[buildsomething]

I've got myself into a bit of problem while trying to remove a gib key from a pulley on an old hit and miss engine that I am trying to refurbish / restore. While trying to remove it.....it was rusted shut....it broke leaving the key inside the shaft and pulley. Here is a Youtube video that explains what happened to me trying to remove it. Its not very long, but does show some closeups of the problem.

http://www.youtube.com/watch?v=As6tyNdPXOE&feature=plcp

I guess this is where I need some help from the experts here on this forum as how I should go about trying to weld a slide hammer onto the end of the gib key so that I can try to remove it. I have tried grasping the key with vice grips but they just don't hold.

I have stick and TIG capability here in my shop, but I have never welded cast iron and for that matter in this type of situation. How should I proceed if at all possible. My last resort would be to drill and grind it out, but that would seem to be my last option.

Richard

[weldin mike 27]

Hi there,

Seems a bit of a pickle you got there, I have no idea if these suggestions will work because they are based on removing rusted bolts, but here goes,

#1 Heat the pin with an oxy torch, but only the pin till dull red hot. A cutting torch is good for this (do not depress the cutting lever). Then let it cool to room temp. Hopefully this will expand the pin then as it cools it shrinks to slightly smaller than original and there for will come loose.

#2 Heat the pin but only from one side and not as hot as before then on the opposite side from heating, melt a candle onto the pin, Supposedly the heat will draw the wax in and free things up.

#3 A last resort. You need a deft hand for this. With an OA cutting torch, start the heat the pin as you a start of any normal cut, as it reaches cutting temp, derpress oxy lever and as it starts to cut into the pin, pull the torch backwards away from the cut slightly. This will enable you to direct the oxy stream onto the molten area without melting the surrounding material.

As i said, Im not sure how these will work, but good luck and let us know how you go.

Mick

[buildsomething]

Hello Mick and thank you for you suggestions.

I think suggestion #1 seems to be the most promising solution without getting myself into too much trouble. Removing these gib keys from old hit and miss engines is a common issue each with a different solution. I will be taking video's of each attempt and post it on Youtube. Hopefully one of them will work otherwise its going to be a drill and grind process which I really don't want to undertake.

Cheers
Richard

[weldin mike 27]

No worries mate,
Remeber, the cooling down is the key because thats when it shrinks.

Mick

[weldin mike 27]

Hey again,
Could you drill and tap it and use abolt to get some more purchase on it. maybe even make a jig and use the bolt to apply outward pressure on key.

Mick

[delraydella]

i was going to say a lot of penetrating oil, but you've already done that.......You might want to try a solution of muriatic acid to eat away some of the rust. A 50/50 solution with water works great on dissolving rust on tools if you let it soak for about an hour.

This one may seem off the wall, I've only read about it, it may or may not work, but try hitting the gib key with a hammer and an aluminum rod to try to loosen it. Supposedly the aluminum rod will transfer more of the hammer strike power vibrations to the piece you're trying to loosen. (???????)


Other than that, heat, or grinding and drilling the piece out. It looks like it will be about as much fun as trying to remove a broken tap!

Good Luck!!
Other Steve

[235711]

Hello Buildingsomething.

I had a good long look at your video of the Gilson Engine. I am going to attempt to convince you to take it to a professional machine shop. Considering it is a working mechanical antique and the craftsmen and tooling that built it are long gone , makes it very special in my opinion. That is why I think you should take it to a machine shop with the proper equipment to have the key and belt pulley removed. My reasons for the suggestion are as follows.
Key Type
The gibs key is most probably tapered (See Fig. 1 & 2 ). That means the key has a slight angle, about 1-5 degrees, on its upper contact face with the belt pulley. Anything less than about 7 degrees is a self locking angle so the friction holding it in place has the potential to be very high.
Drilling
A taper makes drilling it out a’bit more complicated. You must center on the end of the gibs key that contacts the crankshaft when drilling. On a ridged drill press or knee mill the operation would not be an issue; however, attempting to drill it free hand, in my opinion, would not just be difficult but risky too. A broken drill bit would be a game changer. It would increase the work effort required for the repair. It would subsequently also increase the price of the repair at the machine shop.
Corrosion
You mentioned that the key is cast iron. I suspect the crank shaft and belt pulley are also made from cast iron. Depending on how long the mechanism has been assembled and judging by the surface rust seen on the crank snout , it is more than likely that the level of corrosion between the key, belt pulley and crank shaft is beyond the effective influence of any penetrate oil.
Lady Luck
Sometimes the designers of a machine provide a “knock out hole” in on the opposite end of a key slot where a pin driver can be used to knock the key out. Other times it may be possible to drive the key out from the back through the keyway slot in the crankshaft and belt pulley. The trick here, in my opinion, will be to get the gibs key to budge and slide backwards about 1 mm ≈(3/64)” in order to disengaged the angle friction lock between itself , the belt pulley and the crankshaft.
Shrinking the key by means of heating then cooling, as mention in a previous posted suggestion, may also be effective. I will advise caution, however because some types of cast iron may increase in volume after heating and most all have the potential to become very hard and next to impossible to drill if overheated (not even with carbides). As I stated previously I would take it to a professional machine shop to be removed and play it safe.

Fig.1

keyway_3_46.gif (7.01 KiB) Viewed 2128 times

Fig.2

keyway_taper_46.gif (10.07 KiB) Viewed 2128 times

.gif source http://www.roymech.co.uk/Useful_Tables/ ... _BS46.html


Best of luck

235711

[weldin mike 27]

Hey,

Thats some great info. You clearly have a great understanding of the stuff you are posting.

Regards Mick

[buildsomething]

Wow, that is quite a bit of good information. You are absolutely right about taking it to a machine shop to attempt to remove the gib key....but being retired, cash flow is a bit of an issue here.... I do have a full size Bridgeport mill at home that I could jimmy up something to hold the engine in place while I attempt to drill it out as a last resort. That would definitely mean that I would have to build an outrigger of some sort to support the overhang of the engine.....ah the trials and tribulations of restoring old equipment.

I do like the idea of using a mild solution of acid to try to dissolve the rust. Its an easy solution...sorry for bad pun...

In the mean time, I have ordered a lb of Aluminum bronze tig rod that Jodie recommended so that I can attempt to weld a slide hammer onto the end of the gib....if it breaks off....oh well. Someone said to me that if its finally breaks off, do the restoration of the flywheel as it sits.

I definitely be posting my results....good or bad...

Cheers

Richard

[buildsomething]

Well guys, I was able to remove the stuck/rusted cast iron gib key using a tig welder, 3/8-16 bolt and a home made slide hammer.
I tig welded the bolt onto the gib key using silicon bronze filler. I did not heat up the piece nor did I allow it to cool down.
I applied the slide hammer to the bolt while everything was hot and with a few hits, the gib key came right out.
I did do a lot of prep work to make sure that I welded the bolt that was an integral part of the slide hammer to the gib key as parallel as possible.

The video tells all: http://www.youtube.com/watch?v=0vLLZJ1cnI8

Cheers

Richard

[Otto Nobedder]

Excellent!

I'm pleased to hear you've solved this (and apparently your solution was mostly your own effort!)

Let's have a video of the finished product running. (I love those old hit-and-miss engines!)

Steve S

[buildsomething]

Thanks Steve.

That was the first time ever that I welded cast iron to steel and I figured that if I did everything hot, before anything cooled down, it should work....and it did! This time the replacement gib key is going to be steel instead of cast iron.

I have 2 more gib keys to remove on this engine so the slide hammer will come in handy for sure.
As I'm taking the engine apart, I am finding more things that are broken...in cast iron of course....so I still have a lot to learn about that process. I also have to learn how to pour Babbitt bearings. Now I have to build myself a small furnace, just to pour some bearings.

Ah the joys of being retired.....

Cheers

Richard

[ajlskater1]

Good old solving bronze works again, that stuff works great on just about everything for non critical stuff. Another good choice of rod is nickle99 it gives you more strength than the silcon bronze and it is very good about not cracking.

[buildsomething]

I guess that's another filler rod that I need to add to my collection. I heard that the stuff is not cheap, but having a few filler rods might save my bacon from time to time.

Thanks for the info.

Cheers

Richard

[ajlskater1]

Ya its definitely not cheap but I is nice to have around another is called Brutus it is probly the least crack sensitive rod I know of. I use it a lot at work for dissimilar metal like nickel to stainless