Sharpening End Mills

[jroma1]

I would like to know how to sharpen an end mill. In searching the internet I found information on several types of special machines made for that purpose. As luck would have it,the cost of these devices is out of reach for most of us.

However there is a a fixture available for under $100.00 that is said is able to do the job. There is no information on the what and how to use this device. Studying the photo I assume it is held in a vise,the bottom seems to be machined at two different angles. I assume one half of the bottom of this fixture is machined to grind one angle and that the other half is machined for the second angle and whatever angle you grind on the end mill the corresponding angle of the fixture is laid flat on the bottom of the vise. This brings up an important question ,what are the primary & secondary angles?

There is a collar at the top that apparently holds a 5C collet(This holds the end mill)which would rotate to accomodate the amount of flutes in the end mill. There is the suggestion that the fixture was designed to be used with a surface grinder.

I don't have a surface grinder??? I have a vertical milling machine,is there some way to use it?

Is anyone familar with this tool or have any ideas,comments to achieve what I would like to do,I would greatly appreciate
any feedback

John

 

[Tony Wells]

That fixture is only for sharpening the end of the end mill. It is an attachment for a surface grinder. The flutes require a fixture that allows the end mill to twist along the spiral edge of the flutes, with a small finger tracing the helix. There are also two angles involved there as well. A fixture could be made to do this job on a surface grinder too. End mill sharpening is not all that difficult, with the right equipment, but it's probably not practical for most hobby machinists.
Darex makes a decent unit:

http://www.darex.com/index.php?prod...e.pbv.tabs.tpl&option=com_virtuemart&Itemid=5

 

[Pacer]

What Tony said...

That fixture only does the ends and is intended for a surface grinder, however I saw -somewhere?? - a guy had rigged up his mill with a stone and was using one of those things and claimed it worked well? Honestly I questioned that...:thinking:

As you are finding, the complete sharpening of an end mill is done on dedicated machines that can rip a hole in your wallet. The Darex and Cuttermaster are 2 of the smaller benchtop machines that can still be very expensive even used, and are almost solely limited to end mill sharpening only. The larger floor standing machines can at least do a few other grinding operations, but are almost useless with out the many attachments that are needed to accomplish!

Bottom line - for the HSM'er sharpening end mills is not a practical thing unless you happen on a "deal"

I found a Cuttermaster for the 'cheap' price of $550 and have never seen one for less, and have never seen a Darex for under a thousand.

 

[PurpLev]

To add more Questions to this thread-

so what do you guys do with a used end mill? throw and replace? send to resharpen? where would you send to resharpen if that is the path to take?

Thanks,
Sharon

 

[DMS]

Wait... end mills wear you? Seems I always bust mine before I get to that point... I have a box full of the shards that I keep "just in case". As an aside, the shanks of broken endmills make great alignment pins, just be careful if there are any remnants of edge left.

 

[Rbeckett]

I,m with DMS on this one.. I never get to use an end mill long enough to get dull before I do something stupid and break it somehow. The smalller mills are the worst for breakage for me. I can break a 1/8 ball nose in no time flat. And I am being extra carefull because I know they break easilly too. I found a few sets cheap at HF and snatched them up with a 20% off coupon so I have a few spares right now, but as I break em I try to order a better quality replacement.
Bob

 

[Tony Wells]

Lots depends on what material is being cut, the length of cut of the em, and a few other things. If I'm working finish work, I try to use a new one, and after it dulls to a point where it won't give me the performance I want, it gets relegated to rough out work. Small end mills I use up then toss, either in the scrap carbide or HSS pile. There is a tool grinding shop not far away for specials, or larger sizes that are worth sharpening. If they break, they're usually scrapped.

 

[Pacer]

OK a little more thoughts on this subject ---

The process of using one of the sharpeners is simple --- if you have someone to guide you thru the process (IMHO!) I have a highly skilled machinist friend who held my hand, and was telling me how there seems to no decent - if any - written descriptions on doing it, and, since then I havent run across any. The angles/degrees of the grinds vary as the EM size changes - there are 2 on the end and there are 2 on the flutes, all different. The ends are a bit easier to rig up some method of getting another use from and EM, but the flutes are very difficult without a dedicated fixture called an air bearing/spindle. There are a couple other fixtures that will work, just not with the ease of the air bearing, which is a very expensive, precision piece if tooling. Then the method of using the fixture would be (here again, IMHO) best shown how its done.

Sizes of EM sharpening - it gets finicky below about 3/8" size and personally I wont fool with anything below that, and I actually seldom will even do a 3/8 -- 1/2" and above can go pretty fast. I had bought a lathe and mill last year and with the deal I got some 100 assorted EMs 1/2 to 1", recently I set about to go thru them and salvage what were worth keeping and also to get the 20-25 of my personal EMs that had been set aside for sharpening, probably spent some 3-4 hours on 50-60 of them being useful. First time I had put the Cuttermaster to use in probably a year, and probably be another year before I use it again - if then...

There are too many more tools/machines that are much more useful in a home shop than an end mill sharpener...

 

[Tony Wells]

Most definitely agree. You can read the manuals that come with the equipment, and still not be able to properly sharpen end mills. I have been taught, so I kind of take it for granted that it is easy. It is if you know how. If not, it can be intimidating. So, coupling the expense of the equipment (yes, air bearing holder is the best, by far), and the low volume of a hobby shop and it just doesn't make sense to do it at home.

BUT, if you do happen across a deal, you should consider that it isn't limited to just plain end mill sharpening. With the proper attachments, a full T&CG can do just about anything you can put in the mill, and a lot of lathe tools. So don't be afraid to get one of it falls in your lap. Or call me and I'll take it.)

 

[Pacer]

Oops! All that talk and I forget all about the machine Tony is speaking of, thinking only of an "end mill sharpener"---

A "Tool & Cutter grinder" is really another beast, and as Tony says, will/can perform multiple tasks. It will be quite a bit larger - not bench top - with some becoming behemoths, but many having a foot print similar to a small mill. These can often be found cheaper than a end mill sharpener - but here, you have to keep in mind that in performing the many different functions they are capable of, they are all to often being sold as the bare grinder itself, with the accessories having been lost/missing/thrown away, etc, and the machine alone is of little use. Think of the air bearing fixture we spoke of earlier - theyre often missing on a TC&G...