Bad Router Bit Experience

[LCHIEN]

It takes a lot of energy to bend a 1/4" shank.

My only comment is I can't find a picture of a bent 1/2" shank.
Disclaimer - none of these is mine!

[Jim Frye]

Very scary!

[leehljp]

I used 1/4" router and bits of different shapes for 20+ years before buying a 1/2" router and bits. I had probably 30 bits in 1/4" and never had a bent bit. As best I can tell, at least 3 of the picts above were using compact routers. Could this be a factor? My 20+ years with 1/4" routers were more or less full size as compared to compact routers.

Is there anything different in the mounting of a compact router vs full size router?

[Jim Frye]

Not that I know of. My Ryobi TR30 trim router collet seems to lock up just as tight as the others. It does require two wrenches as it has no spindle lock like the others. The much smaller base on the trim routers might be a contributory factor. When I got my trim router, I also purchased a two handle base for it that is much larger and thus more stable than the original base.

[Jim Frye]

I used 1/4" router and bits of different shapes for 20+ years before buying a 1/2" router and bits. I had probably 30 bits in 1/4" and never had a bent bit. As best I can tell, at least 3 of the picts above were using compact routers. Could this be a factor? My 20+ years with 1/4" routers were more or less full size as compared to compact routers.

Is there anything different in the mounting of a compact router vs full size router?

My trim router is the second from the left.

[mpc]

Most of those bent bits look like they were not installed far enough into the collet - too much shank was exposed. So the forces acting on the bit had a longer than proper lever arm to flex the bit. The collets probably didn't have a proper grip either. Collets need a minimum shank length to do their job.

The yellow straight bit and maybe the other yellow bit look like they were installed deeper into the collet.

My Freud bits have a line printed on the shanks showing the minimum collet insertion/depth. That line is closer to the cutting flutes than where these bits bent.

edit: happened to notice in the Bosch 1617 manual that Bosch specifies at least 5/8ths inches (16 millimeters) of bit shank should be inserted into the collet. I'm not comfortable with anything less than about an inch based on the markings of my Freud bits.

edit: I wonder what the operator was doing in the first picture with the green pattern bit. That bearing is quite far from the router base... was the pattern that thick?!?!

mpc

[Jim Frye]

The replacement Freud (not Diablo) bit arrived this evening as promised by the Freud representative. Unfortunately, I have no use for it now, but it will go into the router bit collection for future use.

[capncarl]

Lchien, glad you posted these photos of bent router bits! Someone had a good scare there. I agree, none bent were inserted in the collet far enough. I wonder if these imported bits have as strong of steel as our older built in USA bits did? If anything, i probably overtighten my collets. Something that I haven’t thought about is whether or not to lubricate the threads on a collet? You are not supposed to lubricate the lug nuts or wheel studs on an automobile because the lubricants will allow you to over tighten the lug nut to the point it stretches the stud and its prone to break.
Another thought about the bent bits. It’s reasonable to think that they were inserted in the collet far enough but the collet wasn’t tightened enough and the bit slipped out and bent.

[Holbren]

Not all bits use the same steel but I can't imagine how you would bend those like that. They do appear to be on the larger side for 1/4" shank so could be a combination of poor steel and excessive weight. Still hard to believe.