Sore finger

[Gary Davis]

I have been building an F5-style mandolin with violin edges.  I'm almost finished and then can start on a violin.  The problem I have is cutting the purling channel edges with knives and exacto knives.  Pressing the knives to cut the channels, especially in the cherry back, has left my index finger numb and painful.  Its difficult to continue this way.

What do others use, other than a router, to minimize the pain and numbness associated with this task?

Gary Davis

[chiaroscuro_violins]

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[Don Noon]

CNC... but I guess you'd have to classify that as a router.

If you insist on hand-cutting the channels, I think that making a handle to spread the load would be the only way to save your finger from overuse.

[uncle duke]

9 hours ago, Gary Davis said:

What do others use, other than a router, to minimize the pain and numbness associated with this task?

Staying away from work for 2/3's of a day sometime works.

[Mark Norfleet]

Two more suggestions…, spread out the wear and tear on your fingers over time, and get your knives as sharp as you can.  Very sharp tools make the work much easier!

Make it three…. Use a little old dried soap on your knifes, that helps too.

[HoGo]

Get a gramil like this one. I made this to cut binding channels on my F- mandolins (standard,not violin style purfling). Just go around in few passes and it cuts cleanly and easily with this shape of blade. You can use two blades at once but t will be harder to cut and you will need to pick out the wood before going deeper. Cutting with ordinary knives or exacto's holding them near tip for greater control will certainly ruin your fingers after some time.

[Mik Kyklo]

19 hours ago, Gary Davis said:

 The problem I have is cutting the purling channel edges with knives and exacto knives.

other than a router??

There is no easy way to cut maple by hand without effort. That 's the reason we invented machines.

Every maker knows what you are talking about... If you want healthy hands for long and you want to make a lot of instruments I cannot think many ways.

You buy a rotary tool (and you can find it VERY cheap), you use a proper bit, a base that you can buy find again VERY cheap or make your own https://maestronet.com/forum/index.php?/topic/328668-my-new-home-made-dremel-purfling-router-tool/ and that's all. Some corners or edges you have to finish them by hand. 

You finish purfling chanel in less than 5 minutes (except corners). Once you try that - you never go back! If you look it from the capitalistic or marxistic point of view etc.> Time is money and effort is money too

 

If you do it by hand - there is one way to make is easier // go VERY SLOW, be patient and stop imediately when you feel tension.

Urstudien > Flesch > he wrote about how many violinists destroyed from constant tension and he proposed immediate breaks about 30-40 seconds, if I remember well, to restore the blood circulation. 

[Gary Davis]

Thanks all.   I tried "cutting" with the marking tool (Pfiel) on the front and was not able to keep it in the channel very well.  The suggestions for a custom shaped finger rest make sense and I'll pursue that.  I wish I had the nerve to try a router or Dremel but not to be at the moment.  Maybe I'll practice with a router before I get to the purling stage on the violin.

 

Gary Davis 

[Mark Norfleet]

3 hours ago, Gary Davis said:

I wish I had the nerve to try a router or Dremel but not to be at the moment.  Maybe I'll practice with a router before I get to the purling stage on the violin.

 

Gary Davis 

Cutting the channel with a Dremel works, but set-up and getting the cutter to work well can be a bit of a challenge.  Once you do get it working well it does require intense concentration to do the job right without telltale marks.  The good thing is that it's an easy thing to practice on scrap pieces.
Enjoy!

[Don Noon]

5 hours ago, Mik Kyklo said:

other than a router??

There is no easy way to cut maple by hand without effort. That 's the reason we invented machines.

Every maker knows what you are talking about... If you want healthy hands for long and you want to make a lot of instruments I cannot think many ways.

The only other non-machine method I can think of is hiring someone else to do it.

Come to think of it, my first method was not really a "router"... it was a mini milling machine.  But it was functionally set up as an overarm pin router, a more solid arrangement than a hand-held router.   My hands (wrists) were destroyed long before I started making violins, so hand-cutting purfling grooves has never been a viable option.

[David Burgess]

16 hours ago, Mark Norfleet said:

Two more suggestions…, spread out the wear and tear on your fingers over time, and get your knives as sharp as you can.  Very sharp tools make the work much easier!

Make it three…. Use a little old dried soap on your knifes, that helps too.

These are all great suggestions. A pro maker can easily suffer from overuse injuries. That's why I never (or no longer) do things which are highly stressful to a particular body part, two days in a row. The body does not get better and stronger without sufficient recovery and rebuilding time.

Fortunately, there are so many varied task in the making of a violin, that one can easily rotate without losing any time.

[Gary Davis]

Thanks gentlemen.  Can a drill press be set up as an overhead mill?  

[Mark Norfleet]

2 hours ago, Gary Davis said:

Thanks gentlemen.  Can a drill press be set up as an overhead mill?  

It can, but won't be the right tool for the job for many reasons.  There's likely to be too much play in the quill to do what you want to do accurately and also not have high enough RPM for the size cutter you'll need for the channels.

 

 

[nathan slobodkin]

I have used routers but prefer to do purfling by hand. Because it looks better with the more textured style of work which I prefer.
 

Mark gently with a purfling cutter to avoid having the blade follow the grain.  

Deepen the marked line firmly with a knife to establish the line leaning the knife so the outer edge is perpendicular to the surface of the plate.

Go over the line again pressing the tip of the knife as deep as it will go.

Switch to a knife with a THINNER profile and go over again to get to final depth.

The friction or resistance is from the sides of the knife compressing the wood. Assuming your knife is sharp you can cut full depth in three passes and then removing the waste. If needed you can remove half the waste leaving your original knife cut and then make one more pass with the slim bladed knife before removing the rest.
 

By the way, I have never found a use for exacto  knives in violin making.

 

[uncle duke]

48 minutes ago, nathan slobodkin said:

By the way, I have never found a use for exacto  knives in violin making.

I have, although I'm untrained.  The first mark for the e -string at the nut, some ff hole cutting, some bridge cleaning up and my corners of my plates - I'm near sighted so I may have an advantage with an exacto when not wearing spectacles - I can see real close.

But I'm through making violins though varnish making and playing them still pique my interest for some reason.

[Jluthier]

For me, the smaller the hand grip on a tool, the more it hurts my hands.  So, even though cutting a purfling groove is very find work, I like a knife with small sharp blade but a larger handle.  I use the method described by Nathan above.  

[Gary Davis]

Thanks for the continued advice.  I think I followed Nathan's procedure but probably 1) used a relatively dull knife and 2) used a knife blade that was too thick.  Consequently, I had to make more than three rounds with the knife.

I would be appreciative if folks would identify commercially available knives that get used in your shops.

 

Thanks much - Gary Davis

 

[nathan slobodkin]

6 hours ago, Gary Davis said:

Thanks for the continued advice.  I think I followed Nathan's procedure but probably 1) used a relatively dull knife and 2) used a knife blade that was too thick.  Consequently, I had to make more than three rounds with the knife.

I would be appreciative if folks would identify commercially available knives that get used in your shops.

 

Thanks much - Gary Davis

 

I use the gold colored knives which used to be available from GEWA. I think Howard Core still sells them.

[Gary Davis]

Thanks Nathan.

 

Anyone else have a knife of which they are proud?

 

Gary