Building an Aligator

[vtsteam]

You can stall a steam engine if it stops before the inlet valve opens, and at that point it has no torque. The way to do that is just have a rsistance greater than the output torque, and it will shortly stop.

[f350ca]

Thanks Dave, one of the guys have a copy of that book. Great story but absolutely no technical info. We drove up to Algonquin park and had a look at a somewhat restored one.  
The slide gears were to disengage the paddles when winching, they used the winch and a large anchor to move the log booms as well as winching overland.
The engine we have has the reversing gear on it as did the one we saw.
Your right Steve, when that happens you have to bar it over centre. Then it should go, the force to move the paddle through the water is 
1/2 * density of the water * the square of the velocity * the drag coefficient * the area of the paddle. So it should move the paddle at a very low speed till it builds max torque, then hopefully it has enough momentum to carry itself over the next dead spot.

[stevec]

Greg, I've got a few "final drive" gears from my many Allis-Chalmers tractors. I can check the ratios. If your interested.

Then, of course, we've gotta consider the shipping charges.

Any thoughts of a trip down east this summer?

Steve

[f350ca]

Thanks Steve, we have this set that looks like it would work and looks the part. Will get photo's when I start machining.
As for down east, ya never know, my trips usually get decided the day before at best. Would certainly enjoy a visit.

[vtsteam]

Well this will be a fantastic project with a steam engine aboard to move it. Looking forward to watching and cheering on the sidelines!

[f350ca]

Started machining the shaft that carries the paddles today. Im guessing its the first one made for an alligator in about 100 years. Definitely needed the crane to load this shaft, 3 inch dia 124 inches long.


The shaft will run on rabbit bearings so needed a nice smooth surface. The shaft of coarse is mystery metal from an old sawmill, machines like mild steel so used a shear tool to take the final pass.



Some nice heavy threading, found a couple of 1 7/8 x 8 tpi nuts to hold the paddle assembly on.

[PixMan]

What joy it must be to have and be able to use the full capacity of a lathe like that!

How long of an area did you turn, and how straight did it come out? I assume a fairly low cutting speed to achieve some tool life with the HSS tool, so how long was the part on the machine? Do you have to mill long keyways in the shaft too?

[f350ca]

Thanks Ken, it gets used to its limits every now and then. Turned about 27 inches on the one end, that was in 4 diameters though so the longest cut was about 10 inches. No appreciable taper in that length. Ran it 250 rpm with TNMG inserts, and .0085 feed. Faster would have been nice but was afraid I'd get the shaft whipping. Only one 3 inch keyway where the bull gear goes on. Think I'll use pins to lock the paddles, if they pick up something in the water they might shear and save a huge repair.
I need to bore out the bull gear to fit the shaft, lots of meat in the hub so that won't be a problem, but haven't figured out yet how to cut that keyway. The gear is probably cast iron, haven't checked yet. BUT its 32 inches diameter, even if I had a broach, which I don't it wouldn't in fit the arbour press, its probably a couple of hundred pounds so heavy to try and mount on the front of the shaper. Guess I could grind a cutter and slowly eat it away stroking the spindle on the mill. If I went that route how do you lock the spindle from turning on a Bridgeport clone?

[stevec]

Greg, you could use a keyway bush as you would in an arbor press and lock it in position with pretty well any removable anchor (pin, screw etc.).   

Steve

[f350ca]

Think I get what you mean Steve. Use the bushing when stroking the cutter on the mill, and make the cutter to follow the bushing?