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Seth

Reed Dovetail Angle V Reed Pan Angle

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Posted (edited)

It seems the more I read the more confused I get about what the ideal angle in degrees the old style Lachenal and Wheatstone reed pan dovetails were cut as well as the reeds themselves.  I have read to match the angles

and also to make them a few degrees different so the reed fits tighter, I believe, or maybe it was so that it didn’t seat the edges all the way into the far edges of the dovetail slot in the pan?

 

I was measuring my Lachenal last night the best I could with an angle measuring device that’s way too big for the tiny dovetail but I did the best I could.  I kept getting around 10-13 degrees on the angle of the dovetail reedpan slot using my not so accurate measuring device.

 

I also read on a Makers blog that they made their  dovetail cutter with a 60 degree angle so I’m missing something here.  I think I’m going to take some firm clear plastic and draw the outline of the dovetail in various places and extend the lines with a ruler so I can blow it up and get a better measurement.  It seems that this information would be pretty well known and I’ve been looking.

 

Seth

 

 

Edited by Seth

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Posted (edited)

Is it not possible to take a photograph of the reed slot from the end of the pan, blow it up and  print that? You could also blow up the angle as you suggest.

Edited by Rod Pearce

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58 minutes ago, Rod Pearce said:

Is it not possible to take a photograph of the reed slot from the end of the pan, blow it up and  print that? You could also blow up the angle as you suggest.

That’s possible. I have angle finders but not that small.  What I’ve decided to do is draw several tiny thin cardboard templates in different angles and see which one matches best.  It almost seems like this is a trade secret.  I guess if onenis makkng their own reeds it doesn’t matter  if your not exact as you can adjust to fit.  I cut a parallel slot today in a piece of scrap wood with no dovetail and a Lachenal reed fit really snug and tight so I’m guessing any bit of dovetail as close as possible will be fine.

 

Seth

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Hi Seth,

 

I do not know what the angle is on the old concertinas, but I make mine 7 degrees.  I set on this angle by placing a Lachenal  B2 reed on its side and measuring the angle through filing a piece of wood until it was flush with it, approximating 7 degrees. This was ideal because Dremel produce very small 7 degree router bits, ideal, with some modification in reducing their diameter by grinding the bottom off, for the reed pan slots. Hope this helps.

 

David

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3 hours ago, David Hornett said:

Hi Seth,

 

I do not know what the angle is on the old concertinas, but I make mine 7 degrees.  I set on this angle by placing a Lachenal  B2 reed on its side and measuring the angle through filing a piece of wood until it was flush with it, approximating 7 degrees. This was ideal because Dremel produce very small 7 degree router bits, ideal, with some modification in reducing their diameter by grinding the bottom off, for the reed pan slots. Hope this helps.

 

David

Thanks David, that does help.  The router jig I got from Harold Herrington works great but I just need the proper bit now. I could probably try the Dremel one and make a collet for the router that came with the Herrington jig which takes 1/4” bits.  I’m also building a Dremel pantograph which might work for reed pans as well but it was intended for ends.  I’m mostly a Bagpipe maker but I’m interested in making mini and semi mini concertinas.

 

Started on a smaller square 30 button set.

A505CF80-60A5-484A-AFB7-D3B47A911B33.jpeg

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On 6/27/2019 at 1:46 PM, Seth said:

It seems the more I read the more confused I get about what the ideal angle in degrees the old style Lachenal and Wheatstone reed pan dovetails were cut as well as the reeds themselves.  I have read to match the angles

and also to make them a few degrees different so the reed fits tighter, I believe, or maybe it was so that it didn’t seat the edges all the way into the far edges of the dovetail slot in the pan?

 

I was measuring my Lachenal last night the best I could with an angle measuring device that’s way too big for the tiny dovetail but I did the best I could.  I kept getting around 10-13 degrees on the angle of the dovetail reedpan slot using my not so accurate measuring device.

 

I also read on a Makers blog that they made their  dovetail cutter with a 60 degree angle so I’m missing something here.  I think I’m going to take some firm clear plastic and draw the outline of the dovetail in various places and extend the lines with a ruler so I can blow it up and get a better measurement.  It seems that this information would be pretty well known and I’ve been looking.

 

Seth

 

 

I assume you mean you want to reed frame to fit tightly in the reed pan, which indeed is necessary, but I was recently reminded that it should be tight only at the ends. A tight fit in the middle of the length would squeeze the sides of the frame closer together. If the gaps between the edges of the reed and the frame are already extemely narrow, as they should be, squeezing the frame could foul the reed.

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Makes sense.  I’ve recently been told by makers that even CNC cut reeds , waterjet, mill, etc need filing and fitting work which make sense.

 

ive been told that the angle traditionally is 4 degrees but I’m reading more like 5 degrees on my jig I got from the late Anglo maker Herrington.  A Lachenal reed does fit nicely in the slots I’ve cut so I figured maybe I should cut them at 5 degrees and I can hand file a hair to fit them if needed.  Can’t add material so might be best to go a degree wider on the first batch and change it on the next if needed.

 

 

seth

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6 hours ago, Richard Mellish said:

squeezing the frame could foul the reed.

 

I once indeed experienced that.

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14 hours ago, Richard Mellish said:

I assume you mean you want to reed frame to fit tightly in the reed pan, which indeed is necessary, but I was recently reminded that it should be tight only at the ends. A tight fit in the middle of the length would squeeze the sides of the frame closer together. If the gaps between the edges of the reed and the frame are already extemely narrow, as they should be, squeezing the frame could foul the reed.

 

A common way to avoid that is by cutting the sides of the slot straight, and the sides of the frame slightly concave.

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Reading back through this thread, I think we may have been talking at cross purposes in our private messages. I thought you were asking about the angle of the dovetail cutter, not the taper of the slot. Reed frames are tapered in two directions, the top profile and the edge profile. With regards to the top profile I measured a vintage Lachenal to be 4° and have always stuck with that angle, including when I made replacement reeds for a Lachenal reed pan. I do make the frame sides a bit concave to avoid the pinching problem. Of course the angle of the slot should match the angle of the frame as closely as possible.

 

With regards to the edge profile (the 'bevel'), this varies more between makers. Vintage frames often have fairly rough bevels, perhaps because of the way they were formed in a press tool, and it isn't easy to measure the angle. For my frames I picked an angle of 5º off vertical (i.e. 85º). I have found through experience that reeds fit better and more reliably if the angle of the undercut of the slot is a little steeper than the bevel angle of the frame. I think what happens if you do this is the top edges of the slot act like slightly springy fingers that grip the frame and push it down against the bottom of the slot. Hopefully this rough sketch clears things up.

 

dovetail_sketch.jpg

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