Removing Threads

vincent52100

vincent52100

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Mar 26, 2014
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Good morning. I have a a question. What would be the best way to use my lathe to remove threads from a 1" bolt? I need to make some shouldered bushings. I could cut the threaded portion off but but if i remove the threads I could save the leftover pieces for another project. Thanks
 
Determine the diameter of the shoulder first. It needs to be smaller than the thread root:
crest_root.gif

I would use a right hand 90 degree tool. You may want to use a carbide insert tool for better cut, especially if the bolt is hardened at all. Pay attention to your speeds and feeds....
 
If your lathe is big enough, chuck on the bolt shank to face the end and center drill, then re-chuck on the head.

If not, then hold the bolt by the head in the 3-jaw, center drill for the live center. Be careful the setup may not be very stable, and the end of the bolt will not be square. Use reasonably slow speed for this operation, just in case the bolt comes out of the chuck. Use a steady rest if you have one.

Alternatively, cut the bolt head off to have a longer area to hang on to.

As far as removing the threads, just turn normally once you have a solid setup.
 
Vincent52100,

I turn the threads off of big bolts all the time ( I get them free ), when going through the threads, its like taking interrupted cuts. I use the cheap HF brazed (or glued) carbide bits so that if I run into a hard bolt, I don't worry about destroying the bit, However, I haven't ruined a bit yet, and I've turned a lot of bolts (did I mention I get them free?). Sometimes, I cut the big hex heads off to save for when I need a nut, just center drill, and drill and tap to whatever size I need. For some applications, it helps to have a big nut, even with small dia. threads, so they can be hand tightened. If I need a shaft, that is as long as the bolt with head, I also just turn the hex head down to match the dia. I need. Now, I'm not saying that it makes sense to BUY a bolt and turn the threads off. Much easier, if you are buying stock anyway , to just buy the non-threaded round bar you need. But I'm on a fixed retirement income, AND in case you missed it I GET THEM FREEEEE! Happy machining, JR49
Big Bolt resized.JPG
 
Drill a piece of aluminum, steel or nylon round stock to the same size as the bolt shank. Make sure the OD is larger than the bolt head. Slit one side so it can compress then slide it over the bolt shank and clamp it in a 3 or 4 jaw. Then machine away. This trick also works for holding threaded pieces without damaging the threads.
 
Thanks for all the info. I'll take some pictures tomorrow of what I'm doing with the bolts. I was in a hurry so I bought some bolts at Tractor Supply. Also I needed the head to make flanges. I bet I made making them a lot more complicated than it needs to be!
 
Well, I got them made. I really worked hard to make a simple job difficult:congratulate: I made two bushings from 1x4 grade five bolts. I needed 1" bolts to make the flange on the bushings. On the first one I cut the head down to the correct size and thickness. Then I realized, hey, I've got to turn the shank down to 16mm. So I stated cutting in the middle since I felt that the thickness of the flange would not let me secure it properly. (BTW, I can't use a parting tool worth a darn) The second one I just rounded the head off so I could put in the chuck. I cut it to the proper length (by this time I had ruined my cutoff bit) with a recip saw then turned the correct diameter and drilled the hole. The second went a lot faster than the first. I've got a long way to go! Steel is much harder to work with than aluminum or plastic!

P1010001.JPG P1010006.JPG
 
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