Hi,
I am new to the cnc world and looking for a little help on bits. As of this point I’ve experimented with a few different bits. My main questions is, what length of bit should I be using to cut 1" 3/4 stock? I would like to cut 1/8 inch holes at 1"3/4 depth, as well as cutting the shape of the guitar. I’ve used some 1/4 shank 1/4 OD to cut the shape of the guitar but find that my bits are always a little short. The router I have mounted up is the Dewalt 611. To cut my 1/8 inch holes right now, I have the machine tap the holes with a 1/16th bit inch then I use my drill press. I would like to know if there is a way around this and is there some longer bits to purchase?
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Yeah but what length of bit?
That’s going to be a tad challenging, given that it’s outside the standard range of cut lengths for quarter-inch bits. Certainly available, you will just find them as milling cutters, not router bits. Using a 1/8" bit with that much stick-out is going to be REALLY shaky… Quarter-inch is entirely ok at those lengths as long as you are careful.
McMaster-Carr has a 1 3/4 cut depth. You could also use a reduced-shank bit for the purpose.
Thank you Dan! Exactly what I was looking for. I should’ve known to check McMaster. I figured 1/8 inch holes was a little unstable at 1 3/4 depth but wasn’t sure. Thanks
Hey, no problem. I’m ALWAYS poking around there, they’ve got every cool thing known to man.
That’s something on the order of a 14-cutter-diameter cut, so yeah, that’s probably fairly extreme. You CAN get cutters of that nature, but they’re going to be fragile and very expensive. For 1/8" holes in my stuff, I generally just do as you are and have the X-Carve spot it down to ~.250 deep, then just float a twist drill down that hole as a guide using my drill press. If I had a better speed controller, I’d LOVE to just turn the router down to ~1000rpm and load a bit directly into the X-carve! Although, another consideration, just getting a bit with EXACTLY that projection to move into position, with the tip just barely brushing the surface is going to require 3.5" of Z travel. Practically, you will want the tip to clear by a quarter-inch or so for safety, plus a bit of stick-out more than you need since you don’t want the collet punching the work. So more likely a full 4" of Z for the job. You are clearly set up to do it, given that you’re cutting the same depth with the 1/4" bit, but that’s still hella-lotta Z to use on this machine! I don’t have that much available on my machine after tooling, myself.
The link took me to a 1/4" endmill.
The longest commercially available 1/8" endmills I’m aware of are Garr Tools’ — recommended on this page: Shapeoko CNC Router, Rigid, Accurate, Reliable, and Affordable — http://www.garrtool.com/tooldetaillogin.jsp?edp=41030 — only 1" cutting length though.
Yes, that link went to an extended-length 1/4" endmill. A 1/8 that length is going to be very hard to come by, since it will be so incredibly fragile. It’s very likely made, although it will not likely be full-length cutting. More likely will have half an inch of flutes or so, with a reduced-diameter shank. Chatter would likely be a large problem with that much stick-out. 
EDIT: MSCDirect doesn’t even appear to have them. Likely have to contact a dedicated tooling vendor.
If you use Facebook there’s a group called “The Electric Guitar Builders Resource”. There’s a few people on there I believe that uses an X-Carve that may be able help with pretty much any question you may have on guitar building.
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I used this 1/4" bit when I made my guitar and it worked fine and was long enough. I put 1/4" plywood under the 1-3/4" body blank. The x-carve Z went just high enough to have a little over 1-3/4" of the bit exposed so it could cut all the way through, with a small amount of clearance space above the blank to move around. I wouldn’t use an 1/8" bit to cut through 1-3/4" except to make starter holes like you said.
https://www.inventables.com/technologies/high-speed-steel-2-flute-upcut-spiral
Thanks Steve! I must say your video is what ultimately made my decision on going with the X-Carve!
I think what I’ve decided to do since most of my projects are 2 sided machining, I’ll use a bit that I can cut a depth of .875 and do both of the sides that are 1" 3/4. I was hoping to save a step and do all of one side at once.