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Ford transmission for lathe speed changing

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  • Ford transmission for lathe speed changing

    This lathe has a Ford transmission for speed changing:
    http://stlouis.craigslist.org/tls/2972721042.html
    "Patriotism is the last refuge of a scoundrel"

  • #2
    My lathe is not that big, but I've been thinking about taking a single planetary gear set out of this old Honda tranny and adapting it to my spindle.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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    • #3
      I've had one of those. A big ol' lathe with an automobile (or tractor??) transsion on it. A 4-speed, with the standard H shift pattern and clutch too.

      They say this type of adaptation was not entirely unusual in the era of converting old overhead line shaft machines to electric motor drive.

      It worked fairly well; no doubt at all the guy who built it was a right clever bastard. Made a helluva lotta noise though. (I later converted it to belt drive, and it became whisper quiet. Really. Quietest machine ever. Like, refrigerator quiet almost.)

      The gear ratios weren't so great if i recall correctly.

      .

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      • #4
        I used to know a guy that had an old Sellers 144" VTL that had a tranny out of a 29' Ford on it! Pretty cool... I would post a picture of it but I am not allowed to yet...
        Last edited by Marty J. Roberts; 04-23-2012, 02:57 PM.

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        • #5
          Time for one of my famous un-asked for lectures.

          What works, works. LOTS of older machine tools have been modified using automotive transmissions resulting in a nice (but awkward) range of spndle speeds. Problem with most automotive transmissions is the range they provide is not large and the gear ratios are too few and close together. To be blunt, many were great ideas made lame by poorly chosen components.

          There's a nice discussion of spindle speeds in Machinery's Handbook but briefly:

          You want a range of spindle RPM's appropiate for the materials you have to machine, the tools you have available and the size range so they all work together. Smallers lathe run higher RPM's because they work on smaller stuff. So first you need the range. On the small side we run carbide at 400 SFM on 1/2" dia. Doing the math that's 3050 RPM. On the large side you have 10" dia running HSS in stainless at 50 FPM That's 19 RPM. 19 to 3050 RPM is a large range but if the extremes of machining requires it... Divide the high end by the low end and you get 3050/19 or 160:1 RPM range. Yeah, we're theorizing.

          Next is geometric ratio: How is the range divided into steps for the different cutting speeds. Ideally the steps all have a common ratio whiich is actually an exponent. 1.2:1 is preferred for geared machine tools. It ensures that the cutting tools are running at close to optimum cutting speeds. So taking out example and starting from 19, the next spindle speed whould be 22.8 and the next 27.3, 32.9 and so on. Doing the math this spindle transmission would have 68 speeds and be very expensive if all geared.

          The practical limitation of a multispeed spindle transmission is 100:1 for range and 1.2:1 for the common ratio. You see this in high end production engine lathes made between 1940 and 1980. Most all geared high end machine tool spindle speeds ran from 18 to 24 steps over a 60:1 to 100:1 range. Lower end and import lathes have a lower range of spindle speeds and fewer steps: 210 to 1500 RPM in 8 speeds for example and the steps may not be uniformly spaced. A little geometric ratio error may be OK but if the rooro is large enough you may not have 8 effective speeds. My lathe spindle RPM goes from 740 to 1050 to 1120 then it jumps to 1450 to 2000. PITA and the problem duplicates in the llower range. 18 speeds and I only have 14 that are effective.

          The steps (or splits) in geared ratios of automotive transmissions are not equal. The lower gears have larger common ratios than the higher suiting the requirements of cars and trucks and the hills they have to climb. While they may work well when adapted to machine tool spindle drives there will still be this nagging unequal split deficiency. Also the overall range of an automotive transmission is small: about 2.5 to 1 for a Corvette and 4 to 1 for a medium truck transmission in 4 speeds. So when you eyeball an auto transmission thinking to use it on your lathe (as with that in the OP link) you have to consider the transmission range and common ratio with the existing flat belt ratios and back gear.

          Adding transmission to transmission usually results in "overlaps" where many speed selections are duplicated or so close together there's little difference except at the extremes of the combined ratios. Study the belt speed chart of the average mill drill and you'll see many speeds so close to each other there is little practical difference. You might have eighteen ways to jump the belts but only seven distinguishable speeds.

          Once upon a time "Lima" transmissions were popular retrofits for flat belt driven headstocks. The cone pully was vrooved for a V belt drive and the transmission (available in 4 to 8 speeds) mounted above. It made a nice package with a positive spindle drive with no more need for mashed fingers or belt poles.

          The above was a quick and dirty tutorial on the selection of spindle speeds not inteded for anything but to nudge the curiosity for the user of an older lathe considering an auto transmission etc.

          Many have gone the VFD route where a variable frequency drive is used to vary the speed of the spindle motor and a few ot the geared ratios used to maximize the mechanical advantage. There's a strategy involved. On high HP cuts you wat the spindle motor running at near line frequency to maximize the available motor power so you select the mechanical ratios accordingly. Lighter cuts and you can use the variable speed feature with abandon. Anyway what was once done with 24 geared speeds in the 70's can now be done with 4 widely spaced speeds, a VFD, and a slightly more powerful motor.
          Last edited by Forrest Addy; 04-23-2012, 04:42 PM.

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          • #6
            As others have said, automotive transmissions on early machines are not unusual of a conversion as many conversion kits were sold that were based around auto transmissions. Even Ford sold one from the factory at one time for driving farm equipment in the early days when electric motors were scarce and farmers had one or two motors that were simply swapped between tools/implements much as the old hit-n-miss engines were.
            "I am, and ever will be, a white-socks, pocket-protector, nerdy engineer -- born under the second law of thermodynamics, steeped in the steam tables, in love with free-body diagrams, transformed by Laplace, and propelled by compressible flow."

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            • #7
              Uncle of mine had an old Mcdougal lathe, (made in Canada,) and it had an "Indian" motorcycle transmission on it.

              That transmission now would be worth 5 times what that old lathe would be.

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              • #8
                i have done it a few times the way it works best and the way i have seen it done the most.was to have the transmission driving the overhead pullies with them driving the lathe or mill. that way you could split the speeds by 4 for each change of the belt.

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                • #9
                  Our biggest lathe at the Buckley Old Engine Show machine shop is a Lodge & Davis, probably of a similar vintage to the one in the CL ad. Ours is 24" swing by about 9 feet between centers, and the spindle is also driven by some sort of old automotive 3-speed transmission. Big ol' 2Hp repulsion-induction motor.

                  The interesting thing about our lathe is that the leadscrew is inside the ways. Makes it pull the carriage more evenly, but it's in the swarf.

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                  • #10
                    Originally posted by Marty J. Roberts
                    I used to know a guy that had an old Sellers 144" VTL that had a tranny out of a 29' Ford on it! Pretty cool... I would post a picture of it but I am not allowed to yet...
                    Marty, to post pics here you have to host your photos elsewhere, like Photobucket, unless I misunderstood, and someone else is not allowing you to post pics.
                    James

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                    • #11
                      My 14x40 American has the leadsrew between the ways.
                      We had a place here called Friday tractor that used Dodge parts to build tractors using one tranny behind the other. Works well but had no govenor that I know of. Lots of power and/or speed. 16 forward & 4 reverse but what if you put the other in reverse I guess you would go forward? I;ve driven one long ago now I'm going to have to find one.
                      "Let me recommend the best medicine in the
                      world: a long journey, at a mild season, through a pleasant
                      country, in easy stages."
                      ~ James Madison

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                      • #12
                        There were also purpose built transmissions for machine tools,Drive-All is one such company.-

                        http://www.driveallmfg.com/products.htm

                        I have two of their transmissions,both four speed.Nice units and very durable.
                        I just need one more tool,just one!

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                        • #13
                          Puts a whole new meaning to" 4 on the floor".
                          "Let me recommend the best medicine in the
                          world: a long journey, at a mild season, through a pleasant
                          country, in easy stages."
                          ~ James Madison

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                          • #14
                            Originally posted by J. Randall
                            Marty, to post pics here you have to host your photos elsewhere, like Photobucket, unless I misunderstood, and someone else is not allowing you to post pics.
                            James

                            I am new to all this... It says at the bottom I cannot post attachments... I will try the photobucket method...

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                            • #15
                              here she is lets see if this works! This was flickr and that didn't work...

                              Last edited by Marty J. Roberts; 04-24-2012, 10:14 AM.

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