# Older used endmill will not fit new endmill holder;



## ome (Dec 23, 2013)

Hi guys,
what is the best way to get a stubborn endmill into a new endmil holder. 
They are a 3/4 " shank and a 1.25" shank used that seem to have no burrs. 
Can i use a wire wheel on the grinder or use a 3m pad red or green?
thanks,
Jon


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## Ray C (Dec 23, 2013)

Jon,

Do an inspection to make sure there are no dings at the mouth of the endmill holder and double check there are no burrs on the endmill.  Make sure both parts are stabilized at the same room temperature.

After that, put a muslin polishing wheel on your bench grinder and a very light amount of fine polishing grit.  (Being careful to not cut your fingers) polish the shank of the endmill.  You might have to let it cool off before trying to fit it.

If you touch a grinding wheel to the shank, I can all but guarantee you'll ruin it.


Ray


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## ome (Dec 24, 2013)

Ray C said:


> Jon,
> 
> Do an inspection to make sure there are no dings at the mouth of the endmill holder and double check there are no burrs on the endmill.  Make sure both parts are stabilized at the same room temperature.
> 
> ...




Thanks Ray,
will a wire wheel ruin it as well?     For the muslin, better to use the faster speed grinder.?
3450 rpm. 
How do i clean or polish the endmill holders, they are R-8 endmill holders.


thank you , in advance for all the info that you share. 
Jon


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## astjp2 (Dec 24, 2013)

If there are no burrs, try a simple ball hone on a drill, it will take a few tenths off the inside of the holder with little effort.  Tim


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## george wilson (Dec 24, 2013)

I had a new end mill holder that just would not take a 1" endmill shank. Must have been a tenth too small. I had no real way of dealing with it properly at the time. No tool post grinder. I said the heck with it and just chucked the blasted thing up,backed away the set screw,and took a very light pass with a carbide boring bar. Just VERY luckily,it happened to work perfectly!! I was simply lucky that the dust I cut out of the hole with the carbide boring bar was exactly enough to make it work!!

I don't advise you try this. I was just disgusted with the holder at that time,and did not care if I ruined it. Strictly good luck. The silly thing even ran true!


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## Frank Ford (Dec 24, 2013)

george wilson said:


> Strictly good luck. The silly thing even ran true!



I'm not so sure about that being a matter of luck - you may have luck, but it's quite clear you have the skill, and skill sometimes masquerades as good luck. The more we do and the better we get at our craft the better our luck, I think.  We just don't make those old mistakes even though we're unaware of even thinking about some details.

Truing things on the mill is a great way to keep concentric.  I always take the final pass on the mill rather than the lathe when I'm making a slotting saw or other arbor.  It's the only way I can do the job without spending all day with dial indicators and micrometers.   Just made a dedicated R8 stub  arbor for small cutters with 5/8" holes. Even working between centers on the lathe, I didn't have the confidence I'd get it right, but by mounting it in the mill quill and using my AXA tool holder in the mill vise, I had no problem at all getting things right on.


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## Ray C (Dec 24, 2013)

I'm just not sure about a wire wheel so, in using that... Caveat Emptor...

When you want to take tenths off (or fractional parts thereof) polishing wheels are the way to go.  As for the bore in the endmill holder, I wouldn't mess with that until you discover that several other endmills won't fit.  That's a pretty good case stating the endmill is at fault.  Anyhow, same deal...  Take a wooden stick, chuck it in a drill chuck, wrap some cloth on the end, slather it with grinding compound and have at it.  Go easy, rinse it well, let it cool to room temp and test the fit.  Repeat until it fits.

Ray





ome said:


> Thanks Ray,
> will a wire wheel ruin it as well?     For the muslin, better to use the faster speed grinder.?
> 3450 rpm.
> How do i clean or polish the endmill holders, they are R-8 endmill holders.
> ...


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## ScrapMetal (Dec 24, 2013)

Maybe consider using a brake hone?  Actually if it's "new" and isn't within spec I'd look to return it and get one that was properly sized.

JMHO

-Ron


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## Bill Gruby (Dec 24, 2013)

Hmm -- no matter what you do it has to be accurate. The wire wheel won't be. The brake hone sounds best. It won't take much. Also remember when you make the tight ones fit all others will be loose. 

 "Billy G"


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## Bill C. (Dec 24, 2013)

ome said:


> Hi guys,
> what is the best way to get a stubborn endmill into a new endmil holder.
> They are a 3/4 " shank and a 1.25" shank used that seem to have no burrs.
> Can i use a wire wheel on the grinder or use a 3m pad red or green?
> ...



It may also be the protective finish is too thick inside the bore.  If so I would use a high speed drill and a abrasive pad to clean it.  Good luck


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## Tony Wells (Dec 25, 2013)

This is not a shrink fit holder is it?

Wire wheel shouldn't touch the HSS of an end mill. Wires aren't hard enough. And HSS rarely "dents" or "dings". On the other hand, the holder, if it is a standard holder with set screws it won't be as hard as the end mill, and can be dented or dinged. As others have said, try other end mills......mic the one that won't fit and compare it to other new ones. It's unlikely that it is oversized, IMO. Trouble is more likely in the holder. Do you have a flap-stick?


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## ome (Dec 25, 2013)

Tony Wells said:


> This is not a shrink fit holder is it?
> 
> Wire wheel shouldn't touch the HSS of an end mill. Wires aren't hard enough. And HSS rarely "dents" or "dings". On the other hand, the holder, if it is a standard holder with set screws it won't be as hard as the end mill, and can be dented or dinged. As others have said, try other end mills......mic the one that won't fit and compare it to other new ones. It's unlikely that it is oversized, IMO. Trouble is more likely in the holder. Do you have a flap-stick?


Thanks Tony,
no, where do i get a flap stick?
thanks,

Jon


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## Tony Wells (Dec 26, 2013)

A flap stick, or simply a flapper, is something you make. Everyone ought to have one in their toolbox. Take a piece of 1/4" round stock and hacksaw a slot about an inch long into one end, splitting it. Then you can fold a piece of emery cloth of whatever grit you need and cram it down in the slot you sawed. Put this in your air motor (die grinder) and if you make the cloth length just over the diameter of the bore you are working in, fold it slightly to get it in the bore and hit it with the air. Stroke it like a hone. Fast or slow, as needed, coarse or fine, as needed. If there is a ding on the mouth of the holder, you can pull the spinning flapper just out to the edge, and it will try to push itself all the way out once you get about halfway out, but it will nicely round off the bore/face edge. 

Being hardened, the holder won't easily give up size, so I wouldn't hesitate to go with 80 grit and just flap it enough to give it a little shine first, and maybe hit the edge a little. Just be aware that this will warm up the holder if you run it fast for very long and then if you try the end mill and get it in there......it may stick when temps equalize. Just make sure it's back to room temp before test fitting. And as before, check a couple of other end mills to make sure there really is a problem with the holder.

I can post a pic of one of mine if needed. I have several of different lengths. Quite handy. Until you get used to being slapped around by whizzing sandpaper, you may want to wear gloves while holding the object you are flapping.


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## Alittlerusty (Nov 28, 2015)

Good chance  it's a 25 mm end millholder  alot of the imported stuff is mismarked if that's the case it would be .040" undersized


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## Alittlerusty (Nov 28, 2015)

I meant 19mm which would be about.002"under


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## kd4gij (Dec 5, 2015)

Like Tony said every one should have should have flap sticks of various sizes in there box  and roles of emery. I have a 1/4" steal rod for the die grinder. And several size wooden dowels  that I use for polishing the id of parts on the lathe.


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