My first attempt to make the crankshaft from steel bar.

[minh-thanh]

My first attempt to make the crankshaft from steel bar
It took me a lot of time and patience, I will use it for V2 engines


After finishing it, I wonder: "many members of this forum make crankshaft for engines 4, 6, 8, 12 cylinders with only 1 steel bar - how they have such patience and meticulousness ???
maybe Gods gave them more patience and meticulous !!??
They have a great patience and meticulousness.

 

[Cogsy]

That looks like a tough crankshaft to build. Nice work!

 

[kadora]

Looks perfect , can you send more pictures from crank machining

 

[minh-thanh]

Thank you for complimenting, and...."like "
Hi kadora and everyone !!
Photos when I do it, not much.
First, I need a crankshaft with a 20 mm stroke and can fit a 18mm-thick connecting rod, suitable for bearings, gears ...that I have ., and draw it on paper


And
making shafts for bearings, gears, flywheels ...

And

 

[minh-thanh]

Next :
Make the tool, as well as determining where I will place the pin, that position will be removed when the crankshaft is finished

 

[minh-thanh]

To the important part !!!
Because there are so many materials to remove, I choose a method of removing materials with a hand grinder.
Check again by lathe, and continue until there is little material to remove

 

[minh-thanh]

And :
I made the distant part first , did it slowly, removed little by little, very little material.
Then do the rest

 

[kadora]

Interesting method
How long did you grind off material for eccentric pin and did you cool crank during grinding ?

 

[minh-thanh]

I don't know the exact time, when it heats up I just let it cool.

 

[davidyat]

With all the troubles I've had machining a crankshaft (1, 2 and 4 journals), I decided to try to ASSEMBLE a crankshaft. Here are pictures of my build. I must say, this was a lot easier than machining one. Make 2 webs, drill the holes the proper size and distance between centers, insert the rods, I used 57% silver solder on it to hold everything, machined out the rod part I didn't need and cleaned it up with a jig I had in the lathe. Much easier.

 

[minh-thanh]

Thank davidyat ! This method is really easy.
Yes, I did some, made of brass .
I just think: "please challenge myself a bit" .

 

[NigelW]

Looks great and much easier to fabricate than machine. Just wondering whether anyone has successfully fabricated a multi cylinder crankshaft. Reason for asking is that I'm about to embark on the tiny inline 4 and with it being a flat plane crank, it occurred to me this might make it less daunting!?

 

[rweber]

With all the troubles I've had machining a crankshaft (1, 2 and 4 journals), I decided to try to ASSEMBLE a crankshaft. Here are pictures of my build. I must say, this was a lot easier than machining one. Make 2 webs, drill the holes the proper size and distance between centers, insert the rods, I used 57% silver solder on it to hold everything, machined out the rod part I didn't need and cleaned it up with a jig I had in the lathe. Much easier.

I wonder how you do ensure, that the shafts are concentric and everything is in 90° angle after silver solder. Did you build it with a oversize of a few 10th an the grinded into the final dimentions on the lathe?

 

[davidyat]

I put the two rectangular webs (machined exactly the same) onto my mill. Then drilled the two 1/2 inch holes, 0.501 inch between centers. Inserted the short journal (machined to the distance called for), then inserted the long rod. Then silver soldered everything. Machined out the part of the rod I didn't need. I had an off set jig for the rod journal that I had from another project with 1/2 inch holes, 0.500 apart. Stuck the crankshaft in it and to the lathe. Basically just cleaned up the insides of the webs and didn't touch the rod journal. Touched up the journal with some 1200 grit sandpaper. Then put the concentric rod ends into the lathe and cleaned up the outsides of the webs. The crank was held in the chuck and the other end was held with a rotating chuck that I got when I was at the NAMES show last year that fit into the tail
stock. The whole crank is 6 inches long and I'm not too worried. When I machine the hole for the sealed ball bearing in the engine block, I'll be using my boring head and if the crank is a few thou off, I'm sure the bearing will compensate for that and bring everything into alignment. When I put it into the block I will put it on the site here that I'm recording my build. Here is my thread:
https://www.homemodelenginemachinis...wo-cylinder-double-acting-steam-engine.31081/

 

[kadora]

Hello davidyat
Did you heat crank web joints step by step or completed web at once .
Your silver soldered joints are perfectly done /reflowed/

 

[davidyat]

Installed both rods at once. Then with my acetylene setup with a small tip that would work, I slowly heated up one side til the silver solder would flow then did the other side. Then let the whole thing come to room temp for about an hour.
Grasshopper

 

[kadora]

Thank you Grasshopper
I am planing to hard solder crankshaft web for my straight 4 cyl. in oven .
I hope that evenly heated crank web will not be bent .

 

[minh-thanh]

update my V2 engine project :

 

[davidyat]

Minh,
Your project looks like a takeoff of Vederstein's double action steam engine that I'm currently building. Is this true? Is your engine going to be an internal combustion engine? If so, where are the plans you're following? I've been thinking of building an IC engine and yours looks like a good one to start with. Here is the blog that I created to show my progress on Vederstein's engine:

https://www.homemodelenginemachinis...wo-cylinder-double-acting-steam-engine.31081/

Grasshopper

 

[minh-thanh]

Hi davidyat !
My engine is an internal combustion engine.
I have no plan,
more than 2 months ago, I planned to make a 1 cylinder IC engine, with 2 valves control by camshafts, then I thought: "why not 2 cylinders?" and decided to make 2 cylinders V 90
I am learning and learning, so I often choose the method I can do, step by step...
It's like I did a 2-stroke engine, improve step by step

before :

And now :