8x12 Old Reliable Gordon style restoration project

Working on a restoration project and seeking assistance with a pinion gear for a H.H.Thorp Old Reliable 8x12 Gordon Style Press.

Would either like to: (a) purchase or (b) one to copy, or (c) even measurements and tooth count. The calculations I’ve done do not correspond to stock gear offerings.

Please let me know if you can help.

cheers,
Ash

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Hello Ash,

I have some industrial experience with printing press gears. It sounds like you don’t have a pinion gear at all. If that is the case, you may be able to figure out the dimensions of the pinion gear by measuring 1) the main gear that the pinion gear meshes with, and 2) the EXACT distance between the centers of the shafts which the two gears would be mounted on.

As far as measuring the main gear is concerned, what is the diameter of the gear from the valley between two teeth on one side, through the exact center of the gear, to the top of a tooth on the other side? This is a close approximation of the pitch diameter. Also, what is the number of teeth on this gear? If you give me these two figures, I can probably calculate what the gear pitch is. That will be a start.

Thanks Geoffry,

That’s the problem…we don’t know how many teeth there are. I’m hoping someone who has one can take a photo of it or count them for us. We keep coming up with not whole numbered results in our calculations …which means they cant be correct.

Carefully measure the distance from the center of the shaft the pinion gear is supposed to be on, to the bottom of the gap between the two teeth on the large gear closest to that shaft. (diameter of shaft divided by 2, plus the distance from the surface of the shaft to the bottom of the gear tooth gap) Multiply that distance by 2 and then by 3.1416 and that is the outer circumference of the pinion gear. Carefully measure the center to center spacing of the tops of the gear teeth on the existing gear and divide that distance into the circumference of the pinion gear. Hopefully that will come out close to even and that should be the number of teeth on the pinion gear.

Bob

Ash, I know you don’t have a pinion gear. I want you to measure the gear that the pinion gear meshes with, which is still on the press (hopefully). 1) Measure across that gear starting from a valley between two teeth on one side, going through the center of the gear, and ending at the top of a tooth on the other side. Give me that measurement. That will allow me to determine what the gear pitch is, which will be common to both gears. 2) Count the number of teeth on that gear and give me that number. 3) Measure the EXACT distance from the center of the pinion gear shaft, to the center of the shaft that the other gear is on. The measuring tape needs to be perpendicular to both shafts when you make this measurement. If you give me those three things, I should be able to figure out how many teeth your pinion gear needs to have.