Router Bit Breakage

[wobblycogs]

I was just routing a dado for the bottom of a box and my bit broke. I'm pretty new to routing so I was wondering if this is a common occurance or whether I was doing something wrong?

The piece was pine and I was routing an 8mm deep dado with a 1/4" straight bit (1/4" shank) the speed was set to max as per the instruction manual. The bit has snapped / sheared off just about the cutters where the stem necks in. I had completed a first pass at about 4mm and was about half way through the second pass at 8mm when it broke.

I don't believe I was pushing the bit faster than it could go - having watched plenty of videos on routing I think I route rather slowly but until I'm confident with routing I'd rather be slow and safe. I don't feel the bit had been used that much but it has perhaps been used for a couple of jobs where a bigger bit should probably have been used.

This time the end of the bit just fell harmlessly away and stopped spinning almost immediatly but I did have visions of what might happen if the end had somehow come in contact with the rotating shaft (especially after looking at some of those table saw accident pictures). I was wearing a full face mask at the time but is there anything else I could do to avoid accidents?

 

[miles_hot]

Did you have the bit into the collet the required amount? There is often a line on the shank of the bit showing the max extension possible with the bit.

I had a 1/4" bit break off because I'd put it in a little too far out - I was getting frustrated with the lack of reach in my big dewalt - trimming the side of a cabinet down using a straight edge, goggle one, looking down on a router (held horizontally) - changed stance a little to look at the line and there was a ping, flutter, crash sound and the bit was gone. Found it a week or so later stuck about 6mm into the wood 18' away. The exit path would have been through my head had I been looking down on the bit at the time. I change to 1/2 cutters which are fantistically stronger and never, ever exceed the line now! nice thing about the 1/2" bits is that they're longer so I don't have the same issue that caused the problem in the first place!

Miles

 

[RobertMP]

I don't claim a huge experience of router bits but I have had a few 1/4 in break in the past. My conclusion was you get what you pay for - cheap bits break quicker. If I do use a cheap bit now I will always take light cuts of 2mm or less. A decent make like Trend I'll use the notches on the triton router adjuster for incremental depth cuts. each notch is about 3mm.

I've never had the broken part come flying out at me but thinking about the possibility is a good reminder to wear eye protection at the very least.

Feed rate I tend to judge by feel,sound and how the part comes out. Guess 2ft of 1/4" x 3mm deep might be about 5-10 seconds.

 

[Lord Nibbo]

I have had a few 1/4 in break in the past. My conclusion was you get what you pay for - cheap bits break quicker.

Got to agree, I've broken a few cheap ones within minutes from new. But one I paid more than £20 has been in constant use for years.

 

[wobblycogs]

Thanks, I am happy that the bit was in deep enough although this particular bit doesn't have a depth line on it. I had all but 2 or 3mm of the shaft held tightly in the collet.

The bit is from a selection pack of Faithful 1/4" bits. I don't know the quality but I don't except they are great. I was out of work when I bought them so price was the number one concern.

Sounds like a combination of a cheap cutter and perhaps a slightly too deep cut. Lowering the depth of the cut is a pain as the turreting on the router is about 3 to 4mm a step, will have to do that manually I suppose.

 

[9fingers]

I think there is a place for sets of cheap router bits with a range of profiles for hobby/light use (and I don't mean the bin!!) BUT for regularly used bits such as straight cutting, a few quality bits should be considered.

I find Wealden bits offer a very good compromise of quality and price with excellent service too.

Bob

 

[Racers]

Hi, wobblycogs

Try one of these http://cgi.ebay.co.uk/SINGLE-FLUTED-1-4 ... 2ea542336f
I have had the same problem with 1/4 inch cutters I snapped two in a afternoon doing 2mm passes in birch ply, but since getting a milling cutter like the one above no problems.

Pete

 

[Racers]

Hi,

Just read the discription they are Down Cut so they aren't that good try this one
http://cgi.ebay.co.uk/Galtona-1-4-Slot- ... 518b00f3cd
Or any of the 1/4" ones here http://shop.ebay.co.uk/i.html?_nkw=1%2F ... &_osacat=0

Pete

 

[9fingers]

Pete,

Have you used HSS milling cutters in a router successfully?

My experience has been that they soon loose their edge and then burn.

Your first link (allbeit the wrong cut direction) was for solid carbide which I believe would work OK and withstand the heat/abrasion of wood.

Bob

 

[Benchwayze]

There's an argument for getting an 8mm collet (Trend probably supply one for their routers) Using the 8mm shanked cutters reduces vibration, which can be a cause of bad cuts, dulling and breakages. I know it means buying more cutters, but buy them as you need them. Don't go anywhere near these boxed sets unless they are by a reputable maker.

Never had problems with Wealden or Titan cutters.

HTH

John

 

[Racers]

Hi, 9fingers

I use them all the time they don't last as well as TCT cutters but when sharp they cut very well. I did a load of solid oal worktops and only used 2 cutters (4 ends undermount sink hole etc) a quick tickle up between cuts helped.

I also have some Cobolt cutters and adaptors that work very well and are lasting a long time.


Pete

 

[9fingers]

Pete,

I'll have to give them another try. I once tried a 'Throw away' type (Clarkson FC3) slot drill on timber and it just did not last more than a few feet.

I do a lot of work in metal so have loads of cutters. Will have to experiment.

Thanks

Bob

 

[Chems]

I don't think you need to be on top speed either, for a small bit it puts out to much torque. I bent a Trend bit in my Triton by doing this.

 

[wobblycogs]

Thought you might be interested in an little follow up. I bought myself the four box of 1/4" CMT bits that Axi currently have on offer.

I checked out the 1/2" bits as well but Axi didn't stock the size I needed in 1/2". Wealden only missed out because I needed some other stuff from Axi.

As suggested I knocked the speed down a notch and took it steady but using a quality bit really makes all the difference. Until I fired up the router with a decent bit in it I hadn't realized how smooth running it is, there is absolutely no vibration now and the cuts have an almost mirror finish with no burning.

Many thanks for the advice. I broke the original bit on my secret santa gift and I've been really itching to get on with it.

 

[Mr Ed]

After breaking about 4 bits in 2 days making some doors about 10 years ago I realised that 1/2" is the way to go. Better quality bits also help, but I bet virtually no-one has snapped a 1/2" bit, whereas most of us have snapped a 1/4" one (or ten)

Ed

 

[big soft moose]

After breaking about 4 bits in 2 days making some doors about 10 years ago I realised that 1/2" is the way to go. Better quality bits also help, but I bet virtually no-one has snapped a 1/2" bit, whereas most of us have snapped a 1/4" one (or ten)

Ed

we snapped a half inch straight bit the otherday - grooving in an oak post, it didnt go flying off it just popped and sat in the hole it had made in the post.

I think we were trying to higher a movement rate and it was geting too hot - either that or it was just defective - it was out of an axminster budget 1/2 " set

(for clarity we didnt break the shank - it was about halfway down the cutter bit that broke.)

 

[jimi43]

Thought you might be interested in an little follow up. I bought myself the four box of 1/4" CMT bits that Axi currently have on offer.

I checked out the 1/2" bits as well but Axi didn't stock the size I needed in 1/2". Wealden only missed out because I needed some other stuff from Axi.

As suggested I knocked the speed down a notch and took it steady but using a quality bit really makes all the difference. Until I fired up the router with a decent bit in it I hadn't realized how smooth running it is, there is absolutely no vibration now and the cuts have an almost mirror finish with no burning.

Many thanks for the advice. I broke the original bit on my secret santa gift and I've been really itching to get on with it.

Reading through this thread I was just about to say that the "Faithful" brand is a cheap (I think Chinese) box set and they are not very good at all...they dull so quickly, burn easily and as you can see, liable to snap. NOT GOOD!

I spent more than I did on my first router on a CMT bit at Poolewood (before they shut their shop)...about £30 I believe and I still have it...it cuts beautifully and is clean as the day it came out of the box.

In bits as in saw blades as in tool stock...you get what you pay for.

Glad you chose CMT...I love them but I got a Trend bit for 10p at a bootfair and that one is a gem too! Tiny little bit that does a wonderful job for very small channels.

Jim

 

[Titmantiptoolsltd]

Router tool failure is caused by many reasons but the main ones are
Collet Wear
if cutter the shows signs of 'fretting' brown marks on the shank of a router cutter are a sign of worn collets. The brown stain is caused by vibration that occurs during the cutting cycle.
The collet fails to grip the shank correctly and causes the vibration.
The vibration , if aloud to continue will cause the tool to shear.

The only solution is to replace the collet.

Collets should be kept clean and free from resin, use brass collets brushes each time to remove the tool.

Application

This also could be caused by application, IE Not using the tool correctly -50mm loc and only using the bottom 4-5mm of the tool.

Tool
And as some have mentioned, you do get what you pay for. but if you only have say a run of 2 metres why would you pay the earth. so it is worth weighing up.

its easy to blame the tool when all goes wrong.

regards

Titman

 

[Benchwayze]

It hasn't happened to me yet, and maybe that's because I have more than one router and a few spare collets.

All the same, I gave up serious use of 1/4" shanks some time ago, and where I can I use the 8mm shanks. Gradually I am replacing the cutters as I need them. Still, we never knows when a cutter will shear, so Thanks for that InfoTitman Tools.

John

 

[jimi43]

I must say that I am a little worried about some aspects of the "cheap" tool market.

From a safety point of view, although I am sure that some standards are met and adhered to by importers of cheap bits from the East...I think that some of the steel and manufacturing processes leave a lot to be desired.

It doesn't matter if your crappy screwdriver tip you bought in the market shears the first time you try to take out a screw....or that a screw snaps off when you drive it in but it DOES matter when a tip parts company with a shaft at high speeds experienced by routers.

The same applies to TCT tips on circular and table saw blades...

The market most at risk is the Sunday DIYers....often they buy a router and don't understand the concept of small passes...in the right direction...that sort of thing. In these environments even the best cutters are put under strain but with the cheaper bit...well anything could happen.

Feed speeds are paramount as well...too aggressive and the bit can break under strain, too slow and it may heat up with the stock and compromise the treated steel to make fracture possible in the future.

The point about collets is very well put. Cheaper machines (the £20 special at the department store) may indeed have poorly machined or asymetrical collet geometry at the outset which, coupled with poor bit shank machining could lead to the bit coming out even when new.

Routers are precision machines and therefore need precision manufacture in my opinion. Yes...you can "get by" with cheaper versions...and some may be spot on like my old NuTool 1/4" that has done much service...but generally speaking...and knowing what I know now...I wouldn't risk it...for safety AND quality of finish reasons.

Jim