Official Luthiers Forum!

I wish I could see exactly what you were trying to do when you had that tear out. I have a lot of tricks that I've employed to deal with entry and exit issues. In general, I often do a series of prepatory cuts that establish sharp edges and corners prior to using aggressive cutters. Almost every situation is different so I can't be specific but if you ever get a shot of a nasty situation I'd love to bounce it around with you.

For what it's worth;

I've been able to entirely eliminate tear out in many situations through the use of counter rotating endmills and spherical mills. Being able to program the tool path and have the flutes attack the grain from the proper direction provides all the control necessary to guarantee the result in most scenarios. I didn't go down this path to speed up my cycle time...though it certainly helped. I did it to guarantee the result.

As an example, take a look at the headstock I just posted.

viewtopic.php?f=10123&t=29178

The profile on that headstock was cut with four seperate contour cuts, all written to avoid any situation where the cutter could pull the grain as it cut. Using left turning cutters for two of those contours, I was able to have the flutes attack and cut through the grain such that the remaining stock supported the cut. Nice and clean. By the time I make that cut the whole neck is finished....I don't want to chance anyhting.

Onsrud has a decent inventory of matched left and right turning cutters.

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

I've never thought of using those push-in connectors for vacuum jigs. What are they called?

Sheldon,
They are called "push to connect" fittings and can be purchased from MSC, Grainger and the like. You simply push the tubing in to make the connection. To remove, you hold the collar or ring, inward towards the threaded end, while pulling outward on the tubing.

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tim...
http://www.mcknightguitars.com

Sorry for the delayed response.
Stuart, I don't have too many areas where I still have blowout. I could cut out a lot of time in my programs if I had better control over cornering speeds and spindle rotation but pretty much everything I have trouble with I can get around the issues by either doing an initial light cut or leaving extra material and coming back later and slower to clean it up.

The quick push connectors from Clippard. I ordered them from the local distributor I found on their website. They work great and operate just like Tim said.

Lately I've been working on programming our fan fret neck, making fan fret boards and programing electric guitar parts for our Great Lakes and Galloup electric guitars. That plus finishing all the bodies for the student electric guitar kits and started the necks for the kits.

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Josh Garrett
Galloup Guitars CNC

I know that clippard stuff can be pricey. I usually use these guys for the push to connect, they're pretty cheap, but shipping seems to always be $10. This sucks if you only needs a few items. Most the time the stuff you order is very light so maybe give them a call and see if they can send it regular snail mail for only $0.50 or so.

http://www.poweraire.com/index.php

I make my own push-to-connects by creating a countersink in the side of my tool and sticking an o-ring in there. Then I just jam a small piece of aluminum tubing into the pvc vacuum line.

The middle photo of this post highlights what that looks like. The concept also works very well with wood tooling as well as metal.

viewtopic.php?f=10106&t=28656

_________________
I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic

Stuart

I see that you do a wavy neck joint, can you post more pictures of this as i wanted to do that with my guitars, any pros and cons on this type of joint.

With using a pod and rail cnc machine i also use those push fit fittings, where my jig gets permantly fixed down using vacuum to the pods and then i have a secondary vac system that releases and fixed the part that needs to be machined, so once the first part is completed i can place another on without the jig moving, i presume when you use a metal working cnc that you use bolts or clamps to fix the jig down.

Hey all, today I am cutting a few Great Lakes guitar parts, rosettes and peg head overlays to be precise. Then a few electric guitar bodies for a couple customers. Maybe I'll get to some necks later in the day.

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Josh Garrett
Galloup Guitars CNC