Opinions on Darex endmill sharpener

Does anyone out there own one of the Darex endmill sharpeners? What are your opinions on it? I've got a chance to buy one at a decent price but don't want to take the plunge until I know a little more about the thing.

I am a hobbyist machinist. I bought a used Darex E-85 (like the E-90) fairly cheaply a couple years ago after I came into possession of a big pile of dulled or grossly abused end mills that came with a small vertical mill I bought. I hated to throw them away and was interested in learning about sharpening end mills anyway--a challenge.

The Darex is certainly better than nothing but no professional would mistake it for a serious precision machine. A certain amount of user dexterity, feel, and practice is required. If you are using CNC machines, forget it.

Realize you need an air compressor to run it. Mine is a 5 HP and it is just enough. My air spindle is a bit abused, thus requiring more air.

I feel there is one design problem. The air spindle uses a collar clamped to it which locates the flutes during end sharpening. Problem is, the collar is clamped with just a set screw. The set screw will distort the shaft enough to cause binding of the air spindle when it is used to sharpen the flutes on the side of the mill. That results in some uneven grinds in places on some flutes.

Have also noted some run-out problems with some end mills I have sharpened. Seem to get a high flute sometimes. Do not know why at the moment.

On the positive side, owning it has allowed me to touch-up many dulled end mills that I would have had to toss or send out for resharpening. I also salvaged a number of really grossly abused end mills. That effort was not time effective, I just wanted to see what could be done. I have one Putnam 1/2 inch diameter end mill that I used for practice. Somebody had chipped it and burned it up by running way too fast and no coolant. The sucker was black, blue and all the edges rolled over. It looked as if the cutting edges had melted. Took a while but I returned that tortured piece of junk into a nice cutting end mill. I was real pleased with that.

Another advantage of the Darex is it can be stored on a shelf when not in use. Space is a problem in my shop and another free-standing machine on the floor was not going to cut it. I store it on a shelf and drag it out to the garage (where the air compressor lives) to use.

If you buy one, be sure to get the collet set and stylus with it.

Sharpening an end mill is not a quick job like sharpening a twist drill. A lot more surfaces/edges to deal with. Figure on 20 minutes plus, depending upon initial codition. The really trashed ones took 45+ minutes, but that was a learning experience.

Overall, I regard an end mill sharpener as a very marginal machine for a home shop--handy but hardly a necessity. The money would likely be better put toward a bigger lathe or such. Of course, it depends upon your needs. If all you ever mill is aluminum and brass, forget it. If you mill a good bit of steel, it is nice to have.

Am interested in seeing others opinions, too.

This is the E-90? It will do one fine job on an endmill....but, thats about it! If you can get it for under a grand and its not beat to death, its a good buy. Nice, well made tool, but is limited in use.

I agree pretty much with Bronto48. The machine is handy to have around for touching up HSS endmills. Mostly, we use ours to regrind the end of the flutes (evenly), as the corners are usually dulled. We'll shorten a used one, maybe by the amount of its radius as that is the typical depth of cut. We'll do this offhand on a bench grinder. Then we'll regrind the rough clearance on the end flutes with a good toolroom wheel on another bench grinder. Then, put it in the Darex to even the end flutes up and get a good edge right to the center.

I use my Darex drill sharpener to grind in a split point on a 2 flute slot drill, so that it will center cut decently. That would be the older Darex drill sharpener which looks like a bench grinder, not the new-fangled closed in one.

I have an E90. Mine does not use much air at all. I think I could power it (airwise) for ten or fifteen minutes from a portable tank. The concentricity problems that bronto48 has with his, I do not have with mine. Maybe his air spindle leakage and concentricity are related. I have both CBN wheels (for HSS) and diamond wheels (for carbide). Sharpening the ends of the flutes is a piece of cake with this machine. Doing the edges of the flutes takes some practice. After several sharpenings, the end mills need to be regashed - and the E90 is not set up to do that. So you need another means to accomplish a new gash.

I have done complete teardown and rebuilds on two Darex E-90 machines. Nothing was worn out, but I tore them down and repainted them while replacing some parts that UPS broke. The diecast aluminum parts and the crank handles are too fragile for a combination of UPS and the average eBay amateur packing job. And UPS will not pay for their damage, of course. I guess the extra insurance for over $100 I pay for is only for them losing a package.

I have used one of them and plan to sell the other one. I find my little Sears pancake compressor is way bigger than it needs. I am happy with my results and found it incredibly easy to use. The instructions are well-written, and you can download them and read them before you buy the grinder.

A bad collet might cause a concentricity problem.

Larry

I just bought an E90 for under $500 that has no sign of use at all. Next step, inventory to make sure I have all the attachments. Does anyone know when Darex discontinued this machine?

I have on I bought at auction 10 years ago . It came with a radius attachment which I used once that seemed too cumbersome to learn to use the machine it self is great . You should really use accuracy collets and that helps with run out. It also comes in handy to resize a mill in a pinch . For the ends I use a different fixture on the surface grinder . As with anything else you have to practice to become proficient
Pete