Reducing end mill shank size

[tq60]

Buy the correct holder or collet.

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[gard]

Thanks for the additional information it confirms my suspicion that success with annealing may be iffy at best and take a couple of tries. My thought is if you have an endmill that is of no value to you otherwise, you might be able to soften it with a torch enough that your carbide will cut it. If the cutting edge is protected from the flame perhaps it will not be ruined so you could still use it on aluminum and plastic. In any case it could be an amusing thing to try. MrWhoopee's recipe suggest that success might use more acetylene than a new stepped down bit would cost but whats the fun in that? I have used a carbon arc torch on the arc welder for heating stuff, its probably less expensive than gas. My brief experiments with annealing truck torsion springs I found the "does a magnet stick to it trick" as a reliable indicator of how hot it needed to get, no idea how well that works for other alloys like HSS. After doing a couple you get an idea from the color but that changes depending on how bright the surrounding are. It is kind of cool that a magnet will stick to the steel at one spot, move it 1/4 inch and it falls off.

Another possible use is to use the end mill as a boring bar in the lathe.

 

[Flyinfool]

If you had not already cut it in half I would say sell it on ebay and buy what you need. I had bought a full pallet of misc tooling from a shop closing down. There were a bunch of big cutters that I have no way to use. I sold them one by one on ebay and put all the money into tooling I could use on my machines.

 

[tjb]

What type collets do you have? You can probably buy a 3/4" collet relatively cheaply without going through the hassle of modifying the end mill. And depending on the style collet, you may not need to halve your other end mills.

Here are a couple of examples on ebay:

3/4" R-8 Collet - European Brand | eBay

Note: The Collet pictured may not be the exact Collet that you will receive. Round Collet.

www.ebay.com

ER32 Collet - 3/4 in.

ER32 Collet - 3/4 in.

tormach.com

Regards

 

[Suzuki4evr]

they are harder than woodpecker lips

 

[markba633csi]

I borrowed "woodpecker lips" from another post- I confess

 

[Grinderman]

I don’t really have the means to hold temps for a long time to anneal the end mill so I thought I would try grinding it. I referred back to my copy of Backwoods edition/ Redneck engineering and came up with this plan. I had this Rotozip for a long time collecting dust so I used it. It actually worked quite well. I used up one stone and it took probably an hour to grind down to 1/2” from 3/4”. I ended up with a decent finish and a couple of tenths runout. Redneck engineering at it’s finest/worst! Total cost for the project was $6. Again the goal for this was to have a stubby end mill that would fit in a 1/2” collet/ER20. Thanks for all the relplies.

 

[Flyinfool]

Looks good from here, what ever works.