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Bee Stings Hurting

 
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violinmark
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Joined: 26 Mar 2007
Posts: 6
Location: Atkinson, New Hampshire, USA

PostPosted: Mon Mar 26, 2007 1:55 pm    Post subject: Bee Stings Hurting Reply with quote

Hi Everyone,
I rarely post questions but I do a lot of lurking. I hope this new site does well.

I am working on my first violin. I am presently trying to get the purfling bee stings/miters to match nicely. I have all the usual books (Wake , C&J etc). But I still feel that I do not have the full grasp of how to do this correctly. I have carved most of the corner recesses to the strad style (quite pointy). But I am having trouble getting the purfling to be correct. I am struggling with judging how much to take off the purfling and at what angle.

Does anybody have any practical real life lessons learned or step by steps on doing this?
Do you chop the purfling straight down? square or at slight angle?
Do you trim/shave the purfling from the side to get the miter?
How do you really judge where to make the cut? (mine seem to go from too much to too little in a breath.)
Do you stuff it/drive it tightly into the corner or should it sit in there easy?
Will wood purfling give me a better point than the fiber?
Have you ever tried sanding or filing to get the points?
Could there be an issue with the grooves being too wide or too narrow in the corners?

I realize some of these questions will need big answers. I figure it might be a good way to jump start a lot of conversation on this new board.

Working in microelectronics I am usually not lacking in fine skills but this is definately a time there is nothing like experience.

Thanks All. Your time is greatly appreciated.
Signed - Stung-a-few-times.
(3 ft of purfling in the can and still working on the 1st corner)
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shershey
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Joined: 26 Mar 2007
Posts: 28
Location: Dillsburg, PA

PostPosted: Mon Mar 26, 2007 3:03 pm    Post subject: Reply with quote

Practice, practice, practice!!! Where have you heard this before?

You're going to get a great deal of advice on this topic but, short of the above there really are no short cuts.

1. For starters, begin with a top plate. I always begin purfling w/ the "C" bouts. Get those in first. These pieces do not have the sting on them! Put them in the groove a little long then trim them back with a curved chisel to follow the outer groove when the glue dries. Hide Glue!!!

2. Mark the outer bout "sting" end with a pencil where it touches the inner "C" ones. Add the amount needed to do the sting. then.

3. Cut and fit, cut and fit. It's ok to slightly cut a little taper to the under side of the end of the sting. It is very important to also make sure that the grove has been properly cut and cleaned out to receive this thin piece of purfling "Sting" . It will require a little "sliding in" to the corner to get a nice fit. Once you are satisfied w/ the results, glue it in place.

Most times when this sting "goes wrong" it's due to a poor fit back at the point where the two pieces come together. If it don't fit there, your final "sting" will look bad or crooked.

As for wood vs. fiber. Wood will push in easier but, it's much harder to bend and work. You will be less frustrated if you start with the more flexible fiber.

When you get the tops done...the backs will really give you a run for your money because they need to fit perfectly from side to side. You can't stretch this stuff and if it's too short you will have to start the process over.

Now, read on because other makers may explain this much better than me.

Good luck and buy a bundle of this stuff. Scott.
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Michael Darnton
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Joined: 23 Mar 2007
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Location: Chicago

PostPosted: Mon Mar 26, 2007 3:16 pm    Post subject: Reply with quote

The way I do it is continue the outside cuts until they meet naturally, make the inside cuts, and take out all the wood between them to full depth. Then continue the outer bout outer cut 2mm beyond the natural point you've already established. At that point you have a continuous outer bout line and a c-bout line that dead-ends against it, 2mm from the end. Cut out almost but not all of the a little triangle of wood that keeps the c-bout line from being graceful and stops it from blending with the outer line from the outer bout, and that's it. Does that make sense?

Here's a corner with the edgework not finished.
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violinmark
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Joined: 26 Mar 2007
Posts: 6
Location: Atkinson, New Hampshire, USA

PostPosted: Mon Mar 26, 2007 5:21 pm    Post subject: Reply with quote

HA Scott, practice!!?? nah, I always get it perfect the first time just like my fiddle playing.(not) Until now everything has been fair.

I did cut the corners similar to the way Michael describes. From staring at the poster and courtnall book, it is kinda how I imagined it would be done based on the flow. Most of the corners came out looking reasonable. It wasn't easy to clear the wood all the way to the floor of the groove at the sting. And I did have the tip of some of the inside corners dissapear into the ether of space and time. And I definately wood-butchered one of them, reminds me of a 65 car pileup on the highway.

I am finding it difficult to cut the purfling at the correct angle for them to mate. I go from too much at the inside to too little. I have a real hard time getting the line of the miter to go from the very tip of the inside corner to the end of the stings. Is there a different way to line up these cuts than what the c&j books etc use?

The outside pointy end of the fiber purfling also gets ragged when cutting with a chop stroke. Is there some way of supporting it from the side (on a second cut to fine tune it)? If I lay it down on the side the point comes out clean but nothing else is right. Is this a 1 cut type of thing? Should I just try again ~3mm further back?

I have been using a straight chisel blade to scribe a mark on the purfling for the cut then removing to the bench for making the cut.

Oh, by the way, I can throw a piece of purfling 22.5 ft. I wonder what the world record is?

Thanks again for the replies.
Mark
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Michael Darnton
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Joined: 23 Mar 2007
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PostPosted: Mon Mar 26, 2007 6:13 pm    Post subject: Reply with quote

Well, first, notice that I didn't show you four of my corners.

Second, the cuts for the besting should be concave, not straight, to allow the purfling to collapse into the concavity and become concave on the outside with a straight joint.

Here's how I cut the purfling:
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violinmark
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Joined: 26 Mar 2007
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Location: Atkinson, New Hampshire, USA

PostPosted: Mon Mar 26, 2007 9:51 pm    Post subject: Reply with quote

AH!. So you are cutting the inside of the miter at a curve that matches the curve of the channel. Or is it somewhat compensated to account for the thickness of the purfling as it tapers to a point? That way when the end is pushed into place the curve is straightened out to a flat. This sounds like abstract thinking.
Are there any issues to be expected with the purfling coming apart or delaminated from the end being stressed?

And laying flat to shave the end to an edge instead of a top down chop is what my intuition was telling me to do but I was trying to make it a perfect flat.

I am just about out of purfling so I will either have to make some or order some and wait. I can already see that thinning the veneer could be a shattering experience. I have some birch veneer that is very flexible.
Now all I need is the time.

Is there anything else that I need to know? Besides having a few hundred matchings under my belt.
Thanks
Mark
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Michael Darnton
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PostPosted: Mon Mar 26, 2007 10:25 pm    Post subject: Reply with quote

"AH!. So you are cutting the inside of the miter at a curve that matches the curve of the channel. Or is it somewhat compensated to account for the thickness of the purfling as it tapers to a point? That way when the end is pushed into place the curve is straightened out to a flat. This sounds like abstract thinking. "

Uh, now you're thinking harder than I am. But yes, the first sentence you write does sum it up.
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moronsreign
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Joined: 26 Mar 2007
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Location: Idaho

PostPosted: Mon Mar 26, 2007 10:58 pm    Post subject: stings Reply with quote

One consideration regarding fiber purfle- I personally prefer wood. Fiber tends to be tricky in cutting and cleaning out the channel. You need RAZOR sharp edges to cut it cleanly and it doesn't seem to scrape as smoothly.Also, in pushing the points into the corners, the wood seems to hold it's shape better, especially if it gets wet with glue.
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violinmark
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Joined: 26 Mar 2007
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Location: Atkinson, New Hampshire, USA

PostPosted: Tue Mar 27, 2007 10:08 am    Post subject: Reply with quote

Thanks MR, I have not tried wood purfling yet. But I have found the fiber ends easy to squash in the corner.
Sharpening the business end of a tool to a razors+ edge is usually not a problem, it is the other end of the tool that usually isn't too sharp. Shocked

I haven't had to scrape the purfling to get it into the channel. But I can see from cutting it that it does have a tendancy to get ragged if it is not supported when cutting. Also -- I shimmed the bearing on my dremel tool so it has less slop when cutting the channel.

Thanks
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JWH
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Joined: 26 Mar 2007
Posts: 72

PostPosted: Tue Mar 27, 2007 4:04 pm    Post subject: Reply with quote

Michael:

Could you elaborate somewhat about what has been discussed on another forum concerning the placement of the purfling in the channel at the mitre joint after a finished cut has been achieved, and then leaving in place, while glue is applied to the channel anterior to that point and under the raised purfling. Are there tricks to that technique and are there pictures worth showing of that procedure? If I read things correctly, it's been said that glue upon compression from beneath the raised portion of the purfling should migrate outward to the end of the sting. It would seem, in my mind, to migrate in the opposite direction away from a point already seated, especially getting it to the end of the sting.. Maybe, I am not visualizing properly, but a picture or two would help.
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violinmark
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Joined: 26 Mar 2007
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Location: Atkinson, New Hampshire, USA

PostPosted: Mon Apr 09, 2007 9:06 am    Post subject: Reply with quote

Whew,
My first 8 corners cut and inlaid in place. Glueing in the purfling is next.
This was a very intense effort that took me about 6 hours to complete. I had to come to the realization that my corners were cut with too much space on the inside of the corner. So I have some gaps that I will have to fill. Next time will be better.
Instead of laying the purfling on the bench to trim the miter, I found holding it against my thumb gave me better sensitivity to shaving ultra thin pieces from the miter. (with much care not to cut myself) This was definately an iterative process of remove-shave-insert and repeat. I can see how after doing a bunch, you can get an "eye" for how the end should look.
A piece of advice that a local maker gave me was that sometimes you just have to "stuff" or jam the points into the corner to get the gaps to close and blend in well with how the corner is cut. This worked out very well for me. Another thing that I picked up while doing these corners, is to trim down the thickness of the purfling a little bit just at the last fitting of the corner. This helps get rid of any material that could be interfering with the miter fit that would be trimmed off later anyway. A 10x manifying glass helps also.
Thanks
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