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So the 1/32' end mill I got from LMI snapped off the first time I used it, and I don't know that I want to try again at $15 per.

That'll teach me to try to route a purfling ring in mahogany.

Any thought on other options/sources?

Thanks in advance

Steve

What depth of cut were you pushing, and how fast were you spinning the bit?

Hi John, depth was 3/32" and speed was "too fast", I'm thinking

Steve

Remember, slow and steady, let the bit do the work. It's better to start shallow and make a couple or three passes, instead of trying to cut the channel all at once. I don't care where you get the bit from, if you push it, it WILL break. Really you should plan on it breaking and always try to keep a spare.

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Tim

Stew mac bits are too expensive. I do not use down cut bits, as a machinist /tool maker they will bind up a non cleared hole. These bits at this link are about 1/3rd stew macs price and will do a very good job. They are designed for high speed cutting. I use them at 70,000 rpm.
http://bqtool.com/cart/index.php check out square end mills , call them , they also carry a .020 bit.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

3/32 is too much depth of cut for a 1/32 cutter in my opinion. It it might not even have that much flute length. You're rpm is fine, faster would be even better like john does, you can feed it to fast though, this is probably the actual problem.
Try making you cuts in a few passes instead of one. It'll go better.

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Jim Watts
http://jameswattsguitars.com

Runout in your router (or dremel, or whatever rotary tool you're using) will also cause fine bits to snap.

Joe

Way way way too deep a cut, for a 1/32" bit!

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https://soundcloud.com/jeffreylsuits/he ... -runnin-13

Right, way too deep a cut. The usual rule of thumb is not to cut deeper than the bit radius, so you were six times that. In practice you can go deeper if you keep the cut tightly controlled (i.e., you have a jig controlling the router motion and go slow). And get upcut spiral end mills from one of the industrial supply places like MSC for half the price; less when they are on sale which is often. Downcut bits are not intended for slotting. They pack the swarf down where it can't escape. And don't get a longer cutting length than you need; it just weakens the bit.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.

Thanks everyone. Geez, at this pace, I'm going to run out of mistakes to make...nah, probably not

Steve

look on amazon.com ..I found end mill bits for 6.90 a piece for 1/32 and 5.40 for 1/16 bits..work great and very high quality!!

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MK5acoustics.com

I buy my skinny endmills on eBay at $10-20 per 10 pak. I've used mine a bunch in one year and have broken just one. Hope u have the Wells/Karol jig! The previous depth advice is excellent. Btw, these are mostly 1/8" shanks. I found a very good adaptor from Lee Valley, IIRC.

I would like to know more about how to buy end mills for working in wood. There's a big selection, and I'm at sea about what's the right type.

Is this the type you recommend from CET Direct, Todd?
14003 - 1/16"4FL CARBIDE EM $4.98

And Mike, what do you buy on eBay? The refurbished ones? How many flutes?

Any other suggestions from either of you or other experienced users?

Thanks very much

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Tim Allen
"Never hurry, never rest."

In general you shouldn't use 4-flute cutters in wood, they have no chip clearance and so you're much more likely to either burn the work or break the cutter depending on if it's too big to break or not

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Bob Garrish
Former Canonized Purveyor of Fine CNC Luthier Services

I dunno! I believe they are 2 flutes. Work great. Guess it makes sense they might be refurbished. Given our duty cycle, should not be an issue.

Well yeah....at 20,000 rpm that's true but I've used the same .03", four flute cutter for the last two years and have cut a mile of inlay with it using the following numbers.

Cutting a groove in bloodwood. First cut .005" depth...second cut .01" deeper.....all subsequent depth cuts adding .015"......rpm 4000.....10 ipm on the first and second depths....15 ipm for the rest.

The cutting bit is a standard carbide bit used for milling aluminum.

http://www.mcmaster.com/#four-flute-end-mills/=8r3qzj

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I read Emerson on the can. A foolish consistency is the hobgoblin of little minds...true...but a consistent reading of Emerson has its uses nevertheless.

StuMusic