My new home made Dremel purfling router tool

[Joe Swenson]

I used the StewMac version of the Dremel Purfling tool for my first violin.

 

http://www.stewmac.com/shop/Tools/Special_tools_for_Routing/Purfling_Soundhole_Router_Guide.html

 

However it is a little bulky and long to make the sharp curves in the upper points of the C-Bout.  I saw Michael Darnton's hand held router adapter,

 

http://darntonviolins.com/purflingmachine.php

 

and decided I might not be steady enough at this point to wield such a tool.. So I came up with a cross between Michael's tool and the StewMac tool.  I used the hand held Dremel Flex Shaft extension which has a business end which is a lot lighter and smaller and easy to handle.  

 

 

The router guide tool I made is  small enough for the sharp violin corners and has the nice depth stop the Michael employs, to keep the bit from going to deep on the points where the plates are thicker.  The StewMac version which stays flat on the table, does not use this and so the bit goes too deep on the corners and so when you install the purfling, it goes below the surface at the points.

 

I set the depth stop at 4.1 mm from the table the router bit extends 1.6 mm beyond that.  My plates are typically about 4.0-4.2 mm thick around the bouts at the purfling surface and taper up to 1 mm thicker at the points so this gives me a good channel depth for the 1.8 mm thick purfling I have. 

 

The distance in from the edge puts the closest edge of the channel 3.3 mm and the center of the 1.2 mm wide purfling 4 mm from the plate edge.

 

Ready to cut the channels.  Already did a nice test cut on some repair spruce and its pretty easy to use.  Happy 

 

Joe

[saintjohnbarleycorn]

very nice , do you move the wood or the tool for the cut or both?

[DBurns]

Very nice modification.

I wonder if the manufacteur of the original would be interested in this, since it seems to be better suited to violin making.

Thanks for the post.

[Joe Swenson]

very nice , do you move the wood or the tool for the cut or both?

 

Thanks! I move typically both. starting at the point moving counter clockwise around the plate which keeps the bit pulling into the piece. I made the mistake of going clockwise once and the tool drifted towards the edge making a mess if the channel.  It was the maple back on my 1st violin. It was easy to fix with a little wood filler.  Can't tell now there was ever a problem. 

 

Very nice modification.

I wonder if the manufacteur of the original would be interested in this, since it seems to be better suited to violin making.

Thanks for the post.

 

Thanks! The original tool was made with guitar makers in mind for putting the channel around a guitar sound hole.  I think they just started marketing it on StewMac.com for violin making just like they did the Ibex Purfling Cutter tool for which the dual blade thickness is completely inappropriate for violin purfling channel, yet they sell it as that.  

 

I initially thought I would leave the top adjustable on my tool, drilling a slightly oversized hole so it would be useful for a larger viola setup.  But I got the distance right when I put it together so for now I'm just going to leave it all glued at the fixed position. I'll just make another for viola work next time I start a viola project. 

 

Nice thing is the thread on the Dremel Flex Extension tool is fine thread 1/2"-28 so it was easy to find a tap to thread the oak top plate.

 

Cheers,

Joe

[tango]

Hi

Nice tool joseph.

¿Could you write me the size of the router bit? 1,2 mm may be?

Thanks

Tango

[Joe Swenson]

Hi

Nice tool joseph.

¿Could you write me the size of the router bit? 1,2 mm may be?

Thanks

Tango

 

I used .050" router bits = 1.27 mm.  The first batch I bought were a little odd with small cutting teeth that tended to overheat in the maple.  I went through a couple of these on my first violin.  

 

I bought another set of 10 x .050" bits off Ebay with much better cutting flutes which work great for the 1.2 mm fiber purfling I used.  If you need a 0.1 mm wider channel then a second pass works since the tool pulls away from the edge stop while routing CCW.  Back tracking over the channel widens it just enough for wider 1.3 mm wood purfling I used on my viola.

 

You can see how the bit with the teeth got hot and burned the maple test piece. The spiral fluted bit cuts through like butter.

 

[Bill Yacey]

I think that right hand cutter is a burr for home dentistry.   I remember that there was a big marketing push over up-cut and down-cut spiral bits. Personally, I never found much difference. If there's a little bit of a whisker left behind, it gets removed after the purfling is installed and scraped.

[tango]

Thanks Joseph

 

Very important the teeth issue

 

Regards

Tango

[Oded Kishony]

Has anyone tried one of these Chinese purfling tools?

 

Oded

[Joe Swenson]

Has anyone tried one of these Chinese purfling tools?

 

Oded

 

Hmmm. The metal purfling guide looks like it might be smaller than the StewMac model.  Plus it has a beefy depth stop. The rotary tool looks even bulkier than a Dremel. 

[Joe Swenson]

Getting ready to cut the purfling channels, I relalized I needed to make one more modification to my Oak purfling guide tool.  

 

 

I decided to remove unnecessary width from the front of the guide so I can finish more of the channel on either side of the back button.  This cuts down the amount of hand carving by almost 2/3 I will have to do - which I am getting better at, but is completely unsatisfactory at this point.  

 

I'm still working on how to do the complete channel across the button area with the Dremel tool.  

 

I'm thinking the original StewMac purfling guide tool could be set to extended to reach from the end of the button to where the purfling channels stop on either side of the button.  You just have to cut the end of the button at an arc paralleling the purfling channel. Add a little wood on each side of the end of the button and you could completely finish the slot.  This just needs carefull adjustment so the router bit slides into the center of the exsiting channel so it doesn't create a wide spot.  

 

 

I believe I will try this. 

 

Joe

[Oded Kishony]

Hmmm. The metal purfling guide looks like it might be smaller than the StewMac model.  Plus it has a beefy depth stop. The rotary tool looks even bulkier than a Dremel. 

 

It's rated at 220V but I wonder if it would run at 110V?

 

Oded

[Joe Swenson]

It's rated at 220V but I wonder if it would run at 110V?

 

Oded

 

Here's a better view of the Chinese purfling grove cutter guide without the Rotary tool for $35

 

http://www.ebay.com/itm/Violin-Luthier-Tool-Purfling-Groove-Cutter-Adjustable-Stand-For-Violin-Cello-/281076884204?pt=LH_DefaultDomain_0&hash=item41717ce2ec

 

With three screws sticking out of the bottom, it has no flat surface to set on the bench.  Which is a problem as it looks quite heavy to me.  Depth stop foot looks a little imposing and would tend to obscure the tool contact area with the plate.  You want to have a good clear unobstructed view especially when approaching the points.

 

Thread looks similar to the Dremel... so maybe they're interchangeable?

 

Joe

[Peter K-G]

Joe, It's also easy to do this with a drillpress and a plugg attached to the table as support for the plate edge. It's very accurate, I have seen it work perfectly. I don't want to do that because I want to master the technique the old fashion way.

[Oded Kishony]

Here's a better view of the Chinese purfling grove cutter guide without the Rotary tool for $35

 

http://www.ebay.com/itm/Violin-Luthier-Tool-Purfling-Groove-Cutter-Adjustable-Stand-For-Violin-Cello-/281076884204?pt=LH_DefaultDomain_0&hash=item41717ce2ec

 

With three screws sticking out of the bottom, it has no flat surface to set on the bench.  Which is a problem as it looks quite heavy to me.  Depth stop foot looks a little imposing and would tend to obscure the tool contact area with the plate.  You want to have a good clear unobstructed view especially when approaching the points.

 

Thread looks similar to the Dremel... so maybe they're interchangeable?

 

Joe

 

 

 

The guide pictured is designed to ride on top of the plate not on a flat surface, which is how I prefer to do it since I purfle the assembled instrument.

 

Oded

[Joe Swenson]

The guide pictured is designed to ride on top of the plate not on a flat surface, which is how I prefer to do it since I purfle the assembled instrument.

 

Oded

 

Right I get that. It just seems quite awkward and bulky to support the plate perpendicular to the tool axis, getting smooth turns while maintaining the proper alignment.  It scares me.  

 

I have a hard enough time holding the tool flat on my work surface maintaining a nice smooth motion feeding and turning the plate with one hand and rotating the tool to keep it on the tangent and tight to the edge with the other. 

 

I've sort of figured out a way that works for me but I'd love to see how its done but others with tons more experience than me.

 

Joe

[Joe Swenson]

Joe, It's also easy to do this with a drillpress and a plugg attached to the table as support for the plate edge. It's very accurate, I have seen it work perfectly. I don't want to do that because I want to master the technique the old fashion way.

 

So on the drill press its all plate motion?  Seems like the vertical column of the drill press would interfere with getting to the points.  I know it can when using the drum sander to clean up the inside of the C-bouts.

 

I'd love to learn the "old fashioned" way as well.  But routing is soooooo much easier and cleaner (for me at this point). 

 

Joe

[Bill Yacey]

Getting ready to cut the purfling channels, I relalized I needed to make one more modification to my Oak purfling guide tool.  

 

_MG_7911.jpg_MG_7912.jpg

 

I decided to remove unnecessary width from the front of the guide so I can finish more of the channel on either side of the back button.  This cuts down the amount of hand carving by almost 2/3 I will have to do - which I am getting better at, but is completely unsatisfactory at this point.  

 

I'm still working on how to do the complete channel across the button area with the Dremel tool.  

 

 

 

Joe

I did the same thing on my jig to allow better access in the corners. I wouldn't bother spending a whole lot of time developing jigs to complete the groove around the button. It doesn't take long to complete the groove by hand for this short distance.

[Don Noon]

It's rated at 220V but I wonder if it would run at 110V?

Most likely yes... but at half speed and half the torque capability (1/4 power)

 

I wouldn't bother spending a whole lot of time developing jigs to complete the groove around the button. It doesn't take long to complete the groove by hand for this short distance.

For me, anything I can do to reduce wrist stress is worth it, so I make the jigs.  Cutting grooves "the old-fashioned way" is not an option.

[Bill Yacey]

I'm still alright for now in that respect, but I can fully understand why you would go the template route when you're experiencing physical ailments.

[Joe Swenson]

I did the same thing on my jig to allow better access in the corners. I wouldn't bother spending a whole lot of time developing jigs to complete the groove around the button. It doesn't take long to complete the groove by hand for this short distance.

 

Yeah I spent 30 minutes pondering the situation, arching the end of the button, practicing the tool motion needed to maintain channel alignment, and convinced myself it was too risky.  

 

I ended up cutting it manually as you suggested.  It didn't take long and wasn't too ugly when I got done.  It was my third attempt and the best I've done so far.  Bit the channel was still too wide so I needed to fill the gap with wood putty.  But I have no one to blame as I used an improper knife. I need to take the blades out of the Ibex purfling cutter and make a handle for hand cutting this part of the channel.  

 

 

So the purfling is done now on the violin #2 and viola #1. All dry fit.  Now just need to glue in the strips tomorrow.

 

Cheers,

Joe