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A special tool needed
http://w-ww.luthiersforum.com/forum/viewtopic.php?f=10102&t=3221		 Page 1 of 1
Author:  LanceK [ Wed Sep 14, 2005 10:23 am ]
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I once seen a reverse Forster bit, I believe it was Frets.com, or maybe Charlie Hoffman's site? Anyway, I'm looking for a Forster bit that will allow me to (first) Drill pilot holes in a neck block, then reach in through the sound hole and insert the shaft of the reverse forster bit, and then attach it to my drill and then (PULL) the bit to create a counter sunk recess for the nuts to hide in on my bolt on necks. I would then attach the neck, and cover the holes with a tag. Does this make sense?
Is this a custom tool or can it be found out there?

THX
Author:  Pwoolson [ Wed Sep 14, 2005 10:36 am ]
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MSC industrial or Mcmaster Carr has them. I ordered one a long time ago so I have no idea what the item # is or even what it's called, sorry.
Author:  LanceK [ Wed Sep 14, 2005 10:45 am ]
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Thanks Paul - thats a least a place to start!
Author:  Rod True [ Wed Sep 14, 2005 11:00 am ]
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I think Mark Swanson has something like that.
Author:  rlabbe [ Wed Sep 14, 2005 11:02 am ]
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Lance, what you are looking for is called a reverse cutting, spot-face bit. Spot face means it makes a flat bottom, and reverse cutting, well, you figure it out :)

Go to UStool.com and search for "spotface". There's another place that sells them, but I forget the site.
Author:  Don Williams [ Wed Sep 14, 2005 11:16 am ]
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I think you're better off using your drill press to pre-drill and couterbore the holes than trying to drill virtually blindly. What advantage do think this will give you? None that I can think of. It would be easy to set up a jig to drill for the two bolt holes as well as the hole for the truss rod. That's really your best bet. Nothing like repeatability.
Author:  L. Presnall [ Wed Sep 14, 2005 11:22 am ]
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My guess is the box is closed already and now the holes need to be drilled and countersunk! (G'head, ask me how I know this!!!)   Anyway Lance, if you need it I have a 5/8" reverse spot-facer I can lend you!
Author:  Pwoolson [ Wed Sep 14, 2005 11:24 am ]
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I agree with Don. I thought I'd route the mortise and drill the holes then bore the counter sinks after it was all built up. I had lots of problems getting them accurate.
So if you end up pre drilling them and counterboring them, Reid Tool (obvious url) has piloted counter bores for not too much $. Come to think of it, they probably have the reverse cut bit too.
Author:  LanceK [ Wed Sep 14, 2005 11:26 am ]
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Thanks guys, and Larry, if I cant find that bit localy, ill take you up on your offer.

Author:  Keith M [ Wed Sep 14, 2005 12:41 pm ]
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Lance, I think you could use a wood counterbore replacing the center bit with a piece of drill rod they come in a large variety of sizes. See link.http://www.morriswoodtool.com/Counterbores.htm
Author:  John Kinnaird [ Wed Sep 14, 2005 12:42 pm ]
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Lance
   I took a spade bit and ground cutting facets near the shaft. Now the upper part of the bit resembles the lower part, complete with cutting barbs at the edge. A dremmel with grinder did the work. The shaft of the bit is very close to the diameter of the hole in the block so that the block serves as a bearing of sorts. Anyway, I insert the bit backwards throught the hole, pull the bit into the cut and it works great. Cheap too.

John
Author:  LanceK [ Wed Sep 14, 2005 1:22 pm ]
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[QUOTE=John Kinnaird] Lance
   I took a spade bit and ground cutting facets near the shaft. Now the upper part of the bit resembles the lower part, complete with cutting barbs at the edge. A dremmel with grinder did the work. The shaft of the bit is very close to the diameter of the hole in the block so that the block serves as a bearing of sorts. Anyway, I insert the bit backwards throught the hole, pull the bit into the cut and it works great. Cheap too.

John[/QUOTE]

Genius!
Author:  LanceK [ Wed Sep 14, 2005 1:23 pm ]
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[QUOTE=Keith M] Lance, I think you could use a wood counterbore replacing the center bit with a piece of drill rod they come in a large variety of sizes. See link.http://www.morriswoodtool.com/Counterbores.htm[/QUOTE]
Another great idea! Thanks Keith!
Author:  Howard Klepper [ Wed Sep 14, 2005 4:24 pm ]
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I use a reverse spotfacer from MSC.
Author:  Mark Swanson [ Sat Sep 17, 2005 1:12 am ]
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Sorry it took me so long to see this thread! Indeed I do have a tool I use for this, a machinist friend made it for me. Here's a picture of it.
It's a regular drillbit, but he made another shaft that screws to it. I hadn't thought of John Kinnairds' idea, that would be a simpler solution, I'd think! Wish I'd thought of that one.
Also in this picture is a allen wrench that fits the bolt used, and it's welded to a long T-handle. This fits through the endpin hole, and it makes it simple to screw in the bolts when you build a guitar with a soundhole in a different place, or if you use two soundholes.
Mark Swanson38612.4258564815
Author:  Rod True [ Sat Sep 17, 2005 2:08 am ]
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I have the same bit as you there Mark, I use it to cut out the truss rod access hole at the head of the neck. Never thought of using it for the bolt hole after the body is all together.
Author:  Mario [ Sun Sep 18, 2005 1:31 am ]
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I use the reverse spotfacer from MSC, also. Works really well. No chance of chipping...

The advantage to drilling these holes after the box is closed up is that you are assured that everything is centered and straight. With pre-drilled holes in the neck block, if it shifts even a little during glue up, you then need to enlarge the holes, and/or move things around.
Author:  Kevin Gallagher [ Sun Sep 18, 2005 4:57 pm ]
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I have several different sizes and use the 5/8" reverse spot face cutter for those same holes that you're going to drill when I need to. I usually keep at least 125 neck blocks drilled and counterbored for the neck bolts, but have waited to drill them on occasion...usually on a prototype of any given model or a new design to drill them.

   I do it because it allows me to use a transfer center pin to make a punch mark in the bottom of the mortise slot of the neck block while dry fitting the neck for perfect alignment and location. I then drill the 9/32" indh hole for the 1/4"-20 brass bolt and pull the reverse spot face cutter through to set the head.

   Once the dimensions are determined for any given model or innovation, I drill them before the block ever gets glued into the body, though. It's just less work that way.

   They are an inexpensive tool that really does the job well when needed. no chipping or questions since it runs off of the Forstner leading edge technology.

Regards,
Kevin Gallagher/Omega Gallagher
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