Make smaller diameter bolt from bigger bolt?

Thanks for the info and offer on the Toyota bolts but they are too short. I am going to crank up the lathe soon (tonight?) and try to make some. This will be a fun project for a neophyte like me.

BP
 
Should be fine if you don't have an issue with the larger head of the larger bolt.

What length & type of head did you need?

I needed a LH M6 countersink screw & couldn't find one anywhere at time. So I made a M6 LH screw out of a M8 RH screw.

Standard RH M6 on the left, M6 LH screw that I made out of a M8 screw in the middle, & RH M8 screw that I started out with on the right.
20140209_222127.jpg
 
bpctcb said:
I am going to crank up the lathe soon (tonight?) and try to make some. This will be a fun project for a neophyte like me.
Click to expand...

That's what I had to do. Made mine from O-1. Not sure if that was a good choice as I didn't harden them, and O-1 doesn't cut great soft.
I made double ended studs(one end 12x1.0 other end 1/2-20) so now the Toyota has some american threads.(couldn't get 12x1.0 nuts quickly either)
 
I picked up two 3.5" 5/8 bolts today. I am going to cut off their threaded section then turn & thread the shank into M12-1.0.

Wish me luck! LOL

BP
 
Just curious guys. Single point or die? How do you hold the work? With a center?
Robert
 
Work holding will be the biggest hassle. When I absolutely have to modify an existing bolt I make a split bushing to the larger shank but then you have to make another to hold the finished diameter. This is why it's easier to just use new stock as you can hold the long piece until it's complete and then cut off the new work.
 
rwm said:
Just curious guys. Single point or die? How do you hold the work? With a center?
Robert
Click to expand...

For me making that LH countersink screw above was a bit unconventional. I started with a screw longer than I needed, center drilled the end. Put a philips bit in the chuck then held the screw in place with a center. Single pointed the LH thread, reduced the head size, then cut to length.
 
If it matters, just remember that a turned down bolt won't be as strong as a new bolt in the smaller size, but also because the grain structure will be interrupted from the original cold headed bolt.
 
bpctcb said:
Has anyone tried to make a smaller diameter bolt from a larger size bolt?
I need a couple of M12-1.0 bolts that I cannot find locally. I thought about trying to make some by turning down & threading larger diameter bolts (M14 or M16).
Is this doable?

Thanks,
BP
Click to expand...

I’ve done that quite often, most times just a connivence thing with myself. I can modify a bolt easier and and quicker than running into town to pick them up. Between the time and gas I may even save a few pennies. Yesterday I had a long shoulder bolt that I picked up at the job I retired from ( I collected bolts left over from maintenance technicians ) that I had in my collection. Chucked it up turned it down and retreaded the end to fit a custom 5” Kurt vice speed handle I’m building


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rwm said:
Just curious guys. Single point or die? How do you hold the work? With a center?
Robert
Click to expand...

If I can put a center in I will, personally if available I’d rather start with a 3” or 4” inch long bolt and turn it down because of centering it. The shorter ones you have to be careful on getting them true and take light cuts


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