with_joerg

How to make decent edges

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I followed an internet instruction that did not have any explanation as to how to create decent edges. After following it I now arrived at rather flat edges w 3.6mm edge thickness. How would I go best further from here to make the edge (I mean all around thge back plate) at least half way decent?

I usually avoid to attach photos. But think I cannot avoid it here. I am a newby in this and it is not my intention to compete w craftsmanship and people who have done this half their lives.

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We have a resident Luthier here , Davide Sora. Davide has some instructional videos on Utube that goes over his approach to edge work. They are most excellent for visual help with this task.

an example

 

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50 minutes ago, Thomas Coleman said:

If your edge thickness is 3.6mm I think your only option is to round the edge both topside and bottom side to make what is called a "bull nose"

bullnose-edge.20470817_large.jpg

Just remeasured. It is 4.1 mostly. Have never seen a violin w a Bullnose. Is that a type/design that you can buy in a shop also?

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Forget about the bull nose for now..... at 4.1 you have just enough to mark the crest ,we’re the purfling channel meat the round outer edge,47E5C49A-45A5-4A51-AF6C-A1482ADAE571.thumb.jpeg.e96c1161dc3e0956a759bc528a94c89d.jpegabout one third the distance from edge to purfling, then run a shallow channel ,cutting the purfling down. If you need more thickness ,thin shavings can be glued under the plate to the rib side. After all this rounding the edge up to the scribed channel line and underside.

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Like James says above.  If your edge is 4.1 and not 3.6 you probably have just enough wood to make a traditional looking edge.  A bullnose is not a design you can buy in a shop but it is what you would maybe have to do if your edge was already too thin.

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26 minutes ago, James M. Jones said:

Forget about the bull nose for now..... at 4.1 you have just enough to mark the crest ,we’re the purfling channel meat the round outer edge,47E5C49A-45A5-4A51-AF6C-A1482ADAE571.thumb.jpeg.e96c1161dc3e0956a759bc528a94c89d.jpegabout one third the distance from edge to purfling, then run a shallow channel ,cutting the purfling down. If you need more thickness ,thin shavings can be glued under the plate to the rib side. After all this rounding the edge up to the scribed channel line and underside.

How far/thin should it then become at the deepest point of the groove?

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it depends on the density of your wood but the thickness at the deepest part of the channel should not go below 3.1mm  or so.  I had only recommended the bullnose because I thought your edge was already too thin.  Since it's marginal I would take Jezzupe's advice and really look at Davides video.  He has translations in the comments section.  very very worth your time.

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Some good advice here.

One thing I would reccomend though is that all respect to Davide Sora I think his approach to purfling is way too tentative. Every time you stop the tools when marking or cutting  purfling grooves is another chance for a deviation or change in width of the groove. While Davide has the skill to get good results working the way he does for myself I only lift the marker or the knife from the cut at the points where the grain direction switches and other wise make one smooth cut without stopping or lifting the tool.

As for how thick the plate should be at the lowest point of the channel this changes according to the arch and style of the model. You have to think in terms of both how high the "crest" of the edge is above the purfling as well as where  the lowest point of the edge/arching actually occurs. On some models the low point will be at the purfling while on others it may be considerably further in.

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17 hours ago, James M. Jones said:

That,s a matter of conjecture, 3.5 mm would not be to thin and would give some room on the inside for fairing the curve into the graduations

What would be the best way forward for me? Using scrapers or follow the Hargrave-procedure?

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Rodgers method is designed around an edge that is about4.75 mm thick that then gets channeled , given your thickness I would have a tendency to just mark for the crest and work towards that line, a gouge would be the best tool under the big tool to small tool president. As Nathen pointed out a lot of edges simply run out without much rise to the crest if any, not much to get uptight over ...do your best ...make another.

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On 3/6/2018 at 6:19 PM, with_joerg said:

I followed an internet instruction that did not have any explanation as to how to create decent edges. After following it I now arrived at rather flat edges w 3.6mm edge thickness. How would I go best further from here to make the edge (I mean all around thge back plate) at least half way decent?

I

Double the edges. 

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28 minutes ago, with_joerg said:

??? Don't understand.

Best would then be to ask some of the luminaries giving advice here.  Pretty straight forward thing and definitely slightly easier than the seminal bullnose idea. 

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1 hour ago, with_joerg said:

??? Don't understand.

To Double an edge is to add a layer of wood,to the rib side of the plate,as was suggested earlier, adds thickness,works well.again judging by that 4.1 mm thickness should be no real need for doubling.

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From a post in 2010

On 06/09/2010 at 2:23 PM, PeSt said:

Exactly. and this U channel isn't part of the edge fluting aftel all is done as can be seen at Roger Hargrave's steps:

Roger.jpg

The starting point is a flat platform along the edge which is blended into the finished arching and steps 1 to 9 are done after the plates are glued to the ribs.

As mentioned in my previous post, the thicknessing along the edge becomes a bit of a guess work and the purfling channel would need to be very deep. I therefore do steps 4 and 5 before step 2 and before the plate is glued to the ribs.

So here is my flow, with steps 1 to 3 completed on the loose plate and steps 4 to 7 after the plate is glued to the ribs, whereby step 6 and 7 could be done at the same time.

steps.jpg

Nicolas, this may look more complicated as it actually is and the advantages I see are:

- Plate overhang can be finetuned after plates are glued to ribs, giving a more consistent result.

- Purfling groove is cut after plate edge is finalized and purfling to edge distance is more consistent.

- Blending of edge fluting into edgework is done at the very end, reducing the possibility of damaging the ridge along the edge.

- Purfling goes across pin.

Well, in theory anyway.

Cheers, Peter

 

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Hi With_Joerg

 

I was taught to always read the question three times and make sure that I understood it before attempting to write an answer.

 

You have a plate in your hands. The edge is square and exactly matched to your template. The purfling is in.

 

1.0 Take a file and file a 45 degree chamfer on the bottom edge. The flat of the chamfer to be about 1.2mm. Go slowly when filing the corner edges - try and keep the chamfer equal.

- you must do the bottom chamfer before you glue the plate to the ribs.

2.0 Work the top edge to your final thicknesses.

3.0 Scribe a pencil line mid-way between the outer edge of the purfling and the edge.

3.1 Using an 8mm gouge you cut your the channel in one continuous sweep.  Concentrate on keeping the deepest part of the cut centred on the purfling and the outer edge of the cut on the pencil line.

4.0 File a chamfer on the top edge of the plate. (see 1.0)

5.0 Now chamfer the edges of the chamfers (about 0.5 - 0.6mm flats)  - (I use a fine emery board that my wife uses for her finger nails). Take care not to scratch the ribs - or file away the sharp edge left by the gouge. Your edge is now almost rounded - made up of 7 flats - all less than a mm.

6.0 It now takes very, very little work to round off the edges of the edges of the chamfers into a smooth bullnose. I double over a small piece of 360 grit waterpaper and use a light touch..

7.0 Use a scraper to blend the inner edge of the gouged channel to the arching.

I suggest that you practise this on a piece of scrap off-cut-of-plate. Prepare the edge, carve some arching, draw in some purfling,, add the pencil line etc

Sit back and admire.

cheers edi

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4.1 mm is absolutely plenty to make your edges. I start mine about 4.3. I used to start closer to five, but reduced that because didn't want quite such a deep and abrupt scoop.

Lots of very nice violins have edges that measure about a strong 3mm thick, finished, with a little more in the corners. 

I would suggest you use Roger's method, but scoop out to about  1mm from the edge rather than all the way, finish the scoop, and then roll the edge to wherever you want the peak to be. Doing it this way, you'll find it very much easier to make an even edge.

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