Punch Set Transfer Punches
Last fall I met Tom “TK” Kelly when he brought an old Martin 00-17 in for advice on what he should sell it for at our local Blue Eagle Music. I showed him around the shop, and when we went downstairs where I had two mills and a lathe, he told me that for 35 years his hobby has been machining and that he quit doing it 5 years ago and had a lot of stuff for sale. Long story short I ended up buying his ’39 SouthBend lathe, a great ’59 Rockwell variable-speed, reversible drill-press, an Arboga mill that is quite unique, and a great number of tools and accessories to go with them*. To make room for the new tools, I sold my 10-inch Jet lathe and my Smithy LX-29 mill to my shop-mate Blake Burkholder.
TK retired 5 years ago as an occupation therapist, but before that, in his late teens and early 20’s he repaired guitars at Goose Acres Music in Cleveland Ohio. We became instant friends, and soon TK was back working on guitars again with me in my shop, re-kindling his love of machine work, and really enjoying being back in the guitar-fixing’ world. Along with the tools I bought from him was a set of transfer punches – something I’ve never owned, nor did I realize how great they are to have in the shop. Here’s the first job I used them for.
I had a much-repaired Gibson Heritage model in the shop; it’s bridge had been off and re-glued at least once, and the bridge was split so badly through the bridge pin holes that trying to fill the splits didn’t seem worth it. Plus I didn’t want to remove it and make a new bridge, because I had no idea what I would find underneath it. The guitar really needed a neck re-set because the action was so high, and the bridge had been shaved down so that the saddle could be lowered. Also someone had already filled in the large slot where an adjustable ceramic bridge had been with ebony. My fix was unique, and a last-ditch effort for an affordable and workable bridge, and action. I didn’t start taking photos until I was into the job and realized that some photos might be good for The Looth Group.
001) What you are looking at is the bridge after I had removed the two machine screws installed by Gibson, and routed off the back 1/3rd of the bridge to create a ledge that I then filled with a slab of ebony (with pre-drilled pin holes so that I wouldn’t have to spend a great amount of time trying determine where I should drill the new holes).
002) I epoxied this new piece on using the clamp setup you see here.
Something that I also didn’t get photos of, and another problem for this job was that whoever re-glued the bridge had drilled overly-large holes through it and right through the bridge plate, causing the string ball-ends to pull up into the bridge pad and spruce top; and the string-winds to come up on to the saddle.
003) So, I made a small reinforcing plate from Katalox (a very hard and dense wood) that fit in between the machine screws inside and the large anchors in the bridge pad from the original large adjustable saddle. I dry-clamped this inside to the plywood bridge plate so that I could accurately locate the center of the holes and pre-drill them before gluing the plate in (to eliminate the chance of the drilled holes punching out from the drill-bit). That’s where the transfer punch came in; rather than try to pencil the center down through the pin hole, or use a twist drill-bit the size of the the hole to start it, the punch makes the perfect punch mark for the drill-bit to center on when the piece is clamped into the drill-press table.
004) Perfect little punch holes . . .
005) . . . that were easy to center on when drilling with the piece double-stick taped down.
006) I used the StewMac brass “Acoustic Bridge Bolts”, upside down, to locate and help glue on the reinforcement piece after waxing them so they wouldn’t stick to the bridge pad and bridge . . . .
007) . . . then added two bridge clamps in the center.
008 & 009) That solved the bridge pad problem.
I bought a cheap set from harbor freight and they have been worth their weight in gold. Especially big fan of using them for accurately lining up a hole to my drill press chuck and for installing or drilling out plugged holes.
Installing a new neck or drilling out plugged neck bolt holes*
Thanks for sharing about these Dan.
I learned about using transfer punches when I was a shock and vibration Missile test engineer. We frequently had to modify vibration test fixtures and these allowed us to mark holes precisely on the test site in precision milled 6061-T6 plate rather than send things back to the machine shop.(we had to use the magnetic drill presses to bore the holes and put the aluminum on top of steel.
I should mention -You can also get individual transfer punches from McMaster-carr. I got a wire gauge “G” size transfer punch to use with my StewMac slotted head tuner installation jig, if I use Gotoh open gear tuning machines the drill I need is a metric drill. and then I align on the center with a metric Brad point but and I use one of the Big Gator Drill guides as appropriate.
https://biggatortools.com/shop/ols/categories/drill-guides
https://biggatortools.com/shop/ols/categories/drill-guides