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Roll pin in blind hole removal?

JRouche

Stainless
Joined
Aug 15, 2004
Location
So. Cal.
I have two roll pins (Spring pins, Split pins) I need to remove. The pins are in 1/4" dia. blind holes. They are about 1" long.

I am looking for any ideas besides buying a carbide drill bit or grinding them out.

I can get an "easy out" to grab them but I cannot turn them much and I dont wanna have to grind out a broken easy out.

I have carbide end mills but I dont want to have to burn or grind out a broken end mill either. I think the interrupted cut may be too much.

Any ideas would be very helpful.

Thanks, JRouche
 
Fill the hole with some axle grease,use wooden dowel the size of the hole,hit with hammer and out comes the pin.Works with bushings in blind holes too.
 
see if its soft enough to tap for a #8 screw.

if so tap and use a slide hammer to pull them.

ive had sucess with grease and bushings but little sucess with roll pins as the slot on the side doesnt allow enough hydraluic action...jim
 
Bring it to the engineer who designed it and ask him how he would remove the blind dowels.
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The engineer designed to be an inexpensive, throw away, non-servicable item just as marketing directed. ;)
 
Toilet paper or paper towel mushed to a slurry.
Glass beads (bead blast)of appropriate size.
Corn Meal of appropriate particle size.

All examples of solids in a stifish slurry that will allow itself to get pushed down the bore and will accept the high pressure impact from a hammered fitted punch piston.
The slurry will not easily flow up the slot.
The pin should come out.

HTH Ag
 
Screw in a self-tapping screw leaving about 1/4" below the head out of the hole. Grip with a pair of long nosed pliers or similar, as far down the 'pinch' as you can, then lever them out with nose of the pliers pressing against the surface.
Use steady pressure and if it starts to pull out screw it in a bit more and try again.

Peter
 
How much of the pins do you have sticking out? Can you heat the pin with an OA torch to a cherry read and let cool slowly to kill the temper, then the pin should come out fairly easily.
 
James:

Tap a slotted semi hardened coil of steel with a dinky tap that skeers me just to look at? :eek:

You go ahead.... I'll watch. ;)


I personally would opt for the carbide mill. Preferably one a little undersize to maintain hole size. Try 6mm.

Think Snow Eh!
Ox
 
Ok, all great replies.

I of course went with the simplest, quickest method. Grease and a pin. Just happened to have a transfer punch with the correct diameter. Didnt realize how difficult it was to squeeze some grease into a small blind hole. After getting the grease in I held the punch at the opening of the hole, (after donning my safety glasses) and gave it a healthy whack. Nothin, nothing but a punch stuck tightly. After removing the punch I tried it a few more times, no go.

Then the next method, carbide masonry drill bit. I have many laying around already ground up for metal work. Actually worked, for abit. Then I heard the familiar (all to familiar) crunching of carbide. I wrecked the edges, the face of the tip was fine but the OD of the tip was crunched.

After seeing how easily the carbide ate the pin I went to the carbide burr drawer. Burrs before end mills cause they are cheap and I was not to the point of turning on the mill yet and setting up the part.

I grabbed a brand new 1/4" burr and chucked it up in my cordless, keyless drill motor and went to town. The hole is actually abit larger than 1/4" which worked out good. The burr ate the pin up easily. Being the pin was a little larger there was a thin sleeve of metal left after hogging through. On one hole the burr grabbed the sleeve nicely and with a constant pull the sleeve came spinning out. The other hole was not as easy. The burr grabbed it and spun it but that is all, friction and heat. I went back the the easy-out. Tapped it in slightly to seat it then wrenched it tight. Again I used the drill motor and a constant pull (whole body leanin back pulling). She slowly spun out. Yeah!!

I had tried the drilling deal with cobalt bits, no way. hard pins. That also left out tapping.

Thanks again to all. JRouche

Oh, the engineers over at Henninger really ought to be spanked. Or maybe they didnt want an idiot such as myself taking apart the tool. I am removing a tapered shank from a speeder.
http://www.henningerkg.de/e_800/html/schnelllauf_fraesspindeln.php
 
Ox;
i have seen roll pins that were barely hard. a file will cut easily, and ive seen them that were hard as flint.
for the semisoft ones using a tap that will cut just enough thread for a screw to grip will allow a screw to be threaded in and you can pull with a slide hammer...toolmakerjames :D
i like that maybe i'll change my handle
 
actually you can fill the hole with grease just use a syringe and a large needle and lots of thumb pressure.
make sure the needle is very close to the bottom of the hole...jim
 
The grease will work but you need a loose fit for the punch.
Huh? I thought you would want a tight slip or sliding fit. Maybe thats why it didnt work, mine was fairly tight.

I think it didnt work was due to a couple of reasons.

One being mentioned by ToolmakerJames, the "slot" along the side allows for an escape path of the pressure.

And I think the pin was at the bottom of the blind hole, completely. Without some "headroom" or would that be "bottomroom" there was not enough space below the pin or between the pin and the bottom of the hole.

There was no area for the grease to act upon. Basically all it could do was press on the inside walls of the pin, never able to push on the bottom edge of the pin.

Dunno? JRouche
 
Unless the bottom of the pin was in full intimate contact with the bottom of the hole there is room for the grease to exert pressure. It doesn't even need to get into that space since the air in the hole will be under the same pressure. As long as there are atomic scale gaps there will be pressure on the bottom of the pin.

Significant sideways pressure on the ID of the pin won't be developed if the grease is rapidly moving out of the hole on the OD of the punch since pressure is dependent on velocity. The higher the velocity of a fluid the lower the pressure. The grease/air between the bottom of the pin and hole will have virtually no velocity at first and so will have maximum pressure.
 








 
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