Re: [Harp-L] Reed slot needs to be shortened

[joe leone <3n037@xxxxxxxxxxx>]

On Oct 30, 2010, at 1:31 AM, Vern wrote:

> If it were me, I would try the following:
>
> - Make a brass slug the size of the slot and a tad thicker than the  
> plate, maybe .050".
> - Place it in the slot.
> - Carefully hammer it to expand it in the slot.
> - File it even with the surfaces of the plate.
> - Take it back to the EDM for a re-do.

     The only reason I didn't suggest this was because I assumed  
that there would be a reed already IN the slot...and working around  
it this much would be ticklish. With my method the reed could be held  
high enough out of the way with a straight pin to allow the filing  
work. And I agree, the file should have no teeth on the sides.
     Another idea is to drill an overlap hole at the end of the slot  
and tap to receive a brass screw. Screw is then cutoff flush top and  
bottom and then filed with a square file the same width as the slot,  
(again..no teeth on the sides). You wind up with a 'Pac Man' with a  
square mouth. Resembles a 'circlip'.
> Machinists have been fixing holes this way since rainbows were in  
> black and white.  This just happens to be a rectangular hole  
> instead of a round one.
>
> If the above isn't practical, then you could try the following.
>
> - Coat the plate with parting compound and fill the slot with metal- 
> filled epoxy such as JB Weld.
> - When set, file the epoxy even with the surfaces of the plate.
> - Remove the epoxy slug from the slot.
> - Shorten the slug to the desired slot length.
> - Coat the slug with parting compound and clean the plate.
> - Insert the slug back in the slot.
> - Fill the excess length with epoxy.
> - Remove the slug.

     Yes, this is excellent for extreme cases.
> Epoxy doesn't shrink as it sets up and will replicate every tiny  
> detail of the mold.  Once JB Weld has set up, it can be worked  
> almost like metal.
>
> You should be left with a slot of the desired length.  The longer  
> slug should be fairly easy to file to the desired slot length and  
> check with a micrometer.  It will be ticklish business but it might  
> work.  I have never done it myself so there could be unforeseen  
> problems.
>
> If you use a method that requires filing in the slot, I would cut  
> down a jeweler's file to .080" wide with no teeth on the sides.   
> This could be done on the EDM whose operator owes you the favor in  
> exchange for the boo-boo on the slot.    ;o)
>
> Vern
>
> > On Oct 29, 2010, at 10:56 PM, Doug H wrote:
> >
> > > I got back some custom made reed plates from my EDM guy only to  
> > > find that one of the slots was mis-cut a about .045" too long  
> > > (in .040" thick brass - slots are .0835 wide).  I recall a  
> > > discussion here a while ago about how to shorten a slot.  I  
> > > believe epoxy and/or solder were mentioned. My plan would be to  
> > > try and gracefully place a gob of epoxy or solder in the end of  
> > > the slot and then file it into shape.  Or should I try and make a  
> > > little plug of brass and then solder that into place?  (I have  
> > > lots of brass scraps.)
> > >
> > > I have 8 of these to fix so it is worth doing a bit of research  
> > > first.  All advice or suggestions will be appreciated.
> > >
> > > Doug H