Rupnow-Johnno Vertical hit and miss

Home Model Engine Machinist Forum

Help Support Home Model Engine Machinist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
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
 
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 .
 
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.
 
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!
 
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
 
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
 
A quick google, one mob says it's a high grade mild steel another it's equivalent to 1040 another 1045
John
 
Made a start on the cylinder and finish it next Sunday I hope. IMG_20191103_134251.jpg
John
 
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
 
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.
 
Well I just had a go at making my first one piece crankshaft
IMG_20191110_160122.jpg
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
 
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
 

Latest posts

Back
Top