So...are the Milwaukee Tools MX4 sds plus bits the way to go?

I've been...going through bits and hardware...well...at an alarming rate.  Wondering if I'm already onto the "best thing" by trying to gobble up these MX4's by the lot when they are available.  I'm using 3/8" 3 1/4" KB3 bolts and the Milwaukee 3/8" x 6" seems to leave me plenty of space if I go pretty much all the way into the chuck--meaning I get 4" of usable bit depth.

Also, while I'm asking...is there any way to resharpen spent bits?   

The MX4's are the best bit for the price that I know of. Comparable to Hilti's CX4 but about $40 cheaper per bit. I love them and generally buy them by the 10 pack. You won't be resharpening your bits though. As they dull the tip looses its original diameter as well. While you may be able to sharpen the tip with a belt sander, you will no longer be drilling a 3/8" hole.

Try the Bosch Bulldog Xtreme bits, they have lasted longer than anything else I've tried. The best price I found was on Ebay.  If you are drilling a lot it's hard to beat the 25 pack price. Approximately  $4 a bit currently on Ebay . I have sharpened some used bits in the past with a diamond bit on my Dremel tool, they do not work as well and the shoulders of the drill wear down in diameter making the hole too small to hammer the stud in. Metal recyclers will take you're spent bits, just FYI. It beats putting them in a landfill.

Andrew Jackson wrote:

Try the Bosch Bulldog Xtreme bits, they have lasted longer than anything else I've tried. The best price I found was on Ebay.  If you are drilling a lot it's hard to beat the 25 pack price. Approximately  $4 a bit currently on Ebay . I have sharpened some used bits in the past with a diamond bit on my Dremel tool, they do not work as well and the shoulders of the drill wear down in diameter making the hole too small to hammer the stud in. Metal recyclers will take you're spent bits, just FYI. It beats putting them in a landfill.

Agreed The Milwaukee bits are about half as good.

Sharpening won’t help.   The shoulders wear down making the hole diameter smaller.  These bits are more of a precision breaking tool than conventional drilling tool so sharpening really won’t help all that much.  

Andrew Jackson wrote:

Try the Bosch Bulldog Xtreme bits, they have lasted longer than anything else I've tried. The best price I found was on Ebay.  If you are drilling a lot it's hard to beat the 25 pack price. Approximately  $4 a bit currently on Ebay . I have sharpened some used bits in the past with a diamond bit on my Dremel tool, they do not work as well and the shoulders of the drill wear down in diameter making the hole too small to hammer the stud in. Metal recyclers will take you're spent bits, just FYI. It beats putting them in a landfill.

Damn, that seems expensive. Either that or I got a crazy good deal when I bought 6 Hilti bits for about $3 CAD each. That makes it $2.24 a bit USD!

Cairn War Machine wrote:

Damn, that seems expensive. Either that or I got a crazy good deal when I bought 6 Hilti bits for about $3 CAD each. That makes it $2.24 a bit USD!

There are a few great deals here and there from people just getting rid of stuff?   But I'm talking about a steady supply.  I'm going through more than 20 bits a week...

So...looking for those best bit deals that are real and reliable for some serious development.

Cairn War Machine wrote:

Damn, that seems expensive. Either that or I got a crazy good deal when I bought 6 Hilti bits for about $3 CAD each. That makes it $2.24 a bit USD!

Where and when?  Will you share?  Or just going to puff and taunt?   

Glen Kaplan wrote:

Where and when?  Will you share?  Or just going to puff and taunt?   

I purchased them from a local supply store Victoria, BC, Canada, called National Concrete Accessories. I'm not sure of they will ship to the states though. 

 I think the fact that I purchased them through my works account (I work in construction) might have been what got me such a great deal. 

Also what the heck are you bolting where you go through 20 bits a week!? That's more then 2 drill bits a day! How many holes are you getting per bit? I'm wondering if you got a bad batch of bits, or are just recycling them way to early.... 

Cairn War Machine wrote:

Also what the heck are you bolting where you go through 20 bits a week!? That's more then 2 drill bits a day! How many holes are you getting per bit? I'm wondering if you got a bad batch of bits, or are just recycling them way to early.... 

Drill is probably in reverse! Ha

Glen Kaplan wrote:

...is there any way to resharpen spent bits?   

Yes. Though there have been a lot of naysayers over the decades. I use the old style standard 2-cutter carbide tip SDS bits. Usually sharpening them before use, as the factory edges have a blunt angle. I find that a more acute angle drills faster. No need to be very precise about angles. Ubiquitous, inexpensive aluminum oxide sanding/grinding discs (reddish-brown color), 100 grit or finer (higher numerically), on a body grinder/sander work fast and easily. Some people have said that special diamond abrasive wheels are necessary; perhaps they never tried aluminum oxide. Don't overheat. Cut one of the 4 facets, then let it cool before grinding the next facet. I usually sharpen twice or three times before retiring the bit. When the sides wear down to equal the diameter of the shank, the bit is trash. The friction of the shank on the rock robs power from the rotohammer. Wedge anchors can usually tolerate a slightly smaller diameter hole than you get with a fresh bit, but there is a limit. If the hole is tight, the Hilti KB3 that you are using has a bevel at the base of the cone which helps it go into the hole. The KB3 also has a nice lip above the clip to prevent the clip from riding up and off of the cone. The ITW Readhead "Trubolt" lacks those features, requiring more care while placing in a tight hole. At one time, I used a micrometer to measure the diameter of the carbide tip. Now I just "eyeball" and run a fingernail over the sides to gauge the amount of remaining carbide. 

I haven't tried sharpening the newer style 4-cutter carbide tips with complex angles. You could try with a Dremel and aluminum oxide sanding/grinding drum or wheel. Wear safety goggles. Let us know your results.

Edited to add: My experience is drilling granite, not quartzite. YMMV

Cairn War Machine wrote:

Also what the heck are you bolting where you go through 20 bits a week!? That's more then 2 drill bits a day! How many holes are you getting per bit? I'm wondering if you got a bad batch of bits, or are just recycling them way to early.... 

Hes probably drilling quartzite if I had to guess.

Cairn War Machine wrote:

I purchased them from a local supply store Victoria, BC, Canada, called National Concrete Accessories. I'm not sure of they will ship to the states though. 

 I think the fact that I purchased them through my works account (I work in construction) might have been what got me such a great deal. 

Also what the heck are you bolting where you go through 20 bits a week!? That's more then 2 drill bits a day! How many holes are you getting per bit? I'm wondering if you got a bad batch of bits, or are just recycling them way to early.... 

:)

Yep...someone got me.  Lefty loosy, righty tighty!  I've been doing it wrong this whole time!   :)   jk

Dylan is correct...good old Wasatch quartzite...and always in the most bomber rock around...

It's hard to say how many holes I get per bit because I am actually using 4-5 bits per hole--that way they never get too hot.   I drill for a few seconds then switch out...

It seems to be working as I show up on any given day with about 8 bits total and 3 batteries!   I can easily get 20 complete holes/anchors this way...and it's usually daylight that keeps me from continuing not the gear.

But...I have recently noticed just how expensive my "addiction" has become and at almost $10 per bit retail from Home Depot...well...you get the idea.

Glen, I get 15+ 1/2" holes per bit in North Carolina quartzite with the Bulldog Xtreme bits. By far the least expensive bit for me on a cost per hole basis, when you see how much carbide they have in the tip you'll  understand why they have so much longevity. They have out performed Bosch 2 and 4 flute bits, hilti 4 flute and Dewalt 4 flute by a large margin. The tip of the DeWalt bit broke off  on my second hole, I find the Hilti's overheat faster than other brands, dulling them rapidly in stone as hard as quartzite. It's a good idea to swap out bits like you do, I normally just take 2 with me. The 25 packs are consistently available on eBay, they are also available in smaller quantities there far cheaper than you will find in retail stores. 

Cairn War Machine wrote:

Damn, that seems expensive. Either that or I got a crazy good deal when I bought 6 Hilti bits for about $3 CAD each. That makes it $2.24 a bit USD!

That's a good price,  but I get 2 to 3 times more holes from the Xtreme bits in my local rock. I tried four 3/8" Hilti's last year and they just didn't compare. 

Glen Kaplan wrote:

Dylan is correct...good old Wasatch quartzite...and always in the most bomber rock around...

It's hard to say how many holes I get per bit because I am actually using 4-5 bits per hole--that way they never get too hot.   I drill for a few seconds then switch out...

It seems to be working as I show up on any given day with about 8 bits total and 3 batteries!   I can easily get 20 complete holes/anchors this way...and it's usually daylight that keeps me from continuing not the gear.

I just wanted to say.....  HOLY SHIT!!   That's a lot of work.

A couple years ago I ran into some F-ing hard rock.  Ruined two bits in a few minutes.   I called Hilti tech support. As you say, the key is keeping them cool.  Besides a water-cooled rig (heavy/expensive) he suggested just dousing them in water and squirting water into the hole as well.   Might be worth a try.

I've been using DeWalt bits for awhile.  25 pack is a good option:

https://www.toolbarn.com/dewalt-dw5427b25.html/ 

I'd caution about sharpening...if the bit is dull, chances are its worn out in the diameter as well.  Measure them and make sure they still have enough girth to drill a proper hole.

Yeah...Wasatch quartzite can be hard!  Seems like certain drills of mine didn't do well in it...but for some reason, my Bosch 36V lithium has some type of vibration dampening or some such that really drills well into hard rock.  Slow, steady light pressure...don't push too hard, take your time, clean the hole often.  I bevel the starting hole a bit by rotating the drill in a small circle then drill straight when the drill settles into a straight line.  Seems to help me get a decent hole at the right angle.

One hole one bit is spendy!  Worse yet with a worn out drill bt and a hole that doesn't take the bolt well...

Good luck!

ClimbBaja wrote:

Yes. Though there have been a lot of naysayers over the decades. I use the old style standard 2-cutter carbide tip SDS bits. Usually sharpening them before use, as the factory edges have a blunt angle. I find that a more acute angle drills faster. No need to be very precise about angles. Ubiquitous, inexpensive aluminum oxide sanding/grinding discs (reddish-brown color), 100 grit or finer (higher numerically), on a body grinder/sander work fast and easily. Some people have said that special diamond abrasive wheels are necessary; perhaps they never tried aluminum oxide. Don't overheat. Cut one of the 4 facets, then let it cool before grinding the next facet. I usually sharpen twice or three times before retiring the bit. When the sides wear down to equal the diameter of the shank, the bit is trash. The friction of the shank on the rock robs power from the rotohammer. Wedge anchors can usually tolerate a slightly smaller diameter hole than you get with a fresh bit, but there is a limit. If the hole is tight, the Hilti KB3 that you are using has a bevel at the base of the cone which helps it go into the hole. The KB3 also has a nice lip above the clip to prevent the clip from riding up and off of the cone. The ITW Readhead "Trubolt" lacks those features, requiring more care while placing in a tight hole. At one time, I used a micrometer to measure the diameter of the carbide tip. Now I just "eyeball" and run a fingernail over the sides to gauge the amount of remaining carbide. 

I haven't tried sharpening the newer style 4-cutter carbide tips with complex angles. You could try with a Dremel and aluminum oxide sanding/grinding drum or wheel. Wear safety goggles. Let us know your results.

Edited to add: My experience is drilling granite, not quartzite. YMMV

So true. Those that say you can’t sharpen them probably never tried, just assumed. I use a “Green Wheel” on a bench grinder. I grind for a few seconds and then cool the bit in water. Key is to not get it hot enough to sizzle in water. Sharpened bits work especially well when hand drilling. I don’t know about extending the life of the bit, because I only retire them when the diameter wears down, not the tip. But the diameter doesn’t wear anywhere nearly as fast as the tip, so you can sharpen them and keep the bit drilling fast for the life of the bit, especially on the tough stuff. If you’re tossing them because they’re dull, that’s dumb. Send them to me, I’ll recycle em’. Besides, they come dull and a quick fine tuning goes a long way. It’s like an axe or chainsaw chain. You don’t buy it from the factory and just start using it. Waste of your energy. You fine tune the edges first. Or at least you should. 

Brian in SLC wrote:

I've been using DeWalt bits for awhile.  25 pack is a good option:

https://www.toolbarn.com/dewalt-dw5427b25.html/ 

I'd caution about sharpening...if the bit is dull, chances are its worn out in the diameter as well.  Measure them and make sure they still have enough girth to drill a proper hole.

Yeah...Wasatch quartzite can be hard!  Seems like certain drills of mine didn't do well in it...but for some reason, my Bosch 36V lithium has some type of vibration dampening or some such that really drills well into hard rock.  Slow, steady light pressure...don't push too hard, take your time, clean the hole often.  I bevel the starting hole a bit by rotating the drill in a small circle then drill straight when the drill settles into a straight line.  Seems to help me get a decent hole at the right angle.

One hole one bit is spendy!  Worse yet with a worn out drill bt and a hole that doesn't take the bolt well...

Good luck!

Thanks everyone...it helps to get some tips and tricks rather than just finding out the hard way.  That being said I did just run into the scenario where I was trying to finish a route but didn't have any sharp bits left...and I did learn the hard way just how important it is to have sharp bits, good holes, and plenty of battery...my last 2 holes were extremely difficult to get the bolts all the way in.  The sleeve must've been engaging too soon because the holes weren't quite the perfect size?  Thankfully I was able to muscle through and everything seems to be okay.  Again...I'm using 3 3/4" KB3 SS bolts so I'm guessing things are overkill...the rock is fricking hard!  :)   Yielded a pretty damn fine route that travels through some crazy exposed and steep terrain...probably only 5.10c or so...but definitely 'sporty'   

I'll try the DeWalt bits for sure, good price.  Thanks Brian.

And I'd love to feel/see the difference when jumping up to a 36v versus the TE4a which I'm using...I believe that's only 24v?   Definitely the smaller lighter drill.

Thanks all.

Salamanizer Ski wrote:

So true. Those that say you can’t sharpen them probably never tried, just assumed. I use a “Green Wheel” on a bench grinder. I grind for a few seconds and then cool the bit in water. Key is to not get it hot enough to sizzle in water. Sharpened bits work especially well when hand drilling. I don’t know about extending the life of the bit, because I only retire them when the diameter wears down, not the tip. But the diameter doesn’t wear anywhere nearly as fast as the tip, so you can sharpen them and keep the bit drilling fast for the life of the bit, especially on the tough stuff. If you’re tossing them because they’re dull, that’s dumb. Send them to me, I’ll recycle em’. Besides, they come dull and a quick fine tuning goes a long way. It’s like an axe or chainsaw chain. You don’t buy it from the factory and just start using it. Waste of your energy. You fine tune the edges first. Or at least you should. 

Really awesome to hear and makes perfect sense to me (as I spend some time with the chainsaws too).

I will try to breathe some new life into my collection of bits!   Thanks for the info and the inspiration.

I am also drilling quartzite and am new to this rock.  My first holes I was using new Milwaukee bit.  5 min per hole, going slowly and blowing hole out often.  I then switched to this random bit from my box of stuff and it went in like butter.  1 min hole!   I am trying to find out what it is, ordering one of everything I can find.  I suspect Vermont American.  This one would be very difficult to sharpen, but I did do some blade types after reading the above thread.  Any ideas?  No logo but says German made