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

[crueby]

Nice big chunk o metal - wash it too!

[Johnmcc69]

"You can't cut all the way thru in the lathe or bad things will happen. DAMHIKT."

 Yep. Been there & done that. Many years ago in my toolmaking days I was parting off a large chunk of stock in a lathe & the offcut got jammed between a Chuck jaw & the compound, stopping the machine instantly. Trashed a couple gears, a splined shaft, & broke the compound in half. Only damaged the machine luckily. Months later at Christmas time my co-workers gave me
a large wrapped box, inside were the gears welded to the shaft & mounted to a  stand with an engraved plate that said "right about there".  Sheesh...

 John

[crueby]

"You can't cut all the way thru in the lathe or bad things will happen. DAMHIKT."

 Yep. Been there & done that. Many years ago in my toolmaking days I was parting off a large chunk of stock in a lathe & the offcut got jammed between a Chuck jaw & the compound, stopping the machine instantly. Trashed a couple gears, a splined shaft, & broke the compound in half. Only damaged the machine luckily. Months later at Christmas time my co-workers gave me
a large wrapped box, inside were the gears welded to the shaft & mounted to a  stand with an engraved plate that said "right about there".  Sheesh...

 John

Gotta love co-workers!  Though sometimes its the Dilbert spelling,  cow-orkers!

[awake]

Nice big chunk o metal - wash it too!

Naw - just throw it in the heat treat oven. 24 hours at 1500°F / 815°C ought to do the trick.

[Brian Rupnow]

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---

[crueby]

Brian, would the holding fixture have to be metal? Maybe you could do the same thing with a wood block(s) - plywood turned to discs/rings and screwed together for the rim to sit in. Since you are just tacking the parts, there wont be enough heat in the assembly to set the wood on fire. The wood parts could be turned to precise shape on the lathe.

[Brian Rupnow]

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]

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]

Chris--Thank you for your suggestion. I thought of using wood, but then this idea of the using the faceplate came along and I ran with it.---Brian

[Brian Rupnow]

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.

[crueby]

 

[Brian Rupnow]

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]

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]

In my effort to "avoid the virus" I'm trying to not to go out anywhere to buy more material. I had one big cube of aluminum 3" square, so today I set it up in my lathes 4 jaw and turned three diameters  on it, all in one set-up. One diameter is a "precision fit" into the faceplate mounting hole, one is a precision fit into the 1/2" bore inner flywheel hub, and the third diameter is slightly larger than the hole in the faceplate to keep the plug from "pulling through" the faceplate. The small diameter is drilled and tapped on center for a 5/16" bolt, which holds the inner flywheel hub tight against the faceplate. I'm not a huge fan of setting things up in my 4 jaw, but I can do it when I need to.

[Brian Rupnow]

This didn't go quite as I had planned, but it was very close. I was having trouble getting the rim centered, so I made up a disc with a reamed 1/2" center hole and an outer diameter that was a precision fit into the flywheel outer rim. I put a piece of cold rolled 1/2" diameter in the tailstock chuck, mounted my centering plate on that, set the flywheel rim over the centering plate, then cranked it in flush against the faceplate. I had to make up a couple of "grip plates" to hold the outer rim in place. After I was done, I backed the tailstock and centering plate away and checked the inner diameter with a dial indicator. It had a total indicated run-out of about 0.040" so I spent a half hour tappy tappy tapping on the rim until the best reading I could get was about .015" total indicated runout. The outside and inside of this piece of tube has never been machined so I'm not certain how concentric the inner and outer diameters are. The next step will be to dismount the faceplate from the lathe with the outer flywheel rim still in place, then use the fixture I machined yesterday to hold the flywheel hub perfectly centered. Then I start cutting the "vanes" to length. In a perfect world, the vanes would all be exactly the same length, but it seldom works out that simple.