Hi, I am trying to repair a strimmer and the head on a bolt I am try to remove snapped off. The only way I can access the bold is from the back, although I cannot get anything fixed on the end of the shaft as it's in an awkward place. I purchased a set of screw removal tools but I cannot drill into the bolt as it's too hard. What driller would be best for this 2mm/3mm? Thanks, John.
These are the best drill outs ever, I removed broken wheel studs on a VW van with ease. If you can find some in the UK, had mine for years so don't know of any seller off hand. http://www.aldn.com/Pages/drillOut.php
Is the bolt (screw ?) acually hardened ?....doubtful, but probably high tensile. Centre punch & then use a small drill,if you have one, then work up to the size that you require. A decent HSS should be fine & yes,certainly use cutting lube. Sorry that I can't advise on speeds,but I don't know what gear that you are using.
Oh my the dreaded sheered off bolt. Cobolt drills will and should do the job and do NOT think Dewalts cobalt drills do the job because they won't. Use an engineering supplier to get some quality cobalt drills like Dormer and use a quality cutting fluid. I use Tapmatic #1 Gold. Failing the cobalt route then you can use the hardest drills known to man. Solid tungsten carbide, these are very brittle and smash very very easy so you need to at least start the hole with a cobalt then use a carbide slowly and firmly so you don't smash the drill.
Agree with you about Dormer drills,although I use Supacut as a lube.....but tungsten carbide drills,do they make them? The only ones that I can think of are the Bosch multi construction ones. I'm sure the OP would be better off with HSS or cobalt,but hopefully,he has done the job by now.
Yes they do make carbide drills I have two sitting in front of me on my desk i been staring at for the past few months. One is from Europa Tool and the other is a Dormer. Usually used for my milling and lathing and they are the only drill that can drill out a broken HSS TAP. So easy to smash though, they are so brittle. Seriously, Bosch could not make a quality drill bit for the engineering industry if they used black magic. Bosch make masonry drills and very good ones at that but engineering stuff, hell no. Buck and Hickman(Sheffield steel tooling) do some of the best cutting tools and abrasives i have ever used and compared to German tooling(Other than sandvik) they cut through anything. Mostly all my Lathe indexed tooling is sandvik(German), these carbide metallurgic made cutters are just incredible at cutting through anything including HSS and 316 grade stainless which is a pig for work hardening. Anyway i digress, yes they make solid through and through carbide drills, expensive and very brittle but will cut through anything.
Thanks for the info.I had never come across them, as I did not do much machine shop work, but I should point out that Sandvik are Swedish, based in Sanviken.
Very true i always forget that as they have a plant in Germany and get confused, information overload and all that. Thanks for correcting me.