Last night one of my endmills started to become covered with a black sooty coating. It's a solid micrograin carbide endmill. I can smell it burning as it cuts, and it's producing very poor cuts. It still feels sharp.

Is it time for the endmill graveyard, or is there a way to clean it?

Should I be using something besides solid carbide for better endmill life in wood?

Use a blade or bit cleaner like this http://eagleamerica.com/product.asp_Q_pn_E_400-0027

Try slowing down the rpm, and increasing the feed, if possible. And try to always ramp into the cut, never plunge if possible. Plywood is very tough on bits, so clean them often. Preferably before you smell the burning. :)

Do you mean you are using milling machine end mills designed for metalworking?

Do you mean you are using milling machine end mills designed for metalworking?


Yeah. I'm using solid micrograin carbide endmills. I guess they're normally used for cutting steel? They seem to work fine on wood for the most part. A tool/die friend suggested I get coated endmills as they may be a bit sharper.


Thanks for the link Gerry. I'll have to order some and try it out.

I have used EZoff oven cleaner on saw blades with good results to remove resin build up.

I too am concerned with using bits designed for metal on wood. I always have used bits designed for wood when cutting wood, but have seen others on this site use endmills designned for steel. (?)

Steve

Although they are more expensive, you should get better results using spiral bits designed for wood. They have diferent geometry and more chip clearance.

Also, just a guess, but I doubt coated endmills will make much difference.

If cheap metal cutting endmills give acceptable results, there's no reason not to use them. You'll find that even good quality spiral bits for wood will still gum up fairly quickly cutting plywood, especially at the lower feed speeds used on homebuilt machines.

Try using HSS endmills. They work good on wood and plastic and are much cheaper than carbide. Carbide endmills are more for metal working. Coating the endmill will not help you. Your just wasting your money. Coated endmills are more for very hard metals or abrasive materials or to avoid tool wear on very long production runs.

HSS will not last long at all cutting wood. But feel frre to try it for yourself.

Yeah... HSS dulls really quick in wood...

I've been using 2 FLute aluminum cutting endmills they have different flute geometry than your generic end mill. And coincidently are identical to the eye to say a Freud up-cut spiral router bit. Except the Freud bit is about $18 and the endmill is about $7 from Enco.

And if you are burning you definitley need to slow your spindle down or increase your feed rate. Heat wrecks the endmills, At 30ipm feed rate I run my router around 13k rpm
and never have a problem with burning in Plywood or MDF. In the plywood check your sawdust that you are creating... Is it dust or little chips? You want to make little chips not dust.

Standard carbide endmill can work ok in some woods.Usually two flute enmills work fairly well.They are designed to cut metal and the tool geometry is different than a routerbit.Anoel, I will look into those enco cutters. Frued bits are way overpriced.

I use a lot of metal cutting endmills as router bits on the CNC router - they work great and are often much cheaper than router bits of similar design. HSS will dull too quickly to have any cost advantage.

As mentioned, keep your feedrate high enough where you are getting chips, not dust. Sometimes you would be surprised how fast you should be cutting and how well it works! Don't be afraid to take roughing and finishing cuts if you are looking for a good finish.

Keep the tool bits clean - this is critical. If cutting manmade materials (plywood-MDF, etc.) the glues will bond to the cutter slowly. When cutting hardwoods (or any real woods) the pitch will build up on the cutter slowly. As some point there is enough "Gunk" on the tool where the buildup increases dramatically, and very quickly. Once this starts to happen the tool overheats and is generally ready for a re-sharpen - yes overheated carbide can be resharpened.

Don't wait for the build up to become a problem - clean the end mills frequently. If you look at the land (the flat looking area just behind the cutting edge of the flute) you will see the build up starting, once you see something there, clean the tool. I have found that if you soak the tools in a cleaner called "Simple Green" it will remove the resins pretty effectively.

This product isn't nearly as nasty as oven cleaner or some of the other application specific chemicals that are out there. I keep some in a coffee can (nearly full) for this purpose. However, I also clean other woodworking tools in the same can. If you have a drum sander you probably have learned that they too build up with pitch pretty quickly. If you soak the rolls of abrasive cloth in the coffee can over night, then rinse it off with water, the resin is gone as well and the belt looks like new again and are ready for more abuse (opps, meant use).

Primarily though two things help a lot...

1) Feed fast enough that you are cutting (the same is true in metal working, if you cut too slowly (feed rate) you will rub the tool dull).
2) Keep the tool clean - remove the pitch before it builds up

Chris

I have to say what Cris D has said is mostly what I have done with good success and I have picked up a few pointers.