gib-head taper key removal - help!

anchorman · Oct 25, 2007

any one know any secrets to removing gib head taper keys? application is an old 3ph 1hp motor. there is no set screw or anything on the pully.

I can't figure a good way to pull on the key... is the secret to press the pully further onto the shaft, and then pull the key out? pulling on the pulley would just make it get tighter I think.

thanks,

jon

Forrest Addy · Oct 25, 2007

These can be very difficult if the key is tapered and the hub assembled on the shaft hot and held in place by driving the gib into its taper with several lusty blows of a heavy hammer. This is the usual assembly for old machinery like steam engines where heavy cyclic inertia loads have to be restrain relative movement of the flywheel on the crank.

I don't think this is the case for a small electric motor. The whole idea of the gib head is to permit ready extraction with a rolling drift or a stout screwdriver. Slip the toe of the drift under the head and lever it out. Make sure there are no fugitive set screws in the hub - or worse: a drilled through taper pin filed flush.

true temper · Oct 25, 2007

I have had the best luck just using a puller and pulling the pully off. The ones I have done the key slips in the shafts key way.

FlatBeltBob · Oct 25, 2007

I have run into these keys a few times.
First , turn the moter so the shaft is vertical , and let it soak with penetrant overnight ( I like KROIL )
If there is enough room , drill and tap a hole in the end of the key , then put in a threaded rod . Put on a cross bar and bridge it with shims on either side of the key , crank it tight and let it set for a while. add more penetrant . Sometimes I will build a "moat" to hold the penetrant . Give it a crank every hour or so .
OR
You can also weld a rod on the end , and jury rig a slide hammer to pop it out.
OR
- if there is enough key sticking out , grind a notch in it with a cut off wheel , then use a cat head bar to hook and pry it out . Tap on the face of the pulley to nudge it away from the taper while you try this .
I have the best luck with the first method because it is not so brutal , and causes less damage , but you may not have the right situation to make it work.

Carl Darnell · Oct 25, 2007

The best way would be to make a collar with a keyway to slide over the head of the taper key. Then machine a relief in the bore so you can rotate the collar. That would lock it behind the key head and with a puller pull it out.

Of course that only works if you have some room for the collar.

Have you tried using a crows foot bar to pry it out.

svs · Oct 25, 2007

Make a slide hammer with a pair of vice grips, a piece of threaded rod to replace the adjusting screw, and a chunk of shaft with a thru hole for a hammer. Handy for lots of jobs, and not very spendey.

Scott

tattoomike68 · Oct 25, 2007

SVS I have one of those and it is a handy little devil, everyone should have one.

eKretz · Oct 25, 2007

We get a lot of these on the crankshaft/clutch/flywheel interface on the punch presses we repair. Usually they are already drilled and tapped for a stud so you can get 'em out with a slide hammer. When they're not I usually try a prybar against the head first, and if it doesn't work I drill and tap the head end for a stud (*for slide hammer) with a hand drill. Alternatively, if the tail end of the key is accessible, you can try knocking it out from the tail end with a drift and hammer, just be careful not to mushroom the top of the key.

Forrest has it right on the older machinery usually being the stuff using these tapered keys. Most of the presses we work on have dual tapered keys at 90 degrees or 180 degrees to each other. When we repair the crank/flywheel/clutch fits, etc. we make new ones and knock them in with a 3 lb. hammer. Usually shoot for 1" drive, and fit the keys with hi-spot so they have minimum 90% contact. The slide hammer will take them right out. (up to 1.25" keys, with up to 6" length of fit, on about 4"-6" dia. shafts).

Peter S · Oct 25, 2007

Another method I have seen suggested is to use a wedge or opposing wedges between head of key and pulley face.

Malc-Y · Oct 25, 2007

A method that I have used which so far has never failed is both quick and easy and doesn't involvle any welding, is to find an appropriately sized open ended wrench and place one side of the jaw against the rear of the gib head and the curved outside of the wrench against the pulley then hit the other end of the wrench with a hammer (mind your fingers!) and the leverage should easily extract the recalcitrant key!

Malc.

FlatBeltBob · Oct 25, 2007

Ilike the vise grip /slide hammer trick.
I actually made a slide hammer with an angle iron end , that has a fork ground on , so you can hook onto the vise grip adjuster bolt head .
That way I can use almost any VG as a slide puller

Charles Dolan · Oct 25, 2007

Two folding wedges back to back are the way to go, Over the years I have made literally dozens of pairs of wedges for pushing out all sorts of kit, sometimes all that is needed is to squeeze em past each other with a strong 'C' clamp and they will put tons of force just where you want it!

I really like the idea of a slide hammer rod to take a pair of vicegrips though! I am of to make one now.

Charles.

rke[pler · Oct 25, 2007

Here's a pic of a pair of Visegrips modified into a slide hammer:

Nothing fancy, just worked up with scrap I had hanging around. If you make one try and keep the pull in line with the jaws, it works better that way.

wippin' boy · Oct 25, 2007

yup
slide hammer as above
or just drill and tap end of key for threaded stud hammer wacking device

anchorman · Oct 25, 2007

thanks. I'm sure If I don't do any damage, at least one of those will work.

Peter from Holland · Oct 25, 2007

I think Case or Caterpillar had original tooling for it ( US made for sure)
It was a steel wedge with a tappered crosssection so it stays in
They also had ones which were curved for when the gib was laying back
I used it a lott when I was doing maintanance on a brick plant

anchorman · Oct 25, 2007

Well, here's a report back. just to make it clear, shaft is about 5/8, the key is something like 3/16". so case and caterpillar are out of the picture.

I made a nice little slide hammer attachment out of some vise grips by brazing a nut into a little relief that I cut into the top in order to keep the pulling forces mostly straight. the slide hammer was something I wipped up in order to pull the wheel bearings on my motorbike. already had a nice 1/2-13 thread cut onto the end of the slide hammer so I could put custom pulling attachments on it.

needless to say, that didn't work. It just mangled the end of the tapered key. try #3 was with screwdrivers used as wedges as in my first attempt. didn't help either. finally got out the old gear puller and it saved the day. soaking overnight in pb blaster didn't seem to hurt either.

thanks again for the help,

jon

svs · Oct 27, 2007

rkepler-You give me "puller anxiety". When I needed the tool, I had the best of intentions to make a nice slide rod with cut threads at one end to replace the adjusting screw, but in the heat of the moment decided "aaaagh screw it-the ready rod will be fine". It is, but yours looks so much more refined.

Anchorman, You'll still be glad you made the tool, it's good for stubborn cotter/roll pins, etc.

Scott

gib-head taper key removal - help!

Titanium

Diamond

Stainless

Stainless

Titanium

Hot Rolled

Stainless

Diamond; Mod Squad

Diamond

Aluminum

Stainless

Hot Rolled

Diamond

Diamond

Titanium

Diamond

Titanium

Hot Rolled

Similar threads