Question about Hammer Drills, their bits, and adapters

[gjmontll]

For my current project (building some ham radio antenna masts), I am likely to need to use a hammer drill during the installation. I've never used one, and may rent or buy one.

I see that modern hammer drills take one of three sizes of tool bits, SDS, SDS-Plus, or SDS-Max. I see that some adapters allow you to use smaller bits in larger drills, i.e. a SDS-Plus chisel bit could be used in a SDS-Max drill. Does this go both ways, just like with socket wrenches, where your adapter can go from 1/2" to 3/8" or vice versa?

My question: Do adapters allow use of large bits with small drills, i.e. an SDS-Max bit into an SDS-Plus drill? My on-line search results on this have been ambiguous, and I've found no knowledgeable experts at any of the stores I've visited.

Thanks,
Greg

 

[DavidR8]

SDS-Plus bits have 10mm shanks whereas SDS-Max have 18mm shanks. As far as I understand adapters allow a Plus bit to be used in a Max tool but not the other way around. Or at least I've never seen one to adapt a Max bit to a Plus tool.
I think the reasoning would be that a Max bit could potentially damage a Plus tool whereas a Plus bit in a Max tool would create less force and wear and tear on the tool than a Max bit in a Max tool.

 

[gjmontll]

Thanks Dave,
When you say "... they allow...", I assume you mean the Plus-to-Max adapters.
I agree with your reasoning about avoiding overload, that's what I suspected the manufacturers might say. And yet, if the smaller "tool" (drill) has less power and torque, that might just mean the larger tool bit would merely underperform. (Like having a 2-inch socket (1/2" drive) adapted down to a puny 3/8" ratchet wrench. (My cynical side also suspect the manufacturers would avoid up-adapters in order to maximize their sale of the more expensive drills.)
The immediate tasks will be digging thru hard clay, roots, rocks, perhaps break up some remnant of a cement channel drain, and to drive ground rods.
I will likely just rent a sds-plus tool, if Home Depot (or wherever) has the appropriate bits to fit (shovel, chisel, ground rod driver), upgrading to Max if needed.
Greg

 

[Jake M]

My understanding is that you can not put an larger bit into a smaller rotary hammer, but I'd be willing to bet that the internet could find you an adapter to make it into an egg beater if you wanted. My hearsay based belief is that you really don't want to adapt much smaller than the given range either, as the bigger rotary hammers are literally bigger hammers, and the smaller tools don't necessarily want that.

So my answer to your question is, while "the internet" could "probably" find you any adapter you wanted, (speculating, I've never seen it) these are not drills, they are mini electric jackhammers. The fact that you can out an out of range tool bit in it doesn't necessarily make it a good idea.

My belief, after discussing with sales critters, a couple of shop equipment dealers (think automotive hoists), and a bit of reflection on what bits I see in stores, on the shelf, right now this instant because I'm in a pickle... SDS Plus pretty much covers everything unless you're above 1-1/2 inches. SDS Max only goes down to half an inch or so before it becomes too aggressive to not break tools. Not very handy in that department. Max does however excel by a wide margin with chisels, breakers, and general "jackhammer" tools, where you can get a little more out of the larger shank. SDS plus "demolitioin" tools are a LOT smaller in shank size, and therefore they make the actual tools a lot smaller. Spectacularly useful, but small.

Having rented, then bought an SDS plus- I do not personally think you would want to put a larger bit in a smaller hammer. SDS plus goes (to my knowledge) from 3/16 to an inch and a half. At an inch an an eighth, it's gone from feeling like "a larger drill" to feeling like "it's starting to run out of steam". I'd probably try one and a quarter, but over that I'd probably rent again if I needed that kind of size. Max is a much bigger tool to run the bigger tooling.

I'll tell you this for certain. If you've never run one before, you're gonna love it. If (and only if) owning ends up making more sense than renting- Hold out for the full function selector. Rotary hammer, rotary without the hammer (Drill mode, core drills when you hit rebar for example), and hammer without the rotary (Jackhammer mode). It's not hard to find that functionality, I believe it's more common than not, but it's not guaranteed. Look for it, even if you don't know why just yet. Seriously. Rentals only have to do the immediate job at hand. If you're buying one in any size, you want that.

 

[DavidR8]

I recently rented a big'ish Hilti jackhammer and was utterly blown away at how powerful the thing was. Broke up a 5ft x 2ft x10" thick slab into manageable pieces in about 20 minutes.

 

[Dhal22]

Hilti is the best but Bosch makes a great basic model (Bulldog). Standard sds shank.

 

[gjmontll]

I thank y'all for the quick replies and your knowledge. When this hot spell passes, I'll be making 3 holes each about 3' deep and a foot in diameter. One or two might be hand dig-able, but one may have a thin layer of concrete in the way, depending on exactly where I site the antenna mast.
When I get them erected, I'll post a story here on H-M. There have been some very interesting set-ups at my mill.

 

[Jake M]

...one may have a thin layer of concrete in the way, depending on exactly where I site the antenna mast.
.

How thin? Four inches or less? If you decide to buy (again, I'm not saying for or against....), SDS Plus has that all day long. If you're renting.... Take what they've got and don't sweat it. For one hole, big enough to dig three feet deep... Max would probably be quicker by a small margin in this case. You'll want a couple of "bits" to go with it. Half inch drill, a breaker point, and a chisel, inch or inch and a quarter. While SDS Max will do the job (slightly) quicker, but not much, the SDS plus is quite capable, and more useful as a just in case type tool to collect dust until the zombie apocalypse comes, if you're gonna keep it. Assuming the hole is "through" the concrete, and not just removing some of the edge, I'd bank on a couple hours, although I'd kinda expect more like 45 minutes to an hour. It all depends on the concrete, but it might be significantly more or less. The concrete here is the absolute biggest variable, because literally 80 percent of your time is gonna be "breaking through", with either tool. After you're "in", you can start defining pieces with a drill bit, and breaking out actual chunks, and even insanely tough concrete goes WAY faster. You can buy as many bits as you like, but a half inch drill and a half inch point (spiraled tips are best) would get the job done pretty effectively. (Use the point to break between the holes, DON'T stuff a half inch point into a half inch hole. A one inch or one and a quarter inch chisel would be first on the "probably nice to have" list, but not required. There ARE better, but I've found that among the "on the shelf brands", Bosch drills and chisels to be a good value point to actually get a good, useful tool without going overboard. I've spent a little less that cost me a lot more. Bosch is not I'm sure the only brand that qualifies for that, but I would not cheap out on the bits. That said.....

Somehow I had envisioned a much more involved project than this, and sidestepped telling you what actual SDS Plus weapon I chose to get. For the cost of a days rental, Harbor Freight has one that I'd recommend. (No, I wouldn't recommend. I'm suggesting for your consideration, let's put it that way.) Two out of five stars on a standard rating list. In this case, totally and wholly different project, but the same trigger points applied. One single "need" that just flat out meant I couldn't make do with the "hammer drill" function on my regular drill any more. The one I'm going to (carefully) suggest for you to ponder on is 63443, 63433 (same/same) which is dirt cheap, longer style, (which I find easier for chiseling, the compact style I find easier for drilling), SDS plus, and that's my list of good points. It stinks like cheap plastic until you run it for a bit, then it stinks like burnt electrical so bad you can't even tell that the plastic still stinks. Good old school Harbor Freight style. But it's guaranteed good for as long as the warranty, and easily will handle a job that size, and "probably" several more. Again, I'm only suggesting it because (at least for me), it's the same cost as a days rental. If you'll actually use it a lot- Well, I've got two solid eight hour work days on mine which put it well below renting for me, probably (estimating) five or six actual cumulative hours on the tool, and it's really well worn. Still works fine, but it's well worn. For a commercial tool, that's nothing. For a homeowner? Heck, the cordless electric drill probably doesn't get that much run time in ten or twenty years, even though it's capable of (borderline) commercial use. So, perspectives and expectations apply. For me, the gamble paid off in that when I decided to put properly spaced and plentiful outlets in my basement (probably sixty or so very small holes), It beat the heck out of the hammer drill that I would have used, and would have worked. But I saved many hours, and many broken or worn out bits. (Rotary hammers dont' tear up masonary bits like a hammer drill does, and what you thought was a ruined masonary bit on a hammer drill will still work, and work well with rotary hammer. Plus the holes stay on size a lot better than with a hammer drill, which is great for tapcons, and not having to deal with inserts). So I won the "cheap out" game. But I only won by enough margin that I say you should consider it, solely because of the sproadic and infrequent use of these tools. Make sense I hope?

 

[gjmontll]

How thin? Four inches or less? If you decide to buy (again, I'm not saying for or against....), SDS Plus has that all day long. If you're renting.... Take what they've got and don't sweat it. For one hole, big enough to dig three feet deep... Max would probably be quicker by a small margin in this case. You'll want a couple of "bits" to go with it. Half inch drill, a breaker point, and a chisel, inch or inch and a quarter. While SDS Max will do the job (slightly) quicker, but not much, the SDS plus is quite capable, and more useful as a just in case type tool to collect dust until the zombie apocalypse comes, if you're gonna keep it. Assuming the hole is "through" the concrete, and not just removing some of the edge, I'd bank on a couple hours, although I'd kinda expect more like 45 minutes to an hour. It all depends on the concrete, but it might be significantly more or less. The concrete here is the absolute biggest variable, because literally 80 percent of your time is gonna be "breaking through", with either tool. After you're "in", you can start defining pieces with a drill bit, and breaking out actual chunks, and even insanely tough concrete goes WAY faster. You can buy as many bits as you like, but a half inch drill and a half inch point (spiraled tips are best) would get the job done pretty effectively. (Use the point to break between the holes, DON'T stuff a half inch point into a half inch hole. A one inch or one and a quarter inch chisel would be first on the "probably nice to have" list, but not required. There ARE better, but I've found that among the "on the shelf brands", Bosch drills and chisels to be a good value point to actually get a good, useful tool without going overboard. I've spent a little less that cost me a lot more. Bosch is not I'm sure the only brand that qualifies for that, but I would not cheap out on the bits. That said.....

Somehow I had envisioned a much more involved project than this, and sidestepped telling you what actual SDS Plus weapon I chose to get. For the cost of a days rental, Harbor Freight has one that I'd recommend. (No, I wouldn't recommend. I'm suggesting for your consideration, let's put it that way.) Two out of five stars on a standard rating list. In this case, totally and wholly different project, but the same trigger points applied. One single "need" that just flat out meant I couldn't make do with the "hammer drill" function on my regular drill any more. The one I'm going to (carefully) suggest for you to ponder on is 63443, 63433 (same/same) which is dirt cheap, longer style, (which I find easier for chiseling, the compact style I find easier for drilling), SDS plus, and that's my list of good points. It stinks like cheap plastic until you run it for a bit, then it stinks like burnt electrical so bad you can't even tell that the plastic still stinks. Good old school Harbor Freight style. But it's guaranteed good for as long as the warranty, and easily will handle a job that size, and "probably" several more. Again, I'm only suggesting it because (at least for me), it's the same cost as a days rental. If you'll actually use it a lot- Well, I've got two solid eight hour work days on mine which put it well below renting for me, probably (estimating) five or six actual cumulative hours on the tool, and it's really well worn. Still works fine, but it's well worn. For a commercial tool, that's nothing. For a homeowner? Heck, the cordless electric drill probably doesn't get that much run time in ten or twenty years, even though it's capable of (borderline) commercial use. So, perspectives and expectations apply. For me, the gamble paid off in that when I decided to put properly spaced and plentiful outlets in my basement (probably sixty or so very small holes), It beat the heck out of the hammer drill that I would have used, and would have worked. But I saved many hours, and many broken or worn out bits. (Rotary hammers dont' tear up masonary bits like a hammer drill does, and what you thought was a ruined masonary bit on a hammer drill will still work, and work well with rotary hammer. Plus the holes stay on size a lot better than with a hammer drill, which is great for tapcons, and not having to deal with inserts). So I won the "cheap out" game. But I only won by enough margin that I say you should consider it, solely because of the sproadic and infrequent use of these tools. Make sense I hope?

Jake,
Thanks for your insight, I was at the local HF last week, looking at the HF 63443... but my store only had their display unit on this, and on the 10A model, none actually in stock, or I might have bought one. I have several piece of HF electrical tools, most work okay for me. I may go this route, but on the HF site, too many reviews were 1, 2, or 3 stars.
As I said, I need to make a few hand-dug test holes to find the "ground-truth." I'm guessing the concrete I may encounter is about 3 inches.
Greg

 

[MikeInOr]

I picked up my Bosch SDS plus class rotary hammer for $40 because it didn't run. It took me all of 5 minutes to change the brushes once the new set came in. It works perfectly now.

It takes me 30 minutes+ to drill a 1 1/8" hole 6" deep in cured concrete with my Bosch. 1 1/8" is as big as my drill is rated for. I wouldn't try to go bigger with my Bosch, it would take forever. This was with a good Bosch 4 cutter bit and the drill got VERY hot. I doubt a HF drill would have held up for this job.

It took me about 6 hours to drill these holes in the slab I want to get rid of:



I filled the holes with expanding grout:


I would not spend any serious money on a SDS plus rotary hammer if you need large holes (over 3/4"). 1/2" bits go through concrete quite quickly and 3/4" bits are useable. 1"+ bits are really outside of what they are made for. If I did this project again I probably would rent a properly sized rotary hammer or a jack hammer.

My Bosch rotary hammer is perfect for drilling holes in concrete and rock to mount stuff with lead wedge nuts. Which is what I really bought it for.