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

Help Support HMEM:

werowance

Well-Known Member
HMEM Supporter
Joined
Sep 2, 2011
Messages
958
Reaction score
229
and on that, will the fins of the 2 flywheels be pulling the air in a single direction like this
--> , -->

or will it be pushing from both sides in or both sides out like this --> , <-- or opposite direction
<-- , -->
 

Brian Rupnow

Design Engineer
Project of the Month Winner
Joined
May 23, 2008
Messages
12,254
Reaction score
4,798
Location
Barrie, Ontario, Canada
And that, my friends, is slicker than whale poop!! Here you see one of the finished hubs by itself, and with a nice blade array using a bunch of my parallels. I just wish I had a 1/8" wide slitting sawblade. This was made using a 1/16" saw blade, but I had to go around once to make the slots 1/16", then around once with the blade offset 1/32" then again with the sawblade offset the other way by 1/32". This was far less work than I anticipated. I will make the second hub tomorrow.

 

Brian Rupnow

Design Engineer
Project of the Month Winner
Joined
May 23, 2008
Messages
12,254
Reaction score
4,798
Location
Barrie, Ontario, Canada
This morning I put on my mask ,Purelled my hands, and drove to my metal suppliers who had set my material outside their door. Collected my material, Purelled my hands again, wiped down my trucks steering wheel with antiseptic wipes, and drove home again. Got home, washed my hands for 30 seconds with warm water and dishsoap. My hands have never been this clean. I look goofy wearing a mask. The 1" x 1/8" cold rolled flatbar is exactly what I asked for. The tube is 6" o.d. but the wall is only 7/16", not the 9/16" that I had wanted, but it will do. I could die of old age before my bandsaw would cut thru that pipe, so I will part off "rings" of material 3/4" long. I think I will weld a flatbar across one end with a hole for a live center and hold the other end in my lathe chuck with reversed jaws. You can't cut all the way thru in the lathe or bad things will happen. DAMHIKT. You can however, cut almost thru and then complete the cut on the bandsaw. This was the last material I will require to build this engine, and by the time I buy a set of ignition points and a condenser, it's going to get very close to the $200 mark. The steady-rest is which came with my lathe is way too small to use--looks like it will only open up enough to take 3" diameter stock.
 

awake

Well-Known Member
HMEM Supporter
Joined
Sep 4, 2019
Messages
739
Reaction score
223
Location
North Carolina
Brian, I do have one concern about your plan - I would recommend against using parallels for the fan blades. Not only are they expensive, but the hard steel may not respond well in welding with the mild steel.

Oh, wait - you weren't planning on using the parallels? Never mind, then. :)
 

Brian Rupnow

Design Engineer
Project of the Month Winner
Joined
May 23, 2008
Messages
12,254
Reaction score
4,798
Location
Barrie, Ontario, Canada
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---
 

dsage

Well-Known Member
HMEM Supporter
Joined
Dec 31, 2010
Messages
452
Reaction score
128
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
Brian:
Could you JB Weld tack the pieces together while it's in the lathe. Don't put the JB weld in the slots. Maybe just at the ends so it can be easily cleaned off.
Then carefully take it out of the lathe in once piece.
Then tack it with the welder - just tack it until it's all tacked together.
Then scrape off the JB weld and finally weld it up.
That would allow you to free it from the lathe in one piece while you properly weld it.

Of course it's probably going to warp quite a bit when you weld it but......
 

Brian Rupnow

Design Engineer
Project of the Month Winner
Joined
May 23, 2008
Messages
12,254
Reaction score
4,798
Location
Barrie, Ontario, Canada
dsage---thank you for the suggestion.
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
Project of the Month Winner
Joined
May 23, 2008
Messages
12,254
Reaction score
4,798
Location
Barrie, Ontario, Canada
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.

 

a41capt

Well-Known Member
Joined
Jun 5, 2009
Messages
180
Reaction score
66
Location
Camp Verde, Arizona USA
Brian,

how about if you remove the chuck from your lathe and use it as a fixture for tack welding? The reason I suggest welding away from your lathe is that your TIG welder will initiate its DC arc with a high frequency pulse that can be VERY harmful to electronic devices. When I’m welding, I run a secondary ground to my worktable and machine, and remove all electronic devices from the area (cellphone, etc.).

This is why I can never have a pacemaker. How the hell can I ever quit welding?:p

John W
 

Brian Rupnow

Design Engineer
Project of the Month Winner
Joined
May 23, 2008
Messages
12,254
Reaction score
4,798
Location
Barrie, Ontario, Canada
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
Project of the Month Winner
Joined
May 23, 2008
Messages
12,254
Reaction score
4,798
Location
Barrie, Ontario, Canada
-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.
 

a41capt

Well-Known Member
Joined
Jun 5, 2009
Messages
180
Reaction score
66
Location
Camp Verde, Arizona USA
I think that’s a wise choice Brian.

Distortion of the blades is very possible, and there goes all of your hard work and accurate machine setups. Since there’s almost no load on the fan blades, the stresses involved will be minimal, and a secure tack weld at the leading and trailing edges of each blade, and on each end should prove more than adequate for your needs.

if the blades are inset from the outer rim, thereby making your weld a bit of a reach with the TIG torch, don’t be stingy with the argon. The gas stream/cup/flow is what stabilizes your arc, and it’ll ensure that your arc doesn’t wander and mar the finish on the rim and/or blade.

Best of luck, this is a unique set of “turbines” you’re building!

John W
 

a41capt

Well-Known Member
Joined
Jun 5, 2009
Messages
180
Reaction score
66
Location
Camp Verde, Arizona USA
Oh, one more thing I’ve learned the hard way. Even though you didn’t mention it for this setup, never use a strong magnet to secure/align parts for TIG welding, even outside of the weld area. I got lazy one day and thought I’d give that a try, and what a complete wreck that turned out to be!!! Magnetic fields play havoc with a TIG arc... :oops:

Cheers!
John W
 

Brian Rupnow

Design Engineer
Project of the Month Winner
Joined
May 23, 2008
Messages
12,254
Reaction score
4,798
Location
Barrie, Ontario, Canada
Thanks John--I have experienced the "magnet thing" with my MIG welder. I have a couple of large "corner magnets" here, intended for making corners in fabricated plate-work. They work okay for laying in tack welds, but they do distort the arc if you try to do a continuous bead with the magnets in place.
 

awake

Well-Known Member
HMEM Supporter
Joined
Sep 4, 2019
Messages
739
Reaction score
223
Location
North Carolina
Brian, here's an alternative that I would consider - mount a piece of plywood to your faceplate; turn a recess in it, maybe 1/4" deep, 6" wide so the outer rim just fits snugly. Drill or bore or whatever is needed to mount the inner hub.

Yes, plywood does not seem like the obvious choice when welding, and yes, it will char ... eventually. But by the time you've got one side tacked together, it will have served its purpose and can be discarded.

The one major drawback with this idea is that you will have to clamp the ground directly to the rim. But it avoids using your precision equipment (lathe chuck or faceplate or so on) as a welding fixture.

Note that, in addition to the issue of the electronics in your lathe, welding on a lathe can be a particularly bad idea if you do not provide a direct path to ground. If the ground circuit goes through the lathe bearings ... bye, bye bearings!
 
2

Latest posts

Top