Left to Right -- 1/4" straight bits -- MLCS 1/2" shank (broken), Craftsman 1/4" shank, Freud Diablo Solid Carbide

Eating router bits for breakfast

Not all router bits are created equal. On a recent project I had to make a lot of 1/4″ wide and 1/4″ deep dadoes.

In my 20+ years of using an electric router I’ve only lost a handful of bits, most due to the carbide chipping out or something similar. (Or using a poor quality bit — back when I was starting out and didn’t know any better) Whenever possible I try to buy bits with a 1/2″ shank for the added strength and decreased vibration. Leaving my 1/4″ shank bits mostly relegated to my 1HP Bosch Colt palm router and tasks like using 1/8″ round-over bits — my favorite profile for cleaning up edges on around the shop projects.

Routing 1/4" dadoes in maple ply
Routing 1/4″ dadoes in maple ply

Two weekends ago I was cutting a long dado with a variable speed 2-1/4 HP plunge router with a fence and had my old Craftsman 1/4″ straight bit snap off at the collar which was unusual as I would think it would snap off right below the carbide where the bit narrows slightly and is presumably the weakest point on the bit. I didn’t think much of it and figured ‘eh its a pretty cheap and 15 year old bit’ and went back to the tooling cabinet to grab another bit.

Old 1/4" shank Craftsman bit snapped, now on to the 1/2" shank MLCS bit.
Old 1/4″ shank Craftsman bit snapped, now on to the 1/2″ shank MLCS bit.

The second time out I grabbed an MLCS 1/4″ straight bit with a 1/2″ shank. In looking at the bit (it was part of a set of straight bits and looked like I never used this 1/4″ bit before) I thought to myself, wow that is quite the taper below the carbide. I loaded it up into the collet and got maybe 6″ through the maple and it twisted right off.

A few expletives flew, and I was questioning myself. Have I been spending too long doing hand tool only work? Am I using a router that is over-powered for the task at hand? I thought I was taking it easy as I made my passes — the tool wasn’t bogging down and it was cutting well.

After inspecting the plywood, both times where the bit broke it was hitting what looked like a knot in the veneer core of the plywood — so I think that change in density along with heat and friction was a contributing factor.

I was determined to make more progress on this project as I don’t get as many weekends to woodwork as I’d like. I headed out to Home Depot in the freezing cold and trying to make it there before they closed at 9pm and bought a Freud Diablo solid carbide bit. I balked at the ~$18 price compared to the say ~$5-8 each I paid for these bits from MLCS (but didn’t have the luxury of waiting for them to ship an order to me)

Left to Right -- 1/4" straight bits -- MLCS 1/2" shank (broken), Craftsman 1/4" shank, Freud Diablo Solid Carbide
Left to Right — 1/4″ straight bits — MLCS 1/2″ shank (broken), Craftsman 1/4″ shank, Freud Diablo Solid Carbide 1/4″ shank

I really liked how the Diablo was solid carbide and had a completely straight profile from the shank down to the tip of the bit. The bit worked like a champ and so far I have been very happy with it.

What is the lesson from all this? Remember to go extra slow and take very shallow passes when working with a narrow bit like this. Make sure you adjust the speed (if your router has a variable speed control). Remember that humans and tools are not perfect. Some tooling like these sorts of bits are disposable. Inspect your tools and look for quality designs. Remember that even solid carbide can be brittle — so do what you can to minimize any jarring changes. There are many lessons to be learned and re-learned as you progress in your woodworking career. Don’t be afraid to make mistakes and most of all get back out into the workshop — which is where I am headed right now.

Take care,
-Bill
@TheRainford

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