Replies

1. 
   joeh | Nov 18, 2007 09:52pm | #1

   You can buy a green stone for a bench grinder, google up the cheapest source.

   Joe H

2. 
   IMERC | Nov 19, 2007 05:13am | #2

   carbide grinding stone fer yur bench grinder...

    

   Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming

   WOW!!! What a Ride!
   Forget the primal scream, just ROAR!!!

3. 
   popawheelie | Nov 19, 2007 08:00am | #3

   I use a diamond bit in my dremel.

4. 
   VaTom | Nov 19, 2007 04:19pm | #4

   I use a Harbor Freight diamond wheel in my drill press, freehand as I sharpen all drill bits. 

   PAHS Designer/Builder- Bury it!

5. 
   ubc | Nov 22, 2007 05:34pm | #5

   get The Drill Doctor. It's sold through Sears, Rockler, and Wooodcraft (I think). The more expensive model sharpens up to 3/4" bits.

   One of the best tools I ever bought. The bits are precisely sharpened every time. Learning curve is way low.

1. 
   TomE | Nov 22, 2007 06:54pm | #7

   I agree with the Drill Dr but some of the long bits can be a bit awkward to handle when sharpening.

2. 
   joeh | Nov 22, 2007 08:29pm | #8

    

   get The Drill Doctor

   SDS bits are nothing like twist drills.

   Joe H

    

1. 
   McMark | Nov 22, 2007 09:15pm | #9

   Most poeple don't bother sharpening their roto-hammer bits.  The bit is actually breaking the rock, not cutting it like a sharp twist drill does.

    

   Just use it until it as a unusable mess

1. 
   joeh | Nov 22, 2007 11:54pm | #11

   Most poeple don't bother sharpening their roto-hammer bits.

   Who is "most people"?

   You think a dull bit is as good as a sharp one?

   Just ruin a $50 or $60 bit rather than sharpen it?

   Joe H

1. 
   McMark | Nov 23, 2007 07:35am | #12

   Been in the trades 25 years, all heavy and commercial work.  Most guys use their roto-hammer everyday.  I have never actually ever met anyone who sharpens theirs.

    

   And like I said, they do not cut, they pulverize the material.  I was told by a Hilti rep that sharpening was not needed, and in his opinion, shortened the life of a bit. 

    

   How's that for referencing my opinion?  Not bad.  Your turn Mr Expert.

2. 
   DaveRicheson | Nov 23, 2007 03:49pm | #13

   I think you missed something  here.

   Do you own the company that is supplying bits that get thrown away?

   The OP is asking for ways to extend the lfe of his bits. He wants more MPG for his $50-60 investment.

   Not an unreasonable request, when the $$ come out of your pocket/profit.

   If you believe Hilti salesman,....let' talk about  this small bridge I got for sale.

    

    

   Been in the trades 25 years, all heavy and commercial work

    

   Number of years in the trades doesn't mean much to me. I been around longer than that in commercial and residential, but learn something new here almost everytime I sign on.

   I'm older now than the the guy that told me this many, many years ago.

   "You always do what you have always done, and you will always get what you always got."

   Keep an open mind.

    

   Dave

3. 
   joeh | Nov 23, 2007 06:32pm | #14

   Who pays for your bits, you or your employer?

   Why do they bother to put an edge on them at the factory if there's no reason for it?

   Not an expert.

   Joe H

4. 
   McMark | Nov 23, 2007 09:11pm | #15

   I'm saying it's not worth the effort to job-site sharpen them.  It takes time, shortens the life of the bit (that's right), and does not appreciably shorten the drilling time.

    

   How does not sharpening shorten the life of a bit?  Sharpening removes material, so that would shorten the life.  The bit is going to smack away at the conc, wether it is in a chisel shape or not.  Do you ever sharpen your hammer?

    

   I don't think you guys really understand how a rotohammer works.

5. 
   Sphere | Nov 23, 2007 11:17pm | #16

   I'm sorta in your court on this, we chew up small dia. bits often. But by the time they need "dressing" it can be done with a diamond wheel in a hand held grinder w/diamond wheels that we also have commonally chucked up.

   A 10$ bit? (under 3/8ths) Trashed,a larger bit may get a lick, but if it is so dull that iyt won't perform, it is because the carbide is gone, there ain't NUTHIN to sharpen..so ? It is trash

   If you look closely at the "wings" that are hard enough to require sharpening, they are often nubbed off ( these wings are for clearance only, after the cutter face has chiseled out the soon to be swarf), if the wings are shot, ergo the bit,,it'll self heat till the swarf can't eject or vice versa as the case may be.

   You also can't sharpen the braze from hard tip to soft shank, hitt that and the bit is trash.

   I am with you on this, if it is a dulled, trashed bit...that is what it is, I might get one touch up outta a bit, but that is rare, it works in a way that percusses, not rotational..lose that "edge" and clearance it creates, and heat destroys the binder that holds the carbide to the carrier shaft.

   Measure the wings on a brandy new bit, and note the OAD, vs the shaft , you have a glimpse of the "set" or clearance, like a saw, now reduce that by grinding down or use, and the chip ejection is lessened, chips carry heat and that is good thing to be rid of, because it attacks the carrier shaft and it will no longer be of temper to be re-tipped, unless the  re-tipper requenches the now work/abuse softend steel.

   I can attaest that a re'heat never resolves a burnt out tip, it has become annealed and will not regain the same structure as a new matrix can hold.Spheramid Enterprises Architectural Woodworks

   "If you want something you've never had, do something you've never done"

6. 
   frenchy | Nov 23, 2007 11:50pm | #18

   Sphere,

    I hear what you are saying but I have to disagree with you..

     I bought a Drill doctor and can quickly sharpen drill bits fast enough that it isn't worth not sharpening them.

     Before that I used to toss smaller drill bits and just use more force as required..

     When I had to I would sharpen by eye the bits that were larger too big to throw away.  When I bought my Drill doctor I was surprised at how much easier sharp bits worked than dull or hand sharpened ones. 

    In addition no worry about overheating the bit or sharpening at too steep an angle and have it catch..

    Take any bit you hand sharpened and put it thru a drill doctor and you will see what I mean..  Heck several new bits I've bought would be worthless without the drill doctor because they were sharpened at the wrong angle..   

     I wrote to someone else my actual experiance with my rotary carbide bits.  They last longer when you sharpen them when dull instead of just drilling away.. I understand that sounds counter intuitive , but it's a fact.

    Try it yourself and you'll see. 

      

7. 
   Sphere | Nov 24, 2007 12:56am | #19

   Excuse me, but you just said about three differing things. No worries, I get that way when I drink.

   Show me a drill doctor that can or will include a relief  bevel or a cutting facet for carbide.

   One does NOT sharpen carbide wit either the same abrasive or the same attack angle. HSS will be serviceable with a grind as such produced by a DD , but I'd bet the farm , you are mistaken about carbide SDS bits.

   There is no substitute for a real ( REAL) sharpening on a tip of which the OP was referring to..and TheDrill Doctor is NOT a way to go about it.

   I have spent the last 3 yrs drilling concrete, Limestone, Brick, rocks of unknown origin, just to hang a downspout that COULD be used as a FIRE ESCAPE, in the event. I have used and abused as many bits as seen in every suppliers phlanax, trust me, you wear them down  and chuck them, or else I'd an asss and say that Bosch works for ever.

   There is no magic bullet, they wear out, pure and simple. If you think a grind will fix it, it WILL, for one hole. TRUST ME.Spheramid Enterprises Architectural Woodworks

   "If you want something you've never had, do something you've never done"

8. 
   frenchy | Nov 24, 2007 02:48am | #20

   Sphere,

    I'm sorry but I can exactly replicate the angles involved with my rotary bits using the drill doctor.

     You are correct angles are differant but the model I have replicates them.  There are well over 200 holes drilled thru concrete and granite in my house and I did it with just one bit..   Yes there is plenty of carbide left..

    

9. 
   McMark | Nov 24, 2007 03:04am | #23

   I commonly drill 200 holes with one drill also.  Big deal

2. 
   frenchy | Nov 23, 2007 11:36pm | #17

   McMark,

     If you had a Drill doctor and sharpened regularly you'd know the joys of a sharp bit.  I had to drill well over 100 holes thru 2" of granite and to do so I would stop after about 20 holes and resharpen. 

     Freshy sharpened it took me about 45 seconds  after 20 holes it took slightly over 1 min. 30 seconds.

     Since it takes but about 45 seconds to sharpen it was time well spent.. In addition since it was cutting thru sharp it wore out less of the bit than if I'd just used force and effort to try to make up for a dull bit.

       Finally you are far less likely to break the object you're drilling thru if the bit is sharp.

6. 
   jagwah | Nov 22, 2007 05:43pm | #6

   The absolutly easiest way I found is to take your carbide bit to Lowe's

    

    

    

    

    

    

    

   when you walk through the doors toss it in the trash can and buy a new one. I find I can get them as sharp as new....;)

    

7. 
   IdahoDon | Nov 22, 2007 10:33pm | #10

   Pick up a 4" diamond wheel and 1/4" arbor to fit a drill.  When we're drilling a large number of holes with the sds my diamond wheel isn't far.  A sharp sds drill bit will cut twice as fast as a rounded over one and the drill will last longer as well. 

   I picked up a rotozip 3" diamond  blade in a pinch and ground out the metric hole to fit the only available arbor.  The smaller size seems to work just as well.  Spun on high speed in an 18v cordless is a good speed that makes quick work of it, but still allows a little room for goofs.

   A diamond blade in an angle grinder is probably too agressive to be easily used unless yours is a vs or you want to take down a lot of material.

   Another option if you have a tile saw is to simply hit your sds bits on the side of the blade (run dry to make it easier to see what's going on).

   Another option is the $15 dremel diamond wheel.  I have the wheel, but don't use it for that since the larger wheel works so much better.

   You can also put a 7" dimond blade in a table saw.  The table top makes holding the bit at the proper angle easy.  I wouldn't do this since the handheld drill and 4" blade work so well, but if all you have is this it would work, it's just more a pita.

   Good drilling! 

    

   Beer was created so carpenters wouldn't rule the world.

8. 
   maddog3 | Nov 24, 2007 02:55am | #21

   I don't know if sharpening would be the answer for your bits. especially if you have never sharpened carbide before. if you do a poor job on them they will just wear out faster anyway

   perhaps you would consider having them re-tipped !

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   .

   .

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   , wer ist jetzt der Idiot ?

1. 
   bobtim | Nov 24, 2007 03:00am | #22

   is it possible to get the larger bits re-tipped?  Who would do it, a saw shop maybe?

1. 
   maddog3 | Nov 24, 2007 03:18am | #24

   some shops that I worked for would send their larger bits out for new tips. but I have no idea where..I recall that Berlands in Lombard, Illinois would send in bits that you bought from them. I just did a little snooping and found this place in Floridahttp://www.bamanufacturing.com/repair.html
   .

   .

   .

   ., wer ist jetzt der Idiot ?

2. 
   IMERC | Nov 24, 2007 03:23am | #25

   yup and yup... 

   Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->

   WOW!!! What a Ride!Forget the primal scream, just ROAR!!!