Has anyone tried the BOSCH multi construction drill bits. they will drill through metal, timber tiles and even concrete in impact mode. I was a bit sceptical but you have to try one of these bits. I drilled holes in bricks using my cordless easily and it still drilled timber afterwards. Only thing I dont know is why they are good. Has anyone else used them and do they know how long they last

They are the best bits I have ever used and one of the cheapest. They last fairly well. I have a 6mm that I have used to put in cupboards on the walls in the garage, so it drilled through the chipboard back and 60mm in to sandstock brick. It did this 4 times per cupboard for 18 cupboards, so 72 times. I used the same bit the other day to drill through ceramic tile for a new heated towel rack, with no problems!
Not bad for a $6.50 drill bit!!


Just did the math,
It has done 86cm of chipboard. (nothing special)
4.32m of sandstock brick and still sharp enough to do tile!!

Dear JJ & Timbo,

I had a think about these Bits once a while back, with an eye to using them to drill out old plastic wall-plugs.

This was because:

1) Although normal spiral Drill-Bits have the best point geometry to work their way down the middle of the plug, chew it up, and then spit it out the back, they will undoubtedly blunten when you get to the masonry at the end of the plug's hole.

and

2) While Masonry Bits wont blunten on the masonry at the end of the hole, they hardly have the best point geometry on them to make short work of drilling out a plastic plug.

But when I actually got to the shop and tracked the Bosch "Multi-Construction's" down for a "looksie", they turned out to have almost the same point design on them as a conventional Masonry Bit. So I didn't buy them...

Do they look the same to you, or do you reckon they'd do a better job of drilling out a plug than a normal Masonry Bit? They're certainly reasonably priced...

Best Wishes,
Batpig.

The Bosch "Multi Construction" bits, are similar to Joran/Irwin's "Unibit" and the Artu "All Purpose" Drill bits.
They actually all share an otherwise unique geometry.

Like a conventional Tungsten Carbide tipped bit they have a fairly coarse cutting angle (112 degrees i think). Unlike conventional bits, however, they lack the "negative" relief grind in front of the cutting edge. This makes them more easily sharpened on a green stone or diamond wheel than other hammer bits.

This allows a "sharper" cutting edge, still at the coarse angle, to be presented to the workpiece.
For this reason, under no circumstances should they be used on a hammer setting, which would very quickly dull the edge!

Due to the lack of a hammer setting, I find them useful for delicate cordless drilling in softer materials, such as clay brick cutting masonry plug holes. I've found that hammer drills tend to wander off-course, taking the path of least resistance, resulting in a loose plug or dynabolt in soft brick.

They're especially effective in low-speed delicate work, but are painfully slow in hard materials. I wouldn't recommend using them for drilling well-seasoned slabs due to the slower cut and increased wear to the cutting edge.

Another common use for these bits is in fixing bottom plates to a concrete slab. I firstly use an 8 or 10mm. "dowel" bit to bore into the plate, finish with the unibit as it bores satisfactorily but slowly through the last bit of wood and into the slab, and then sink the dynabolt hole with the same-sized bit in the Rotary Hammer. Quick, accurate and easy with absolutely no damage to any of the 3 bits.

I'm told that they'll also bore metal, but I really can't see this as a viable use, as tungsten carbide is just too hard & brittle for smooth metal cutting, and the geometry just doesn't seem right.

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Doctor, my brain hurts!