Building the Trevithick engine

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Thanks Bighoss.--There is certainly a lot of steps involved. If I was rich instead of good looking, I'd have had the gear water-jet cut.---Brian
 
And that, my friends, is a beautiful thing. I have a new description of anxiety---It's that feeling you get when you've finished the 108th tooth and you move the rotary table one more step, and take a final pass to see if you are cutting metal or air. All went well.
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It's never quite as easy as I think it's going to be, but I like this. I tapped the side of the boiler and installed the big gear with a 3/8" shoulder bolt. Sid had commented that I should have used gears with a larger, coarser tooth, but I think this doesn't really seem that far out of proportion.
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Hi Brian,
I've been looking a t your work off and on ever since I started machine on my retirement. I stand in awe of your artistry. Keep sharing.
Cheers
 
Davidl--Thanks for saying Hi. I enjoy designing and machining so much, and I do like to share the steps involved with others. I love it when folks step by and have a look and leave a comment.---Brian
 
I was hoping to post a short video of all the gears and flywheel turning, but I didn't quite make it. My butt is absolutely kicked for today. Tomorrow I'll put a set-screw in the flywheel hub and make a short video. It has been a day long thrash here, but I'm happy with what I've accomplished.
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Looks good Brian, At the moment I would only got half of that done before I was kicked for the day
Cheers
Andrew
 
To the "Gallery"--Your model is wonderful. It is obvious that you put a great deal more effort into your model than I have. Congratulations on a beautiful and well crafted machine.---Brian
 
After yesterdays hard slog, I wanted something a bit less critical to make today. A smoke-stack!!! Has to be visually appealing but no real finicky sizes and meshes involved. Good stuff!!! All I need on this end now is a faux burner door and a spigot to get my compressed air inside the machine.
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Brian, ive been watching and wondering about the gear ratio on the drive. thats a whole lot of BIG to little from what learned playing with my legos back in the 70's early 80's. where i first learned about gear ratios. but from that lesson BIG to little means fast and power robbing. - i guess i just want to know more about this situation or even if you feel this is a situation(such as but not limited to - to fast or not enough hp to move it). (discusssion mode here not saying bad or anything) ive been holding back on asking but curiosity has got this cat....
 
Best answer--The brass gear which is attached to the "crankshaft" is little. It drives a "big" gear. That means that the big gear will rotate more slowly, but will develop considerably more torque. Speed and torque are diametrically opposed--one goes up, the other comes down and vice-versa. The big gear turns two smaller gears, so they rotate faster, but lose the torque benefit. If I was designing something from "scratch" I wouldn't do it this way.--But remember, this design was first established 215 years ago. People were designing all kinds of new machinery and there wasn't a clearly defined method behind what they were doing. People designed a lot of new mechanical things that ultimately failed. If something failed, they didn't do it that way the next time. If something was a success, then the design was copied and refined.
 
The ratio is drivers / driven - the big wheel has nothing to do with the ratio - its as if the brass gear was directly driving the wheel gear - the big wheel is just an idler and means of transmission.

Regards, Ken
 
Today I had to make 4 temporary wheels for this thing. They are the same diameter and thickness as the finished wheels will be. I can keep track of where things should be and how to make dimensional allowances for it up to a certain point, and then I start to lose bits and pieces. This way keeps me on track, one less thing I have to be thinking of and remembering. These wheels were made from scrap pieces of 3/8" plate. Also, I machined an air inlet tube and screwed it into the back-plate just to the left of the smoke stack. It is a cold, wet, and dismal day here and I'm about to head upstairs and lose myself in a good book.
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Best answer--The brass gear which is attached to the "crankshaft" is little. It drives a "big" gear. That means that the big gear will rotate more slowly, but will develop considerably more torque. Speed and torque are diametrically opposed--one goes up, the other comes down and vice-versa. The big gear turns two smaller gears, so they rotate faster, but lose the torque benefit. If I was designing something from "scratch" I wouldn't do it this way.--But remember, this design was first established 215 years ago. People were designing all kinds of new machinery and there wasn't a clearly defined method behind what they were doing. People designed a lot of new mechanical things that ultimately failed. If something failed, they didn't do it that way the next time. If something was a success, then the design was copied and refined.
Mechanical evolution!
 
Before I can make any more progress, I have to back up a little and repair a problem. The elbows which feed air to my 4 way rotary valve are interfering with the inside of the "boiler" pipe. I have designed a new "close fit" elbow, and will be machining and installing a couple of them today, so I can start working on the business end of my Trevithick.
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This is the new "clearance style" 90 degree elbows finished. You will notice a small hole in the top of the right hand elbow. I didn't plan that. A dab of J.B. Weld will fix it. Tomorrow, assuming everything fits properly, it's almost time to turn my hand to the mechanism that operates the 4 way valve.
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