End play problem with (SDS+) drill (edited) when using a long 450mm drill bit

[benaround3]

Hello

I purchased a Wickes Rotary Hammer drill this week, Model PDH26DS1.1

I had also purchased a drill bit 16mm x 450mm

The hole I need to drill is 16mm x 350mm through external brickwork

I have not used a SDS set up before.

There is some backward and forward movement of the drill bit sliding in the chuck, which is intentional due to the design, but I notice there is also slight lateral play where the drill shaft is held in the chuck.

I have to use a long drill bit, 450mm, and so this play translates to over 10mm at the far end of the bit and is very noticeable when the drill is in operation before the bit is applied to the work, such as to make it not possible to start with a clean hole.

My query is, is this normal? I found drilling a smaller pilot hole made it possible to stabilise the far end of the 16mm bit when drilling the final hole but I was still concerned at the amount the drill bit was wobbling.

 

[ETAF]

is the drill bit an SDS drill bit

I'm not aware of any wobble in my dewalt - and used to drill brickwork for coach bolts recently 14mm I think may have been 16mm

but i have put a SDS Drill bit in a normal chuck and got a lot of wobble!!!!

 

[Deleted member 174758]

is the drill bit an SDS drill bit

Yes - see here

There shouldn't be that much run- out. Can you wobble the drill bit in the chuck, or is the bit bent? (Roll it along a kitchen worktop to check - if bent it can't roll straight)

 

[benaround3]

Definitely SDS plus. Rolling it on a worktop shows a slight bowing which definitely should not be there so I will exchange it and keep posted.

 

[Harry Bloomfield]

All SDS have some side to side float, they have to have this to be able to move to hammer. They don't grip the bit like an ordinary rotary drill chuck.

 

[^woody^]

Start the hole off with a smaller diameter and shorter length bit. The larger bit will then follow this and not widen the hole.

 

[Deleted member 174758]

Start the hole off with a shorter bit of the same diameter is what Bosch and Hilti used to tell you when SDS first appeared... Smaller hole to start with means there is more chance of a 2-flute SDS drill shimmying and producing an out of round hole as it enlarges the hole (a bit like a 2-flute countersink can in wood)

 

[benaround3]

is the drill bit an SDS drill bit

I'm not aware of any wobble in my dewalt - and used to drill brickwork for coach bolts recently 14mm I think may have been 16mm

but i have put a SDS Drill bit in a normal chuck and got a lot of wobble!!!!

Maybe not but the drill bit I am using is 4 x the length needed for a single brick

 

[benaround3]

Update
Wickes agreed to exchange or refund the bent drill bit if I could find a straight one in the store. 4 on the shelf, only 1 was straight. But there still seems to be excessive end play. In the mean time Wickes Customer Service Technical have advised that the end play I describe is excessive and offered to refund the drill. I have had diverse opinions on what amount of play is acceptable. Some say it is unavoidable, others say there should be none, so I might shop around.

 

[Harry Bloomfield]

I have had diverse opinions on what amount of play is acceptable. Some say it is unavoidable, others say there should be none, so I might shop around.

It's simple, the end play is there to allow the bit to move as it is hammered. Without the movement, the SDS hammering would not work. The bit latches into the SDS chuck, via a ball bearing latch, so as to allow that essential movement.

 

[cdbe]

I've got a cheapo 1m long bit, you should see the end of that wobble around. You should be drilling pilot holes, SDS drills are not precision instruments, a 16mm without a pilot hole can easily destroy a brick.

 

[Harry Bloomfield]

I've got a cheapo 1m long bit, you should see the end of that wobble around. You should be drilling pilot holes, SDS drills are not precision instruments, a 16mm without a pilot hole can easily destroy a brick.

I have three 1m long, various sizes ones bought so cheap, it would have been rude not to buy them. It's unreasonable to expect a long bit not to exhibit some bend in it.

 

[Deleted member 174758]

It's unreasonable to expect a long bit not to exhibit some bend in it.

That's one good reason to buy decent quality bits. Better manufacturers put a lot more effort into quality control

 

[Harry Bloomfield]

That's one good reason to buy decent quality bits. Better manufacturers put a lot more effort into quality control

They may leave the factory perfectly straight, but a 1m long x 16mm will soon bend in use. Which is why you start deep holes with a short pilot drill.

 

[Mike13]

That's one good reason to buy decent quality bits. Better manufacturers put a lot more effort into quality control

Agreed, I was in a hurry for some long wood bits, bought some cheap chinese ebay specials, set of 6 for £3, several of them just unwound when the torque demand got higher, at least I still have two in the set that have the correct direction of twist in them...
Hilarious to watch them just reverse the twist!