Rupnow-Johnno Vertical hit and miss

[Johno1958]

Hi Ray,
No I never got that job but not to worry.I have been a little busy with other things at the moment and for me this is going to be a long build . I definitely will need some help along
way though . Just got some cast iron for the cylinder and I have some key steel that I will have a go at making the crank with, might be a bit hard going but I have heard it
machines quite well.
John

 

[el gringo]

Johno, what is key steel in the US?
Ray M

 

[Cogsy]

Johno, what is key steel in the US?
Ray M

Pretty sure you guys call it key stock - the stuff for making keys to fit in keyways.

 

[el gringo]

Pretty sure you guys call it key stock - the stuff for making keys to fit in keyways.

thanks Cogsy... I found this online, helped me understand.
https://www.huyett.com/AboutUs/Blog/Blog/October-2019/What-Key-Stock-Material

Ray M

 

[Johno1958]

Ray from what I read it's a medium carbon steel . I find it convenient to use sometimes because it is easy for me to get right sizes but pricey .

 

[Cogsy]

Weird - I've never considered keysteel would be different grades, I've always just assumed it was some sort of standard and you just bought it coated or not. I have a few chunks of the cad plated stuff and it machines ok. Not terrific to cut but leaves a reasonable finish.

 

[John Antliff]

I always believed that key steel was a mild steel as it is designed to shear or deform in the event of over thrust. It generally is or should be softer and more yielding than the shaft or driven part so that in the event of overload only minor damage results!

 

[Brian Rupnow]

John --I don't think that is right. A keys main use is to transfer torque. A shear pin is designed to fail in the event of overload in the system, but keys are not. By the time that there was enough load in the system to shear a key, something else in the system would have failed.---Brian

 

[el gringo]

John --I don't think that is right. A keys main use is to transfer torque. A shear pin is designed to fail in the event of overload in the system, but keys are not. By the time that there was enough load in the system to shear a key, something else in the system would have failed.---Brian

I have seen brass keys used to shear at a point to protect an expensive or more difficult to replace part in power transmission.
Ray M

 

[Johno1958]

A quick google, one mob says it's a high grade mild steel another it's equivalent to 1040 another 1045
John

 

[Johno1958]

Made a start on the cylinder and finish it next Sunday I hope.
John

 

[el gringo]

Made a start on the cylinder and finish it next Sunday I hope.View attachment 112028
John

good to see your progress...looking good
Ray M

 

[Johno1958]

Got little time so i finished off the cylinder and also made a dovetail cutter, flame hardened.
John

 

[Johno1958]

The best I can measure the bore it is 25.3 mm or 0.996 inch . I do have a brake hone or would a barrel lap be better to bring it to an inch.
John

 

[Brian Rupnow]

Johno-- About final size. I use a three stone brake hone to knock down any high spots and then make the piston to suit the bore (whatever it is). If you are using Viton rings there won't be any problem. If you are making your own rings or buying your rings then you should try and hold close to the 1" bore.

 

[awake]

Great work on the dovetail cutter - and on the cylinder!

 

[Johno1958]

Well I just had a go at making my first one piece crankshaft

and stuffed it up.I went slightly undersized on the
long shaft and the bearing fit is too sloppy. I could rescue it by changing from metric bearings to imperial but I want to have another go.This time I will try some s1214 steel instead of key steel when I manage to
get some.
John

 

[el gringo]

you might try 1144stressproof....
Ray M

 

[Johno1958]

I would love to Ray but you can't buy it in Australia and the cost of getting it mailed from the USA is jaw dropping.
John

 

[el gringo]

I would think 12xx would distort easily...maybe someone could chime in for direction.
Ray M