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Stuck SDS drill bit

In an old Ferm SDS drill

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pgk pgk20/09/2020 20:05:12
2563 forum posts
293 photos

The drill had been neglected in a drawer in the barn and only gets used rarely. I did have cause to drill about 50 holes with it a few months ago and broke the 5mm drill bit. I bought a replacement bit and used it last week to mount some new external wall boxes but can't get the bit out. Could this be a case of SDS2 into SDS1? Any tricks? I've tried the obvious from tapping gently round the drillbit base to clamping it in a vice and hauling on it and standing the whole thing up and filling round the dril-bit base with penetrating oil and leaving it a few days. The chuck end has a square based attached by 4 capscrews to the dril body which may be my next approach in the hope that there's access to the mechanism.
What are SDS bits made of? Any point in planning to try and mill/drill the bit out?

pgk

Michael Gilligan20/09/2020 20:15:40
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20182 forum posts
1053 photos

I may have been lucky, but ... when I had a similar problem with my Hilti, it was simply a matter of cleaning out the brick dust from the pull-back sleeve mechanism ... if it can't move far enough, the little ball won't release the drill bit.

Hope it proves as easy for you !

MichaelG.

.

Edit: This should help focus the mind:

https://en.wikipedia.org/wiki/Chuck_(engineering)#Special_Direct_System_(SDS)

Edited By Michael Gilligan on 20/09/2020 20:25:46

JohnF20/09/2020 20:26:07
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1152 forum posts
190 photos

Here is an article about SDS shanks **LINK** it may be useful ? I guess you are talking about SDS & SDS plus shanks ?

Material for the drill shanks will be some form of alloy steel capable of being heat treated, never had a reason to try but it probably is not too hard and more likely made tough and shock and wear resistant.

Looking at the article it seems it may be possible to insert standard bits into a plus holder ? but not the other way around ? Have you tried running the machine in reverse with hammer action on for a short time to see if it releases the bit ? Did you grease the bit before inserting into the holder/chuck ? [not trying to teach Grandpa to suck eggs etc ]

John

DC31k20/09/2020 21:01:44
686 forum posts
2 photos

The diagram in the article to which Michael links is very useful:

(https://en.wikipedia.org/wiki/Chuck_(engineering)#/media/Filepecial-Direct-System-chuck.png)

The (normally rubber-like) end cap, not numbered in the diagram, but cut through by the upper and lower II section arrows, should just prise off. This will allow access to the collar that retains the balls.

As he says, a good clean and lubricate should solve your problem and endcap removal will allow you to check that the collar is retracting properly. The balls have to come out from the outside or they would fall into the chuck every time you remove the bit.

I have only seen it once before, and I hope it is not the issue here, but I once had an SDS drill bit that was improperly heat treated such that the hammering action mushroomed the end of it within the chuck. This made it very difficult to remove.

pgk pgk21/09/2020 14:11:21
2563 forum posts
293 photos

I'm feeimg suitably stupid at not having really bothered to figure out how these chucks work. the image link is invaluable and I should have looked it up myself!
Re-examining things the balls are clear and move around easily but the drill-bit flutes aren't aligned. I guess that hammering into the dense brickwork of my barn jarred it out of the groove. Wrenching at it doens't work so I'll try reverse drilling another hole in the hope that sorts it..otherwise it'll be a case of taking the chuck off to see if there;s access from the back. I've been tied up with other stuff but will report back.

Thanks all

pgk

old mart21/09/2020 17:42:26
3771 forum posts
233 photos

I cannot imagine just how an SDS drill bit could have turned once fitted, but if the drill is dismantled and the shaft with the chuck is removed and the pneumatic striker is taken out, where the striker fits is a bore right through to the rear of the drill bit. Every time I fit a bit in an SDS drill, I first pull it back and forth to ensure it is correctly fitted, it should slide freely about 10mm.

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