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Evan
02-28-2008, 11:02 AM
I've been experimenting using my CNC mill to grind end mills. Seems to work pretty well.

http://vts.bc.ca/pics3/tcgrind1.jpg


http://vts.bc.ca/pics3/tcgrind2.jpg

Scishopguy
02-28-2008, 11:25 AM
Evan...I never thought about it but obviously there is no reason that it wouldn't work well. Nice job! My exposure to CNC is very minimal and I don't know much about it. One of those things I would like to learn some day.

best regards

quasi
02-28-2008, 11:27 AM
that is a very handy machine, Evan. That looks like a fair size end mill, are you going to use it in your little Swiss horizontal?

Mcgyver
02-28-2008, 11:59 AM
thats a neat application, how did you get the helix angle right? also, you're putting on the back clearance by offsetting the axis? - how does it cut?

ptjw7uk
02-28-2008, 12:21 PM
Good going Evan, like the use of hard drive magnets I find them very useful
although I get a few finger pinches as they are very powerful.
Peter

ahidley
02-28-2008, 12:33 PM
Why not use an air bearing and your spindle and table . That way you dont have to do any programing?
At least thats how I sharpen mine. Works great.
I DO like the magnet idea..........

Oldbrock
02-28-2008, 12:39 PM
I am impressed, always ground them on the tool and cutter grinder. I would really like to see the program. Peter

Evan
02-28-2008, 12:53 PM
The program?
G91
G1 A180 X-1.65 Z-.1
G0 Z.1 X1.65 A90


Change the angles and the indexing as necessary and repeat as necessary. This is only semi automated as yet but I will develop a full program with values to insert for each type of end mill. The kicker is that little CBN cup wheel. $140.00 retail. Of course, I don't pay retail and that one is a used one to start with.

The back clearance is put on by simply adding about 15 degrees to the flute indexing and .001 to the depth. Zip. The helix angle is automatic. Just measure the amount of twist in degrees over a set distance and tell the control to do that plus the distance and it will interpolate correctly automatically.

Oh yeah, it cuts just fine (aluminum only, not good enough for steel) and I use it on this mill. It's from a set of el cheapos I bought for practice purposes.

dp
02-28-2008, 01:32 PM
Clever use of old disk drive parts, Evan.

DR
02-28-2008, 03:35 PM
The helix angle should be marked on new end mills.....


Evan, maybe you can come up with a wheel profile to re-flute regular end mills and sharpen hogging (corncob) end mills. Aluminum oxide should work for limited usage.

Somewhere I've seen charts relating to the amount of diameter reduction is okay prior to needing a re-fluting. I used to have a Boeing chart for this, but can't find it now.

For those who don't understand....there's a limit to the amount taken off the diameter of an end mill. Once you get to a certain reduction the cutting edge loses it's positive rake making the cutter ineffective.

Mcgyver
02-28-2008, 03:52 PM
....there's a limit to the amount taken off the diameter of an end mill. Once you get to a certain reduction the cutting edge loses it's positive rake making the cutter ineffective.

when i grind the periphery, i take a minimal cut figuring that way I'll get many many resharpens. On say a 3/4" end mill, any sense as to how much can be ground away before you completely loose positive rake? I know its progressive, but am wondering if there's a rule of thumb.

John Stevenson
02-28-2008, 03:54 PM
It's a neat idea.
The Italian Biessie routers have a series of sub routintes to reground it's own standard shape router cutters with a small radiused diamond wheel, these are carbide cutters.

It probably has about 12 or 15 pre programmed shapes for the more common cutters.

I mentioned this a while ago to one of the other guys on the Mach development team and he was going to have a look at doing some wizards as Mach calls it's conversational programs.

There are also a couple of people in the UK working on a dedicated tool and cutter grinder using Mach.
I believe that Gavin Osman is working on a 5 axis one but I can't be certain.

.

DR
02-28-2008, 04:06 PM
when i grind the periphery, i take a minimal cut figuring that way I'll get many many resharpens. On say a 3/4" end mill, any sense as to how much can be ground away before you completely loose positive rake? I know its progressive, but am wondering if there's a rule of thumb.


The chart I've seen had various amounts of diameter reduction based on the original cutters amount of rake. How you were supposed to easily determine the original rake, I don't know.

Boeing's chart was absolute...only such and such percentage reduction of diameter and that was it. With resharpened cutters at Boeing, in recent years it was apparent they were re-fluting all cutters as they sharpened them. Obviously done on CNC grinders.

clutch
02-28-2008, 05:52 PM
For those w/o A axis capability and/or cnc, I wonder if you tied a string and weight to a shaft coupled to a spin indexer and used a finger rest, would a bridgeport work also.

Please keep ways protected.

Clutch

Norman Atkinson
02-28-2008, 06:17 PM
Clutch, it is all a question of thinking.
If you put a lathe in a horizontal position it is a lathe.
If you stand it upright, you have a drilling machine or a horizontal miller.
You simply lock the saddle to drill and extend the worktable for a mill.
If you rev it up so that an abrasive wheel is capable of removing metal, your lathe, mill, drill and whatever becomes a grinder. If you fiddle with the top slide and remove the feed screw, you get a shaper.
If you tie a rope to the lathe, and fling it off your boat, you have an anchor!
If you remember to tie the other end of the rope to the boat.

Sounds crazy but that is more or less how it was done.
Remember the largest unexplored area in the world is now what is kept under your hat! It's fun to find out some of the things which are hiding there.

Cheers

Norman

mochinist
02-28-2008, 07:36 PM
That is pretty slick Evan

P.S. A video would have been nice

BobWarfield
02-28-2008, 07:41 PM
Please keep ways protected.

Clutch

Given the very small work envelope needed, it seems like you could make a plexi shield that is U-shaped and capped so that there's only access at the top, and any grit is caught in the bottom. Attach a shopvac to the right side that is on-axis with the end mill and even less grit would escape.

Best,

BW

Evan
02-28-2008, 07:48 PM
I could see in the light that virtually all the grit was being captured by the magnets. Also, my way system is easy to clean. As well, the CBN wheels don't shed any appreciable amount of grit so everything coming off the grind is magnetic.

oldtiffie
02-28-2008, 07:56 PM
This is a good start.
http://www.hanita.com/hanita_protected/tec00016.htm

John Stevenson's wife's ebay site has a very good CD on "Tool and Cutter Grinders" for sale on her eBay site. I have lost my link to it. Perhaps someone who has it would re-post it.

John Stevenson
02-28-2008, 08:06 PM
Tiffie,
Try this site.

http://www.metoolsonline.com/

They have pulled off Ebay because of the hassle with Ebays new costs and feedback policies.


.

lane
02-28-2008, 08:19 PM
Evan`s All in one machine Mill , Lathe ,cutter grinder . What is next. O, I know a 90 head for it then He can surface grind, and horizontal mill.

oldtiffie
02-28-2008, 08:19 PM
Tiffie,
Try this site.

http://www.metoolsonline.com/

They have pulled off Ebay because of the hassle with Ebays new costs and feedback policies.


.

Thanks John.

I will book-mark that URL.

For others:
I have no commercial interest or association with John.

OK - now that is out of the way.

I have bought that CD from John's wife's previous site on eBay. I can tell you that if you are "into" "T&C grinding" that CD is for you.

At 6.75 (~ US$13.50) it will be hard to beat. It is not so much what it costs to buy but what it might cost if you don't!!.

T&C grinding is an interest of mine and I think that I am "reasonably aware" in that regard, but the CD raised my eye-brows on several occasions. Sure there will be some, maybe a lot, of stuff that is machine-specific but I am more interested in the principles and processes.

TGTool
02-28-2008, 11:19 PM
http://www.metoolsonline.com/

They have pulled off Ebay because of the hassle with Ebays new costs and feedback policies.


.

I'm all for that, but having a little temporary difficulty. At the login/new customer page I get no where. Whether I say I'm a new customer, or say I want to sign in, it always repaints the same page.

Perhaps that frustrated piano accompanist has turned to web site creation, "Vedder I play on der black keys, or vedder I play on der vhite, you ALWAYS sing in der cracks."

Norman Atkinson
02-29-2008, 04:47 AM
My EBay went beserk and it was impossible to get anywhere.
After a bit of head scratching, I deleted my "Favorites" entry and re-entered it.

I had a go at 'Gert's' site and found that it couldn't count. Maybe it is Leap Year fever! Funny?

Cheers

N

Evan
02-29-2008, 07:50 AM
I just visited John's web site and created an account with no difficulty at all. The confirmation e-mail arrived a few moments later. I think I shall order a complete set of dividing plates sent to John. I wonder how much he pays for a chargeback? :D

John Stevenson
02-29-2008, 09:03 AM
Cheers Evan,
That's one way to keep stock levels up. :D

.