bosch hammer drill questions

Terryb,

You are absolutely right to be fed up with drilling holes in concrete with conventional three jaw chuck hammerdrills.

The  three jaw chuck hammer drill uses a toothed plate to give a bump effect to the chuck, thereby creating a sort of hammer action.  the problem with that is that it doesn't allow for alot of travel compared to an sds system.

To answer your question, sds stands for slot detente system which basically refers to the groves on the bit and the way it is held in the chuck.  if you will look at the bit you will see a couple oblong grooves on the sides of the shank as well a as a straight groove for the drive system to turn the bit.  the oblong grooves allow the bit to travel back and forth much more in the chuck thereby hammering much more effectively. In the sds drill itself there is a tube and piston system which drives the bit in and out much more efficiently than a conventional hammer drill.

You will often see bits labeled sds or sds plus, these are the same and will work in sds drills.

Sds max is a differently configured chuck and is used on larger rotary hammers (which is what an sds drill is also)

Spline drive systems are used on the largest of rotary hammers and allow for the largest hole drilling capacity. The cons of the spline and sdsmax systems is the cost of the hammer and bits.

Basic sds bits and drills up to 1 1/4 inch can be had for about 300 dollars give or take and the bits range from 7 bucks for a tapcon bit to 40 or 50 for a 1 inch bit.

Sds max and spline systems prices are much more for the drill and bits however they will drill larger holes vs a basic sds drill. Max and spline systems are routinely used to drill 4 to 6 inch holes repeatedly or hundreds of smaller holes in a couple days time. If you need a drill that big it is usually more cost effective to rent.

Sds/plus drills are more comfortable in the 1 to 1 1/4 inch range.

Also if you are in the market for a drill spend a little more and get a three function drill,  which will drill, hammer and drill, or just chip or hammer only. That is the best thing for light chipping of concrete junk, or removal of ceramic tile. Really makes it easy.

Also you will find that even though the bits are more expensive for sds drills you will get far more holes out of a quality bit than you did with a traditional hammer drill, and you will get far better speed/ production time from the drill. Drills alot faster than hammer drills.

Oh and one of the things I see people doing wrong with an sds drill is to really lean on it like a hammer drill. Whats wrong with that is that the drills effectiveness comes from the bit being allowed to travel as much and as powerfully as it can when the drill is leaned on excessively, it reduces the effective travel of the bit unlike the older hammer drills. Just keep enough pressure on it to let it drill.

I hope this answered some of your question.

Well said Webby! 

The only thing that I would add is that if most of the holes you'll need to drill are in the 1/4 - 1" range a SDS or SDS plus rotary hammer is the tool to buy. 

I've got a really nice SDS Max Hilti rotary hammer because I needed it for large holes.  It works great but when I want to drill a 1/4" hole for a tapcon I've got a converter chuck that will accept a smaller SDS bit, but I'm always worried that I'm going to over power the bit and break it.  I'll keep my eyes out on Craig's List to pick a smaller rotary hammer for the small stuff.