Removing Stuck Key from Keyway

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DOILY

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Now I've removed the coupling from the gearbox end of the propshaft, next hurdle to enable me to remove the shaft from the boat, is removing the key the from the shaft where the coupling was located. It's a straight key, not woodruff, approximately 4mm x 40mm. The keyway stops short of the end of the shaft. I've tried yanking it with mole grips and also tapping the ends with a small cold chisel. Nothing's happened.
Are there any tricks of the trade please?
 
You might try a bit of heat,
There are special insulated mats that plumbers use to protect the surrounding area from the heat of a blow torch, you might also want to use one of those.
 
Provided there is a short bit of keyway at the end of the key you can get it out by using a small cold chisel sharpened so that its point gets under the end of the key. I have a small cow mouth chisel which is ideal, but you can even do it with sharp a centre punch. If there is no space it can be very difficult and if heating fails you may have to resort to drilling the key, but that is very much a last resort. If the keyway is round ended (i.e. made with an end mill) tapping it endwise tends to jam it at the ends, so you need to work with the chisel at both ends alternately.
 
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Sharp cold chisel applied to the end of the key as close to the shaft as possible. Make a nick and lever up the key (with a shim under the chisel to save marking the shaft)

You might need some one to hold the prop to stop it moving back.
 
DOILY said:
Now I've removed the coupling from the gearbox end of the propshaft, next hurdle to enable me to remove the shaft from the boat, is removing the key the from the shaft where the coupling was located. It's a straight key, not woodruff, approximately 4mm x 40mm. The keyway stops short of the end of the shaft. I've tried yanking it with mole grips and also tapping the ends with a small cold chisel. Nothing's happened.
Are there any tricks of the trade please?
Click to expand...
Your just not hitting it hard enough. Use a small sharp chisel or center punch on the end or side starting horizontal to make an indentation then move the angle down to impart an upwards force to the key. If room is tight get a very tight bite with the mole grips from above and then hit the grip jaws with an hammer from below to drive the key out. Don't be shy and support the shaft if it flexes or moves to much using either method.
 
As mentioned above, you're probably being a bit too gentle, give it a good whack... After the heat
 
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https://www.practicalmachinist.com › general › stuck-sh...


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I have seen keys held with a screw from the opposite side. May i suggest that you rotate the shaft & check the otherside, to see if there is a grub screw hidden in the grease, before you start bashing things. It may be from the key side. A key should not need much to shift it.
 
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