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Fast pitch lead screw source

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  • Fast pitch lead screw source

    On another metalworking forum (which some of us frequent), there is a thread going on about building a flypress or manual screw press for various forging or cold forming operations. The difficult part of the build is obtaining a fast lead screw and nut, with the consensus being that around 1-3/8” to 2” OD with at least 2”-3” lead and 1 TPI, 2 or 3 start is optimum, in either an Acme or modified square thread. The fast pitch is needed so the operator can get plenty of movement with only partial turns of the hand wheel.


    The thread I mentioned discussed building the screw and nut but I just can't believe someone isn't already making something similar for industrial use. I searched the 'net and found companies like Roton and Nook Industries but the fastest I can find in stock has a 1" lead. However, newly imported machines from India have these size screws (as well as antique ones made in the US or England in the last century) so I know they are/were available.

    Anyone know of a source for something like this without having to reinvent the wheel?

    Thx, Hollis

  • #2
    How much torque does it need to handle?
    Free software for calculating bolt circles and similar: Click Here

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    • #3
      Hi Hollis,

      If McMaster doesn't have it (they don't -- I just checked), you're probably SOL. More importantly, a 2"-4 general purpose, rolled thread acme is about $35/foot. Unless you're making the frame from scrap, I don't see how that can possibly be price competitive with a flypress from Old World Anvils?
      "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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      • #4
        A 100 lb flywheel could generate 6 tons - I didn't calculate this but it's an approximate figure based on various info gleaned off the web. I'm guessing the thread will need to handle 12,000 lbs dynamic load.

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        • #5
          Hmmm, have a 2.5"od ball screw with 2 tpi. Been trying to figure a use for it, wonder if it would work for a flypress?
          Should spin faster but maybe the sudden stop would be a problem?

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          • #6
            Originally posted by lazlo
            Hi Hollis,

            If McMaster doesn't have it (they don't -- I just checked), you're probably SOL. More importantly, a 2"-4 general purpose, rolled thread acme is about $35/foot. Unless you're making the frame from scrap, I don't see how that can possibly be price competitive with a flypress from Old World Anvils?
            L,

            OWA quoted me $1400 for a press and $1500 to ship it - I can spend a bit and still be way under that number (and I will build from scrap). One additional feature is that I can increase the open die height over the cast ones and make it more friendly to forging. Most of the surplus ones on the market were coining machines and 5" of daylight is a lot for sheet metal work. If I can find a good source for the nut/screw, I'll develop a blueprint design and BOM for anyone who wants to build one.

            G,

            I think you'll need a solid nut; a ball screw will probably come apart.

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            • #7
              A multi start ACME thread maybe?

              Pete

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              • #8
                Got a lathe? Gear for it. Long leads are a PITA and a lot of work. Most of the work is repetitive but none of it is rocket science. Most lathe index trains allow you to swap gears around to double or quadruple the coarsest available lead.

                Naturally you will have to use multiple starts and you can't use the half nut unless your coarse lead is a neat multiple of the lead screw. So figure on multiple leads and reversing back.

                I can cut 1" leads right from the existing quick change and if I swap two gears I can cut 4" leads.

                If you do much long lead thread cutting you might wish to power the leadscrew driving the spindle back through the index train. If you do be careful. Index trains are not as robust as the headstock transmission.

                Screws are not mechanically efficient: 8 to 25% is typical for hard steel screws running in oiled leaded bronze nuts at 50 ft per minute. Look carefully at your application before you decide on a screw power transmission. Consider a harmonic drive toggle press. If you build it strong enough you can get 100 tons as the toggle goes over-center yet have close control over the strike.
                Last edited by Forrest Addy; 11-04-2011, 10:25 PM.

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                • #9
                  I have a lathe that will cut 4 TPI but I also have a secondary goal here and that is to develop a "kit" so a hobbyist without a lathe can build one. These screws are being made new in India today (and maybe the US?) so it's just a matter of better sourcing on my part.

                  This is very old technology and screw presses are shown in Diderot's Encyclopedia in the 18th century. I can visualize the first ones forged straight with two ribs then twisted hot to make the screw form, followed by a babbitt bearing.

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                  • #10
                    How about Roton? They've got a huge selection of stuff. This is a link to their "Hi-Lead' threads but they have other products as well...

                    http://www.roton.com/hi-lead-screws-...x?line=Hi-Lead
                    Keith
                    __________________________
                    Just one project too many--that's what finally got him...

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                    • #11
                      Originally posted by LKeithR
                      How about Roton? They've got a huge selection of stuff. This is a link to their "Hi-Lead' threads but they have other products as well...

                      http://www.roton.com/hi-lead-screws-...x?line=Hi-Lead
                      I haven't looked over their entire catalog but 1.00" lead was the highest I saw in a larger screw.

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                      • #12
                        http://www.mooreinternational.co.uk/...precision.html

                        not sure how much good that does...it is multiple start, don't know which becomes more important to the project though you did mention "ideal" (?)

                        If you know they are available in products out of India, are you saying you don't want India as a direct source (if that is even possible, not knowing the numbers you are talking about)? Because if that is a viable source then more hits occur in the search process.
                        http://gmhitech.in/multiple-start-le...rer-india.html

                        Edit: there are a few more manufacturers out there but so far its the combo of large diameter w other details that is the stumbling block, seems to be either or but not both and sometimes only one part of parameters you gave...most of what I have found is precision and I am not sure that is a good definition of what you want...could be some from those that make screw jacks but, relatively speaking, IMO, those are not high precision (very poor choice of wording but all I got right now) and so a whole different search/mfg process

                        Edit II: http://www.duffnorton.com/productdetails.aspx?id=8645

                        getting closer, 3.75", 1.333 lead, double start is listed
                        Last edited by RussZHC; 11-05-2011, 03:04 AM.

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                        • #13
                          This is a link to a domestic importer of the type of machine I'm discussing herein:

                          http://www.oldworldanvils.com/flypresses/index.html

                          Russ, I have nothing against India sources - just need the correct parts for the thing to perform properly and I believe this would be a good home shop project if components can be had at a reasonable price. For me, that would be $400 or less since the remaining parts can be fabbed from pipe and plate; it's just not that tough with the right screw and nut. Depending on how you value your labor, I think a fully usable machine can be built for under $1000.

                          BTW, the reason you want to have a fast screw is so the flywheel handle can be pulled a short distance for movement. That way, you can "bump" the work with short but powerful strokes.
                          Last edited by HWooldridge; 11-05-2011, 07:53 PM.

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                          • #14
                            Just so as no misunderstanding...I mentioned India sources since they come up for sure in nearly any search related to machinery and most other things mechanical BUT in the only experience I was relatively close to, it became a matter of how practical a solution it was, quality was OK (though it was a series of quite inexpensive pieces to start with) but trying to get small amounts was a whole different matter and since I assume you are looking at developing some sort of kit or add ons to make a full product, I was just not sure how viable having to order say 5000 of anything would be...

                            Personally, I think your reply was the way this could develop and from time to time have wondered if there is not, here, a network that could develop into a bit of a cottage industry...

                            Edit: re-read your reply (post # 13), and my assumption about wanting a kit it incorrect (I was thinking more along the lines of Hemingway, sp?) you are after those couple of pieces that not many may be able to make at home...got ya, it sinks in eventually
                            Last edited by RussZHC; 11-06-2011, 12:12 AM.

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