk said:

  

Does an audience really care what the violin's purfling looks like?

 

Yes, if your audience is made up of a bunch of luthiers. 

[MikeC]

6 hours ago, David Rosales said:

Yes, if your audience is made up of a bunch of luthiers. 

Luthiers with really good eyesight or under the age of 40

[Davide Sora]

11 hours ago, MikeC said:

 Where can I get more blades? 

The blades for the purfling cutter that I found for sale were always too thick to be used in pairs with a double bevel, also the steel was not so good. The best source for blades of excellent steel and appropriate thickness in my opinion are the ones sold as a spare blades for X-acto type knives or similar, you can find them 0.5 and 0.7mm thick.

Of course they will need to be brought to the appropriate width and resharpened with the appropriate shape.

[David Burgess]

On 1/16/2022 at 12:48 PM, Crimson0087 said:

 

 

 

Can you share your source for that purfling marker/cutter?

It's very much like the one I prefer to use, but mine took a lot of dinking to get it to where yours is.

I like to have backup tools.

[David Stiles]

Mine is very similar and came from Dictum. 

https://www.dictum.com/en/cutting-tools-jbe/purfling-channel-cutter-702522