Using up my small bore DOM cylinder liner material and left over bevel gears, I build an easy runner with a light weight flywheel. Longboy's "THREELING ALONG" engine story coming this week! 
Longboy's "THREELING ALONG" Model Engine.
- Thread starter Longboy
- Start date
Help Support Home Model Engine Machinist Forum:
THREELING ALONG a milestone engine for me being number twenty of my gas engines. 
This 33cc model begins with an order from Amazon for some flywheel material.
In the box, four cast iron casters. Four inch diameter by 1 inch tire width.
Squaring up the caster flywheel. The hub is bored to 1/2 inch to receive a pressed in T-shaped steel hub. A new bore for a 5/16 in. shaft is drilled then along with a 7degree taper for collet lock mounting of flywheel to the shaft.
Narrow the tire to 3/4 in. width and face off and file smooth.
The collet is Delrin, matched taper to the new hub. A brass disk on hub end draws the flywheel onto the shaft and collet.
The finished flywheel is very light at 17 ounces. I have a steel disk that bolts to the backside if I need the extra heft.
This 33cc model begins with an order from Amazon for some flywheel material.In the box, four cast iron casters. Four inch diameter by 1 inch tire width.
Squaring up the caster flywheel. The hub is bored to 1/2 inch to receive a pressed in T-shaped steel hub. A new bore for a 5/16 in. shaft is drilled then along with a 7degree taper for collet lock mounting of flywheel to the shaft.
Narrow the tire to 3/4 in. width and face off and file smooth.
The collet is Delrin, matched taper to the new hub. A brass disk on hub end draws the flywheel onto the shaft and collet.
The finished flywheel is very light at 17 ounces. I have a steel disk that bolts to the backside if I need the extra heft.
Attachments
Last edited:
I too enjoy just ordering these caster wheels for flywheel use. I’m employing a much larger version on my build of Rudy’s Pioneer.
I’m following what appears to be another of your great designs!
John W
I’m following what appears to be another of your great designs!
John W
Some common parts made the same way over the years!
Con rods on 1/4 x 3/4 alum. flat stock.
Cylinder heads. Cylinders, crank webs look the same here and I build air cooled with the fins.
Valves. Currently using 12L14 steel. Easiest to cut and shape small dia. stem valves
Shaft collars. I use these as a shaft stop up against bushings for 3/16in. shafts on the engines. Hole though offset on 3/8in stock with 6-32 set screw.
Brass bearing carriers. Either R1810ZZ rollers or Oilite bushings support the crankshaft in the frame.
Pieced together crankshafts are a challenge. Crank webs are marked for direction and sequence. Parted off by pairs. Drilled for main shaft and throw pins then parted off from each other.
THREELING ALONG's crankshaft is a little more unique for my application here.....will be talking about it................ next post!
Con rods on 1/4 x 3/4 alum. flat stock.
Cylinder heads. Cylinders, crank webs look the same here and I build air cooled with the fins.
Valves. Currently using 12L14 steel. Easiest to cut and shape small dia. stem valves
Shaft collars. I use these as a shaft stop up against bushings for 3/16in. shafts on the engines. Hole though offset on 3/8in stock with 6-32 set screw.
Brass bearing carriers. Either R1810ZZ rollers or Oilite bushings support the crankshaft in the frame.
Pieced together crankshafts are a challenge. Crank webs are marked for direction and sequence. Parted off by pairs. Drilled for main shaft and throw pins then parted off from each other.
THREELING ALONG's crankshaft is a little more unique for my application here.....will be talking about it................ next post!
Attachments
Last edited:
The crankshaft for THREELING ALONG is made with two shafts, four crank webs and three main bearings. Two of the main bearings are in the upright frame segments of angle aluminum. Main bearing between cylinders one and two is supported down from the ceiling of the deck. This will give the appearance of a floating crankshaft in motion up front.
Cylinders one and three have a pressed on shaft web for an overhung attach of their con rods. Unlike cyl two with a pair of webs for its con rod. A single web cannot primary balance out the assembly just removing metal from the throw pin hemisphere of the web on this project.
The solution is to add weight to the other hemisphere here in the form of a brass shell cover. Lots of swarf yielding a five percent remains for the shell needed.
Cyl. two webs get a different treatment in attachment. I will be using the "Slit & Grip" method!
(a what Longboy)?
Cylinders one and three have a pressed on shaft web for an overhung attach of their con rods. Unlike cyl two with a pair of webs for its con rod. A single web cannot primary balance out the assembly just removing metal from the throw pin hemisphere of the web on this project.
The solution is to add weight to the other hemisphere here in the form of a brass shell cover. Lots of swarf yielding a five percent remains for the shell needed.
Cyl. two webs get a different treatment in attachment. I will be using the "Slit & Grip" method!
(a what Longboy)?Similar threads
