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  • Bob Engelhardt
    replied
    Originally posted by Mcgyver View Post

    in your choice of flavours, and it'll be there the next day. What an age we live in!

    https://www.mcmaster.com/threaded-ro...ion~left-hand/
    Did you notice the oddball threads that it's available in? E.g., 3/8-10 & 12. 'Never heard of 3/8-10 & 12, but they have it in LH !

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  • SLK001
    replied
    Here's a source for both RH and LH ACME screw all thread, in many different metals:

    https://www.roton.com/products/acme-...ineering-data/

    Leave a comment:


  • tom_d
    replied
    Originally posted by Dan Krager View Post
    I had dismissed the notion of making the screws in two parts joined in the middle because I have never seen LH all thread. It really exists?
    .
    You've received some great suggestions here. As to the purchase of left hand threaded rod here's a link to a known reputable supplier of all sorts of good things:

    https://www.mcmaster.com/Threaded-Ro...readed-rods-9/

    Leave a comment:


  • SLK001
    replied
    Originally posted by Richard P Wilson View Post
    Lucky, lucky people! I could grow old and die here in the UK trying to source small quantities of stainless left hand and right hand Acme allthread, but to you guys its no problem at all.
    Yeah, it really is nice living in a country where we are citizens, not subjects.

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  • Mcgyver
    replied
    Originally posted by Dan Krager View Post
    I had dismissed the notion of making the screws in two parts joined in the middle because I have never seen LH all thread. It really exists? I could easily weld two pieces together and turn the weld down.
    s.
    in your choice of flavours, and it'll be there the next day. What an age we live in!

    https://www.mcmaster.com/threaded-ro...ion~left-hand/

    Leave a comment:


  • 754
    replied
    To start with I have done a lot of sinle point threading, dontvrecall ever having used a follow rest.
    one tine i cut a 1/2 thread on s shaft and it was lets say 18 inches long or longer, tell you what i did,
    cut the whole shaft till test nut fit one end with a bit of clearance . of course that would mean both ends.
    Then I marked the area or part of the area that nut would not go over. Maybe with masking tape? Then using the final cut number from before, i increased the cut in small steps over a few inches, you can see if its cutting much or not.. then work along like that till nut starts to fit.
    on a long thread that is all yhe same hand you can use a second nut. It may not be uber consistent, but Hey It Works..

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  • JoeCB
    replied
    If I recall, the specialty woodcraft stores sell screw sets for making ones own clamps... just add the wood jaws.

    Joe B

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  • I make chips
    replied
    How about buying some Jorgensen clamps on ebay and just keeping the screws.

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  • Richard P Wilson
    replied
    Lucky, lucky people! I could grow old and die here in the UK trying to source small quantities of stainless left hand and right hand Acme allthread, but to you guys its no problem at all.

    Leave a comment:


  • SLK001
    replied
    Most hand screws I have are ACME threaded. One approach to doing this would be to purchase RH and LH ACME All-Thread and weld/pin the two parts together. This would be far easier for a novice that trying to single point a long thread. Where I live, a steel thread will rust in no time, so I would use a stainless variety of All-Thread.

    Leave a comment:


  • Dan Krager
    replied
    I'm overwhelmed with the responses. Thank you, gentlemen.

    Yes, it's unknown metal in 8' lengths from a web supplier. It does look much better than hardware store stuff and it threads nicely in short runs by hand. The LH die is part of an ALPS set I bought from across the little pond and being inexperienced in metal work I didn't notice an important detail. Turns out to be BSW thread type. It is a split round die for cutting new threads, not a rethreading hex die and I was careful to start it with the appropriate side, but it doesn't cut nearly as nicely as a trusty old Little Giant RH 3/8-16 RH. So it is likely as one of you pointed out to be a die weak in quality. My holder of choice was a hex stock with only one set screw and it's likely that, like holding in a 3 jaw, it compressed the die. The threads I did cut run smoothly in the mating dowel pin threaded with the matching tap from the set. Thank you for pointing that out. I have a smaller stock for 1" round that has three set screws, one of which holds the die open against the pressure of the other two. So there might be hope for that setup.

    The notion of cutting partial threads on the lathe between centers and finishing with the die is a brilliant suggestion, a method that completely escaped my thought processes! It is certainly doable and I will try it.

    I had dismissed the notion of making the screws in two parts joined in the middle because I have never seen LH all thread. It really exists? I could easily weld two pieces together and turn the weld down. I very much like the idea and if I can locate the requisite all thread, I'll do that. I didn't get enough material to finish the job because my math is bad, I guess, so nothing wasted to get all thread to finish. The issue might be that the all thread will be UNC and my dowels have BSW form. They should be compatible enough to work, yes?

    Arcane post showed up while writing this. You overestimate my metal working skills! Yes, I fed the rod through machine driven die by hand turning carriage feed to match the cutting action, something my lathe is capable of, but I didn't have enough nerve to use. The die seemed to be clearing the chips adequately because it was successful for 8 of the 9 1/2" run. I was getting impatient and upped the speed and that lead to the "catastrophe". Probably as you pointed out because the chips weren't clearing fast enough and jammed. Made me lose my nerve to repeat with changes....

    The wooden jaws will be beautiful when finished. They are red oak rafter cutoffs that I found stacked in a metal rain barrel and had been soaking there for some unknown time. They are through and through black from the tannin reaction with the steel barrel. I made one hand screw with wooden threads (all RH) and it was beautiful under an oil finish. The wooden threads were its weakness. I don't have enough of that black wood to make handles for these, so what to do has not been fully decided. Whatever wood, they will be London pattern to match all the other wood working tool handles in my shop.

    I try to keep an open mind to useful methods when I approach a project and God only knows how long I've thought about getting this done, but I know it's been over 30 years! It's time....and I need the clamps!

    Thanks again.

    DanK
    I'll report back in a week or so to show progress in pictures.
    Last edited by Dan Krager; 09-22-2021, 07:05 AM.

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  • Arcane
    replied
    Dan, you said you fed the rod by feel through the turning die. Just to clarify, you were backing off and clearing the swarf from the die regularly weren't you? Like every half turn?

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  • Mcgyver
    replied
    lynn's approach is practical. Then there is just threading in the lathe with a die stock; not the way to make a new lead screw for ultimate lathe build, but you can get a usable result. I don't like the die held in the 3 jaw for a few reasons. Dies are hard and will easily slip in the three, so you end up torquing like crazy and that could close in the die making it tight on the work, even with an adjustment screw. Things broke either because of that it was a crap/dull die (crap dies are meant to hold the garbage pail down)

    I'd probably go with joining via silver solder (brazing) two piece of threaded rod. Its not fussy work or work where high accuracy is needed....and its a lot of threading so a low cost off shelf solution makes sense. If you didn't have a the capability of brazing, make a small union in the middle, thread each into it and loctite. Make the union short enough it doesn't foul the nuts in the clamp pieces.
    Last edited by Mcgyver; 09-22-2021, 06:35 AM.

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  • JoeCB
    replied
    Rich had some good advice. Additionally, with a good quality adjustable die, you might try first opening the die using the adjustment screw, Open as much as you dare, not breaking the die!. Then run your thread. after all the rods are threaded "oversize" , adjust for the proper size and run again. Always use good cutting oil.
    Also mic the rod stock, it might be oversize. Which by the way will be a problem even if its "on size" , ie normally when die threading its best to have stock a few thousands under size. Measure a few hardware bolts and see, I'll bet that your 3/8 bolt measures about 0.368 - 0.370 or so. For what you are doing , you don't need or want a tight full thread, just a nice loose running fit, so that you can spin those parallel clamps. AND get some 12L14 steel, like Rich said.

    Joe B

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  • toglhot
    replied
    Make yourself up one of these, put it in the tailstock, the work in the lathe chuck and do it up tight. Find a bit of round stock that fits in the chuck key slot nicely, or use a spanner on the jaws. Lock the die holder in place with the die holder arms resting on the compound and turn the chuck back and forth. May take a while but you do get a nice thread.

    Alternatively, cut a thread on the lathe and finish off with the die.

    Use bright machining steel, not black rod. Use a split die with it opened up as wide as possible. You can cut the first 25mm or so on the lathe to get the thread straight, then transfer the job to a vice and hand held die holder with the split die opened up as far as possible, slowly closing the die up with successive runs. I threaded these 6mm x 45mm threads this way. There was a 3mm hole through the centre.

    Takes time, but!
    Attached Files

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