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pottyengineering small holes centring tool

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Stewart Hart07/08/2020 08:54:10
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Moderator
651 forum posts
354 photos

I been having problems getting the small holes to run true for injector cones from this post it seems like I'm not the only one to have problems **LINK**

Have come up with this idea its probably bin done before its so obvious and it seem to work well basically its a piece of 5mm HSS with a 60 deg point ground concentric on the end and sectioned like a D bit this is held in a handle then a light spring and a cone with sliding fit 5mm hole. the cone keeps the tool centred on the bar and you simply compress the spring and the tool cut a nice centre perfectly in the middle of the bar.

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pgk pgk07/08/2020 10:53:00
1912 forum posts
288 photos

If the tail stock is truly in alignment then surely the same effect is achieved just with a very short tool in a tailstock collet? I can understand it would help if there is slop.

pgk

IanT07/08/2020 11:16:20
1613 forum posts
151 photos

It's a useful idea if you do have any concerns in this area...especially if you need to really extend the tailstock drill over the table for some reason.

Not the same application but this week I've been cutting up an old trailer that hasn't moved out of my back garden for about 20 years. My old angle grinder quickly packed up - so I purchased a new Bosch one (a very nice bit of kit) and managed to get most of it reduced in size but still needed to get the axle off the frame - it being very heavy and too awkward to handle on my own.

The bolts were rusted solid and I couldn't easily get at them being between heavy 'U' channel. A simple steel guide was turned with a 12mm dia x 15mm deep hole at one end (to fit the bolt) and a 5mm through hole at the other. This was fitted over the bolt and a centred 5mm hole drilled with an electric hand drill - which was opened up gradually to 10mm. I was then able to chisel off the remaining bolt end and continue step-drilling into the nut until it span off. I had four to do and it took about an hour - but I think it was much quicker/safer than trying to cut the heavy channel as access underneath and in other areas was very restricted.

So simple drilling guides have many useful applications..

Regards,

IanT

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