CY, I was strolling through the postings, saw yours and got curious. First thought was, "That should be a simple thing to find out." Went to links on this site, various on-line dictionaries, called some home-improvement stores, talked with a number of people. I see why you posted. Not a lot of people seem to know.
One guy I talked to said, "I've worked with power tools for more years than you want to know and have never heard search a silly question! I said, "Then give me the silly answer." I think his head almost exploded, but he finally admitted he didn't know. I thanked him anyway.
What I finally got (and I can't swear it's right) is SDS: Slotted Drill Shaft. Anyway, they are specifically used in a certain type of rotary drill hammer, designed to accept that type of shaft/shank, usually for masonry work. Hope this helps; moreover, hope it's right. Maybe someone will give a definitive answer. Gordon in N.C.
I'm not positive but I believe that the SDS drill bits were devoloped by Hilti for their hammer drills. The "slotted drill shaft" sounds a good as any I've ever heard. The original design called for two slots milled in the driil shaft lengthwise on opposite sides of the shaft. I say original as the is now a SDS max which has some additional rroves milled in the drill shaft. The new Max bits will work in the old drills but not the other way around. Just to add confusion to the whole thing there are at least 2 different diameters involved here.. One is about 3/8 and the other 9/16 or so. I believe there are other mfgs now using this format as I see the bits in places like HD. You used to be able to only get them from Hilti. Steve
the SDS uses a cylindrical shank on the tool, with indents to be held by the chuck. A tool is inserted into the chuck by pressing in, and is locked in place until a separate lock release is used - no tightening required. The rotary force is supplied through wedges that fit into two or three open grooves. The hammer action actually moves the bit up and down within the chuck since the bit is free to move a short distance. Two sprung balls fit into closed grooves, allowing movement whilst retaining the bit. SDS relies on a tool having the same shank diameter as the chuck - there are three standard sizes:
* SDS-Plus: a 10 mm shank with two open grooves held by the driving
wedges and two closed grooves held by locking balls. This is the most common size and takes a hammer up to 4 kg. The wedges grip an area of 75 mm² and the shank is inserted 40 mm into the chuck.
* SDS-top: a 14 mm shank similar to SDS-plus, designed for hammers
from 2 to 5 kg. The grip area is increased to 212 mm² and the shank is inserted 70 mm. This size is uncommon.
* SDS-max: an 18 mm shank with three open grooves and locking segments
rather than balls. It is designed for hammers over 5 kg. The wedges grip an area of 389 mm² and the shank is inserted 90 mm.
Many SDS drills have a "rotation off" setting, which allows the drill to be used for chiselling.