Subject: Sharpening end mills by hand, and machining acrylic

From: [email-masked] (Chris Paris)
Date: 23 May 1995 15:58:55 GMT

I'm using a 1/2" HSS end mill in a woodworking router table. I didn't
know that trimming a 36" edge of 3/4" medium density fiberboard would
dull the cutter severely in just one pass, but that's sure what
happened. It was bad. So I thought I'd try to sharpen it. My first
attempt just made it worse as far as I can tell. Finally I got some
improvement, but it's still not nearly as nice as it originally
was. BTW, I have had plenty of experience and success sharpening plane
and chisel blades. I think what happened is I rounded the cutting
edge. Is there a way to effectively sharpen end mills by hand?

On a related note, it occurred to me that the cutting angle on an end
mill may not be the best angle to use for cutting wood. I'm also
cutting acrylic sheet with this, and the concern of cutting angle is
especially appropriate for the acrylic. I've read in books on working
plastics that acrylic cutters should scrape and not cut like a
metalworking tool. The end mill seemed to do all right on the acrylic
before I dulled it with the MDF though. Now it does more melting than
cutting. Do you know where I can get an end mill-type cutter that's
ground for cutting acrylic and polycarbonate?

--
Chris Paris <[email-masked]>    Support censorship -- go to CMU
For information see http://www.cs.cmu.edu/Web/People/kcf/censor/

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From: [email-masked] (Norman Billingham)
Date: 24 May 1995 17:12:43 GMT

Chris Paris ([email-masked]) wrote:
: I'm using a 1/2" HSS end mill in a woodworking router table. I didn't
: know that trimming a 36" edge of 3/4" medium density fiberboard would
: dull the cutter severely in just one pass, but that's sure what
: happened. It was bad. So I thought I'd try to sharpen it. My first
: attempt just made it worse as far as I can tell. Finally I got some
: improvement, but it's still not nearly as nice as it originally
: was. BTW, I have had plenty of experience and success sharpening plane
: and chisel blades. I think what happened is I rounded the cutting
: edge. Is there a way to effectively sharpen end mills by hand?

: On a related note, it occurred to me that the cutting angle on an end
: mill may not be the best angle to use for cutting wood. I'm also
: cutting acrylic sheet with this, and the concern of cutting angle is
: especially appropriate for the acrylic. I've read in books on working
: plastics that acrylic cutters should scrape and not cut like a
: metalworking tool. The end mill seemed to do all right on the acrylic
: before I dulled it with the MDF though. Now it does more melting than
: cutting. Do you know where I can get an end mill-type cutter that's
: ground for cutting acrylic and polycarbonate?

Try any major supplier of woodworking router cutters.  they have cutters
designed for both your MDF and acrylic.

MDF is full of glue and will tear the edge off HSS in seconds.  Carbide
tipped router tools are costly but last well.

Norman Billingham
Sussex University
England
: --
: Chris Paris <[email-masked]>    Support censorship -- go to CMU
: For information see http://www.cs.cmu.edu/Web/People/kcf/censor/

---

From: [email-masked] (william thomas powers)
Date: 25 May 1995 10:29:31 -0400

[email-masked], refering to a previous post, writes:
>> Toss the endmill. They are too cheap to bother to resharpen properly.    
>> University of Pennsylvania 
>> Physics Department 
>
>Now I understand the US budget better.
>Charles

Yes Charles; if we decide that it is more expensive to repair an item
than to replace it; we choose the cheaper route.

If this is not the process in the UK it would go far in explaining the
UK tax load!

Personally; like many hobby folk; I tend not to factor in my time as
part of the cost of fixing something and enjoy learning a new skill;
but then I do not sell my work, or employ expensive workers....

Let's call off the cheap shots before we stoop to things like: "they like
fixing things; thats why they built (pre-Ford) Jaguars' electrical systems
they way they did" .  

Instead let's talk about metalworking;  I'm making pattern welded sceaxs, 
a couple of the late 13th century folding knives, (number 309 in _Knives and
Scabbards_, Museum of London); open hearth cooking equipment and doing some
sand casting using my forge to melt the metal.  What are you doing these days?

Thomas who knows who Abraham Darby was and where he worked
Columbus, Ohio
USA

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From: [email-masked] (Jon Gellman)
Date: Tue, 23 May 1995 23:56:19 GMT

>ground for cutting acrylic and polycarbonate?

you'll do just fine with a standard endmill on either material. The rake
is far more critical in drilling, where the work can get pulled up by the
bit in a pilot hole or at the exit point . A milling machine is more controlled,
and a router is going so fastit makes less of a difference.
Keep in mind with polycarbonate that it ISN'T acrylic. An acrylic cut tool
will often leave your work a pile of melted goo that won't break. The
scraping action works great on acrylic due to it's brittleness, but the PC
will make a mess of strings that are real tough in the best of cases.
A lubricant like Safetape is great also, but water will work well too.

BTW, I was booted from the CMU design dept. years ago for making things
that worked and being generally uncooperative.

Jon

Jon Gellman Effects
[email-masked]
NYC, NY

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From: Harold Borders <[email-masked]>
Date: 24 May 1995 01:38:26 GMT

Toss the endmill. They are too cheap to bother to resharpen properly.    
McMaster-Carr and MSC have a variety of endmills in stock and one of them   
should fill your needs. 
 
Also, when doing MDF (or any glued-up composition board), use carbide   
tooling. The glue plays hell with the HSS. 
 
-Buddy 
--  
________________________________________________________________ 
 
Harold W. Borders (Buddy) 
Instrumentation Specialist 
University of Pennsylvania 
Physics Department 
209 South 33 Street 
Philadelphia, PA 19104 
 
Work (215) 898-8591 
Home (610) 352-5417 
_________________________________________________________________

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From: Charles Lamont <[email-masked]>
Date: 25 May 1995 07:38:05 +0100

-- 
Charles

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From: Mike Rehmus <[email-masked]>
Date: 25 May 1995 15:57:35 GMT

>Now I understand the US budget better.

Must be Pick On Charles Day.

When one can get an end-mill for under $10 dollars (Chinese, Polish or Indian 
origin), the high costs to get it sharpened, especially if it has been had at with a 
poor technique (remember he attempted to sharpen it with an improper technique) far 
outweigh the cost of a new mill.

If he were talking about a US-made end mill from someone like Niagra, it might be a 
different story.

Most of us don't toss anything anyway, we recycle old HSS bits into other tools and 
keep them cutting for years.

Best,

Mike Rehmus

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From: [email-masked] (J. Kimberlin)
Date: 25 May 1995 17:46:22 -0700

In article <[email-masked]>,
>Now I understand the US budget better.

You got it.  resharpening end mills takes a decent machine like a Darex 
at $1000+ or something like a Cincinatti T&C Grinder at a lot more.  Here 
it will cost $5-6 to get a simple 3/8" 4 flute end mill sharpened at a 
sharpening service.  Surplus, I've purchased these at $4/lb in useable 
condition.  New, the imports are $3.80 and up each.

In my experience, the UK is quite expensive and the pound is really worth 
about 35 cents US$ in purchasing power.  When the pound was worth $1.06 
or so a few years ago, I got a lot of stuff from the UK and thought it 
rather reasonable.  Actually, I think it is taxes that are the problem.  
UK stuff is really good quality - for the stuff I want.

BTW Charles, if you can sharpen end mills and use them, perhaps our junk 
could be your treasure.  I save mine for (who knows what) and will send 
them anywhere for postage.  Not that I have many.  I just dump everything 
in a shoe box and every so often look at it and put it back on the shelf.

JerryK

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From: [email-masked] (Greg Lewis)
Date: Fri, 26 May 1995 09:18:04 GMT

>in a shoe box and every so often look at it and put it back on the shelf.

There's a business opportunity here....  (;-) I once knew a guy who
built his own boat -- a big one. One of his plans was to go into
smuggling.  Not drugs or diamonds, mind you, but T-shirts, tennis
shoes and dull drill bits. He was going to take them to the
Phillipines where, with the proper consideration to the right
authorities, he would be able to get them into the country. The dull
drill bits would be resharpened for futher use. If we all sent our
dull end mills to Charles as scrap and he sharpened them and sent them
back as useable end mills, do you think that would help the trade
balance any? (;-)

___________________________________________________________________
[email-masked] 	 	 They don't Photojournalism
sequence 	 	 Call this place Department of Mass
Communication 	 An institution
     and Journalism 	      	   	     For nothing

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From: [email-masked] (Chris Paris)
Date: 26 May 1995 20:46:32 GMT

> If he were talking about a US-made end mill from someone like Niagra, it might be a 

For what it's worth, it's a US-made end mill by Morse. I think it was
about $12.  My solution is going to be to replace it, and keep the HSS
away from MDF and plywood in the future..

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From: [email-masked] (DREW DIAMOND)
Date: Tue, 30 May 1995 09:48:00

In article <[email-masked]> [email-masked] (Chris Paris) writes:
>From: [email-masked] (Chris Paris)
>Subject: Sharpening end mills by hand, and machining acrylic
>Date: 23 May 1995 15:58:55 GMT

 Is there a way to effectively sharpen end mills by hand?

Interesting thread you have started Chris. If after all those "throw it away" 
suggestions; you still want to have a go at  sharpening your own end-mills 
(we are not all rolling in money!), look up Model Engineer for 18 Feb '94, 
pages 212, 213. "re-sharpen your end-mills freehand" by Wilfred Vermieren.

Well-written (IMHO) article, where the writer shows us how to re-sharpen 
end-mills using ordinary workshop tools. 2 pages, 10 clear photos.

Regards, Drew Diamond.     Telecom Australia Research Laboratories.