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Thumper---A new 1 3/8" bore i.c. engine

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  • It is in William Harris's book The Steam Donkey Engine. The book is copyrighted so I cannot scan the drawing and put it out here. If con get a look at a copy of his book it is on page 34. Basically it is just a metal disc machined to closely fit the ID of the tube. This one had a step machined in the OK with the smaller diameter facing out of the tube so you can machine a little of the tubes ID. The disc had a hole bored in the center that fits on a shaft which allows it to rotate. The shaft is held in a chuck on the tail stock of the lathe. He used a cast iron wheel to make the disc and gave it a good lube before securing it to the shaft with a bolt and washer. The shaft had a shoulder machined in it to stop the wheel from moving toward the tail stock. Hope this description makes it a little clearer.
    Larry - west coast of Canada

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    • Originally posted by Cuttings View Post
      It is in William Harris's book The Steam Donkey Engine. The book is copyrighted so I cannot scan the drawing and put it out here. If con get a look at a copy of his book it is on page 34. Basically it is just a metal disc machined to closely fit the ID of the tube. This one had a step machined in the OK with the smaller diameter facing out of the tube so you can machine a little of the tubes ID. The disc had a hole bored in the center that fits on a shaft which allows it to rotate. The shaft is held in a chuck on the tail stock of the lathe. He used a cast iron wheel to make the disc and gave it a good lube before securing it to the shaft with a bolt and washer. The shaft had a shoulder machined in it to stop the wheel from moving toward the tail stock. Hope this description makes it a little clearer.
      you mean a mandrel??

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      • I guess you could call it a mandrel. I hesitated to do that because the disc actually rotates on it rather than being fixed to it. By the way in his drawing the old wheel he used to make the disc looks to be around one inch thick. No dimensions give kind of made to suit.
        Larry - west coast of Canada

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        • Something like this, a live bullnose center?

          Click image for larger version

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          Paul , P S Technology, Inc. and MrTibbs
          USA Maryland 21030

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          • Paul - No, it is nothing like that. If you can picture a one inch thick disc mounted on the end of a shaft so it can rotate freely but not move back and forth on the shaft. The OD of the disc is machined to fit the ID of the tube you want to support, then say 3/4 of the one inch of the width is machined to a smaller diameter to allow a tool bit to get in and machine a little of the ID of the tube. When it is set up the larger diameter of the disc goes in the tube first and is pushed in far enough to leave a little of the ID exposed to allow for some clean up machining.
            This isn't easy to try and put a drawing into words so everybody will understand.
            Larry - west coast of Canada

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            • As you can see, I'm making this up as I go along--(which isn't that unusual). Paul--I have a large bull-nose like the one you show, but it is only 3" diameter. My pipe is 5 1/4" inside diameter. I'm thinking forward to the next steps in this flywheel fabrication exercise. In a perfect world, I can hold the outside rim (6" tube parted off to 3/4" wide) in my lathe 3 jaw chuck. I can slide the hub (with slots) over a piece of 1/2" cold rolled steel and hold it in my tailstock chuck. This will guarantee absolute concentricity. I could then cut the flatbar "fan blades" to a perfect precision fit between the hub and the outer rim. Then tackweld both ends of the flatbar to the hub and the outer rim.---This sounds good, but their are some fairly sophisticated controls in the electrics of my lathe, and I think that any kind of electric welding would probably damage my lathes circuitry.----Or---I can counterbore a 1 1/2" hole into a large piece of 6" wide aluminum flatbar and in the same set-up counterbore a 6" diameter recess to center the outer flywheel rim. Have to think some more on that, because the blades are the full 3/4" depth of the hub and outer rim. I don't have a piece of 6" wide aluminum anyways, and I am not going to venture out into "virus country" again. I do have a 10" faceplate which I might be able to do something with. Any good suggestions will be entertained---
              Brian Rupnow
              Design engineer
              Barrie, Ontario, Canada

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              • Brian, anxiously waiting to see some of your first practice pieces with the new tig. I am fighting the urge to buy a tig.

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                • Okay---I'm having an idea. If I mount my faceplate on the lathe, then I can use 1/2" hex bolts thru the existing slots and use a dial indicator to center the outer rim perfectly on the faceplate.---Then dismount the faceplate from the lathe, and turn a center spigot that is a precision fit into the faceplate center hole, with a 1/2" diameter nose on it to fit the hub onto.

                  Brian Rupnow
                  Design engineer
                  Barrie, Ontario, Canada

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                  • This would let me mount the hub on the turned center spigot, and the outer rim and hub would be perfectly concentric. Then I can fit the "blades" into place and get a decent tack on each one. This method allows me to do any welding or tacking with the faceplate dismounted from the lathe completely.

                    Brian Rupnow
                    Design engineer
                    Barrie, Ontario, Canada

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                    • How about a new sharp blade for the bandsaw, then cleanup the bore of the rings in a three jaw chuck?

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                      • That worked out very well. A lot of moaning and groaning from the lathe, occasional shots of cutting oil, and a very slow advance. I left about 1/16" wall which I will cut with my bandsaw.

                        Brian Rupnow
                        Design engineer
                        Barrie, Ontario, Canada

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                        • And that is about as far as I'm going to take things today. Tomorrow I will work on getting things all set up on my faceplate.
                          Brian Rupnow
                          Design engineer
                          Barrie, Ontario, Canada

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                          • those will certainly give you plenty of TIG practice!

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                            • Matt--I don't think I will use any continuous welds. This flywheel is self contained and the radial forces will all concentrate on the outer rim. Too much weld will distort things. For now I am considering a weld on each side of the blades where they contact the hub, and a weld on each side where the blades contact the rim. So, each individual blade will only have four small welds, one at each of the four corners of the blade.
                              Brian Rupnow
                              Design engineer
                              Barrie, Ontario, Canada

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                              • do you have a way to balance them??

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