Help snapped a SDS bit in the chuck

[mark the spark2]

Hi folks does anybody know how to get a snapped off SDS bit out of a Bosch GBH 2-20 S. I have stripped the chuck down so that just the hardened sleeve is showing with the hole in it for the ball bearing. The problem is that the drill bit has splines on it which have sheared off and when you try to get hold of it with long nose pliers they just slide off as it has snapped off about 20mm from the end of the sds bit and when you line the splines up and pull on it, it catches on something and the pliers just slide off. I have also tried drilling into the end of the broken bit to screw into it but as its hardened it just smashes the drill bit.If your wondering how I did it I was drilling with 25mm x 1000mm bit through a church wall which is made of flints and lime mortar. What makes it worse is that it wasnt my drill. Many thanks for your comments and no religous jokes

 

[Andy™]

i think drilling a hole into the end and adding a screw is probably the best way to go

 

[roys]

Don't know if it will work, do you have an arc welder? Start the weld on the broken stub, switch welder off once you have established the arc, should only take a second, let it cool, know hopefully you will have the welding rod to pull on to release it.

Hope that makes sense.

 

[Andy™]

good plan... but where are you doing to attach earth to?!

 

[mark the spark2]

Many thanks, do you have any idea what type of drill bit to use, as standard "jobber" bits just shatter when trying to drill into the broken end of the SDS bit?

 

[Andy™]

any metal drill bit should do, just take it easy

 

[mark the spark2]

I like the welding idea but like Andy said where to earth it is the problem unless just pushing the snapped off bit against the sleeve is enough to maintain earth, then of course there is the problem of touching the sleeve with the welding rod.

 

[roys]

Can't the earth just go on the outer sleeve?

 

[mark the spark2]

Probably be ok but I will have to have a chat at my friendly garage and borrow their welder.

 

[roys]

Good luck as you mentioned, go easy it will just be a quick 'spot' as you don't want to weld your drill to the chuck, that would be bad.

Let us know if it works.

 

[mark the spark2]

Yeah will keep you posted on events. You would have thought that you could take the chuck bit out of the gearbox assembly and knock it out from the back, but it seems to be a sealed unit unless someone knows different.

 

[Andy™]

im sure you can make it an unsealed unit and know it out from the back

but im not so sure it will go back together though!

 

[mark the spark2]

Thanks Andy. Thats the problem if it doesnt go back together i will have to buy the owner a new one. Searched the net for advice on taking it apart but nothing yet.

 

[m4tty]

Take it to your local machine shop. they will be able to sort it for you.

Could try a blob of chemical metal onto a rod and stick rod to broken bit? May not work tho most prob but may be worth a try depending on how tight it is in the chuck?

 

[Sidewinder]

In this situation I would treat this like a broken bolt & reach for the arc welder as has already been suggested, the method is fundementally the same, however, as I have practice I tend to build the weld up out of the hole & then affix something to the tower of weld to pull / screw the offending item out.

Another is that if the drill is too hard for a HSS bit, to resharpen a mason master on a silicon carbide (green grit) wheel to similar angles to a normal HSS 118 deg positive rake then try drilling the bit with that.

Mind I'd just shove it in my lathe to drill it if I needed to!

Other option to drill is a Stellite bit.

Remember though that if you can't drill it, a normal tap is only a little bit harder than a normal HSS drill so once drilled you'd have to tap to screw something into it, which you may not be able to do.

The other option IF you can drill it is to hammer a bit of "soft" material in as the stub is probably not too tight. e.g. drill 5.5mm, hammer a bit of M6 stud bar in then you may be able to pull it out. The core dia for an M6 thread is just above 5mm, the od will be just below 6mm so in a 5.5 hole you will flatten the peaks of the thread like barbs thus you may be able to pull it out, also you could then rig something up to use a nut as a puller against the face of the chuck.

IMHO, welding is best!

We used to use some trick rods for this job.

HTH

 

[mark the spark2]

Thanks will give at least one of your suggestions a go. Will let you know how i get on.Ta

 

[batty]

Can't you just pull back the release mechanism and then give it a good shake it should just fall out unless you have damaged the chuck if it is damaged a new chuck will probably be needed anyway.

 

[Apache]

Can't you just pull back the release mechanism and then give it a good shake it should just fall out unless you have damaged the chuck if it is damaged a new chuck will probably be needed anyway.

Batty, I thought the same but I have a 'rare earth magnet' pick up tool that would give some extra purchase. I'd try that first

 

[sellers]

Can't you just pull back the release mechanism and then give it a good shake it should just fall out unless you have damaged the chuck if it is damaged a new chuck will probably be needed anyway.

Thats always worked for me!

 

[Oscar21]

It must be possible to stip down the chuck further, I did it to an el cheapo one the other month, took some thinking about but it worked. look for circlips holding collars on.