A tricky problem to measure.

[sycle1]

I have a tricky problem to solve.
Basically I need help.
I need a way to measure the truss rod in this neck accurately.
The hole in the end of the maple neck is 3/8" which makes for a tight working space for getting a measuring tool in there.
I have nothing that will reach deep enough into the neck to get to the rod.
Is there a tool available that could measure it?


Normally I would just pull the neck apart and remove the truss rod however on this one I can't for too many reasons.
Appreciate any help, information, idea's etc.

Thank you
All the best
Mick

 

[Just for fun]

Why not just try a couple nuts until you find the one that fits.

 

[Bone Head]

I don't know how accurate you need to be, so this might not work for you. Measure the 3/8" hole; record that. Use pin gauges to measure from the edge of the 3/8" to the side of the rod. Record that as "A". Repeat that at 180 degrees from "A" and record that as "B". Add "A" and "B", and deduct that from the 3/8" hole's diameter.
You should repeat those steps I would guess at least 3 more times. This would also give you an idea of how centered the rod is in the 3/8" diameter. You will also find that some finesse will be necessary (hold your tongue right) to get the accuracy you need.
Good luck.

 

[Weldingrod1]

Cast it with one of the meteorology compounds?
Are you trying to measure the flats on the rod, or the hole?

Sent from my SM-G715A using Tapatalk

 

[Eddyde]

You could grind down the outside jaws of a caliper to fit. If you have an old one or buy a cheap one new.

 

[markba633csi]

I would just take a small strip of aluminum and then carefully bend it or file a slot till it just slips on, then take it out and measure
You could probably get within a couple thousandths that way

 

[JC Whitney]

Sounds like a good job for a thread identifier set, the kind that's strung along a cable (< $20 on Amazon). Walls of the sockets should be thin enough to fit in there, although you might have to clean up the thread end if it's bunged up.

 

[RJSakowski]

Is the rod threaded? I can't tell from the photo. If it is threaded, perhaps a variant on Just for Fun's suggestion. Most likely a nut won't fit but you could tap different sized holes in a length of rod and try threading then on. If the rod isn't threaded, then Bone Head's method should give you a fairly good value. I would make the measurements on different diameters in the event that the rod and/or the hole aren't perfectly round.

Another way would be to drill different sized holes in the end of rods and try fit to get a go/no go range. Kind of like sizing a hole using pin gages. Depending upon your availability of suitable drills, you could get fairly close to the true value. It looks like the rod diameter is in the 1/8" range so you should hav a faily good selection if number drills to use. Check the drilled holes with pin gages to verify their actual diameter.

 

[sycle1]

Thank you everyone for your great suggestions I very much appreciate your help.
That is why this forum is so damn cool.
Will try the suggestions and get back to you with how it went.

 

[Flyinfool]

How smooth is the pin?
IF the pin is smooth casting would work.
I am sure that the wood is to rough for casting, you would never get the cast out of the hole.
You could put a roll of paper, tubing around the hole in the wood and then cast the pin, the paper liner will allow the cast to pull out of the hole.