Replies

1. 
   fingers | Jun 12, 2007 12:46am | #1

   I'll take a stab at this.  The SDS vs. SDS plus vs. SDS max refer to the shank configurations that fit the chuck on a rotary hammer.  There's also a spline drive configuration, but I think they're kind of phasing those out in favor of the SDS style.  Basically SDS and SDS plus will only go to a certain size bit, whereas SDS max will fit bigger bits.  (I've used up to a 4" core drill on my Hilti SDS max)

   A hammer drill is useful only if you have to make a few tapcon sized holes in concrete.  It'll take a long time and vibrate the hell out of your hands if you have more than just a few.  If you're trying to drill granite, it'll take all afternoon.  ( Ask me how I know this)

   A demolition hammer is to break up stuff so the rotation action or rotation/hammering action isn't as critical.

   I know my hilti ATC 76 will do light demo (chipping up tile . . . that kind of thing), straight drilling (never tried that, that's what a hole hawg is for), but it really excels at drilling in concrete, rock, granite, etc.

   I think the key is sizing it for what you'll do most often.  If that's drilling for tapcons, many on this forum like the Bosch Bulldog SDS.  It'll handle that with ease all afternoon long, whereas if you're breaking up concrete slabs you'll want a true demolition hammer.

    

2. 
   renosteinke | Jun 12, 2007 01:46am | #2

   You pretty much have to look at the tool bits to understand the differences ... and the limitations!

   the SDS shank is maybe about 1/2" diameter. Think about it ... that piece of steel can only do so much! In practical terms, SDS is limited to drilling a 1" hole in SOFT masonry, core drilling to 2 1/2", and chiseling 4" concrete (or a lamp post base).
   SDS "Plus" is a minor variation on the SDS shank, and does not have a greater capacity.

   SDS Max and Spline have about double the steel in the but .... so can do larger jobs. Of course, the larger size, greater weight of the tool itself might be considered a clue ....

   Hex shanks are defined by the width across the flats; again, bigger is stronger.

   Tool terminology is not consistent at all. While a "7/8 SDS" tool is trying to tell you 'forget the 1" bit- I'm made for smaller stuff" .... on a 7/8 hex drive tool, that is the size of the shank! It's safe to say that the hex tool is a LOT bigger.

   "Hammer drills" provide only minor impact, and are limited to setting those plastic screw anchors.

   "Roto-hammers" are the next step up. Some will drill; all will hammer AND drill at the same time; and some will hammer (chisel) as well. They are available in various drives and sizes. They are great for most any hole you need to make, and the ones that chisel can do light demolition.
   Is 'bigger' better? No. How heavy a tool do you want to carry up a ladder?

   Demolition hammers use the hex shanks, and do not drill; they chisel only. They are available in a variety of sizes, starting at about 35 pounds.

   What to get? Well, I suggest three approaches:

   1) Forget the box stores, and visit a REAL tool house. The staff there knows what they're talking about;

   2) Visit rental companies, and try out a few different tools; and,

   3) Start off with cheap Chinese clones. Available at about 30% the price of 'real' tools, using them is a low-cost way to learn the limitations of each. Then, go out and buy a good tool that fits your use the best.

3. 
   BillBrennen | Jun 12, 2007 10:07am | #3

   For SDS tools and Jacobs chuck hammer drills, the listed sizes are generally the largest hole they recommend you drill with a solid bit. Core bits can go larger in the same tool, since they only remove a ring of material, not the entire hole's worth.

   As noted by others, SDS is way more powerful than a similarly sized tool for round shank bits. The special shank design gives a much more efficient use of the available motor power. In an SDS tool, only the bit is going back and forth with the hammer action, unlike a hammer drill where the whole chuck has to go back and forth with the bit.

   SDS and SDS-plus use 10 mm shanks (a hair over 3/8" diameter.) SDS-Max tools use a 20 mm shank, so twice the diameter, 4 times the cross section at the shank.

   Some hammers are just that, only hitting action, like a jackhammer for instance. Roto hammers drill with hammer action. Bigger ones will have a hammer only option, but some of the smaller SDS ones do not have hammer only ( AKA "chipping") function. Some tools also have drill only function, mostly the smaller ones. This is handy in soft masonry.

   Bill

4. 
   rasconc | Jun 12, 2007 03:57pm | #4

   Welcome.

   You got the pretty much full story to answer your question.  Unless you are just going to do a couple of holes for small anchors I would skip the hammer drill and go to a rotary hammer.  I have a Milwaukee corded 3/8 hammer that I have retired to do kreg jig pocket hole screw duty, hardly ever use any of the other three cordless ones unless it is just a small hole or two.

   I got a used Bosch Bulldog and the next step up SDS plus jobs and they are the go-to hole makers in masonry.

   I bought one of the Chinese versions on ebay for next to nothing (got to watch and be patient) about 30 delivered with bits.  I gave it to my son but it seems to be pretty good for intermittent use.

   Makita Pit Bull is basically the same as Bulldog.

   You will find more uses for the chipping function than you ever thought of.

   Bob

1. 
   BryanSayer | Jun 12, 2007 05:04pm | #5

   ditto the chipping function. I wish I had held out for one that does chipping. I picked up a Hilti TE-6 S on ebay, but wish I had looked for a TE-6 C with chipping.