Broke Bosch Router Bit

[jimsto2]

I have broke TWO bosch router bits today, from Lowe's! They were 1/4" straight cut mortising bits, both 1/4" cut & shaft dia. I was making 1/8" deep cuts in the bottom of a 30"X24" piece of maple butcher block workbench top. I was making 2 slots across the 24" width in multiple passes for a total of 7/8" deep. I assumed the first bit was weak but after the second break I guess it is me. I have not used many 1/4" bits in the router and I was moving pretty slow. I will but another brand next time, cut shallower & slower. Any suggestions?

Milwaukee 1.75hp fixed base router
Bosch 1/4" diameter, 1" CL, 2 flute bit.

Thanks for your insight.

Jim :icon_scra

 

[WoodWrangler]

It's not the brand, it's the size. I've broke many of the 1/4" bits (and posted some of those out here, I believe). Not fun. Just gotta keep the cut really light.

Recommendation: Get a solid carbide spiral bit. Never broke one of those!

 

[Canuck]

You may also want to try an upcut spiral bit. They will clear chips faster than a straight bit and possibly reduce some of heat generated that I believe weakens the bit a bit. (In my limited experience anyway.:embaresse)

I also try to use 1/2" shank bits whenever possible.

Good luck (I know bits ain't cheap and you want them to last more than one project.)!

Wayne

 

[mkepke]

A couple thoughts...if you can use another tool to remove some of the waste, you can reduce the loading on the next router bits you need to buy. For example, can you make a couple plunge cuts using a circular saw ?

Another suggestion would be simply to switch to a HSS spiral bit. An upcut spiral is a much more efficient design for cutting mortices. I used a cheapo HF bit to make 80+ 1/2" deep mortises in walnut..and I didn't baby the bit with 1/8" cuts.

-Mark

 

[Travis Porter]

Seems like an inferior quality bit to me. I would take them back and get a refund. Taking a 1/8" pass in hard maple should not ruin a bit like that. Still, I agree with upgrading to a spiral bit. You won't regret it.

 

[MrAudio815]

A 1/4 bit shank on Hard maple is not good, you probably heated up the bit quite a bit, especially if you didn't give it a rest after the first pass and then with all that heat it failed and broke.

If you are going to continue using the 1/4 shank, then try doing light cuts and giving the bit a break to cool down.

Otherwise go with a 1/2 shank. MLCS is a great place for the average woodworker on their low end bits that is. I have this set, and they have worked GREAT~! http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/set66.html

 

[Dragon]

+1 for MLCS. I've ordered from them twice now and will do so many more times I'm sure. The first bit I bought from them I've already used to the point it just wasn't cutting. After a post on here I went and bought a diamond hone and slicked it right up again. It'll get used this afternoon, (pics to follow), and we'll see how well I can hone a bit.

Compared to the 1/4" shank bit I have from Lowe's, far superior even though the 1/2" shank bit from MLCS was wayyy cheaper than the one at Lowe's. You may wish to call them "lower end" bits and compared to the prices from such as Freud and Amana, they are but I find the quality to be right up there. Even though it's been a few years since I last used a router, I have no complaints with MLCS and their customer service and free shipping are definite pluses in my book.:icon_cheers

 

[jimsto2]

Well, it must be something I'm doing wrong!!!:BangHead:

I bought a Whiteside solid carbide 1/4" shank and diameter 1" cut length spiral upcut bit and broken it 3-1/8" into the next pass still making 1/8" deep passes.

I'm moving slow but not slow enough I guess! I just need to complete this pass and one more to finish. This has been a frustrating process.

Jim

 

[Travis Porter]

What brand and model of router are you using?? Are you sure it is an 1/8"? Are you getting any burning? How much of the bit is in the collet and how far out is the bit extended from the collet?

 

[Mike Davis]

Are you using guides on both sides of the router?

Or a jig of some kind?

It may be a streak of bad luck but, I'm wondering if there is something else going on.

 

[Dragon]

:dontknow::icon_scra Got me Man. I'm no pro at routing for sure but it does sound like there's a malfunction at the junction somewhere either in your tool or your process. I dang near wore out a 1/2" shank bit this afternoon and nary a blip out of anything. Threw shavings and chips dang near to the neighbor's house in the process.:rotflm:

 

[jimsto2]

I am using a Milwaukee 1-3/4HP single speed, 24,000 rpm router in the fixed base. Got it new for Christmas. I do have guides clamped on both sides of the router, they have not been removed since starting the groove.

When the last bit broke I was removing 1/8" of wood but I was at a total depth of 3/4". I'm setting the depth each pass by hanging the bit over the edge of a workbench and measuring with a metal rule.

The only observation I have is that the Whiteside bit was not perfectly centered in the groove that was started with the Bosch bits. However, it was off by only a hair more than 1/64" by my Starrett ruler! So, the bit was cutting that amount the whole 3/4" depth on one side plus the additional 1/8" in the bottom.

Thanks for all the help & advice.

Jim:dontknow:

 

[Dragon]

Well.........if your feed speed is slow enough that you're letting the bit do the work and not yourself, then my only suggestion would be to go with a 1/2" shank bit. It does sound like the side loading couple with the bottom load is over stressing that little 1/4" shank. Not to mention just the thought of a router bit breaking at the speeds those things turn at gives me the heebie-jeebies.

Have you noticed or felt any chattering at any time during the cut? Theoretically, the bit should turn smoothly while cutting with no perceptable chattering or binding. I know that maple is hard stuff and does wear on the cutting edges pretty quick.

 

[MrAudio815]

Well, it must be something I'm doing wrong!!!:BangHead:

I bought a Whiteside solid carbide 1/4" shank and diameter 1" cut length spiral upcut bit and broken it 3-1/8" into the next pass still making 1/8" deep passes.

Jim

Jim your going to be spending a lot of money if you keep buying those 1/4 shank bit's. :tongue2: Plus who knows where that next bit flies? It may just hit you and put a nice size hole in you. :saw: At those speeds, That is just SCARY~! Also do 1/4" shank bit have a rating of 24,000rpms?

Buy a 1/2" shank, and you'll never go back at least for major stuff like that. I really don't want to be reading one of your post...."Hit by a Router bit" :no: :no: :no:


Pictures would also help us to help you figure things out~!

 

[ehpoole]

Gheez, I disappear for a couple months (December and January are usually bad months for me) and I return only to discover everyone's destroying their new toys! :BangHead:

I use my routers quite a bit and can honestly say the ONLY bits I've ever broken were 1/16" mortising bits... I've overheated a few others, worn out yet more, but never broken any other bits.

That said, I am a firm believer that a router bit and its router should be matched properly. If you are chucking a 1/4" mortising bit (especially a deep 1/4" bit) in a large 3-1/2 HP plunge router and hit a hard section of wood, the mass of the router is just going to carry that bit straight through that hard section with very little detectable resistance to the operator. As a result, you won't slow down your feed rate and are in effect force-feeding the bit.

On the other hand, chuck that same bit in a 1HP Colt Palmrouther or laminate trimmer and you will immediately notice the extra resistance and slow down until you are through the the hard section and in the clear once again.

As for questions regarding RPM ratings for 1/4" bits, most small diameter 1/4" bits are rated for 30-35K RPM, it's only as the diameter increases that the RPM ratings will decrease. I'm not sure using a 1/2" shank 1/4" mortising bit would help appreciable because ALL of the shearing force in such a bit is inevitably focused at the collar where 1/4" bit meets 1/2" shank, rather than evenly distibuting the same force over the entire length of a 1/4" shank bit. The 1/2" shank bits truly shine when you are working with bit diameters greater than 1/4".

I would agree that Spiral bits (so long as they are up-spiral) and up-shear mortising bits (Freud and Whiteside both have some selection of up-shearing bits (the carbide cutters are angled with regard to the shank rather than parallel). Just avoid down-shear and down-spiral bits as these will only pack your dado/groove with waste.

 

[jimsto2]

Matthew,

This is the only 1/4" bit I have bought. However, I don't know if a 1/2" shank would help since it would just neck down to a 1/4" at the cutters anyway. But, I looked for a 1/2" and they didn't carry any at Lowe's or Woodcraft. The Whiteside spiral bit was chucked to about an 1/8th above the top of the flutes and broke off clean at the bottom of the chuck. I will go very very slow with the next bit.

Thanks again for the input.

Jim

 

[SubGuy]

Something doesn't sound right.:icon_scra I've cut hard maple with my 1 3/4 hp Skil. I used a straight bit a cut 1/4" inch out of 2 edges 42" long. I used only 1/4" Bits and the board was 1 3/4" thick. I made 2 passes and went slow. Maybe, your not turning fast enough (RPMs) and not clearing enough wood chips compared to your feed speed. Can you post a pick of the end of the break? I would like to see what the metal looks like after shear. That may help diagnose your problem. Seems like the only things we can rule out is that your bits are ok. Maybe your technique, your router or the wood is the problem.

 

[NCPete]

Zach brings up a good point, what speed were you turning that bit? I suppose I should some day read the owner's manual (does anyone but Norm actually do that?) to my routers, but I tend to turn the speed up to max when turning a bit like you describe, and then let the chips fly!

 

[jimsto2]

I've returned all the bits, so no pics. The last one broke at the collet smoothly. My router is fixed speed at 24k rpm.

I must assume that I was moving too fast. I'll let you know how tonights re-try works out. I'm going to go very slow & shallow.

Thanks, Jim

 

[jimsto2]

Well, I finished my grooves. :eusa_clap

I just cut the last 1/4" in five ultra slow passes.

Thanks again for all the advice.

Jim