I'd never considered the difference between hammer/percussion/impact drills until today, then saw something in the SF catalogue that was suitable for percussion but not hammer. Haven't managed to find out what the difference is. Many sites seem to use the 3 words for more or less any type of drill that's can be used on masonry, so is there a simple explanation, please?
At one time there was only really one sort of hammer drill - and the term hammer or percussion was commonly used. Then came SDS drills came along to confuse the issue. Hammer is now often used fr SDS and percussion reserved for the older type of hammer drills.
Ordinary "percussion":
(like) ratchet plates which caused the chuck to move in and out rapidely, rapidly create the hammer action.
There was a 'Red Head' hammer drill, which just hammered whilst you manually cranked the drill bit back and forth.
Then the SDS. I suspect the method of creating the hammer action of the SDS and the Red Head might be similar, but has anyone any details of how the hammer action is actually produced?
Usually there is a swash bearing to translate rotational motion into linear oscillation. This is connected to a cylinder, into which sits a close fitting hammer block. The linear oscillation of the cylinder is thus transferred by pneumatic lock to the hammer block, which can then strike the drill bit via a impact pin or bolt - the drill being free to move back and fourth in the SDS chuck by virtue of the flutes in its shank.
If you look at:
The way I look at it is, rotary percussion drill is a drill that happens to percuss, a rotary hammer is a hammer that happens to rotate.
Read the wikipedia article on SDS, and look at the patent links for the original Bosch patents. There are cross-sections that make it clear.
and combi drills; hammer is [now] for SDS. Just done some searches on SF and that's how the terms seem to split.
I'd always assumed that the 2 terms were interchangeable, then came across the item that was (un)suitable for 1 only.
Thanks for all the links and info.
so I am invisible and no one likes my simple and accurate description.
Indeed. I don't think there was ever a formal proclamation that this is how it is to be from now on - but it seems like a common use of the terms.
When there was one type of drill, they certainly were. Now its not so clear cut.
Personally, when someone says "Hammer drill" to me - I still think in terms of non SDS machines. Whereas "Rotary hammer" I would associate with SDS. Still I refer to a SDS drill as a SDS drill - saves any confusion!
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Harry Bloomfield saying something like:
Pixies with teeny-tiny little sledgehammers. There's also the belt-fed blank version.
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember F Murtz saying something like:
It's not that. It's just that either term could still be used interchangeably; deliberately, ignorantly, or otherwise.
Just call the old ones hammer drills - for that's what they were known as at the time, and call the newer ones SDS, for that's what they are. The marketeers and other ignorantists of the world can call them what they like - we know differently. We also know the useless tossers in ad agencies will never grasp things like that because they 'don't do technical'.
Thanks, I had heard there was some pneumatic element to it.
Sorry. I liked it at first reading but then found it confusing in that it didn't actually tell me which was which. If I get a false mnemonic I'm stuck with it and the same applies to one that I find to be confusing (to me).
When there is only 1 'version' a poor term doesn't really matter, but then along comes something similar and good names have run out due to misuse initially.
Of course, hammer drills always rotate and rotary hammer drills don't (always)!
The difference, in terms and usage, become important as soon as something comes along that's suitable for one but not t'other. If it's ' for use with percussion but not hammer', then I like to know which is which.
Perhaps I'll try to stick with 'percussion' for non-SDS - until I forget.
They are two different machines the rotary hammer drill is like a jack hammer which has a fairly heavy hammer action but also can rotate relatively slowly. The percussion drill is a drilling machine which has a fairly high but light percussion rate. I still think my first description was the simple answer asked for.
(I liked it) :-)
approx 1100 RPM for most SDS machines...
High percussion rate (>=20k bpm not being uncommon), but low energy (fractions of a Joule per blow)
Originally a hammer drill was a drill that you hit with a hammer. I still have two different sized bit holders and a number of bits. Some of my house bricks - and even the 'plaster' - in my last house were very hard, and I found an old fashioned hand drill and a 14lb hammer was the quickest way of making holes. They would still be useful in confined spaces where a heavy modern drill won't fit. Sadly I can only see one advert for a second hand set:
(This site takes me back: I still use quite a few of the things on it: and would have more if I could now afford them!)
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