Oversized Router Bit Problem

[Raymond Fries]

First I want to thank everyone for their feedback on the Box Joint Mystery thread. I have brought resolution to the problem. It was partly due to my setup and partly due to an oversized bit.

Does anyone know the specs that router bits should meet?

If you buy a 3/8” slot cutting bit, shouldn’t it cut a 3/8” slot? If the package says 3/8”, then it should cut a slot .375 and not .379 or some other number that is close. I am on my second Freud bit and it is still cuts an oversized slot. Although the bit does measure .375 across the cutting edges, it cuts a wider slot because one of the cutting edges is further from center than the other.

I am using an Incra positioner for joinery and with this bit I have to micro adjust the positioner an additional .004 every time I want to cut the next slot for box joints. This does not seem like much but it adds up. For a 6” wide project, you need to add an extra 1/8” of wood to come out even. I do not think I should have to do that.

My setup problems are resolved because the ¼” straight and ¼” dovetail bits are perfect and produce tight fitting joints; these were also Freud.

I think I might have to start looking at another brand like Whiteside or CMT to see if there is greater consistency on tolerances.

Can anyone recommend a brand that consistently delivers a cut as advertised on the package?

[Rob Russell]

Raymond,

2 things:

1) Please increase the font size of your posts - the small font you use is hard to read for some of us with eyes over 40 years old.
2) I'd contact Freud and let them know what you've run into. In general, they make high quality tooling, including stuff that's used commercially and in industrial applications. I have to believe that they would want to know about quality control problems such as what you have run into.

Rob

[andy brown]

Hi,
Could your Router be running out of true? Maybe try the same kind of test with a couple of bits and check your results to see if they're all out or not.
Andy.

[Charles McCracken]

Raymond,

The 3/8" bit should be cutting 0.375" and the way that the edges are ground should preclude the possibility of the cut diameter being off center. However, I don't doubt your results and would like to see the bit in question to verify if there is a problem in our processes. Please PM or email me and I will arrange for the return of your bit for evaluation and replacement.

[Raymond Fries]

The first bit I got was returned to Oak Tree in Fort Wayne IN, 260-637-0054, and exchanged for another identical bit. Bill said they would return it to Freud. YOu could call Bill to see if it has been shipped yet.

That bit was brought into our engineering shop and put in a Bridgeport milling machine. A Starrett dial indicator showed that one of the cutting surfaces was about .0015 further away from center than the other.

The bit questioned for this post has not been checked on the mill yet. I assumed it was the same problem as the first since I got perfect results with the 1/4" straight and 1/4" dovetail bits. If I am missing something in my setup then I apologize to Freud for my error. I will check it with the dial indicator and e-mail or PM the results to you and we will go from there.

[pat warner]

Not a typical way to produce a net pathway cut, (with a cutter of the same size).
Even if the cutter is .375". deflection, setup slop, runout, router or workpiece control, etc. will easily widen the path.

Cut should be stage routed with narrow cutter.

[Cliff Rohrabacher]

Does anyone know the specs that router bits should meet?

There is no spec. They do what ever they please and if you don't like it, it's caveat emptor. Buy your self a good set of micrometers and send the ones back that don't meed YOUR specifications.