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Cello endpin hole too large


violins88
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5 hours ago, violins88 said:

Inexpensive cello. The endpin hole is way too large. Can I put a coating of glue and sawdust on the inside of the hole? Then ream out? I can’t be the first to encounter this problem.

Never tried sawdust + glue. I can't say, but  I don't feel it would be strong enough.

For a very small gap I did one time a small sheet of wood with a plane Then roll it inside the hole, cutted and glued. Then reamed to the end pin dimension.

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18 hours ago, David A.T. said:

Never tried sawdust + glue. I can't say, but  I don't feel it would be strong enough.

For a very small gap I did one time a small sheet of wood with a plane Then roll it inside the hole, cutted and glued. Then reamed to the end pin dimension.

Don't you call that a spiral bushing?  :lol:  That's what I'd do, just like for an oversize peg hole.  :)

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11 hours ago, violins88 said:

@Mark Norfleet no, I don’t have an appropriate reamer. I plan to make one, but I won’t say how, because you are professionals and would cringe.

Actually, my friend is a machinist and might make me one. Yes, maybe it is a simple project for him. 

if the gap you have to fill is small (let say less than 1mm) and target to ream a spiral bushing (wood fine sheet) then you can put double face adhesive on your endpin, then put sandpaper all aroud it. it t takes time to do it properly (spirale sandpaper), but it is possible and that way you will be sure that it will perfectly fill your dimension.

that way your endpin becomes your reamer.

carefull measurement can make it possible. need to stop reaming little before due to sandpaper thickness

This way it is enough to ream a small  piece of wood like a wood sheet. But for sure not for a complete bushing pîece

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Holfter in Stolberg sells what he calls “Stachellochausbuchser-konisch” (in English roughly spike hole bushing- conical) which is a maple tube, about 4cm long with the reamer taper, which one can cut to length and glue in. I couldn’t find it online, but in the printed catalogue it’s on page 72 with the catalogue number 688020. Catalogue price €28,50

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A few nice things about making the bushing with a metal lathe, or purchasing the tapered tubes that Jacob mentioned, is the increased accuracy possible.  It's also very nice to be able to cut the inside diameter taper as close as you dare to the final need.  One has to allow for possible or known needed corrections though.  Apart from the time and wrist savings by doing it in the lathe before glueing it in, drilling a plugged endpin (or end button) hole in an instrument has always made me a bit nervous.

 

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8 hours ago, Mark Norfleet said:

A few nice things about making the bushing with a metal lathe, or purchasing the tapered tubes that Jacob mentioned, is the increased accuracy possible.  It's also very nice to be able to cut the inside diameter taper as close as you dare to the final need.  One has to allow for possible or known needed corrections though.  Apart from the time and wrist savings by doing it in the lathe before glueing it in, drilling a plugged endpin (or end button) hole in an instrument has always made me a bit nervous.

 

Why?

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39 minutes ago, nathan slobodkin said:

Why?

Why what Nathan?

Once an endpin hole is cleaned up with a reamer, cutting a plug to fit on a lathe designed for metal working is very quick and easy, as is removing the material from the center which would usually be removed by drilling and hand reaming.  I still wind up doing hand reaming to get the final size and pin direction, but it’s much less than I used to do.  After doing the inside and outside diameters of the bushing I remove it from the lathe, test fit and mark the level of insertion.  I then stick it back in the lathe and use a narrow cutoff tool to cut the length at the small end and through most, but not all of the bushing at the large end prior to gluing it in.  Once it’s glued, cutting through the rest with a hand saw and trimming it flush with a gouge is less work than if there were more material left as there tends to be if one puts a solid plug in.

I hope that answers your question!

That said, it’s probably not worth getting a lathe just to make bushings!  I do love having it for bushing peg holes though.  It’s soooo much faster and cleaner.

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Sorry Mark. Your last line was "drilling a plugged end pin hole in an instrument has always made me a bit nervous." Reading that and David's comment I am picturing some shared horror story which I have not yet experienced. I do see that being able to turn the inner diameter of the bushing would certainly save time and wear on one's wrist.

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No horror stories that I’ve experienced or witnessed, but I’ve always been concerned about drill bits catching and causing too much stress on the area being drilled, or in the case of a cello, flipping it.  It’s of course possible to sharpen bits such that this risk is minimized.  
The only endpin horror story I’ve heard, and you may know of this one, is of someone holding a cello upside down vertically to asses endpin alignment.  The pin was apparently in the socket backwards and not tightened.  When it slid out, it went through one of the upper bout ribs.  

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FWIW, I do these plugs on a wood lathe. 

Turn a piece of wood to some estimated taper, turn off the lathe and hold the reamer up in front of the workpiece blocking your view of the work to gauge the error, then turn the lathe back on and cut off what stuck out. Do this a couple of times making sure that the piece is straight-sided and you have a perfect match to the reamer. The error might be a couple of tenths over the length of the reamer, which is nothing, really. The whole thing takes me less than five minutes, probably.

But Mark's idea of pre-boring the hole has me thinking....

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2 hours ago, nathan slobodkin said:

Sorry Mark. Your last line was "drilling a plugged end pin hole in an instrument has always made me a bit nervous." Reading that and David's comment....

Dr. Ruth Westheimer could probably have answered bushing and drilling questions better than either Mark or I. ;)

One of her most famous quotes was, "“When it comes to sex, the most important six inches are the ones between the ears.” :)

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I still have not touched the inside of the endpin hole. I now see that it was originally cut at an angle, so that the spike slants toward the front of the cello, when extended. When the spike is retracted into the body, the other end it gets close to the back of the cello. Should the angle be changed?

 

 Thanks 

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