I've been researching roto-hammers to add one to my toolbox. I've had good luck with Milwaukee products in the past,So that would be my first choice. My primary uses are for driving ground rods, and drilling through concrete for SE cable (2" core bit or smaller) However I would like the ability to drill to 4" if the situation arises. What I don't fully understand is the difference between SDS,SDS MAX,or Spline Drive. I'm also confused with the choice of "thinwall" and "thickwall" core bits and their specific applications. Thanxs, Dave
Well, you're on the right track by first defining your need; that is, how you intend to use the tool. In fairness, you will probably end up getting two, or even three, of these tools, for different size jobs.
For most of your needs, including core drilling up to 2 1/2", an "SDS" drive tool - the smallest of the batch- is fine. The tool is reasonably lightweight and handles well on a ladder.
The next step up is the "SDS Max" and "Spline" drives. These have a larger diameter drive shaft, and are used for more demanding jobs. They are the smallest tools to be of any help in driving ground rods, and a driving attachment is available (Use it!). It seems that there is more available in "SDS Max" than "spline."
The final category are "demolition hammers." These tools hammer only, they do not drill. They are very effective in breaking concrete and driving ground rods- though hauling even the smallest (35 lb.) up a ladder is no fun. Typically, they use 1 1/8" hex shank tools.
All of these tols are pricey. While this forum has had many opinions expressed as to brands, I suggest that you rent various models, and find your own preferences before you part with the cash.
SDS, SDS Max, and Spline refer to the type of chuck the tool has. Just like English and Metric the types aren't interchangeable. Generally speaking SDS Max and Spline are found on the bigger rotary hammers and SDS Max has pretty much replaced spline. Some manufacturers even have a "conversion" chuck that allows you to use, say, spline, in an SDS Max tool. That could be useful if you had an assortment of spline bits and buy a new tool.
I'd second the suggestion renting any tool you're considering buying.
SDS Max is becomming much more popular than spline. I can see it becomming the standard not too far in the future.
I have a Makita 4000(?) rotary hammer and I LOVE it. Extremely well made. As nice or nicer than the many Bosch drills I have used in the past.
I personally think Hilti is ridiculously over priced. Real nice and well made but come on. Maybe the big commercial and/or union shops can afford them, but not lil' ol' me. And I have seen failures with them as well. I have a small Hilti 1/2" hammer drill. The armature went on it. I priced a replacement and it was more than a whole new drill from a comparable mannufacturer.
"Anyone who has never made a mistake has never tried anything new." -Albert Einstein
We have been using the Hitachi DH38YE 1 1/2" rotary hammers for about ten years and I will buy nothing else. They last longer and hammer harder than Bosch and Milwaukee hands down. Hitachi hammers cost much less and last longer. I have been very happy with the Hitachi SDS drills as well.
Been happy with our Milwaukee spline drive. Sometimes it will not drive a ground rod in all the way. It seems like the clutch kicks in too soon but it's well used so maybe something is wrong. Bosh is good too. Hilti is the top of the line but more pricy.
You might consider one with interchangable chucks. I have a Metabo, I think it's a model KHE28 but don't remember for sure. It was a little more money but it takes the place of two drills on the truck. It can be used as either an SDS plus rotary hammer or a 1/2" keyless chuck drill.