Scary moment, router cutter snaps

[Wizard9999]

Just come in from my workshop after a bit of a scary moment. I was cutting a groove (dado?) on my router table in the side of a piece of oak, one of four pieces that are intended to receive a panel to form the lid of a box I am making. I was using a 6mm straight cutter which came as part of a set of six 1/2 inch cutters from Trend and the groove is a shade over 6mm deep. About a third of the way into the cut there was no resistance against the cut so I stopped the router and removed the piece I was working on. The cutter had sheared off the shank below the level of the table :shock: . I still haven't found the part of the cutter that sheared off and I suspect it has dropped into the router / table.

Clearly I am extremely glad the cutter did not have the scope to take off into the air at a possibly deadly velocity. Having gathered my composure I wanted to get some thoughts on the cause. My initial guess is that by cutting a groove the same depth as the router cutter is wide I pushing the cutter way too hard. Should this have been done in 2 or even 3 passes?

I'd like to learn my lesson and not repeat this!

Terry.

 

[Steve Maskery]

It's easily done. 1/4" cutters are quite vulnerable and grooving is quite a demanding procedure because there is virtually no clearance for 50% of the circumference.
Next time take it easy. 3mm at a time is enough.

Today I've been doing raised panels. It's a 1/2" shank, so very much more robust, but even so, I've been taking passes of no more than 1.5mm. In this case it is because even at 1.5mm, that is still quite a lot of wood, given the 3" or so diameter of the cutter.

Nice and steady, eh?

 

[Wizard9999]

Thanks for the advice Steve and also thanks for not making me feel like a complete idiot .

Terry.

 

[MotamJoinery]

I had a similar experience, was routing dados and the bit broke and went flying into the window. It could have easily been a serious injury.

I learnt my lesson and also invested in Groove cutter (Wealdon Tools do good groove cutters)

 

[skipdiver]

If they came in a set, are they the professional range? I have a Trend router cutter set that is classed as a starter set and wasn't that dear. You can get a 15 piece Trend starter set for £40, so they are not going to be the best metal. I only use them now and again if i am out on a job and just need to 'v' something or round over a shelf, stuff like that. I wouldn't use them for heavy duty table or repeat work. Just a thought.

 

[paulm]

Using a slot cutter bit allows better waste clearance from the slot and won't break like a narrow straight cutter might Terry, but failing that then as Steve says half of the cutter diameter or even a third as the depth of each pass, and moving the wood slowly to allow time for the waste to clear will help.

 

[pcb1962]

Using a slot cutter bit allows better waste clearance from the slot and won't break like a narrow straight cutter might Terry,

I was about to suggest the same, I have this set which I probably paid half that price for, worth looking out for next time they have it on offer.

 

[custard]

For narrow grooving on a router table, in order of preference I'd use,

1. Up cut spiral bit (clears the waste, sheering action delivers decent quality cut, but expensive and not available in really small sizes)
2. Slot cutter (robust with virtually no risk of snapping, separate arbour allows combination/multiple cuts, but difficult to guard as requires a big gap in fence or an inconvenient false fence, cut accuracy can be poor with some cheaper brands, and the cut quality can be a bit rough)
3. Straight cutter (cheap, huge range of sizes, but fragile and slow, may need a second cut to clear packed in waste)

 

[Wizard9999]

Lots of really helpful advice guys, very much appreciated.

I followed some previous advice when staring out and buying my first cutters. It was suggested I buy a cheap set and then replace the ones I found I used most, I got it wrong earlier it was not a set of six but this set of 15 https://www.trenddirectuk.com/set-ss9x1-2tc.

The slot cutting bits loo far more substantial and I understand what is meant in terms of the waste being dealt with better. In this instance two of the slots are stopped, if I used a slot cutter for those presumably it would be more difficult in that the radius of the cutter means you would need to chisel out part of the slot to make it usable? Does that make sense?

Terry.

 

[skipdiver]

Lots of really helpful advice guys, very much appreciated.

I followed some previous advice when staring out and buying my first cutters. It was suggested I buy a cheap set and then replace the ones I found I used most, I got it wrong earlier it was not a set of six but this set of 15 https://www.trenddirectuk.com/set-ss9x1-2tc.

The slot cutting bits loo far more substantial and I understand what is meant in terms of the waste being dealt with better. In this instance two of the slots are stopped, if I used a slot cutter for those presumably it would be more difficult in that the radius of the cutter means you would need to chisel out part of the slot to make it usable? Does that make sense?

Terry.

Yes, that makes sense. If you want to carry on with the same kind of bit, buy one from Wealden that's better quality and take your time when using. I have thought about buying some of the spiral bits as Custard suggest but have not tried them yet, so can't comment.

 

[andersonec]

Had the same thing happen to me but it was a very thin spiral bit, it dropped into the router and cost me sixty squids to get it removed and to repair the router, i now have a piece of thick (ish) plastic mesh positioned on top of the router (below the collet),,,,,just in case.

Andy

 

[Mike Jordan]

For 6mm grooves I have found that solid carbide single flute cutters are less likely to break in use. The type which have two carbide edges brazed into then are very prone to breakage so I never touch them. The single drawback to the solid carbide apart from only one cutting edge is that they are noisier in use.

 

[Wizard9999]

Lots of really helpful advice guys, very much appreciated.

I followed some previous advice when staring out and buying my first cutters. It was suggested I buy a cheap set and then replace the ones I found I used most, I got it wrong earlier it was not a set of six but this set of 15 https://www.trenddirectuk.com/set-ss9x1-2tc.

The slot cutting bits loo far more substantial and I understand what is meant in terms of the waste being dealt with better. In this instance two of the slots are stopped, if I used a slot cutter for those presumably it would be more difficult in that the radius of the cutter means you would need to chisel out part of the slot to make it usable? Does that make sense?

Terry.

Yes, that makes sense. If you want to carry on with the same kind of bit, buy one from Wealden that's better quality and take your time when using. I have thought about buying some of the spiral bits as Custard suggest but have not tried them yet, so can't comment.

Yes, looking at the Wealden site. unfortunately they do not do. 1/2" shank 1/4 spiral up cut bit as far as I can see. But even a std traight bit will no doubt be far superior tan t one I was using.

Terry.

 

[skipdiver]

Just had a look at that set you linked to and it's the same as the one i have. I bought it to stick in my toolbox to take out on jobs and it gets very little use. I have had it about ten years and i haven't taken half of them out of the box yet. It's just used as a standby to give me a lot of options out on site. I wouldn't trust them for heavy work in a table.

 

[skipdiver]

There is one on there. £22.50

http://www.wealdentool.com/acatalog/Onl ... t_229.html

 

[Wizard9999]

There is one on there. £22.50

http://www.wealdentool.com/acatalog/Onl ... t_229.html

Thanks for looking for that Steve, but the £22.50 one I can see is 1/4" shank and 1/4" cutter, I need 1/2" shank and 1/4" cutter.

Terry.

 

[custard]

I need 1/2" shank and 1/4" cutter.

Terry.

You can get that combination as carbide spiral bits, not at all common but one or two manufacturers do 1/2" shank with cutters that are less than 1/2",

https://routercutter.co.uk/solid-carbid ... routerbits

I use them for morticing, grooving, housing joints and all sorts of jobs...guess there's always a first time but I've never snapped one yet!

 

[custard]

Incidentally, they're the UK distributor for Whiteside, who are a kind of American Wealden. Excellent kit, and the UK distributor must have trained in Japan because the way they package the orders up is a work of art!

 

[Racers]

I have snapped a couple of the cheap 1/4" cutters in the past its east to do.
I have a solid carbide (cobalt) slot drill that seems to be unbreakable and unbluntable, its like this but solid carbide.

http://www.ebay.co.uk/itm/PRESTO-HSS-SL ... Swxg5X0qPq

Pete

 

[skipdiver]

There is one on there. £22.50

http://www.wealdentool.com/acatalog/Onl ... t_229.html

Thanks for looking for that Steve, but the £22.50 one I can see is 1/4" shank and 1/4" cutter, I need 1/2" shank and 1/4" cutter.

Terry.

Yeah, my mistake. Wealden cutters are generally excellent though, so the fluted cutters should perform well. Have you not got a collet reducer?