removing a roll pin
I have a broken off roll pin, about 1/8" dia. Broke off flush in a cast iron gearbox. it is not critical just lines the cover up Would drilling help me grab it. wil lI need to get a carbide drill.
The other one came out easy. can I hook it at the bottom and use a slide hammer?
Roll pins are very hard as you already know. Your problem pin must be in a blind hole or you could just shove it through. I think If you tried to attack it with a drill, being only 1/8" in diameter, you would end up with a broken drill and a broken roll pin.
Because the pin is so small, I have used a small torch tip to anneal them before, right in the hole. This takes the temper and 'spring' out of them and makes them almost loose enough to grab with a small pick. Good luck!
You might try some penetrating oil ( Kroil, PB Blaster) and a easy out if you can find one of the correct size ( doubt it on hand) I have never tried to drill a roll pin, but assume the pin your working on is hardened.. I'm not even sure an easy out of the correct size would do much good... Plenty of love and penetrating oil, maybe some heat as well.
Yes it is a blind hole. Since it has a slit down one side I guess the fill it with grease and use a pin as a piston trick will not work.
PS that idea was stolen from drill chuck removal tips here.
If you can hook it then try that first. I have drilled them out before and always had some problems with the relieved pin grabbing the bit.
In addition to hooking them I have also ran a hardened self tapping screw in them then popped them out with a slide hammer.
to remove a flush roll pin of small diameter in a blind hole:
(this procedure is for hardened, slitted roll pins):
1. drill (use cobalt drill @ smaller diameter than roll pin) hole through base material, at a 45 degree angle, into the roll pin. ensure that you have either created a 'crater' or a hole in the roll pin. start the hole from roll pin about 1/8" away, depth about 1/8" (distances for your roll pin size).
2. using -stainless- hook (it has to be hard, & very strong - an 'L' shape hook is what i use (do not use 'S' shape), insert tip of hook into crater (that you made in) roll pin & pull out. use base material for leverage. add lube oil if rollpin is stuck. be prepared to use a few hook tools (breakage).
this is an effective means of removing flush mounted roll pins from certain japanese car ignition locks that are about 1/16" diameter x 3/16" long (pretty hard roll pins = more than one drill). However, base material is aluminum, or zamak. I am always able to drive another roll pin in afterwards (sometimes i may need a little locktite).
Another way to heat and anneal a roll pin is as follows........
Take a small stick welding rod and knock off the flux at the end. Grind it a bit so it'll go into the hole in the pin tight. Turn the amperage all the way down on the welder. Hook the stinger to the rod and gradually turn the amperage up, giving the pin time to heat up. You can probably get a 1/8 pin red hot with 30-40 amps at most. Once its hot, gradually reduce the amperage so it doesnt cool fast enough to reharden. At that point it should be fully annealed. It might come right out, but if not it'll be soft enough to easily thread a hard screw into it so you can get a slide hammer on it. It generally works much better than a torch because it puts the heat exactly where you need it.
Originally Posted by Bill D
Use some heavy putty or clay
Make a roll of it and keep pushing it in the drilled hole
Than give some blows on your piston and ad some more putty if needed
Putty or clay works better if there is some leaking
You can also drill a hole from the back of the casting or the side
But this is defenitly the way to remove a pin out of a blind hole
Peter from Holland
The small torch and heat is the key. Then, use a dental tool with a minute hook end and simply pull it out. Think of a small croche needle but smaller.
Pretty neat idea! I wonder if a battery charger would work also?
Originally Posted by metlmunchr
Yeah, Metlmunchr, that is a good idea, I'll have to remember to apply it next time I wonder if that would work to 'upset' a frozen stud as well? I guess I'm a bit chicken to short circuit the welder that way, I don't know how long it is safe on the welding machine, to do that?
One trick I have used when using some old hard facing welding rods that had gotten slightly damp over time, and would introduce porosity at the start of the weld before they really got warmed up, was to short circuit the electrode to the table for 10 or 15 seconds to let it get good and warm (red hot would be overdone and damage the flux most likely). The heat would dry out the coating and then they would deposit as good as new. We would notice the quality of the weld because we often machined our hard surface deposits and were never happy with porosity. But these were relatively brief short circuits at an amperage well below the top range of the machine.
forget all the heating, beating and other crap and get an eighth inch
carbide ball burr
position control is important so you stay on center, but spin her up
use coolant and cut it out.
takes maybe 60 seconds
i have done several fuller transmission mainshaft rollpins in this manner, shafts that have been scrapped because machine shops cannot get those hard little bastards out.
at least the shops in this area can't get them out.
i use a dremel tool and plunge right into the little bugger, taking a bit
at a time, and use anything handy for coolant.
8 bucks for a burr and a minute is well worth the effort.
the welder should be fine. when welding it is a short circuit. Stick welders are rated at 50% load. Even a cheapt should be able to run 25% for a hour or so. A battery charger I do not know.
Originally Posted by metlmunchr
Does it need to be welding rod? Would a piece of drill rod work?
This got me thinking (dangerous, I know): Assuming something besides welding rod can be used, is there a way to tin the rod with silver solder (or whatever), flux it up and have the rod solder itself to the roll-pin as everything cools? Obviously, if you did it wrong you could wind up silver soldering the roll-pin into the hole...
My interpretation was that the welding electrode gets tacked to the ID of the roll pin anyways, and you can just yank the whole assembly out.
Originally Posted by Cal Haines
I have gotten them out with a piece of wire with a hook on the end by putting the hook in first then adding a second piece of wire to lock the first in, yank with vise grips, repeat.
I haven't tried this on a roll pin but is has worked on other tubular objects stuck in a blind hole. My trick was to find a tap that was a bit bigger than the inner diameter of the stuck part, screw it in until it grabs and starts spinning the part, then pull out while turning.
If the pin is damn hard this might not work, but it will if you anneal it with the welder trick (good technique munchr!)
I've had success just screwing a hardened drywall screw into the roll pin and pulling it out with a slide hammer. Metalmunchr (above) adds softening the pin for a good bite -- a great idea. In any case, might try just the screw to start. In my case, there was enough bite to do the job, even with a hard screw into a hard pin.
Always found the hardened self tapping screw to be harder than the roll pin. Most broken roll pins I have seen were sheared off and they are not as hard as you would think.
I have a couple of simple slide hammer pullers I made over the years from threaded rod, flange nuts and a coupling nut along with a chunk of steel with a hole for the sliding hammer.
I've got a box of Socket Head Cap Screws with various smaller screws, bolts tig welded to the ends. Every time I think I have all sizes covered another comes along.
Without a doubt it's almost the handiest tool in the box when assembling/disassembling machinery.
I'm not saying this is better than any of the other methods above but if you already have the slide hammer and ends it couldn't be much faster or easier....
... Does it need to be welding rod? Would a piece of drill rod work?...
A common nail would probably work just fine.