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Thread: Need to turn down some 3/8" threaded Rod to 1/4" on both ends

  1. #1
    AVRnj is offline Plastic
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    Default Need to turn down some 3/8" threaded Rod to 1/4" on both ends

    Hey everyone,

    New here.

    I have 5, 18" 3/8" threaded rods that I need to turn down to 1/4" on both ends for about 1/2" length for a prototype I am building.

    Because these are 18" long, it does not seem like a mini lathe from Harbor Freight will do the job.

    Its not realistic for me to buy a several thousand dollar lathe for this purpose, so I am wondering if there is a way to do this (safely) using a drill press, or other home technique, or if anyone has any recommendations on how to find a company that will do this for me, for money of course?

  2. #2
    tjd10684 is offline Cast Iron
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    Your breaking the cardinal rule mentioning HF chinese hobby crap, but to answer your question a small lathe in that size range would be perfectly capable of doing that

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    Most anyone on this site can do it. Just post a request.... note where in NJ you are to find someone local. I can do it if you want to mail the rods to Ohio. Check the rules, no faster way to get your thread locked than to talk about h f junk.

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    jrmach is offline Stainless
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    2X in 2 days that someone has mentioned those JUNK lathes.So sad to see people wasting their money.Heck,,the guy yesterday had 4 of them.Sad,sad,sad.

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    jamie76x is offline Cast Iron
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    Quote Originally Posted by jrmach View Post
    2X in 2 days that someone has mentioned those JUNK lathes.So sad to see people wasting their money.Heck,,the guy yesterday had 4 of them.Sad,sad,sad.
    Those are the guys that have money to waste.

    Myself, I'm too poor to buy cheap things.
    Putch and tailstock like this.

  6. #6
    72bwhite is offline Cast Iron
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    What those lathe shaped objects don't have a head stock hole bigger then 3/8 ?

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    AVRnj is offline Plastic
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    Quote Originally Posted by 72bwhite View Post
    What those lathe shaped objects don't have a head stock hole bigger then 3/8 ?

    Everyone, point very well taken about the cheap Chinese junk!

    My apologies!

    My point more than that "junk" was just a mini metal working lathe.

    My understanding was the 6" x 10" or 7" x 12" lathe's that are in the mini/micro category were for stock up to 10" or 12" wide.

    Honestly, I would love to buy a good quality mini/micro lathe and be able to do this myself, I just did not think I could do this with that length of rod.

    Again, I apologize for breaking rules and offending anyone.

  8. #8
    72bwhite is offline Cast Iron
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    Point being stick it out the back I could easily thread the end of a 10 foot bar on my 12x 42 lathe as long as it will fit threw the head stock thread one end then flip it around and thread the other.
    Not seeing a problem unless no hole in headstock, so what's the problem?
    If you can't do it post a RFQ some one will probably do it for beer money less then an hour of work really.
    Now don't use those HF carbide tools sharpen a piece of HSS the HF carbide won't cut on a real lathe either.

  9. #9
    Putch's Avatar
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    chuck up on that all-thread with about 9" sticking out from the chuck and do your turning from there, the work will be much more balanced with the same amount on either side of the chuck jaws

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    AVR, check you PM inbox.

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    AVRnj is offline Plastic
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    Everyone, thanks much for the suggestions.

    I am going to look into getting a good mini or micro machinist lathe.

    If this is not against the rules, can anyone recommend a good one for me, that is reasonably priced?

    I will stay away from cheap Chinese junk.

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    Long Tom is offline Stainless
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    That will be tricky. The Chinese stuff is everywhere in that category of machine.

    Simplest would be a small South Bend or Logan. Relatively cheap and then you'll get full value back out of it when you sell, assuming you buy reasonably well.

    For what you need done, if I were in a "git 'er done!" mode for a prototype, I think I'd buy the 3/8" rod, carefully take it down to ~1/4" on like a bench grinder, spinning it in my fingers, then use a 1/4-20 die to form the threads. Those threaded rods are soft steel and easy to cut threads on*. Would it be perfect? Nope. Would my prototype be moving forwards in like an hour? Yep.

    Or, drill into the end of your allthread rod, and tap it 1/4", then thread a piece of 1/4" rod into it with loctite or epoxy on the threads. If it's in tension in should still be fairly strong.

    Or, pay someone to bang it out properly on a lathe.

    When I worked in prototyping the emphasis was in moving the ball forwards ASAP. It's different if it's a production prototype, but for testing ideas, our mandate was move fast, stay nimble, don't get bogged down. YMMV of course.

    * easy as in mechanically easy. That stuff is sticky, gooey steel that is a bit of a pain to single-point threads in cleanly. If you get a lathe you'll want to chase the cut threads with a triangle file.

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    Quote Originally Posted by AVRnj View Post
    My point more than that "junk" was just a mini metal working lathe.
    Well, I've never used one of those pieces of $#!T, but don't they have a bore through the spindle?

    Or were you planning on turning that 18" piece of 3/8" between centers?

    Quote Originally Posted by AVRnj View Post
    My understanding was the 6" x 10" or 7" x 12" lathe's that are in the mini/micro category were for stock up to 10" or 12" wide.
    Me thinks you might need to do a little bit of homework on how to operate a lathe before coming to any assumptions.

    Quote Originally Posted by AVRnj View Post
    Again, I apologize for breaking rules and offending anyone.
    No reason to apologize to any of us for embarrasing yourself with your comments...it's your own pride...you might want to apoligize to the moderator of this forum for not being able to read the following before you posted though...just a thought...

    Machinery Discussion Guidelines

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    Oakct is offline Plastic
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    Quote Originally Posted by 72bwhite View Post
    Point being stick it out the back I could easily thread the end of a 10 foot bar on my 12x 42 lathe as long as it will fit threw the head stock thread one end then flip it around and thread the other.
    Not seeing a problem unless no hole in headstock, so what's the problem?
    If you can't do it post a RFQ some one will probably do it for beer money less then an hour of work really.
    Now don't use those HF carbide tools sharpen a piece of HSS the HF carbide won't cut on a real lathe either.
    Trust you have a feed to on that lathe. Going to be fun times if not!

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    AVRnj is offline Plastic
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    Quote Originally Posted by Long Tom View Post
    That will be tricky. The Chinese stuff is everywhere in that category of machine.

    Simplest would be a small South Bend or Logan. Relatively cheap and then you'll get full value back out of it when you sell, assuming you buy reasonably well.

    For what you need done, if I were in a "git 'er done!" mode for a prototype, I think I'd buy the 3/8" rod, carefully take it down to ~1/4" on like a bench grinder, spinning it in my fingers, then use a 1/4-20 die to form the threads. Those threaded rods are soft steel and easy to cut threads on*. Would it be perfect? Nope. Would my prototype be moving forwards in like an hour? Yep.

    Or, drill into the end of your allthread rod, and tap it 1/4", then thread a piece of 1/4" rod into it with loctite or epoxy on the threads. If it's in tension in should still be fairly strong.

    Or, pay someone to bang it out properly on a lathe.

    When I worked in prototyping the emphasis was in moving the ball forwards ASAP. It's different if it's a production prototype, but for testing ideas, our mandate was move fast, stay nimble, don't get bogged down. YMMV of course.

    * easy as in mechanically easy. That stuff is sticky, gooey steel that is a bit of a pain to single-point threads in cleanly. If you get a lathe you'll want to chase the cut threads with a triangle file.
    Tom,

    Thanks much for the suggestions. I had not even thought about doing this on a bench grinder, but that would work.

    It's even easier than you say, my 1/4" ends don't even need to be threaded.

    One end will fit inside of a bearing to be able to turn freely, and the other will fit into a motor coupling that is 1/4".

    Neither end needs to be perfect at all, I think I will give this a shot, thanks!

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    AVRnj is offline Plastic
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    Quote Originally Posted by traditional-tools View Post
    Well, I've never used one of those pieces of $#!T, but don't they have a bore through the spindle?

    Or were you planning on turning that 18" piece of 3/8" between centers?
    Nope, was not planning on turning it between centers. I looked at the only models I could see in person, and did not see that the headstock had a hole through it where the stock could come through, it looked like only a few inches of the stock could fit into the chuck on this model, and it looked like it based on where the feeder's max distance was, was the 10", hence the 7x10. See, I did look into a lot of this stuff, and tried to read about it, but found it very frustrating and could not find any good information.

    That was why I came here, to seek help, not to be insulted by people like you.


    Me thinks you might need to do a little bit of homework on how to operate a lathe before coming to any assumptions.


    Quote Originally Posted by traditional-tools View Post
    No reason to apologize to any of us for embarrasing yourself with your comments...it's your own pride...you might want to apoligize to the moderator of this forum for not being able to read the following before you posted though...just a thought...

    Machinery Discussion Guidelines
    Trust me sport, I am not embarrassed, not in the least. I am more than confident in what I know, and more than comfortable admitting that I don't know plenty there is to know on this Earth.

    I have seen at least 10 questions along the lines of mine, are you running to each of their threads and asking them to read the same rules, and to apologize to the moderator?

    If you don't like my post, you could have ignored me, or reported me to the mods if I was in violation, not sure why you felt the need to insult me for looking for help.

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    awake's Avatar
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    AVRnj,

    My comment will likely get this thread locked, but I'll make it anyway. The statement from another poster that he has never used one of these mini-lathes is telling. If he had, he might be more impressed than he would want to admit. They are certainly not professional / production machines (this is why they are verboten on this forum), but within their limited envelope they work surprisingly well. The job you are describing would be a perfect fit for these machines, so much so that if I were doing it, I would very likely put it into my 60-lb. Grizzly 7x12 rather than my 1-ton Cincinatti TrayTop.

    Some significant limitations of the 7x12 and similar machines:

    1) Small through-hole in spindle -- big enough for your 3/8" all-thread, but not much more
    2) Small depth-of-cut (DOC) -- I think the biggest I've comfortably taken on the Grizzly is around .025" DOC.
    3) Apron controls are too close together -- have to be careful not to bump the compound feed when turning the handwheel
    4) No power feeds (except using the half-threads, which I personally avoid)

    All of these are good reasons why they are laughable toys in a production shop; if the work would even fit in it, it would wear you out taking multiple small cuts, all by turning the handwheel. If you have a decent large machine with reasonably high top speed, plus collets or a good chuck that can grab a small diameter rod, there is nothing the big machine cannot do that these little machines can do.

    On the other hand, if you happen to find one for $50 in a fire sale, as I did (literally), or if you want or need something small enough that you can pick it up and take it with you or store it in a closet, these imports are better than people on this board tend to think. For me as a hobby machinist, the Grizzly has been a great second lathe. I can easily work to a half or even a quarter of a thousandth (all the precision I ever need for my projects) on it as as easily as on the Cinci. Admittedly, I do most of my work on the Cinci, because it is so much faster at removing metal. But I prefer to use the Grizzly when 1) the work is very small diameter (the chucks on my Cinci won't grip smaller than 1/4"), or 2) when I need a metric or even an odd-ball thread -- this is a place where the change gears are actually an advantage.

    With a reasonable selection of change gears (most of which I made myself, since my $50 deal only included the 20-tooth and the 80-tooth gears), I can get within .05% (worst case -- usually .01% or even closer) to just about any thread I need, whether metric, module, DP, or inch. For example, I recently needed a 19.5 tpi thread for an antique woodworking plane that I was repairing for someone. No such tpi on my Cinci quick-change gearbox, but my change-gear program popped up 5 different combinations that would generate an exact 19.5 tpi on the Grizzly using my existing change gears. Note that I could theoretically make a set of gears for the Cinci that would allow all sorts of odd-ball threads ... but it would be a lot harder (at least for me) and more expensive to make the large gears needed for the Cinci than it was to make the small, light-duty gears needed for the Grizzly.

    Let me stress again: these are not production / professional machines, not even close ... but neither are they useless.

    Okay, Milacron, lock it!
    oldbrock likes this.

  18. #18
    Big B is offline Hot Rolled
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    AVR,

    Don't get so offended here. The first person to reply to your question told you that you were breaking forum rules by mentioning chinese junk machines. Regardless of anyone's personal opinion is about said machines, those are the rules. Then you charged ahead and kept talking about them. Follow the rules here and you will get lots of help.

    BTW, If you are fitting bearings to these shafts, I would think that you would want them to run concentric. Grinding them by hand on a bench grinder would be one of my last choices. As has been mentioned, there are plenty of people here who would likely do a job like that for little or nothing, IF THEY LIKE YOUR ATTITUDE. Work with us and we will work with you.

    Big B

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    Anvil Jenkins is offline Hot Rolled
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    Quote Originally Posted by awake View Post
    AVRnj,

    My comment will likely get this thread locked, but I'll make it anyway. The statement from another poster that he has never used one of these mini-lathes is telling. If he had, he might be more impressed than he would want to admit. They are certainly not professional / production machines (this is why they are verboten on this forum), but within their limited envelope they work surprisingly well. The job you are describing would be a perfect fit for these machines, so much so that if I were doing it, I would very likely put it into my 60-lb. Grizzly 7x12 rather than my 1-ton Cincinatti TrayTop.

    Some significant limitations of the 7x12 and similar machines:

    1) Small through-hole in spindle -- big enough for your 3/8" all-thread, but not much more
    2) Small depth-of-cut (DOC) -- I think the biggest I've comfortably taken on the Grizzly is around .025" DOC.

    4) No power feeds (except using the half-threads, which I personally avoid)
    As far as using half nuts to feed, isn't that how the simpler SB9's work ??...and some of the other things are to an extent true. The Model C is the one I am talking about, earlier called the "workshop lathe"....no cross slide feed and the only carriage feed is via the half nuts.

  20. #20
    awake's Avatar
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    I've not used an SB9, so I can't say from personal experience ... but I have often wondered if these much-maligned imports are really all that different, in capabilities and controls, from some of the home-shop grade American lathes of years past. Zamac gears, anyone?

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