On 15/08/2020 14:54, Jeff Layman wrote:
On 15/08/2020 11:13, John Rumm wrote:
On 14/08/2020 21:07, Jeff Layman wrote:

I'll check tomorrow and compare shank patterns.

Having said that, if yours works different to mine and does hammer with
the chuck in, you may have a second problem, since a normal drill
bit is
not designed for = 2 Joules of hammer energy per blow - so you might
just shatter the carbide off the end anyway!

I hadn't considered that. Is the tip of an SDS drill bit of
different/heavier construction than an ordinary masonry bit?

Yup, and the fluting on the shank different at well to clear waste
faster. Some bits are two flute, and some are four. In some respects,
SDS bits are more akin to a rawl tool style design - designed such that
the masonry is pulverised by the high impact energy, and the rotation is
basically there to clear the waste, and move to the next are to be hit.
Its all about the hammer rather than the drilling.

Out of interest I just compared some masonry bits with identically sized
SDS bits (8, 10, and 12 mm). The masonry bits were Bosch and unbranded;
the SDS were unbranded. The main difference was the flute shaping. The
Bosch 8 and 10mm masonry bits were about a mm less in diameter than the
equivalents SDS bits, but the unbranded masonry bits had the same
diameter as the SDS bits. Other than that there was no difference. As
far as I could tell, the Tungsten Carbide tips were of identical size in
thickness and depth, so I don't think the SDS bit tips are any stronger
than masonry bit tips.

I did the same earlier, and noted that there were some differences
between the Bosch multi-material and the SDS, although interestingly,
less difference between the SDS and a conventional Masonry bit.

The Bosch have a slightly steeper angle at the tip, and the carbide is
shaped with a flat sharp side on the leading edge. The SDS is bevelled
on both leading and trailing edge. Shank on the SDS was slightly
slimmer, and had a higher twist rate of flues. The Bosch design is
presumably influenced by the need to have a sharp edge to give it the
ability to cut wood / steel as well as masonry. The conventional masonry
bit had a profile similar to the SDS - but obviously its useless in
things other than masonry.

I also had a close look at one of my add on chucks, and noted that does
have the full SDS+ flute pattern, so in theory could be hammered. I
might have to find a masonry bit I don't care about and try and see what
happens!


--
Cheers,

John.

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