Drilling out taper pins

I have to punch out 5 or 6 #7 taper pins that are in a very bad position.
If I can't get any out what are the thoughts of the group about drilling
them. How big shoulld the drill be? Should I drill from the big end of the
pin to relieve the pressure? Any hints would be appreciated. TIA
Reply to
RR
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Taper pins are like dowel pins and are generally at least case hardened and tend to be a b**** to drill. If at all possible make up a puller with a tapered slot you can slide over the head of the taper pin. Somthing like a machinist's jack turned inside out. I have seen these made from an apprpriate size fine thred bolt. The bolt is drilled and reamed to take the size of taper pin you want to pull, and then slotted on the side to allow the puller to be slid over the pin, and cut to length. A nut is then run over the puller and torqued down. If you suspect corrosion, torque the puller as much as you dare and apply Kroil, and let it set over night or over the week end. Be sure to have whatever it is that has the pins in it blocked so that when it comes loose it won't be damaged or hurt anyone/thing.
GmcD
Reply to
F. George McDuffee
I've never run into a taper pin that was anything but dead soft. I just checked McMaster and all their taper pins are either 12L14 or 18-8 SS.
I don't quite follow this, but am interested. I've been in the OP's situation a few times and am always looking for a new trick. One thing that's worked for me is to find or make up a shaft collar with an ID slightly larger than the shaft with a set screw that will bear on the small end of the pin and a hole on the opposite side to accept the large end of the pin. Position the screw over the pin and crank away. A 2-piece clamp collar solves the problem of not being able to slip a solid collar over the end of the shaft.
Ned Simmons
Reply to
Ned Simmons
Perhaps I'm just not seeing this clearly in my head, but it seems to me that if they are in such a bad position, how will you have enough clearance to get a drill over them? And if you have enough room to drill them, why can't you drive them out with an improvised punch?
- Michael
Reply to
DeepDiver
I have had two nightmares with tapered pins. Both were steel tapered pins going into aluminum bodies. It was like they were fusion-welded in their whole length. I used heat, penetrating oil, drilled and tapped and made a puller, NOTHING. Wasted a whole week in total. Sure hope it works better for you.
I didn't have any trouble drilling and tapping them, though. Problem was, just the top part came out -- the taper pins broke!
GWE
Reply to
Grant Erwin
First of all I doubt if you can drill them out, dont they have threaded holes for a slide hammer?Are they in blind holes?
Regards
Daveb
Reply to
DaveB
I would drill an undersize hole, and then follow with drills of increasing diameter. When you get most of the pin out by drilling, finish with a tapered reamer. If your drilling damages the sides of the tapered hole, you may have to ream oversize, and use a larger replacement pin.
Reply to
Leo Lichtman
I agree.
Harold
Reply to
Harold and Susan Vordos
The problem is that there is not enough room to swing a hammer. I have to lay on my back and swing upwards. There is room to drill as a last resort.
Reply to
RR
No. They are ordinary taper pins
Reply to
RR
Sometimes, you don't need to swing a hammer. Have you tried tapping on the punch with a small solid block of metal? How about using a prybar against the punch? If not enough room for a standard punch, make up an improvised punch from a small piece of drill rod just smaller than the diameter of the pin.
Remember, once the pin moves a short distance, the taper will lose it's grip and then it should come out fairly easily. It's not like you have to drive out a straight pin (which can have a tight interference fit along its entire length).
- Michael
Reply to
DeepDiver
My thought is that if I were to drill into the large end most of the way through maybe it would relieve the pressure enough that I could then have the small end to punch on
Reply to
RR
Try drilling and tapping the big end to as large a size as possible. Fit a stud into the tapped hole then a couple of spacers and a nut. Soak well with penetrating oil, a couple of days later apply heat and bad language. Tighten the nut and hope for the best. Sometimes it worked for me.
Tom
Reply to
Tom Miller
That's a good theory, but you're likely to drill through the side of the pin, creating more problems than you can solve. Tapered pins are usually fairly easy remove, given a good enough whack. A heavy piece of stock can substitute for a hammer, which might be a good choice, especially if the pin stands above the shaft by a small amount. No punch necessary.
I'd use the drilling as a last resort.
Harold
Reply to
Harold and Susan Vordos
Dynamite??
Regards
Daveb
Reply to
DaveB
I've seen blasting caps used to loosen up a stuck grease fitting but not dynamite.
DaveB wrote:
Reply to
RoyJ
If there is room to drill, there might be room for a short barrel air hammer. Another thing that may help is to back up the shaft with a heavy bucking bar of some sort. Don Young
Reply to
Don Young

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