New Manufactured ABS METRIC THREADING Compound Gear. Allows you to turn metric threads on your SAE (English) Atlas/Craftsman 10 & 12" lathes using 1/2" wide gear hubs (total width of compound sold here 1"). Shown is installation a Quick Change version. Substitutes for your final 48T idler which drives the input on your Quick Change gearbox. May also work with other SAE lead screw lathes like some Southbend / Logan using 1/2" bore bushings using 1" thick compound gears of 16tpi. Allows you to use your lathe to accomplish metric threading. A link is provided below shows many details of how this works including where to set your Atlas/Craftsman Quick Change Gearbox to get the thread pitches you want. This may also be used on gear change lathes (TH series) with similar results. Key to photos: (item is lighter gray compound gear in lower right of each photo)Photo 1: Still in SAE modePhoto 2: Running in SAE modePhoto 3: Still in Metric mode (note position of slide gear has changed)Photo 4: Running in Metric modePhoto 5&6: Example of Metric Threading Compound Gear you are buying. Photo 7: Quick Change gearbox SAE chart for reference. Questions and Answers Q?: Can I still use my lathe for SAE (English) threading when this gear in place? A: Mostly yes! Pitches 8-120tpi remain with slider in OUT position. The slider is shown with white bushing on my lathe. You sacrifice only first line of the A-IN row which are very course threads 4-7.5tpi. All other SAE thread pitches (slider "OUT" positions) are available for SAE threading and carriage feed turning. If you need a coarser pitch (4-7.5tpi), simply remove the gear and return to stock configuration. Photo of a standard QC panel is shown above. Q?: What kind of service can I expect from an ABS gear?A: I have been running ABS gears in my lathe since 2015 with no failures or visible wear. My motor is 3/4hp and I can take large enough cuts to stall the motor with no tooth damage. Of course, if you crash the carriage feed, you will always do some sort of damage. Normally a crash strips out the carriage feed bevel gear key or a change gear bushing. If the plastic gear or change gear coupler fails before your bevel feed gear, A GREAT DEAL OF MONEY will be saved. I have not made this mistake to learn what breaks first. Thankfully! Q?: My lathe is a gear change lathe. (TH series) Will it work for me?A: For a TH series (gear change) lathe, set up for TPI shown on QC gearbox chart below but replace an idler in the chart with the Metric Compound so you are driving the small side of the Metric Compound while the big side drives the input (or idler engaged with) your lead screw reverse gearbox. Q?:What metric thread pitches does this make available?With the gear in place as shown and in Metric Mode (slider IN towards head-stock), you will have the following metric pitches available to you with an Atlas/Craftsman quick change equipped lathe: Answer:Left Lever, Slide Gear, Right Lever Position = Metric Pitch,......A,IN,Position [3=6.00mm], Position [6=5.00mm], Position 9=4.00mmB,IN,Position [3=3.00mm], Position [6=2.50mm], Position 9=2.00mmC,IN,Position [3=1.50mm], Position [6=1.25mm], Position 9=1.00mm D,IN,Position [3=.75mm], Position [5=.65mm], Position 9=.50mm C,OUT,Position [8=.45mm]D,OUT,Position [1=.40mm], Position [2=.35mm] Quoted from thread on airgunguild.com: "So how does this work?.... Well, it speeds up the lead screw.... Using the inner 32T drive gear doubles it to start with.... The key is the two new gears, pinned together on that double keyed hub, so that they rotate at the same speed.... When you move the slider to the "IN" position, and engage it with the new 44T idler, it turns the 52T gear at the same speed.... This speeds up the input gear for the QCGB by 52 / 44, which is 1.181818 times.... then multiply by 2, and you get 2.363636 times as fast for the lead screw as in Imperial mode.... If you select the 60 TPI position in the QCGB, you end up with 60 / 2.363636 = 25.385 TPI.... almost exactly a 1 mm pitch.... When you try and cut a 1 mm pitch thread, you are actually cutting one that is 1.0006 mm pitch.... In 10 threads, the total error is only 0.0002".... ie negligible...." Google "Atlas Metric Threading Gear" to find full publication and further detailed photography. Made from ABS by additive manufacturing process. Part is bronze Oilite bushed. ABS will not dissolve with standard lubricants or become soft in a hot garage or workshop. Made by Dave from YouTube's Crafted Channel. I own many Atlas lathes on which to test my parts. I have run plastic parts including my ABS gears for over 4 years making big cuts. My lathe is powered by a 3/4 HP motor and I can stall it with big cuts never breaking any teeth. Subscribe my channel and see my many Atlas lathe projects, tips and modifications. This item is one special compound gear bronze bushed made from ABS. Nothing else included. Items in background of photo's are used as props to illustrate use and not included in the auction. Quick change gearbox chart is shown as reference for comments in description and not included. Besides, I love my Atlas 10" lathe. You ain't getting it! Look for new products from me. Your suggestions welcome.