- Joined
- May 16, 2015
- Messages
- 162
3 change gears
Rain/snow today Brrr!!and it's Monday ,perfect time to get out of the weather and do some figuring out. Sorry about the pic orientation can't seem to get it right phone and I don't always agree. About a year ago more or less I bought a 1945ish sb9b from a somewhat unscrupulous character on Craigslist. So many lessons in such a short life lol. long story short I'm missing most of the change gears. Skip to the bottom if u don't feel like reading my venting I will summarize the questions I have at the bottom. Since I've had the lathe Ive done lots of useful borings and turnings such as repairing a snapped shaft in a pruner transmission, making some bucket cylinder pins for my mini excavator, tool holders like a Morse taper# 2 for a geometric head , some knobs and a bunch of other stuff I can't think of . The geometric head I have will only go up to 5/16 but I do have a decent amount of chasers from 4 machine screw up to 5/16 but the most useful sizes for my little corner of the world are 1/4 " to 1". Now that I'm more comfortable with thelathe I want to get set up to thread with it .So the gears I have are the 2-32t tumblers driving a 24t-16t compound gear, 72t-18t compound gear, 80t gear and a 60t gear. I am missing 2-32t, 36t, 40t, 44t, 46t, 48t, 52t, 54t, and a 56t. Quick interwebs search and lo and behold there they are!! except these ones are made of 24k gold by the price of them( not that bad but $200-$250 for a near complete set of the normal change gears old but look okay ) now comes the problem: I decide to do some measuring on the gears, the spindle is 24t spline and badly worn but that's coming later. It measures 1.3"on the o.d. so (24+2)/1.3=20 diametric pitch , measure tumblers 32t yadayada 20 dp rear stud gear same then front stud gear 16t 1" od so(16+2)/1=18 diametric pitch and the remaining 60t ,72-18t, and 80t gear are all 18dp. So someone made do with what they could find maybe atlas gears or whatever. Now there aren't any gears with different diametric pitch running tooth to tooth the change happens at the stud gear 24-16t compound one half is 20dp and the other is 18 dp. So if I buy the change gear sets online which don't have the 72-18 and the 60 or 80t gears that are 18 dp on mine I'll still be stuck. Pretty sure I'm going to buy a set of the import gear cutters and probably make an arbor for them to make a whole new set of gears tumblers and all. Now I've been using the power feeds with the gears I do have and the spindle and the rest of the gears run fine even with the worn spindle spline and a broken tooth on the 72t gear(the gears I have can be set to about .0028 per rev on the longitudinal feed which is the second slowest feed for this lathe) I can take a deep enough cut to slow the chuck down with the belt running as tight as I think it should be without fear. So I need to buy a set of cutters that are 20dp with a pressure angle of 14 1/2 degrees. Does that sound correct??? Also my spindle is 1 1/2"-8 tpi. Eventually I'll have to replace that as well but want to get a threading first. And to be clear I won't be mass producing any threads but I have threaded 4-5 different things in the last month with hex and round dies but only have a few up to 1/2 " plus some power tapping on the mill that was cool!! I have the lathe and a Bridgeport with a 90 degree attachment for the head a 12" horizontal rotary table with a small chuck ( no dividing plates but the table is a 90:1 ratio so each rev of the handle is 4 degrees and the handles vernier has 80 divisions or 20 divisions per degree , kinda feel like I can get it close enough to work. I plan on holding the gear blanks in an arbor I made , I'll post more pics in a moment of the setup. So 2 questions first diametric pitch of 20 with a 14.5 degree pressure angle based on spindle being 24 tooth and 1.3 " o.d. (24+2)/1.3= 20 DP second question is 14.5 degree pressure angle correct kinda just assuming that don't know or understand how to figure that .I'll ask my setup questions in abit
Rain/snow today Brrr!!and it's Monday ,perfect time to get out of the weather and do some figuring out. Sorry about the pic orientation can't seem to get it right phone and I don't always agree. About a year ago more or less I bought a 1945ish sb9b from a somewhat unscrupulous character on Craigslist. So many lessons in such a short life lol. long story short I'm missing most of the change gears. Skip to the bottom if u don't feel like reading my venting I will summarize the questions I have at the bottom. Since I've had the lathe Ive done lots of useful borings and turnings such as repairing a snapped shaft in a pruner transmission, making some bucket cylinder pins for my mini excavator, tool holders like a Morse taper# 2 for a geometric head , some knobs and a bunch of other stuff I can't think of . The geometric head I have will only go up to 5/16 but I do have a decent amount of chasers from 4 machine screw up to 5/16 but the most useful sizes for my little corner of the world are 1/4 " to 1". Now that I'm more comfortable with thelathe I want to get set up to thread with it .So the gears I have are the 2-32t tumblers driving a 24t-16t compound gear, 72t-18t compound gear, 80t gear and a 60t gear. I am missing 2-32t, 36t, 40t, 44t, 46t, 48t, 52t, 54t, and a 56t. Quick interwebs search and lo and behold there they are!! except these ones are made of 24k gold by the price of them( not that bad but $200-$250 for a near complete set of the normal change gears old but look okay ) now comes the problem: I decide to do some measuring on the gears, the spindle is 24t spline and badly worn but that's coming later. It measures 1.3"on the o.d. so (24+2)/1.3=20 diametric pitch , measure tumblers 32t yadayada 20 dp rear stud gear same then front stud gear 16t 1" od so(16+2)/1=18 diametric pitch and the remaining 60t ,72-18t, and 80t gear are all 18dp. So someone made do with what they could find maybe atlas gears or whatever. Now there aren't any gears with different diametric pitch running tooth to tooth the change happens at the stud gear 24-16t compound one half is 20dp and the other is 18 dp. So if I buy the change gear sets online which don't have the 72-18 and the 60 or 80t gears that are 18 dp on mine I'll still be stuck. Pretty sure I'm going to buy a set of the import gear cutters and probably make an arbor for them to make a whole new set of gears tumblers and all. Now I've been using the power feeds with the gears I do have and the spindle and the rest of the gears run fine even with the worn spindle spline and a broken tooth on the 72t gear(the gears I have can be set to about .0028 per rev on the longitudinal feed which is the second slowest feed for this lathe) I can take a deep enough cut to slow the chuck down with the belt running as tight as I think it should be without fear. So I need to buy a set of cutters that are 20dp with a pressure angle of 14 1/2 degrees. Does that sound correct??? Also my spindle is 1 1/2"-8 tpi. Eventually I'll have to replace that as well but want to get a threading first. And to be clear I won't be mass producing any threads but I have threaded 4-5 different things in the last month with hex and round dies but only have a few up to 1/2 " plus some power tapping on the mill that was cool!! I have the lathe and a Bridgeport with a 90 degree attachment for the head a 12" horizontal rotary table with a small chuck ( no dividing plates but the table is a 90:1 ratio so each rev of the handle is 4 degrees and the handles vernier has 80 divisions or 20 divisions per degree , kinda feel like I can get it close enough to work. I plan on holding the gear blanks in an arbor I made , I'll post more pics in a moment of the setup. So 2 questions first diametric pitch of 20 with a 14.5 degree pressure angle based on spindle being 24 tooth and 1.3 " o.d. (24+2)/1.3= 20 DP second question is 14.5 degree pressure angle correct kinda just assuming that don't know or understand how to figure that .I'll ask my setup questions in abit