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

[Vern <jevern@xxxxxxx>]

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.

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.

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
>> 
>