Max regrinds

316head · Apr 4, 2020

I keep hearing from tooling reps that carbide drill should not be reground more than three times. Are there other reasons than drill diameter getting a bit smaller with every regrind?

Milland · Apr 4, 2020

The center web may be getting thicker too, but I'd think that wasn't a huge issue when the points are split anyway. I suspect they'd prefer you bought new drills rather than turning the jobber to a stub.

One other possibility is that the cylindrical margin on the flutes may wear enough with use that at some point the risk of binding and breakage gets too high. This could correlate with the typical wear associated with three repointings. Just a guess...

Limy Sami · Apr 4, 2020

95% they want to sell more drills

3% drill getting too small (IMO - at best that's dubious as we're talking less than ''10ths'' taper)

2% common or garden bullshit

Shop Supply Guru · Apr 4, 2020

I sell a Walter brand drill that has the little round grooves around it. You may have seen it advertised the DC170? Look it up you’ll see what I mean about the grooves it’s a very unique design. Anyway my point is they advertise you can regrind 5 times or more with each of those grooves being a marker for the regrind. Really the only potential issue with regrinding many times over is the size going down with the natural back taper. Manufacturers and good regrind shops will be able to repoint a carbide drill even if it’s all chipped up.

michiganbuck · Apr 4, 2020

There are a ton of reasons for not sharpening a drill a salesman might site
The drills get shorter and operators cant be trusted to make depth adjustment.
Drill lose some diameter and so may cause a part to go out of tolerance
A tight hole can break a tap .and cause a scrap part.
With varying length drills, one may need hire more expensive, talented workers.
All valid reasons. Sounds like a Politian selling a bill of goods.
Drill diameter gets small about .0005 to .0008 per inch of length, other than that they get better the shorter they are with proper sharpening, that include a web thinning if needed..

eKretz · Apr 4, 2020

Well OP, first off, are we talking solid carbide drills or indexable?

CarbideBob · Apr 4, 2020

If this a solid carbide drill ... fire your tooling rep and do let them never darken the doorstep again.
Yes, we would like to sell you more but many care about customers even when it means our paycheck or commission gets cut.
If you work in sales that is a hard call when talking this. 30 regrinds means a smaller take home pay even if you do the regrind side.
Bob

ChipSplitter · Apr 4, 2020

CarbideBob said:
If this a solid carbide drill ... fire your tooling rep and do let them never darken the doorstep again.
Yes, we would like to sell you more but many care about customers even when it means our paycheck or commission gets cut.
If you work in sales that is a hard call when talking this. 30 regrinds means a smaller take home pay even if you do the regrind side.
Bob

What about endmills?

michiganbuck · Apr 4, 2020

IMHO endmills should be sharpened down to a stub...the OD is straight so no loss
of OD size if just end sharpened.. With OD sharpening they lose their original standard size and get larger relationship to the web thickness and that limits how much they can be sharpened. end mill have a very thick web and that is what makes them very strong.Some sharpen hands thin the web as they get smaller..I never care for doing that because it takes a lot of wheel so limits the value of doing so.

Big B · Apr 4, 2020

I've also heard that you should change the oil on your car every 3,000 miles but I don't do it and have never had a problem. I change it at 5K and the manual says 7,500. Like my dad would have said, the people that recommend only sharpening the drills three times are the same people that sell drills.

TGTool · Apr 4, 2020

The best thing I can think of relating to the salesman's recommendation is that it gives me an idea for a new screen name. Max Regrind. Kinda like that.

316head · Apr 22, 2020

We regrind almost everything. Endmills. Drills (both HSS and HM. HSS has to be big and long=expensive). Exchangeable drill tips. Reamer heads. You name it. That is, if the rework price is 1/3 of the original or less.

DDoug · Apr 22, 2020

Topic titles need to inform what your topic is actually about

Been noticing you have a problem with titles...please try a little harder.

Greg White · Apr 23, 2020

digger,some cheese?
Gw

DMF_TomB · Apr 23, 2020

316head said:
I keep hearing from tooling reps that carbide drill should not be reground more than three times. Are there other reasons than drill diameter getting a bit smaller with every regrind?

.
I have seen 13mm carbide drills with a .020" or 0.5mm back taper. if you drill pilot holes 100mm deep and holes undersize even 0.03mm I have seen longer length drills (drilling holes deeper) randomly vibrate til they break cause pilot hole was slightly small and very long length drills usually make bad reamers.
.
drill tip was about 7mm length consistent dia til you reached the back taper. so drill resharpened more shorter length would drill small holes. possible they dont recommend drill use once the consistent tip diameter is used up ?

Mike1974 · Apr 23, 2020

316head said:
We regrind almost everything. Endmills. Drills (both HSS and HM. HSS has to be big and long=expensive). Exchangeable drill tips. Reamer heads. You name it. That is, if the rework price is 1/3 of the original or less.

Gawd I hate reground endmills, unless it is the end only. Used to work at a place like that. Carbide is relatively cheap now for smaller (1/2" and under) tools.

DMF_TomB · Apr 23, 2020

Mike1974 said:
Gawd I hate reground endmills, unless it is the end only. Used to work at a place like that. Carbide is relatively cheap now for smaller (1/2" and under) tools.

.
1.000" dia carbide end mill about $300 to $400. new, i often used resharpened end mills especially if over 0.5" dia
.
when only sharpened on end often the flutes get taper wear, so milling a keyway slot the key wont go to the bottom of slot cause its smaller.

eksinger · Apr 23, 2020

Depends on your end mill requirement.. I have a reocurring G-10 job that i use regrind carbide end mills that went dull from a previous job, then dedicate the end mills to a rougher for g-10.. i get a few grinds out of these.. only taking no more than .005 off the dia and .03 off the ends at at time.

Max regrinds

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