Scary Repairs: Two Pedullas With Broken Truss Rods

[Bruce Johnson]

I'll be updating this thread soon. We have started working a little bit on the two Pedullas. Unfortunately, I've got some big distractions right now that are disrupting my schedule and my brain. You may have seen on the Secret Underground Lab thread that my long time friend and fellow Luthier Mike Lipe died last week. I'm quite literally cleaning out his shop (right down the hall from mine) and helping his estate sort it all out. This is going to take up a lot of my time over the next few weeks. But, I've got to do it.

Alex and I will get back on the two Pedullas soon. Quick notes:

On Inara's, we tried valiantly and were unable to get the fingerboard to come loose by heat. Wouldn't budge. So, we've made the decision to get out the fixtures and rout it off. It'll get a new ebony fingerboard.

Mike's is a different situation. As he noted above, the truss rod isn't broken, the square end is just rounded off. I've looked it over, and I think I can machine up a small steel cap that will fit over the end, and pin it to the rod. If it works, it may get the truss rod functional without having to replace it or do any big surgery. But....so far I haven't been able to get the truss rod to turn at all in either direction. It may be badly frozen up. So, it could be that the steel cap will just snap off the end of the rod when I try to turn it. Then we'd be back to the original plan of pulling the fingerboard and replacing the truss rod.

But I think it's worth a try. Even if it fails, it will be nice to work out a technique for fixing a Pedulla truss rod that's rounded off.

That's where we are right now.

 

[Bruce Johnson]

What is the reason Mike created his own unique type of TR, and why did he reverse to usual way of tightening/loosening it?

To make a better design neck than other builders! Why else? Remember, in the early '80's, there were only a few Boutique builders around. There was no real supply of aftermarket truss rods that you could buy, other than Gibson-style kits. There were no double-acting, double-rod truss rods in production at that time, that I know of. Mike may have been the originator of the rotating-rod type of DADR truss rod.

In the rotating-rod design, one of the rods rotates inside the neck as you adjust it. It has left hand threads on one end and right hand threads on the other. Turning the rod one way pushes the two end blocks apart, bending the assembly one way. Turning it the other way pulls them together, bending it the other way.

I haven't looked at Mike's rods closely, but I believe the reason why you have to turn his left is because he has the rotating rod on the top and the stationary rod/bar on the bottom.

Most of the commercial DADR rods that you see around today have the rotating rod on the bottom. Turning it clockwise (normal bolt tightening) bends the neck back. I think that's the main reason why they put the rotating rod on the bottom.

I assume that the reason Mike put the rotating rod on the top was to raise the adjusting end higher in the headstock for better access, and less wood to cut away in a weak area.

 

[Fishheadjoe]

a few years ago mike came out with a different design tool which is much better and gives better access to the nut. you have to be very careful as this rod is in reverse, right to loosen left to tighten. the one you are describing is made of cheap white metal that cracks and will strip the nut.

Well, all I can say is that I posted the wrong tool! Doh! I mentioned Harpsichord when I should have said Auto-harp! Apologies to all. That said, so far, the tool has worked fine and fits the end of the rod with very little play. And I am fully aware of the reverse threads on the rod.
Following this thread with interest!
My bass is from the 90's and I am wondering if Mike changed his finger board glue between the 80's (Inara's bass) and mine. As I mentioned earlier in the thread, my tech said the finger board came off mine relatively easily, with heat and patience.
Fishheadjoe

 

[MrLenny1]

I'm gonna bookmark this. I own a 1991 Pedulla.
Still works fine but you never know.

 

[Bob_Ross]

My bass is from the 90's and I am wondering if Mike changed his finger board glue between the 80's (Inara's bass) and mine. As I mentioned earlier in the thread, my tech said the finger board came off mine relatively easily, with heat and patience.

Back in the mid-1990s a friend told me that Pedulla had switched from aliphatic resins to epoxies a few years earlier. Never heard that “officially” substantiated, but it sounds plausible.

 

[Bruce Johnson]

Yes, we're pretty sure that the fingerboard on Inara's Buzz was put on with epoxy. We worked at it for about a half hour and only got about an inch of it loosened. And it was taking so much heat that we were worried about main neck laminations coming apart. So we stopped.

I've had an idea in my mind about building a special "hot wire" rig specifically for removing fingerboards. Hot wire cutters use Nichrome wire, a metal alloy that has high resistance. You can buy nichrome wire in different gauges (diameters). Mount a length of it in a frame, pulled up tight, with insulators at both ends. Apply electricity through it and it heats up. Up to red hot or anything in between. Adjust the voltage to adjust the temperature. Set the temperature to where the wire just slices through the glue without scorching the wood. And it wouldn't heat up the wood very much at all. I may quickly rig this up and test it out.

 

[Inara]

Yes, we're pretty sure that the fingerboard on Inara's Buzz was put on with epoxy. We worked at it for about a half hour and only got about an inch of it loosened. And it was taking so much heat that we were worried about main neck laminations coming apart. So we stopped.

I've had an idea in my mind about building a special "hot wire" rig specifically for removing fingerboards. Hot wire cutters use Nichrome wire, a metal alloy that has high resistance. You can buy nichrome wire in different gauges (diameters). Mount a length of it in a frame, pulled up tight, with insulators at both ends. Apply electricity through it and it heats up. Up to red hot or anything in between. Adjust the voltage to adjust the temperature. Set the temperature to where the wire just slices through the glue without scorching the wood. And it wouldn't heat up the wood very much at all. I may quickly rig this up and test it out.

That sounds like a very neat and useful tool, Bruce!

 

[96tbird]

Yes, we're pretty sure that the fingerboard on Inara's Buzz was put on with epoxy. We worked at it for about a half hour and only got about an inch of it loosened. And it was taking so much heat that we were worried about main neck laminations coming apart. So we stopped.

I've had an idea in my mind about building a special "hot wire" rig specifically for removing fingerboards. Hot wire cutters use Nichrome wire, a metal alloy that has high resistance. You can buy nichrome wire in different gauges (diameters). Mount a length of it in a frame, pulled up tight, with insulators at both ends. Apply electricity through it and it heats up. Up to red hot or anything in between. Adjust the voltage to adjust the temperature. Set the temperature to where the wire just slices through the glue without scorching the wood. And it wouldn't heat up the wood very much at all. I may quickly rig this up and test it out.

like foam cutters:

Woodland Scenics Hot Wire Foam Cutter https://www.amazon.ca/dp/B0006KSMEU/ref=cm_sw_r_cp_api_i_3kwnCbY7310TE

 

[Jeff Scott]

...Nichrome wire...

IIRC, that's what we used to ignite/launch our Estes rockets when we were kids.

 

[Bruce Johnson]

like foam cutters:

Woodland Scenics Hot Wire Foam Cutter https://www.amazon.ca/dp/B0006KSMEU/ref=cm_sw_r_cp_api_i_3kwnCbY7310TE

Yep, that's the idea, just heavier duty. It's going to take some force to drag the wire through the glue joint, so I need to go with heavier gauge wire than those foam cutters. McMasters sells nichrome wire up to 1/16" dia. I don't think it needs to be that big, but I'm thinking something like 0.030"-0.040" wire.

Make a wooden frame about like a slingshot with some nice metal clamp blocks on the ends of the arms. Rig it up mechanically, measure the actual resistance, and do some math to figure out what combination of volts and amps I need. I'm thinking a 12 volt battery and a big wirewound rheostat, and a temperature gauge.

 

[Bruce Johnson]

IIRC, that's what we used to ignite/launch our Estes rockets when we were kids.

That's the stuff! A battery and some nichrome wire to light the fire.

 

[Gilmourisgod]

Heh. Estes Rocket Launcher. We used to rig them up to a mailing tube, color it all up camo with magic markers, Bam! Instant bazooka, hours of fun with no eye protection. I realize now that I had what they are calling a “free range childhood”. The wire cutter sounds ingenious, more Mad Science from the master.

 

[Pilgrim]

The wire cutter idea makes perfect sense to me. It ought to be possible to get a tough enough wire to stand the stress, provided that you don't need such a large diameter wire that you can't get it between the neck and fretboard. You'll need some pretty strong mounts for the ends, and the wire may stretch if there's much stress.

 

[sissy kathy]

The wire cutter idea makes perfect sense to me. It ought to be possible to get a tough enough wire to stand the stress, provided that you don't need such a large diameter wire that you can't get it between the neck and fretboard. You'll need some pretty strong mounts for the ends, and the wire may stretch if there's much stress.

Ceramic insulators under compression do pretty well.

 

[Bruce Johnson]

The wire cutter idea makes perfect sense to me. It ought to be possible to get a tough enough wire to stand the stress, provided that you don't need such a large diameter wire that you can't get it between the neck and fretboard. You'll need some pretty strong mounts for the ends, and the wire may stretch if there's much stress.

Yeah, that's the idea. It needs to have a certain amount of strength to be dragged through the joint. But it's supposed to be heating and melting the glue as it goes.

I took an educated guess and went ahead and ordered a roll of 0.040" nichrome wire last night from McMasters. It was $13 for 21 feet of the wire. I'm going to go ahead and try building this right away. If it works on some test pieces, maybe we'll be able to save the fingerboard on Inara's Buzz after all. This would definitely be a nice tool to develop out.

By the way, on Inara's Buzz we encountered a pin, about 1/2 in from the nut. Mike used brads or staples or something to align the fingerboard while gluing it. A problem with any fingerboard removal technique. Obviously, the hot wire isn't going to cut through it. The hot wire will have to be pulled gently, to feel if it's catching on a pin. If it catches, stop, extract the wire, and slip a Zona saw in to saw through the pin. Then carry on.

 

[Bruce Johnson]

Ceramic insulators under compression do pretty well.
View attachment 3276988

That's a bit excessive! Actually, at the ends of the arms, I need to clamp the nichrome wire mechanically and to make electrical contact with it. I'm picturing a maple "slingshot" with some steel clamp blocks out at the ends.

 

[Bob_Ross]

IIRC, that's what we used to ignite/launch our Estes rockets when we were kids.

Heh. Estes Rocket Launcher. We used to rig them up to a mailing tube, color it all up camo with magic markers, Bam! Instant bazooka, hours of fun with no eye protection. I realize now that I had what they are calling a “free range childhood”.

Thread drift: Remember Jet-X wicks? These were for igniting Estes rocket engines sans electricity; just light 'em with a match, and it burns like the bomb fuses in the old Batman TV show. One of my favorite “free range childhood” memories was when I realized that you didn't need to bother with the whole Build A Model Rocket part, you could just buy some Estes rocket engines and Jet-X wicks and light 'em, throw 'em, and duck!

 

[Gilmourisgod]

One More Thread Drift (I promise):
I had a Revell plastic model of the German ME-262 Swallow, the first production Jet fighter of WWII. It so happened that the plastic engine nacelles hanging below the wings were almost perfectly sized for two Estes rocket engines. You can see where this is going. "It'll Fly!". No, it won't, because no matter how carefully you cut the two fuses to length, one of them will ignite first, transforming the model into a jet-powered Helicopter of Death, spinning at 12,000 RPM about three feet off the ground, for the few exciting seconds before the sharp plastic wing leaves a scar that I have to this day. My childhood featured a lot of burns and stitches.

 

[Matt Liebenau]

One More Thread Drift (I promise):
I had a Revell plastic model of the German ME-262 Swallow, the first production Jet fighter of WWII. It so happened that the plastic engine nacelles hanging below the wings were almost perfectly sized for two Estes rocket engines. You can see where this is going. "It'll Fly!". No, it won't, because no matter how carefully you cut the two fuses to length, one of them will ignite first, transforming the model into a jet-powered Helicopter of Death, spinning at 12,000 RPM about three feet off the ground, for the few exciting seconds before the sharp plastic wing leaves a scar that I have to this day. My childhood featured a lot of burns and stitches.

Burns and stitches are how we learned. That's why kids these days don't know nuthin. Too sheltered.







Oh, and get off my lawn!!

 

[Ross W. Lovell]

One More Thread Drift (I promise):
I had a Revell plastic model of the German ME-262 Swallow, the first production Jet fighter of WWII. It so happened that the plastic engine nacelles hanging below the wings were almost perfectly sized for two Estes rocket engines. You can see where this is going. "It'll Fly!". No, it won't, because no matter how carefully you cut the two fuses to length, one of them will ignite first, transforming the model into a jet-powered Helicopter of Death, spinning at 12,000 RPM about three feet off the ground, for the few exciting seconds before the sharp plastic wing leaves a scar that I have to this day. My childhood featured a lot of burns and stitches.

You are my hero!

I hope you play bass good, don't like my dreams shattered.