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Roll pin removal

Posted: Fri Feb 09, 2018 11:19 pm
by Andy51
A question for the engineers out there. Not AMC- related, but I need to remove a roll pin, approx 2 mm diameter, inserted in a blind hole in alloy. I do not think I can drill it out with a carbide drill as they would be too weak in that size. On option is to drill down the centre of the pin (1.5 mm drill will pass through) until it breaks through the other side of the alloy, then drill back through to the base of the pin with a 2 or 2.5 mm drill and punch it out with a drift. This, however, would leave a visible hole which would be hard to fill invisibly. Any better suggestions? Andy

Re: Roll pin removal

Posted: Sat Feb 10, 2018 1:36 am
by Expat
Hi Andy. Never had an issue quite like it but your idea is a good ‘un.

No idea how tight a fit the pin is obviously but the first thing floating into the grey matter is, would one of those tiny sheet metal screws get enough grip without expanding it too much to yank out?

Okay, I thought it sounded reasonable. :)

Steve

Re: Roll pin removal

Posted: Sat Feb 10, 2018 1:59 am
by 242017
Mig or tig weld a nut on the rest of the pin....The heat of welding it will help getting it free and the aluminium will not be affected......Drilling things like this always ends up with the drill finding the soft material

Re: Roll pin removal

Posted: Sat Feb 10, 2018 7:32 am
by g5wqian
although its small , its hard , you might be able to screw a suitable setscrew down inside the roll pin to get some grip on it , or you might need to get a tap down in there and put a thread in it and then drop a screw in , but being that small i dont know how youll get on .
you could try making a small slide hammer but whether it will just pull itself out i couldnt say .

if any of the roll pin sticks out you could use an old drill chuck to grip it .

on the other hand the aluminium will expand more than steel when heated , so heating up the alloy with a blowtorch may be enough to allow you to pull the pin out without much effort .

obviously you dont want to melt the aluminium , so get a bar of ordinary hand soap and rub it over the area you are working on and when the soap turns brown its as hot as it wants to get .

Re: Roll pin removal

Posted: Sat Feb 10, 2018 9:22 am
by Mick D
Hi

The only way I am aware of and the one which will result in the best result is as you suggest, drill through to locate a larger drill from the back and punch out - that's what I'd do.

As far as re-instating the finish - a small 'blob' of aluminium TIG welded over the hole and then dressed back with a file or burr - match the finish with wet and dry followed by Solvol Autosol if polished or gentle work with a pointed punch if it's cast.

What is the function of the roll pin? - there may be 'out of the box' solutions.

Regards Mick

Re: Roll pin removal

Posted: Sat Feb 10, 2018 11:26 am
by Andy51
Hi, thanks for your ideas. The pin is only about 2mm diameter and protrudes less than that, so nothing to get hold of. It has been in place in the alloy over 40 years, so plenty of time for electrolytic corrosion to increase its grip in place! The pin holds a front wheel speedo drive (no longer needed) in place - I want to fill in the hole the drive sits in. The pin is just over 1.5mm bore, so too small (and too hard metal) to tap and use a screw, I suspect a screw of that size would snap, leaving me worse off. The welding idea might be worth pursuing but I don't have the kit and, being tight, like to do things myself! Andy

Re: Roll pin removal

Posted: Sat Feb 10, 2018 12:19 pm
by 242017
Then buy a new one...because in the end it will save you time and money

Re: Roll pin removal

Posted: Sat Feb 10, 2018 2:32 pm
by Mick D
Hi

Does it protrude enough to enable you to get a grip with a pair of flush cutting snips or nail pullers - if so you should be able to lever it out.

I guess you probably don't have the above tools but could grind a set of normal jaws to be flush cutting.

Regards Mick

Re: Roll pin removal

Posted: Sat Feb 10, 2018 2:57 pm
by robcurrie
If you don't have a welder, you could try a bodger trick: put a nail inside the roll pin and attach a car battery to it momentarily with jumper leads, there is a good chance the nail will be welded to the pin and heat it up to red hot which will soften it and make it drillable if the nail doesn't stick.

Rob C

Re: Roll pin removal

Posted: Sat Feb 10, 2018 4:01 pm
by bitza
I would not try to tap a thread in it if it is a split roll pin, they are usually hardend and you might break the tap.
The old trick to remove flush or broken studs is find a flat washer same hole diameter as stud / pin,
tack with mig welder, then build up weld grab with mole grips, the alloy expands faster than steel broken
Stud / pin usually comes out.