Shoe pegs or epoxy to fill bridge holes

[Farrell]

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Hello Dale,

I use West System epoxy in quite a few applications, but I must admit, =
not many where I am drilling repetitive holes through a significant =
thickness of cured epoxy. However, I am aware of the gumming potential =
that you speak of. My pinblocks that I make are epoxied together with =
West System epoxy, but the "glue"/epoxy lines are relatively thin so I =
don't experience gumming action. Are you applying unthickened epoxy to =
the holes? I would highly recommend thickening up your mixture with #404 =
High-Density filler. From the West System web site:

404 High-Density Filler
404 High-Density filler is a thickening additive developed for maximum =
physical properties in hardware bonding where high-cyclic loads are =
anticipated. It can also be used for filleting and gap filling where =
maximum strength is necessary.=20

Generally speaking, with use of any of their fillers, you will end up =
with less resin and hence less gumming action. However, the thicker the =
mix is, the more difficult it will be to get epoxy into all those little =
holes - but maybe running a squeegee up and down the bridge root top a =
few times will work it in good enough - perhaps worth a try. Beyond that =
comes Joe's idea of shoving a piece of hard wood into the hole after the =
hole has been partially filled with thickened epoxy. I think that when =
most folks take this approach, they are thinking "gluing wood =3D need =
tight fit". But with epoxy, this is not the case - a loose fit is =
better. If you can find a source for small hardwood dowels that will go =
into the holes without drilling, that would save time. The reason for =
shoving small dowels into the holes is perhaps less for filling the =
holes, although obviously it plays that role also, but rather to simply =
drag the epoxy down into the hole. If you used dowel lengths slightly =
less that the hole depth, the potential exists to still make all this a =
one-step operation - you could epoxy bridge cap on at the same time. But =
then you would be working with 500 or so itty-bitty little pieces of =
wood - hmmmm, maybe not all that bright an idea.

Even more crazy ideas might include running a small router bit down the =
bridge root top to route out a ditch that would go through the bridge =
pin hole field. That would certainly make getting the thickened epoxy in =
there nice and easy. You would definitely want to be sure though that =
the thickened epoxy wouldn't gum up your hot drill bit because you'd be =
hitting it in every new bridge pin hole.

Or, do like Andre does and just route the root down to a point below the =
old bridge pin holes.

Do you have a web site Dale?

Terry Farrell

> Dale,
> I usually use 1/8" maple dowel. It's easy to cut with my shank =
nippers. of
> course this gives you an extra step of drilling with an 1/8" bit, so =
you
> have a good fit for the dowel. Actually, it doesn't take much time to =
do
> this step, as you're not interested in "accuracy", but just to size =
the
> holes. I've had the same problem with filling the voids with epoxy, in =
the
> "pre-capping operation.
> Best Regards,
> Joe Garrett, RPT,
     List
      For years we have used shoe pegs to fill the remaining portion of =
the bridge pin holes after the caps are taken off in preparation for new =
caps. I had a good system using shoe pegs and the Bolduc wood glue to =
secure them. The glue doesn't gum up in  the bit as does most other =
glues I've tried & with this simple system I can usually drill a set of =
bridges painlessly in about an hour or so.

      The problem is that no one in the shop enjoys pounding square pegs =
in round hole except my wife Trix & she's often to busy stringing =
etc.......  Also the pegs are getting hard to find in quantity. Any way =
I recently tried the West systems epoxy treatment squeezing it into the =
holes. Relatively quick & painless except for the guk/sticky factor.  =
Ater this I immediately glue on the caps also with epoxy.
    After it cured for about 5 days I drilled for the new pin holes but =
the residual epoxy seems to powder up or alternately stick to the bit. I =
find this characteristic unacceptable.  Then every other hole or so I =
must run the bit thru some thin scrap spruce to clean the bit the drill =
again & over & over etc. Tedious useless activity.
    I'd be interested in someone else's technique who has more =
experience with epoxy in this application. I like the idea of epoxies =
hardness and all that but I do a fair amount of bridge work & can't =
handle the aggravation. What am I missing?

    Dale Erwin
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