How do i sharpen end mills without a surface grinder?

i just recently started getting into machining. I live on a farm, so its not hard to find stuff, and i found a box of old, high speed steel end mills. only one of them works good (it was in a bag and covered in some old machine oil) but all the others are rusty and dull, i have looked up how to sharpen them, but everything ive seen requires some sort of jig and a surface grinder, i have neither. is it possible to sharpen them without those, and if so, how?

Jason,

Welcome to the forum.

Without a proper tool & cutter grinder or some fixture for a surface grinder you won't have any success trying to sharpen them..that's the bad news. The good news is that there is a glut of inexpensive end-mills out there, some OK, some better. For a beginner, that would be the way to go, in my book. Do a little search for end mills and you'll be amazed how cheap they are..these are HSS items, not carbide.

Stuart

Speaking of inexpensive endmills, here is a link to a craigslist add. I don't have any affiliation with the seller, but I did buy some 3/4 inch 4 flutes from him, all good quality american made. A couple showed minor use but most looked brand new. You can find a lot of stuff like this on craigslist if you keep an eye out. New old stock, regrinds, etc. Good luck and welcome!

end mills - tools - by owner - sale

Jason Murawski said:

i just recently started getting into machining. I live on a farm, so its not hard to find stuff, and i found a box of old, high speed steel end mills. only one of them works good (it was in a bag and covered in some old machine oil) but all the others are rusty and dull, i have looked up how to sharpen them, but everything ive seen requires some sort of jig and a surface grinder, i have neither. is it possible to sharpen them without those, and if so, how?

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How cheap do you want to be?

The first suggestion, is to put them in an envelope, and send them to someone with the proper equipment.
If you ask around locally, you may even find a fella doing some cutter grinding in his garage to keep a hand in and keep some social life going.
But a CNC equipped cutter grinding shop will likely be cheap as a manual shop, and the machine will probe the cutter, grind it, and you get it back with a known size.

There are several 'hobby' sets of plans to build your own Cutter sharpening equipment, ranging from pretty basic (Guy Lautard's "Tinker Tool and Cutter Grinder" Plans) to fairly complex (Quorn Tool and Cutter Grinder, castings available from Martin Model Supply).

Or buy an air spindle and set up a dedicated bench grinder of whatever seems your best set of stolen ideas.

Tool and cutter grinders are fairly cheap to buy. Not so much all the accoutrements that will be needed to make it do all the things it may be able, plus the additional time you will have to invest to learn how to make it work the way you expected it to when you first got it.

You can hand grind them for long enough to get reasonably good at it - but they will still be a sorry lot compared to machine ground

Here is one way to do such things, but not seen often. Not too many of these strictly manual set ups laying around, and the 6500 lb grinder is unusual in a non commercial shop.

There are a few have-to-bes like in everything good - accurately rotating - accurately indexing - knowledge of cutting tool geometry. Note reference to 1908 info.

FWIW, I recently got one of those fixtures for sharpening end mills on the surface grinder. It does a fine job with the bottom, but the end mill will still be junk if the flutes are worn, which they usually are near the end. Thus my success rate is fairly low. I don't yet have an air spindle. My advice is also to shop around for decent inexpensive HSS end mills. You'll save a fortune in time and money in the long run.

In my experience the corners on the tip of endmills take the worst of it. I have had reasonable success shortening them a bit with a bench grinder to get fresh corners on the tip. Even easier is to knock the corners off resulting in a chamfered end that still cuts.

Won't give you a new endmill but will extend the life, especially if you are doing rough work and don't require the best finish.

From your description it sounds like your collection may be too far trashed to make use of the above. Could come in handy in the future.

strokersix said:

In my experience the corners on the tip of endmills take the worst of it. I have had reasonable success shortening them a bit with a bench grinder to get fresh corners on the tip. Even easier is to knock the corners off resulting in a chamfered end that still cuts.

Won't give you a new endmill but will extend the life, especially if you are doing rough work and don't require the best finish.

From your description it sounds like your collection may be too far trashed to make use of the above. Could come in handy in the future.

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Best discovery (ever!) I made, was solid carbide end mills with a radius on the corners from the factory.

In sub-half inch sizes, they were pretty cheap, considering that they usually got screwed up in a bad feed move, rather than actually worn out when cutting anything non-ferrous.

A .015" Rad on the corners cleared away the weakest part of the cutter, and if the print didn't call out a perfect square in the corner, it was my go-to. If the print wanted a larger rad, the catalog would provide!

all 2 flute end mills can be sharpened by hand so basically only one flute is cutting like a 1 tooth flycutter
.
like in over 4 decades of machining and if you run out of a certain size end mill and you really have to use that size i have maybe a few hundred times hand sharpened a 2 flute end mill to act as a one flute end mill to get the job done
.
sure some machinist never hand sharpen ever. like some are surprised its even possible to hand sharpen a twist drill. when a apprentice i often was given a box of several hundred items to hand sharpen for practice. when done i was given another box of hundreds of items to sharpen
.
hand sharpening a tap is most difficult. usually they never are as good as machine sharpened but in a pinch they often will work for a few holes

Being a man with dreams bigger than budget I try to save money every were possible . I only use end mills were a fly cutter will not work . Flat out the cheapest way tool wise to make a slot is to drill the stock out with a drill bit advancing 1 dia just barely braking thru to adjacent holes then use the end mill to finish when you factor in high labor cost it does not make as much sense .
Sets of Chinese fly cutters are pretty cheap , buy some carbide brazed bits to fit get a green wheel On a bench grinder and learn how to grind the cutters . This will allow you awesome finishes and the ability to finish the job , and not get stuck on dull cutter.
I find large surfaces that are done with smallish end mills look like a plowed field as appose to a cd .
In aluminum and plastics Razor sharp HSS bits preform better

You can do a reasonable sharpening of the end of a end mill by hand if you are steady, and have a well-dressed grinding wheel of a medium grit aluminum oxide with very sharp 90 degree corners. The sharp corners are necessary to thin the web between the two cutting edges. You need to present the end mill to the grinding wheel so that the web on the center of the end mill is slightly concave to permit only the tips on the outer periphery to be in contact with the workpiece.

Jason Murawski said:

How do i sharpen end mills without a surface grinder?

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First you learn to use CAPS. Then you use one of these;;

“Flat out the cheapest way tool wise to make a slot is to drill the stock out with a drill bit advancing 1 dia just barely braking thru to adjacent holes then use the end mill to finish”

Sorry, but that is a horrible, tedious and painful way to cut a slot. Just get your rpm right, go full depth and feed consistently. Don’t waste your time with a bunch of rusty old HSS end mills. Unless you are wanting to learn and willing to invest in the proper tooling. Otherwise you will be forever frustrated with poor performance, wasted effort and piles of scrap to show for it.