Router bit rant

[tfischer]

Was working on making dovetail joints for my dresser project yesterday - I had hoped to get them all done. After about 2 drawers worth, my router bit broke. I didn't *think* I was forcing things (I'd already done 7 drawers from the other dresser with it) but it snapped clean in half at the shaft. So, I grumbled, and grabbed my backup bit. That one worked for about 3 joints, then started working very badly... evidently' it was already dull and those final joints killed it. Looked around online to see if I could pick up another bit locally, but the only place that had that exact bit was Rockler and they were already closed for the day (who closes at 4pm??)

Anyway, just a rant. The were both MLCS bits by the way... always had decent luck with them but with this project I found myself breaking a few bits now. I don't *think* I've changed my router technique for the worse that much recently lol.

[Bill in Buena Park]

That is frustrating. I've always been puzzled by Rockler's early hours as well. Is your backup bit carbide tipped? If so, and you have a flat diamond file/hone, you can possibly sharpen the bit with a few passes on the flat face of the carbide (not the beveled edge, so you don't change the bevel profile. I have the HF bit set, so probably a step down from MLCS, but I've used this method a couple times to dress a bit and keep going until I need a new one.

[cwsmith]

Doesn't MLCS have some kind of warranty? Perhaps not against dulling as I suspect that no one would warrant that, but possibly against failure of the shaft.

I've only had one bit ever fail at the shaft, it was a Ryobi 1/4 inch straight bit. It was brand new and I had just started to use it to edge a pine board... got about a foot down the board and it snapped on me.

CWS

[tfischer]

Doesn't MLCS have some kind of warranty? Perhaps not against dulling as I suspect that no one would warrant that, but possibly against failure of the shaft.

I've only had one bit ever fail at the shaft, it was a Ryobi 1/4 inch straight bit. It was brand new and I had just started to use it to edge a pine board... got about a foot down the board and it snapped on me.

CWS

Yeah broke 2 1/4" straight bits trying to do stopped dados earlier in this project. I didn't think I was forcing the board.

Ended up switching to doing most of them on the table saw, and then cleaning up the ends with the router. Not ideal

Those were MLCS also.

[gerti]

Maybe your router is running backwards... That seems like an awful lot of bad luck with route bits! Or are you working with granite on this project?

[tfischer]

Maybe your router is running backwards... That seems like an awful lot of bad luck with route bits! Or are you working with granite on this project?

LOL.

I picked up a dovetail bit at Rocker tonight... one of their $13 cheapos, just to keep going with the project. It cut really well, better then the MLCS I think. I already ordered another one from MLCS too so I can compare sometime.

I actually finished up all the dovetails tonight. Very glad to have that part of the project done... 14 different drawers of numerous heights.

[LCHIEN]

Dovetails bits can be extremely fragile - the neck on the common ones used for the dovetail jigs have an extremely thin section that will break with sideways pressure, much moreso than all the other bits.I seem to recall that it's thinner than the 1/4" shank.
If the bits are dull or the cutting pressure too great they will break quickly.

This is the Whiteside 1/2" 14° 1/4" shank dovetail bit, the type I think is commonly used for dovetail machines.
Note the undercut just above the shank where the bit is very weak. They usually break right there.

Note that the flutes also extend down and cut significantly into the 1/4" shank.
It wouldn't surprise me that the metal cross section area in the narrow necked part is half the metal cross section area of the main 1/4" shank, making a very weak point.

[LCHIEN]

Yeah broke 2 1/4" straight bits trying to do stopped dados earlier in this project. I didn't think I was forcing the board.

Ended up switching to doing most of them on the table saw, and then cleaning up the ends with the router. Not ideal

Those were MLCS also.

MLCS used to be quite reasonable with great customer service.
I broke a 1/4" carbide spiral bit and called them. I was trying to do a groove with a 1/2" deep cut. 1/4" sprial bits have a lot of material removed in the spiral and the cross section area is as bad as or worse than the dovetail. He told me I shouldn't remove more than 1/16th at a pass but he graciously sent me a new bit for free,
I'm a lot better with tools and technique now and haven't called them for years. But I do give them my business because of their service.


1/16th inch is not much, I regularly push it to 1/8" if I need to. Of course with dovetails you can't make a shallow cut and repeatedly make it deeper - you have to set one depth!. What you have to do is make a few light passes across the fingers limiting how much you take off and then when your bushing starts contacting the fingers, go a little more slowly and deeper in. Don't try and cut deep into the fingers on the very first pass!

[tfischer]

The dovetail bit actually broke midway up the shaft - right where it entered the router collet. The straight bits did break off at their weak point.

All but the second dovetail bit that dulled were essentially brand new bits, but they were purchased years ago (at least 5) so I don't really expect them to replace them due to the time since the sale happened.

[atgcpaul]

Now that you mention it, I only got a few drawers done with my HF DT jig before the bit snapped at the neck like yours. I got the Rockler bit and the rest was OK.

[tfischer]

Now that you mention it, I only got a few drawers done with my HF DT jig before the bit snapped at the neck like yours. I got the Rockler bit and the rest was OK.

Good deal. I did about 9 drawers with this bit before it broke (on this project, I may have used it in the past too). Glad to be done with the DT's.

The other thing that screwed me up was the supposed pneumonic "lower to loosen, heighten to tighten" for adjusting the fit of the DT's. That only works if you consider the router upside-down as if it's in a table, which is totally what I was NOT doing at first lol. (it's an odd pneumonic since you tend to do DT's freehand in most jigs, not in a table)

[LCHIEN]

"mnemonic"

[Bill in Buena Park]

The other thing that screwed me up was the supposed pneumonic "lower to loosen, heighten to tighten" for adjusting the fit of the DT's. That only works if you consider the router upside-down as if it's in a table, which is totally what I was NOT doing at first lol. (it's an odd pneumonic since you tend to do DT's freehand in most jigs, not in a table)

I believe the reference is to the cutting side of the router base plate, not true "up" or "down". It just happens that with the router in a table, the reference is more obvious.

[dbhost]

I've never had an MLCS bit fail, but failure can happen with anything... Not sure, but I would check with them to see if there is some sort of warranty on them. Like others have said, not against dulling, but there shouldn't be a shaft failure.

[Carpenter96]

A couple of years ago I made 130 Tool Box centre pieces with half-blind dovetailed corners (10 each corner) I used 2 Busy Bee 1/4 inch shank bits for the entire project and neither broke and have since been re-sharpened. They were about $12 ea. So that's about 2600 DT's per bit.

Regards Bob

[JimD]

This bit is one I don't buy from MLCS. I buy lots of bigger bits from them but not little ones with a neck down like Loring illustrated. I've broken them too. My current one is a CMT. It's done lots of drawers and still works fine. I would try a Freud and have used a Whiteside. For most bits I do not go with "premium" brands but for this sort of bit I do.