Have I told you how much I hate 1/4" shank router bits?

[Henry W]

I have on occasion had a 1/4" router bit slip in the collet - and in fact that was the very reason that prompted my purchase of a PC 690 router kit. There was no PC 890 router yet, so that tells you how long ago that was. Anyways I try to use 1/2" shank bits as much as I can, although clearly that is not always possible.

Earlier this year I made an "exact-width" dado jig; there are many ideas out there, but I used The Wood Whisperer in general (several things I did not like about that). I hate dealing with offsets, and so decided to use a top bearing flush trim bit (top-bearing meaning the bearing closer to the router body than the cutter is). Since the primary purpose is to cut dadoes for 'undersized' plywood, I need to use a bit smaller diameter than 3/4" - so 1/2" cutting diameter it is. Those (I thought) are only available in 1/4" shank - so that's what I have used. 1/2" diameter, 1/2" cutter height, 1/4" shank - to pbearing. Bought at Klingspor's - their brand made by Whiteside I believe.

Cutting '3/4" ' dadoes in plywood for cabinets - this has worked great. A few items on the learning curve, but no real surprises.

Then this week I have tried using the jig and the same flush trip (or pattern bit, or template routing bit - lots of different names for this); the material this time was solid maple. I was cutting (hand held) about a 2" wide x 1/2" deep slot, 36" long. In attempting to do this I had the following sequence occur:

- the bit slip in the collet, (switched to another collet)
- the bit slip again, and the set screw fly out of the 'bearing holder ring thingy' (well I presume it did b/c it is no longer there; replaced it); switched to another PC 690 router
- the bit come out of the collet!!!!! No damage to me or really to project - (bit is toast, and collet was trashed)
So far two collets and two router have had this issue. So I
- bought a NEW bit and new collet
- had a repeat of all the above! New bit (tightened with HULK grip) came out of new collet in use within 3-4 minutes, and set screw was gone again!

Eventually I used a collar and a straight 1/2" bit on a 1/2" collet to hog out the waste (should have come to that strategy earlier!). Using this I was able to cut to depth, I just needed to flush up the sides of the groove. For that I now am the the not so proud owner of a new 3/4" cutter height top-bearing bit to 'flush up' the edges. THis bit worked for my needs today, but won't work for undersized plywood dadoes.

As I write this I think now that I was being too aggressive with the depth of cut; 3-4 passes for 1/2" deep cut. At the time I thought this was reasonable - 1/8" deep or so x 1/2" max (cutter diameter).

These are stopped cuts, so a Table saw dado set would not have been a good option - perhaps I should/could have wasted out a bunch with a track saw ?!?!?

Anyways - that's explains so of my disdain for 1/4" bits.
(NOTE - i have a 1/4" shank, solid carbide bit that I have used often to cut mortises many times) on the same router with the same collet.

Thanks for letting me vent!

 

[bainin]

Maybe some counter-intuitive help in Nicks video here ...I hope it helps , though I [prefer the 1/2 shank bits also !

 

[JimD]

I have also had bad experiences with 1/4 inch shank bits moving in the collet including at least one ruined project. So I use 1/2 now almost all time.

Worst example of the other thinking I have seen is in our shop at church. I volunteer there and the tools are mostly donated. There is a decent Kreg router table with a PC 7528 motor - with a 1/4 inch collet. I got a 1/2 for it but now I can't find it. There are two large sets of nice carbide bits with - 1/4 inch shanks. What a waste. They are not useless but are risky. They will probably work but why would anybody take the risk. And why would anybody put a 1/4 collet - and only a1/4 collet, on a 15A router motor? I've had a bit slip in my Bosch Colt. A 7528 could shatter a 1/4 inch shank.

 

[junquecol]

Man, it's been a bunch of years since I've seen Nick.

 

[Henry W]

Maybe some counter-intuitive help in Nicks video here ...I hope it helps , though I [prefer the 1/2 shank bits also !

Yup pretty familiar advice ... but does not explain how a NEW bit in a NEW collet slips? That was a big surprise.

 

[bob vaughan]

Years back Delta had a router bit slippage problem. Their solution: clean the bit shank with lacquer thinner or the like. Do the same to the collet bore. The last and most important detail: wipe the tapered sides of the collet socket with a little oil or graphite and don't let that stuff get in the collet's bore.

 

[Henry W]

Years back Delta had a router bit slippage problem. Their solution: clean the bit shank with lacquer thinner or the like. Do the same to the collet bore. The last and most important detail: wipe the tapered sides of the collet socket with a little oil or graphite and don't let that stuff get in the collet's bore.

Lube the socket but not the bore? Not sure I understand what is what here. Care to give any more details or explain the terms?

 

[bob vaughan]

Take the collet out of the router. Clean the socket the collet goes into (the end of the commutator). Wipe on just a mere trace of oil inside of that tapered hole.

 

[Rwe2156]

Henry, there’s no reason it should slip. If the bit fell out completely something is radically wrong. I use 1/4” shank bits all the time & yes, it’s happened, but I can’t even remember when.

Are you letting the bit bottom out? Hold it off the bottom 1/8” or so.

 

[Henry W]

Henry, there’s no reason it should slip. If the bit fell out completely something is radically wrong. I use 1/4” shank bits all the time & yes, it’s happened, but I can’t even remember when.

Are you letting the bit bottom out? Hold it off the bottom 1/8” or so.

Agreed - there is no reason......

One additional (critical?) fact I forgot to add when writing initially is that I I likely had this bit extended 'too far' out of the collet to get the depth of cut I needed. More than half the depth of collet was in contact with the shaft of the bit, and it certainly wasn't 'bottomed out (I'm aware of the potential bottoming out problem).
I expected more flex in the bit and a rougher cut - but not it to lose grip (or the bit entirely).

 

[Rwe2156]

Agreed - there is no reason......

One additional (critical?) fact I forgot to add when writing initially is that I I likely had this bit extended 'too far' out of the collet to get the depth of cut I needed. More than half the depth of collet was in contact with the shaft of the bit, and it certainly wasn't 'bottomed out (I'm aware of the potential bottoming out problem).
I expected more flex in the bit and a rougher cut - but not it to lose grip (or the bit entirely).

Yeah, I’d say that a critical fact.

One little trick you can do is take the collect completely off, insert the bit and find the maximum distance it can be exposed, and make a mark. As long as a little of the shaft is behind the bottom of the collect, it will bite.

 

[Henry W]

Yeah, I’d say that a critical fact.

One little trick you can do is take the collect completely off, insert the bit and find the maximum distance it can be exposed, and make a mark. As long as a little of the shaft is behind the bottom of the collect, it will bite.

Thanks DrBob!. I am uncertain that I understand (again).
You write "find the max distance it can be exposed..." How does one do that?
Hate to ask the dumb question but maybe there are others that can benefit from answers to my dumb questions.

 

[JimD]

Anybody ever had a 1/2 inch shank bit slip? I haven't. I've used them for a lot more cuts than 1/4 inch shank bits. There are things that cannot be done with 1/2 inch shank bits but where they will work, I don't see the point of trying to dot all the is and cross all the ts so the 1/4 inch shank bit won't slip. Twice the surface area definitely reduces the chance of a bit slipping.

In addition to the slipping risk there is the bending risk. I had a small panel raising bit bend during a cut too. 1/4 inch shank. I was not using a very powerful router nor was I taking a heavy cut but the shaft bent. Scary.

If it is not clear already, I do not like 1/4 inch shank router bits. Whenever a 1/2 is available, I think they are the wiser choice.

 

[Henry W]

Anybody ever had a 1/2 inch shank bit slip? I haven't. I've used them for a lot more cuts than 1/4 inch shank bits. There are things that cannot be done with 1/2 inch shank bits but where they will work, I don't see the point of trying to dot all the is and cross all the ts so the 1/4 inch shank bit won't slip. Twice the surface area definitely reduces the chance of a bit slipping.

In addition to the slipping risk there is the bending risk. I had a small panel raising bit bend during a cut too. 1/4 inch shank. I was not using a very powerful router nor was I taking a heavy cut but the shaft bent. Scary.

If it is not clear already, I do not like 1/4 inch shank router bits. Whenever a 1/2 is available, I think they are the wiser choice.

Pretty much my sentiment exactly Jim : "Whenever a 1/2" is available, I think they are the wiser choice."
Except in this case 1/2" shank bit was not (easily) available - I will report early next week how the 1/2" shank bit performs.

 

[Rwe2156]

I’m sorry but there is no more risk of slipping with a 1/4” shank.

Thanks DrBob!. I am uncertain that I understand (again).
You write "find the max distance it can be exposed..." How does one do that?
Hate to ask the dumb question but maybe there are others that can benefit from answers to my dumb questions.

I’m sorry guys there is nothing inherently different about 1/4” shank bits. It pays to clean up the shaft occasionally as well as the collect.

@HenryW —Simply put, I push the bit all they way til it bottoms out, eyeball how much is above the collect then pull it out just a little. You never want the bit bottomed out in the collet because the collet has to find it’s way down the taper.

You can mark the bit if you want then make another mark where you think the minimum would be in the collet.

Keep in mind collets differ brand to brand, on most if at least 1/2 the shank is in the collet you’re ok.

If you need more protrusion than that, you need to find another way, it’s not safe.

The first pic is bad - too much protruding, the second one is better.

 

[bainin]

"I’m sorry guys there is nothing inherently different about 1/4” shank bits."

I'll bite - wouldn't the total surface area in contact between the bit and the collet be roughly half for the 1/4 bit compared to the 1/2 (assuming the collet length is the same, the circumference is 2X for 1/2") ?

Wouldn't that affect the total friction possible between the collet and shaft?

I'm not sure I ever looked down the throat of the collet but it seems like a circumference clamping friction grip to me.

b

 

[Rwe2156]

"I’m sorry guys there is nothing inherently different about 1/4” shank bits."

I'll bite - wouldn't the total surface area in contact between the bit and the collet be roughly half for the 1/4 bit compared to the 1/2 (assuming the collet length is the same, the circumference is 2X for 1/2") ?

Wouldn't that affect the total friction possible between the collet and shaft?

I'm not sure I ever looked down the throat of the collet but it seems like a circumference clamping friction grip to me.

b

The reality is if it is seated properly and the collet tightened its not going to slip. Seems to me if anything you can crank a 1/4” bit tighter.

I have “a few“ routers. I’ve never cleaned a collect, but I have taken sandpaper to a few shafts.

 

[McRabbet]

I need to agree with DrBob. Clean bit shafts and collets are critically important and it is imperative to avoid having the bit bottom out. Of utmost importance, the junction between the bit and the shaft often has a small fillet transition that must be above the top of the collet (the collet cannot grip anything larger than the shaft diameter). I put a "space ball" (used in cabinet door rail and stile grooves to insure the panel floats) in the bottom of the router collet opening to help avoid bottoming the shaft. I tighten the collet nut securely using the wrenches provided by the manufacturer. I have never had either sized shaft slip in my experience and I've done lots of routing (I own 6 routers, some with just 1/4" collet capacity, others with both 1/4" and 1/2" collets). If you don't inert the bit correctly and tighten the collet properly, it will slip.

 

[tri4sale]

Anybody ever had a 1/2 inch shank bit slip?

Twice on my CNC. Really not sure what caused it. Could have been pushing it too hard, but 1/2" bit slipped and dug thru the board and into the spoil board, where it started to smoke.

 

[Henry W]

I’m sorry but there is no more risk of slipping with a 1/4” shank.

I’m sorry guys there is nothing inherently different about 1/4” shank bits. It pays to clean up the shaft occasionally as well as the collect.

@HenryW —Simply put, I push the bit all they way til it bottoms out, eyeball how much is above the collect then pull it out just a little. You never want the bit bottomed out in the collet because the collet has to find it’s way down the taper.

You can mark the bit if you want then make another mark where you think the minimum would be in the collet.

Keep in mind collets differ brand to brand, on most if at least 1/2 the shank is in the collet you’re ok.

If you need more protrusion than that, you need to find another way, it’s not safe.

The first pic is bad - too much protruding, the second one is better.

Bob
Agree on your pics - and that does describe my practices (in general at least). Honestly I suspect that I was not 'observant enough' or careful enough on the amount of protrusion I used. This case of a 1/2" deep dado in maple is far deeper and a tougher cut than my previous work doing dadoes into plywood - !/4' deep max.

Shaft was cleaned by the way - and as I said before, certainly not bottomed out.

Thanks for your advice! Thanks to all respondents actually.
Good reminders on what good practice for something as fundamental as loading a bit into a router collet.