For this month’s contribution to GEM, the “thread” of conversation I have chosen
is a little more technical than previous ones, and for this reason, I enlisted the help of another List member,
Chuck Balyeat, to check that I’ve got everything right!
The question came in to the List “does anybody have any gib secrets that they want to share?” from someone who
wanted to have the information on how to drill out a key and keep it all centred, in case such action was ever
needed on his engines. To give some idea of the efficiency of the mailing list
system, a reply to this query was posted in fourteen minutes!
Instead of the usual number of contributors, this article is mainly the work of two or three knowledgeable people.
I took a 3" piece of 7/16" key stock and drilled the center to 1/4". I placed the drilled key stock
in the key groove and clamped it down. Then with a 12" long 1/4" drill bit I used the clamped down drilled
key as a guide for the long drill bit. After about 3 inches of drilling I found the backside of the key.
Next, remove the drilled guide and chuck a 12" long 3/8" drill bit. Being careful and assuming you did
a good job of centering the 1/4" drill hole you made in the key stock guide you can drill the hole out to
3/8". This leaves the 7/16" key with paper thin flat sides in the groove. My drilled key stock was dead
on and when the 3/8" drill went through it stayed centered. I did not have a single drill mark on the shaft
or the inside of the wheel.
Finally take a puller and pull the wheel off. I did not have a large enough puller so I made one with 2"x1/2"
flat stock and some 1/2" all thread. It took more time turning each nut back and forth to pull the wheel off
than anything. Maybe about 1 hour from start to finish including drilling but if I had had a real puller the job
would have been quick.
The drilled guide I made is none for the worse so I can use it again on the next project that uses a 7/16"
key. This same procedure should work on other sizes of keys also.
A guide bushing and a properly sharpened drill bit are the two main ingredients. The bushing can be as simple as
a piece of pipe clamped into the unused portion of the keyway, to something more elaborate that has to be machined.
I had to use the latter since my key was at the end of the shaft keyway. I took a piece of round stock and machined
a counterbore in one end the diameter of the shaft. On this same end, a slot was machined the width of the key.
This now allowed the part to slip up on the shaft and over the end of the key, keeping everything centered. In
the other end of the stock, a hole was machined the diameter of the guide drill we wanted to use. This hole was
centered in the previous slot for the key end. Since everything is now precisely centered by the guide bushing,
using a sharp drill should produce a straight
hole into your key. I drilled a hole that could now be tapped to accept a hardened bolt to pull the key.
I just recently used this to remove some 5/8 x 6in. long keys from an 8 hp Olds I am working on. However, I might
add that if the keys can be removed by some other method other than drilling, I would recommend that first. I do
not like drilling either for fear of some misalignment.
Remember always try to push the flywheel onto the shaft before trying to remove the gib key . They taper up to
the outside so pushing the flywheel on can loosen it. You can also remove them by tapping a hole in the key and
then using threaded rod /washer /nut/and jack plates to push against. You can pull it out. Slap hammer optional.
I had to make a drill guide for one recently and held a 3/8 key in a four jaw chuck and drilled it out; went quite
nicely. The bit had to be sharpened a couple of times before I came out on the other end on the flywheel, but it
never went awry.
Has anyone ever seen the Gib Key tools that resemble a tire spoon or pry bar with funny s curves at the end? I
was looking through one of the older GEM's, from the 70's I think, and saw one pictured with an article on how
they were used.
Immediatly I recognised it as our favorite tire removing tool. I used it on a few
stubburn keys over the years and it worked like magic. The secret is in proper
blocking between the head of the key and the flywheel so the tool can get a good grip.
A Gib Key tool is a combination wedge and pry bar. The pry bar portion does the hard work. The wedge portion is
good for getting the keys out that you can't quite pull out with your fingers. Remember, this is not designed to
hit on so the wedge is used in a prying motion.
The tool unusual. Thank Goodness I looked through old GEM's and happend to see an article on it. Otherwise it would
have been in our tool collection and only been used as a tire iron.
Hope this information is of use to some of you.