Pot insertion is way difficult... help? unreg?

[unreg]

So, all the soldering is done! But, it is, so far, impossible to insert my 3/8” long shaft diameter pot into the 3/8” mounting hole.

Should I sand the side of the hole?

If so, are there any sanding tips or recommended tools? If no, how do I correctly insert this pot?


I remember removing the old pot was difficult too.


I have already tried pulling down on the long split shaft (my guitar was on its face) with a pliers. That was a bad idea bc I closed the split a little. It should be possible to bend that split back to restore its shape right? I hope so...


edit: Does this fit in the guitar wiring section? (It has to do with a pot insertion... not wires.)

final-edit: Now I believe I’ve asked this question (in the edit) before. Pot insertion counts as wiring bc it’s involved in internal guitar fixing.

[newey]

First off, your post is fine where it is.

As for the split shaft, a little gentle leverage with a standard screwdriver should open that back up. Just don't go all Schwarzenegger on it.

For the hole, you have basically three options, in the following order of preference:

If you have a Dremel Mototool (or similar, but it has to be variable speed), use one of the cone-shaped grinding tools to ream out the hole. Work slowly. Recheck the fit after a little bit, then do more if needed.

Or you can roll sandpaper around a pen or pencil of the appropriate size. This is probably the safest method, but if it's way off this could get tedious. But, if this guitar is valuable or vintage, this is the way to go, much less chance of destruction.

Finally, the easiest way, and the one I use (but then again, understand that most of the guitars I work on are cheap P.O.S) is to use a variable speed electric drill with a 3/8 bit to ream the hole out a bit. Be careful not to oval-shape the hole, and again, go slow. I'm assuming based on your question that this is a rear-cavity guitar, not one with a pickguard- if so, work from the top down into the cavity, not from the cavity up, so that any chipping around the edge of the hole is on the inside of the cavity. But I would not do this on any guitar with any real value to it, as this is the most dangerous method of the three. Quick and easy, though. . .

[unreg]

Thank you so much newey!

May 11, 2020 5:44:29 GMT -5 newey said:

First off, your post is fine where it is.

As for the split shaft, a little gentle leverage with a standard screwdriver should open that back up.

PRAISE GOD!! So happy that’s fixable; going to be careful.

May 11, 2020 5:44:29 GMT -5 newey said:

For the hole, you have basically three options, in the following order of preference:

If you have a Dremel Mototool (or similar, but it has to be variable speed), use one of the cone-shaped grinding tools to ream out the hole. Work slowly. Recheck the fit after a little bit, then do more if needed.

Don’t have a dremel Mototool.

May 11, 2020 5:44:29 GMT -5 newey said:

Or you can roll sandpaper around a pen or pencil of the appropriate size. This is probably the safest method, but if it's way off this could get tedious. But, if this guitar is valuable or vintage, this is the way to go, much less chance of destruction.

This is the way I will go. It is a rear-cavity guitar... no pick guard. Should I sand from the top down into the hole here too? It was expensive for me... but there are tons of more expensive guitars.

[newey]

With sandpaper, it won't matter which way you go.

[blademaster2]

For the guitars that I built I *always* used to drill the hole slightly smaller than I wanted, and then do the sandpaper-on-a-dowel step. The dowel would be around 2/3 the size of the hole.

I would mostly sand in a circle by turning the dowel (or pencil or pen) and moving it in a circle at the same time, and make only small motions up and down. That way I would minimize the chance of splitting the wood (although I used fairly fine sandpaper for this). This gave me very smooth holes and a perfect fit for the controls to slip through. It is also a good idea to very slightly sand a curve into the wall of the holes so that the threads of the controls are less likely to catch on the wood and cause splitting either on installation or on removal.

[frets]

Unreg,
All of the mentioned techniques are good ways to enlarge a control hole. But if you’re  feeling uncertain or a bit nervous about it, I think you’ll find this video helpful. It is most conservative in its approach.

[unreg]

Thank you newey, Blademaster2, and frets!

I’ve already sanded with a colored pencil wrapped with 180 grit sandpaper (400 grit was way way to slow)... taped the ends of the sand paper to the colored pencil with scotch tape. It worked excellently... but, now the pot slightly spins when trying to tighten the nut around the top. I used the regular washer so maybe that’s part of the problem... another washer, black color with a large wavy (with many “points”) hole, came with my CTS pot, so I’m going to reread about it and probably use that washer.

Thank you for that video frets! Sanded the hole last night, but just watched that excellent video.


edit: Used sand paper left over from junior high Industrial Tech class... 80 was only readable on the edge of the final sand paper I used, but it definitely wasn’t 80 grit.

final-edit: Oh, thank you frets again, that video made me aware of a possibility that I’ll have to buy a new knob... sigh, oh well.

[blademaster2]

I generally avoid washers that bite into the wood or cause high compressive force. When I tighten pots I usually press the pot from the back as I tighten the nut from the other side. Once it starts to grip the wood on the inside I usually have no trouble from then on.

[unreg]

May 12, 2020 17:57:47 GMT -5 blademaster2 said:

I generally avoid washers that bite into the wood or cause high compressive force. When I tighten pots I usually press the pot from the back as I tighten the nut from the other side. Once it starts to grip the wood on the inside I usually have no trouble from then on.

Thank you blademaster2!

Maybe I won’t remove the pot... maybe I will. Last night I, with the guitar right side up, grasped the pot from underneath with a wrench, while tightening the nut on top with a smaller wrench. I worked great; the pot doesn’t move... though, I was thinking that it may move if the nut becomes loose.

The top of the shaft only protrudes just enough for the nut to be in contact... though, it is securing the pot. I can turn the volume knob and the nut remains in place. Thought maybe there is something between the top of the pot and the cavity’s ceiling; however, I did notice that the new CTS pot has a raised portion at the base of the shaft. So, maybe that different washer is wide enough to go around that raised part. Regardless, the pot is stable now.