Need to enlarge input hole but how?

[LP Freak]

I screwed up and ordered my new build with a 3/4” hole for the input instead of a 7/8”. So what’s the best way to enlarge the hole without chipping the finish?

 

[bagman67]

The first question is whether you really need to enlarge it.  If you are planning on using a standard Tele jack cup or an Electrosocket part, yep, you do - but if you are planning on a square or football jackplate, you don't need to worry.


Now, that question out of the way -


If you have access to a drill press and appropriate clamping gear, you just clamp the body in place with appropriate padding, and use a 7/8" Forstner bit to bore the hole out.


If you do not, another way to approach this would be to apply masking tape to the area you need enlarged and scribe the tape with the 7/8" diameter circle you want.  If you have access to a woodworking vise, clamp the body on place to make it easier to work on; but if you don't, you can still proceed, it will just be a bigger pain.  Now:  Trim away tape over the existing hole, and then wrap 80-grit sandpaper around a length of 1/2" or 5/8" dowel.  DO NOT HURRY THIS PART - sand your way out to the line, a little at a time.  Make sure you are sanding parallel to the hole sides and not at an angle.  The last thing you want is to chew up the sides of your hole beyond the 7/8" circle, and end up with bare wood or a gap that your jack plate won't cover.


Best of luck -


Bagman

 

[bagman67]

Addendum:  A sufficiently narrow wood rasp or rounded file might work faster than the sandpaper-wrapped dowel. BUT BE SLOW AND CAREFUL in any event. 

 

[LP Freak]

The first question is whether you really need to enlarge it.  If you are planning on using a standard Tele jack cup or an Electrosocket part, yep, you do - but if you are planning on a square or football jackplate, you don't need to worry.


Now, that question out of the way -


If you have access to a drill press and appropriate clamping gear, you just clamp the body in place with appropriate padding, and use a 7/8" Forstner bit to bore the hole out.


If you do not, another way to approach this would be to apply masking tape to the area you need enlarged and scribe the tape with the 7/8" diameter circle you want.  If you have access to a woodworking vise, clamp the body on place to make it easier to work on; but if you don't, you can still proceed, it will just be a bigger pain.  Now:  Trim away tape over the existing hole, and then wrap 80-grit sandpaper around a length of 1/2" or 5/8" dowel.  DO NOT HURRY THIS PART - sand your way out to the line, a little at a time.  Make sure you are sanding parallel to the hole sides and not at an angle.  The last thing you want is to chew up the sides of your hole beyond the 7/8" circle, and end up with bare wood or a gap that your jack plate won't cover.


Best of luck -


Bagman

I was planning to use a standard Switchcraft 1/4” jack but it obviously requires a 7/8” hole. Is there a smaller type available that works with a 3/4” hole?

 

[mayfly]

Standard switchcraft jack will work just fine in a 3/4" hole.

As Bagman pointed out, you'll only have trouble if you plan to use an electrosocket or a standard tele jack cup.

 

[LP Freak]

You’re right it does fit, but damn it’s snug. I’ll probably just grab a drum sander for my Dremel and ream it out a little.

 

[Cagey]

Yeah, not all of them will go in. Sometimes, just buying a different jack will help. The phenolic separator plates sometimes end up with indexing slots cut around the outside that are larger than they need to be, effectively making it into a larger diameter.

You can also try just grinding those nibs back.

If you'd rather (or have to) drill than grind away with a Dremel for 3 weeks, you're much better off plugging the hole by gluing in a short length of 3/4" dowel, then re-drilling for 7/8". Trying to drill into an existing 3/4" hole to enlarge it more can be challenging with nothing to center the bit, even with a drill press.

Regardless of how you do it, opening the hole up past 3/4" kinda needs to be done, as the contact for the tip connection needs room to move back as it bends away from the plug while going in. If the hole's tight, you may eventually get the jack in, but then once mounted to a plate you'll have trouble plugging into it.