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Thread: Woodruff Key Removal
03-22-2003, 10:23 PM #1
OK, I'm sure this is a novice question for this forum.
I'm working on an engine, and I need to remove a woodruff key to pull a seal off a shaft. I've worked at prying it out and have avoided the hammer for fear of damaging the shaft bearings. I know they are installed with a slight interference fit, but this thing won't budge. It's a stainless shaft and stainless key.
So what's the trick to removing woodruff keys? I've thought of shrinking it with dry ice or liquid nitrogen, although I have no idea where I'd get liquid nitrogen.
03-22-2003, 11:58 PM #2
Woodruff keys can be the most difficult things to remove without resorting to force. If you have room to do it, try a pin punch of the closest size to the width of key, first holding the punch parallel to the shaft and on the end of the key, tapping with a small hammer. If the key doesn't budge try holding the punch at right angle to the shaft with the punch at the end of the key tapping straight down. The key should basically rotate in the keyseat until you can grab it with a vice-grips and pull it out. Of course this only works this easily in a perfect world! Personally, I think woodruff keys should be outlawed. Being a machinist who does lots of shaft repair requires me to have a s***load of cutters on hand, that maybe have to be used once a year on a shaft that can't be rebuilt with a pratt&whitney keyseat or a basic keyseat instead
03-23-2003, 12:25 AM #3
I've removed some woodruff keys by locking on a visegrip and prying against it.
It sometimes damages the key, but that is usually not a big concern.
03-23-2003, 12:38 AM #4J Tiers Guest
The rotation trick has pretty much always worked for me, unless the top of the key is bunged up. Then it is the worst thing you can do, cuz it wedges in and messes up the shaft.
Vice grips work if it was gonna come out anyhow. Otherwise for me they always slip off and make things worse. I must just not have the *touch* for it.
The punch or piece of CR scrap along the shaft with a babbit hammer is pretty good, if you can hold the shaft and not mess up bearings etc. A little bit of a wedge shape to the piece of scrap is good.
I agree, ban the beggars.
03-23-2003, 10:01 AM #5D. Thomas Guest
Sounds like you can't take the shaft to a workbench vise, where you could grip the entire exposed surface and pull on the shaft to free the key, but perhaps you could take the vise to the key and yank on the vise ? (depends on how much room you have and vise size and weight of course)
03-23-2003, 10:14 AM #6
The last key I had to remove, I just drilled and tapped the thing, put a screw in it, and then pulled it straight out by the screw. I'm not real experienced here, but it worked like a champ that time.
03-23-2003, 10:52 AM #7
If you are willing to damage the key, pulling it out with a pair of side cutting pliers (dykes) from one end almost always works. Grab one end with the cutting edges and lever it out like you are pulling a cotter pin. (Yes I know it's crude, but it works better than vise grips) Beyond that, I once had to tig weld a bolt to the key and use a slide hammer on the bolt.
03-23-2003, 12:25 PM #8
Personally if it was up to me I'd outlaw straight keys in all of the smaller sizes. At least if they are cut using endmills. Woodruff key cutters tend to produce much more accruate keyways in terms of width control simply because of their greater rigidity. As for getting them out the side cutters and slide hammer options are the best. With the price of woodruff keys I wouldn't be too worried about trashing it
03-23-2003, 09:49 PM #9
Thank you for all the quick responses.
I've tried, vice grips, pin punches, side cutters, and even wood chisels - no dice. I'm not worried about damaging the key, I have four spares. Actually I only have three spares now. I used one to make a test drill. I'm going to drill and tap it in two places and fabricate a little handle that I can attach to the key and apply some leverage to rotate it out of the seat. Only problem is, the biggest screw I can use is #8. Can you believe this little sucker is only 3/16 x 1 and will not come out.
Definately going put a little neversieze on the replacement.
03-24-2003, 10:44 AM #10
I've fought with keys during restore of an old Emco lathe and found two things which worked and prevented shaft or machine damage. I took the point out of an automatic center punch, put some shims behind the key (to protect a bore in my case), and repeatedly punched the key up and out by catching the front edge of the key with the edge of the punch. The old punch was apparently harder than the key and came out unscathed.
03-24-2003, 12:08 PM #11
Frustrated: I would try a slightly different approach. I would use the screw idea but drill deep enough to use the screws as a jack. Drill through the key and use the screw pushing on the bottom of the keyway to push the the key out. the problem of getting full thread to the bottom of the hole can be reduced by turning the thrreads off the last bit of the end of the screws. Beware....stainless with a stainless key... bad combination, has an afinity to gall and stick, could be at the root of your problem. Ross
05-17-2003, 07:08 AM #12
Stainless to stainless -- probably galled. The only way I know to tackle this is to use a miniature abrasive cutoff wheel and cut down the length of the key on the centerline. Really tedious.
05-17-2003, 11:07 PM #13
Could you just take a cutter for that size key and set it up to "make a new keyway", but doing it on top of the old key? That seems like a better idea.Just a thought...
05-20-2003, 10:17 AM #14
If you can sacrifice the key, I have a method that may work. It's worked for me. You could weld a piece of bar or something to the key. Then turn or pry, or whatever on the bar and it should bring out the woodruff key. I personally don't like woodruff keys, but to each their own preference.
05-24-2003, 07:26 PM #15
Here's an idea that I devised yesterday afternoon. I had a 1/8" wide woodruff key in a leadscrew in a casting about 5" wide and 10" long. The key had to come out before the leadscrew could be removed from the casting. I tried all the standard ideas using punches, chisels, and vice grips. No movement at all, and a fair amount of material chiseled off the key. This one was stuck! After a bit of thought, I grabbed the key in the mill vise, not easy because it is only 1/16" high and there is a small chamfer on the jaws of a Kurt vise. The casting hanging out the side of the vise was shimmed and clamped. After that, it was easy to drill through the shaft into the bottom of the keyway. Remove all from the vise and drive the key out with a pin punch. Worked a treat! And that key was in hard. I always grind the sides of woodruff keys to a push fit; no drive fits for me.
05-25-2003, 12:22 AM #16
what kind of engine are you working on?
05-25-2003, 02:20 AM #17
Sometimes heat woks for me.
The idea is to heat up the key only, very quickly being careful not to touch the shaft with the miniature torch.
Put some WD 40 on first.
You want to "swell" the key, and by cooling down it will loosen a bit.
Do it several times. Works for bolts too.
05-25-2003, 10:17 AM #18
If you have a heliarc welder you can weld a small rod (maybe .125 DIA by 12" long) to it make a wieght to slide on it and use it as a slide hammer. It's a desparate measure but I've used it sucessfully.