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Poorly reground end mill

jamesu229

Hot Rolled
Joined
Feb 20, 2011
Location
Grant Alabama USA
Last year I bought a "professionally" reground Garr 630 1" , coated for around $50. It sat around here close to a year before I needed it at the day job. Tuesday I took it in to run as a finisher, just to make my life easier. It could only handle a .002 radial cut without major chatter. The back of the primary grind is dragging, as is the primary on the bottom. The hook angle is actually negative. I have never used anyone else's regrinds before. I can see why I have such a hard time out on a sales run. Anyone else get junk like this?BAD END MILL.jpg
 
I can’t comment on other people’s grinding but I regrind my own in a darex e90 I bought. I feel my re grinds cut better than factory new and have found a few factory grinds that are not ground concentric. It’s not hard to do and I picked it up after about two Endmills. Other than being off size I don’t see a problem with regrinds

I have only ground hss though not carbide.
 
Confused ...
Don't you do this as a side and know it better than most here? I most certainly respect your knowhow here.
Conflict of interest with the day job and a vent which I get in spades?
There are and always will be regrind houses that are not great at all things.
Yes I have this and it protected by the system.
Rasing a fuss as a user is not good for your career in bigger shops.
One has to tip toe here even when you know all is wrong.
Bob
 
When I was doing a lot of silver contacts, I often ground end mills, also using a Darex E90. The silver was brazed on, meaning that it was automatically annealed and soft, about like machining 2S aluminum. The critical parameter was clearance. If there was any rounding on the edge or drag, the silver would scuff and ball up. There were times when I couldn't find a usable cutter and would regrind new ones. I did them on a surface grinder with a normal wheel, not a cup one as is usually shown for such a setup. I had the Darex turned so the wheel was grinding almost parallel to the flute, blending the grinding marks more smoothly. I was never completely happy with available ones until Garr carbide cutters showed up.

Bill
 
Confused ...
Don't you do this as a side and know it better than most here? I most certainly respect your knowhow here.
Conflict of interest with the day job and a vent which I get in spades?
There are and always will be regrind houses that are not great at all things.
Yes I have this and it protected by the system.
Rasing a fuss as a user is not good for your career in bigger shops.
One has to tip toe here even when you know all is wrong.
Bob

Great input Bob! I have just never been on the receiving end of grinding tools. Mistakes happen, but as true with any manufacturing process(or remanufacturing) a bad part should not get out the door. I guess I did kinda go about my thread in the wrong way, but I was simply amazed by the lack of clearance angles. The main point is, now I see why people are skeptical about resharpening. I also sharpen other industrial tools and scissors. Hair stylists will not tolerate a bad sharpening! 1 bad pair and you lost at least 1 customer, probably more due to word of mouth.
 
The most annoyed I have been with regrinding was when I sent about 10off 16mm carbide endmills ,they had been done 2 or 3 times already removing a few thou each time but on this occasion the regrinder saw fit to take them down to 15mm, maybe he did not want to see them again.
 
From here the OD looks poor also. I have known shops that would only have end mill cut-off and then end-only sharpened..Often one can get 4 uses or so that way and retain the original OD size...Make good sense for some shops, yes it depends on the use and wear land...
I used to sharpen a flat nose corner end mill for better surface finish..it had a .030 or so flat with normal clearance at the intersect of the OD and end at the end face...then normal dish going to center...
Big end mills say 1/2" Dia. and larger getting OD clearance right is easy.. Smalls, say 1/4 and less are more difficult IMHO
 
The most annoyed I have been with regrinding was when I sent about 10off 16mm carbide endmills ,they had been done 2 or 3 times already removing a few thou each time but on this occasion the regrinder saw fit to take them down to 15mm, maybe he did not want to see them again.

Repeat after me "If you do a job poorly enough, you don't get asked to do it again."
 
....... The main point is, now I see why people are skeptical about resharpening. I also sharpen other industrial tools and scissors. Hair stylists will not tolerate a bad sharpening! 1 bad pair and you lost at least 1 customer, probably more due to word of mouth.

Yes one sees a lot of customers with a bad taste in their mouth for regrinds/reworks. Once they get a bad batch it is very hard to turn their opinion around.
This due to some places that just don't know how to design a cutting tool or the whys involved yet got a deal on a T/C grinder.
Often guys who worked in grind shop but always set up this or that job to worked out angles written down in a book or on scrap paper.
How hard can it be?

My wife cuts hair, the old guy who did her sharpening forever has retired and she is fit to be tied. Says the new grinds she gets from several sources "pushes" the hair. (I'm not sure what this means)
Talks to me "You sharpen stuff with all kinds of fancy machines, why can't you do these for me".
I won't touch such with a ten foot pole. "That's not what I do honey, you need to find an experienced professional".
Bob
 
My wife cuts hair, the old guy who did her sharpening forever has retired and she is fit to be tied. Says the new grinds she gets from several sources "pushes" the hair. (I'm not sure what this means)
Talks to me "You sharpen stuff with all kinds of fancy machines, why can't you do these for me".
I won't touch such with a ten foot pole. "That's not what I do honey, you need to find an experienced professional".
Bob

Is the problem scissors or clippers? I once saw a sharpening machine for clipper blades. It was a large, circa 3', disk rotating maybe 100 RPM. You would drop the blade on the disk and hold it with finger pressure until you figured it was sharp enough, then slide it off into your other hand. There are similar machines on the market, much smaller and I think wet. I seem to recall that they are Japanese made. Check a woodcarver magazine. Get one and teach her to do her own to her satisfaction. She probably doesn't want a smooth super sharp edge but one with what barbers call "tooth", very fine saw edges. That would keep the hair from sliding out of the clipper instead of cutting.

Re end mills, I tried several services.They ranged from poor to terrible. I asked one why he wouldn't grind a fine enough edge for my use. His reply was that he couldn't take the time. I bought a Darex E90.

Bill
 
Scissors. She calls them Nics and will use nothing less. Crazy price tags.
Really?, $500-$800 for a pair of scissors? She says there is world of difference.
Plus side is that I get free haircuts.
Bob
 
By "push the hair" she probably means they push the hair toward the tips as she closes them. The sharpening shop is probably using too fine of a wheel which leaves the flats too polished and the hairs just skid across it. A slightly coarser wheel would probably prevent this by leaving some scratches that are perpendicular to the cutting edge which will hold the hairs for the cut.



Yes one sees a lot of customers with a bad taste in their mouth for regrinds/reworks. Once they get a bad batch it is very hard to turn their opinion around.
This due to some places that just don't know how to design a cutting tool or the whys involved yet got a deal on a T/C grinder.
Often guys who worked in grind shop but always set up this or that job to worked out angles written down in a book or on scrap paper.
How hard can it be?

My wife cuts hair, the old guy who did her sharpening forever has retired and she is fit to be tied. Says the new grinds she gets from several sources "pushes" the hair. (I'm not sure what this means)
Talks to me "You sharpen stuff with all kinds of fancy machines, why can't you do these for me".
I won't touch such with a ten foot pole. "That's not what I do honey, you need to find an experienced professional".
Bob
 
Smooth edge scissors are great for paper and cloth..Hair scissors need one blade to be sharp but have a file like edge so it catches the hair and not push it along..I don't know if one can buy scissor's files any more but a diamond flat flat file of about 80 grit might work..No i don't sharpen them..

Likely it might be an Ok side business if one had a portable sharpening machine in a van..at $3 each and do perhaps 10 pair..might make 30 bucks and hour..or not. Go from town to town and sleep in the van down by the river.

I did build a machine for sharpening dog clippers..That is a tough field because the customers bite..yes a 30" diameter cast iron lapping wheel..It worked marginally good..but not good enough..gave up on that project.
 
Confused ...
Don't you do this as a side and know it better than most here? I most certainly respect your knowhow here.
Conflict of interest with the day job and a vent which I get in spades?
There are and always will be regrind houses that are not great at all things.
Yes I have this and it protected by the system.
Rasing a fuss as a user is not good for your career in bigger shops.
One has to tip toe here even when you know all is wrong.
Bob

Bit cornfused here, why doesn't the OP reveal the supplier of this bad re-grind ?
 
I understand how a sharpening shop can mess up on OD clearance. Suppose customers cutters are put into trays. Then all the 3/8 are done, then 1/2s and so on with taking all same size back into each tray to save set up time. Different manufacturers have different radial rake so they set on a riding finger differently..so changes the clearance..Even doing one customers tools there may be different brand cutters. There is no excuse for wrong end clearance.

Also an end mill is a long part to hold only at one end..

I know some one will say every cutter should be indicated but that might not be done in every shop.

Working at Jim Robbins(seat belt die shop) we used end mills with having centers at both ends..they were the best HSS end mill I have ever used..Yes with only a short recess at the cutting end they were not plunge cutters. Forgot who made them..Back in the 60s most end mill cutters were HSS.. We did make our own carbide end mill cutters at Cut More tool..with a 1/4 or 3/8 slug of carbide silver soldered in a 3/4 or 1" shank. they ran like a machine gun with red hot chips.
end mill end cutters photos - Google Search
 
Yes one sees a lot of customers with a bad taste in their mouth for regrinds/reworks. Once they get a bad batch it is very hard to turn their opinion around.
This due to some places that just don't know how to design a cutting tool or the whys involved yet got a deal on a T/C grinder.
Often guys who worked in grind shop but always set up this or that job to worked out angles written down in a book or on scrap paper.
How hard can it be?

My wife cuts hair, the old guy who did her sharpening forever has retired and she is fit to be tied. Says the new grinds she gets from several sources "pushes" the hair. (I'm not sure what this means)
Talks to me "You sharpen stuff with all kinds of fancy machines, why can't you do these for me".
I won't touch such with a ten foot pole. "That's not what I do honey, you need to find an experienced professional".
Bob

This may get deleted, if so I understand. Unfortunately I didn't have a camera person available, so I ended up out of the center of the video.

ISS Scissor demonstration - YouTube
 








 
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