# Transposing gears, the crazy way



## RandyWilson (May 21, 2020)

We won't get into why I bought an old American lathe when I had banished all things Imperial (and Whitworth) along with all things pushrod from my stable thirty years ago. But I did, a South Bend 14 1/2 dual tumbler. The only thing in my defense is the lathe came with all of the stud gears for the metric kit, only missing the 120/127 transposing gear.  No problem? Problem.

 I had read that the lathe used an odd 14dp change gear set.  I verified that the stud gears were indeed 14dp. No one, not even Boston Gear, lists 14dp. So the hunt went on in odd spurts and starts, usually when I needed to cut a metric thread. 14DP is tough. I looked at the math of going to 127/100. It can be done, but would require a different stud gear set. So I looked into doing the 37/47.  I determined the diameter was too small for the gears to engage.  The 63/80 might work, but again, it would require making all new stud gears. In 14dp.

 Then in a different thread, we learned how to make gears in FreeCAD.  Alright, here we go. Drew up the 120/127 gears, and went searching for someone that could print them. It didn't take too long to find someone that was willing to print from my CAD files. They wanted to use their own slicer, but didn't want involved in the actual design. Hot damn. Yea HAH. So off to the design I go. I pulled the idler gear off of the lathe to measure the bushing diameter, hub depth, and all that needed stuffs.  Bore is 7/8, hub depth is 1 5/8. Going good, nothing hard here. But something doesn't look right.  Something is just... off. I take one of the 14dp stud gears and roll it around the idler. It does NOT mesh. 

 This is something I have not seen in any of my diggings, not here, not PM. The SB 13, 14.5 and 16 all use the same gearbox ratios, the came 6TPI lead screw pitch, and the same tooth count on the metric transposing set. What I have not seen anywhere is while the SB13 is 14DP as often quoted, the 14.5 is 12DP!!  You 16 owners are on your own. I would *assume* they would be the same, but....   There is a clue in the SB parts manual. The shipping weight ont he metric kit for the 13 is 73lb, the 14.5 is 121, and for some reason the 16 is only 65. 

 So my change gear set is from a SB13. And  I'm back to square one. At first I thought about making the transposing gear and the 64 tooth gearbox gear in 14dp and just switching out the entire set as needed. And I could make a 24 stud gear and a xx tooth idler so I can just leave it at DP14.  But that's not the way SB intended life to be. And I really didn't buy all this machining equipment to have someone ELSE make things for me. And I'm skeptical of plastic drive gears keyed to a shaft.  I have a DRO equipped mill. I have a lathe. I have a dividing head. I have a large rotary table. I even have aluminum blanks of approximately the correct size.  HHS 12dp gear cutter sets are available from China.com.... ought to be good enough for low speed lathe gears in aluminum. The math is simple. I have zero experience. Checkity check, we're good to go. 

Next up, teaching the dividing head a new number. I've looked around for a cheap 127 reference. Ironicly, the one odd source I found was a late MGB starter ring gear. But alas I banished those from my garage thirty years ago (see above). It's looking like I am going to end up drilling my own index plate.  Damn prime numbers.


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## silverhawk (May 21, 2020)

I am in that same boat. My dividing head uses a 4" index plate. I cannot have all 127 holes in the same circle because it won't fit. I will drill a 127 hole plate, then use that to drill another 127 hole plate, and repeat once more. It should then be accurate enough to make a gear.

Of course, you can always buy a 127 tooth gear and index based off of that. It might be easier, but not as cheap. 

joe


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## ttabbal (May 21, 2020)

Could one 3D print the first dividing plate to avoid drilling 127 holes in a throw-away plate? It would be decently accurate, so you might be able to skip the extra drilled plate. How are you getting the holes all in there? Multiple rows with an offset? Larger diameter?


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## RandyWilson (May 21, 2020)

As I see it, I have two ways.  First, I could build an arbor, adapters, supports and a lock to use a different gear, or I am sure I can borrow a MGB (127 10DP) flywheel from an old employer. This is a lot of one-off fabrication and dialing in. Or, I can start a new plate for my dividing head with the first pattern being 127. 

I have said before that normal avoids me. Everything I get near ends up being odd, rare, weird and obscure.  One morning about a year ago this ad popped up on CL for a dividing head, among other items. I talked to him and found he had bought the machine equipment from a farm auction and was reselling what he didn't want.  I knew the general area of where he was, but Google maps wouldn't show it. When I dropped a pin at the location, Google maps would only say it was "near North America" and gave me hiking instructions.  We shall say this guy was a bit back in the swamps near the Va NC line. His business was rebuilding Detroit Diesels. This dividing head was a big honking chunk of cast iron. And it didn't turn. It was a lot bigger than I was expecting. The thing is 100lbs, I was driving a little two seat convertible, and I was fresh off of abdomen surgery. I bought it or $50 as I remember, and the guy wouldn't even help me load it. I got it home, cleaned it up some, found a name. Kempsmith. Vintagemachinery even had a manual for it, dated 1916. 

 So, I have this antique 10.5" dividing head that came with only one of the two plates. The plate I have goes to 117 holes and is 7.25" in diameter. According to my measurements the thing will hold a plate with a circle up to 9.25".  Indeed, the manual says optional plates are available up to 199 holes.  So my thinking right now is to pick up a hunk of plate, cut out a circle around 8.5-9 inches, and drill the 127 pattern. This will leave me plenty of room, both in and outside the 127 circle, to add in anything needed that's not on the first plate.


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## Lo-Fi (May 21, 2020)

Does your dividing head have an auxiliary input to the plate and output from the spindle? 
Mine is an antique and has these features which allow differential dividing by gearing the spindle back to the plate. 
If so, we can figure out what gears you'd need to cut to get the gearing right (hopefully with the plates you have) to index what you actually want to end up with. I've been through the journey myself and had a great time cutting gears - mine only came with a single, lonely 30 tooth gear. 
Don't worry about slogging through charts, they're never complete. I've written a pc program that runs calcs based on what you actually have that you're welcome to use if you have that option and decide to go that route, of course. You did say "normal" avoids you  

Also, for what it's worth: 3D printing dividing plates works very well too. I've printed myself a plate with 8 different patterns on it and successfully cut gears with it. It won't last forever, but it's plenty accurate. May be a good option, even if you farm that out.


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## craptain (May 21, 2020)

Depending on the dro on your mill, it should be possible to program a 127 hole "bolt circle. Perhaps not conventional but.... 

Sent from my ONEPLUS A6013 using Tapatalk


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## benmychree (May 21, 2020)

I was faced with the same problem, but had a universal dividing head and gears, the gears are specified for 127 divisions in the B&S book on milling, titled "Practical Treatise on Milling and Milling Machines".  The gears needed to be cut, the 120 and 127 tooth were too big to cut on the dividing head without raising blocks, so I cut a smaller pitch gear to fit my antique Flather automatic gear cutter, and cut the full size coarser pitch gear on it.  I can now cut 127 tooth change gears for others if they make the blanks, and have all the cutters for all even pitches and some odd numbered pitches, and some metric module pitches as well.


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## benmychree (May 21, 2020)

craptain said:


> Depending on the dro on your mill, it should be possible to program a 127 hole "bolt circle. Perhaps not conventional but....
> 
> Sent from my ONEPLUS A6013 using Tapatalk


Likely, you would have to make a longer sector arm to reach the larger circle, and some dividing heads will not accomodate larger plates


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## RandyWilson (May 21, 2020)

I may or may not have to block up the dividing head. I need to get it up on the table and measure. It's a nominal 10 1/2" swing, the gear maths to 10.58" diameter. I most likely will have to block it with something like an 1/8" parallel. It will be that close. 

In my case, the sector arm will handle the factory 9 7/8" optional discs. The sector won't, but mine are "broken" right now anyway. 

The DRO has already been taken for a test pass at 127.  That and making sure the divider would handle the disc size was the first step.


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## silverhawk (May 21, 2020)

I think both options should work. If you can use the bolt circle function on the dro, that will make it easier. Use that to make a new index plate. 

If you can't get the dividing head onto the mill, though, that's a problem. In that case, the 127 tooth MGB flywheel will work if you can key your blank to the flywheel and lock them together. Then just lock a vertical shaft to the mill table and a way to index off of the flywheel. You would need an adapter for the flywheel-to-blank. It should work well enough. 

joe


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## brino (May 21, 2020)

Great thread, I am really enjoy it.
Thanks to all the contributors!
-brino


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## Ulma Doctor (May 21, 2020)

Maybe 47/37 tooth gears for transposition instead of 120/127?


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## RandyWilson (May 21, 2020)

I talked about the 37/47 earlier. There are two reasons I don't go that route.  First is it just isn't the way the lathe was meant to work. The other is the working diameter of a 37/47 12dp (half of each) is about 3.5". There is a sign inside my gear cover that says you must be at least 5.25" tall to ride this banjo. It won't fit. At least it won't fit without adding a second idler. 

@Lo-Fi  Somehow I missed your post. Yes, this antique has the capability to do relative indexing. But alas I only got the dividing head. No spare plates, no tailstock, no gear train support. I really think that making and setting up a 127 dividing plate will be the easiest part of this job. the DRO will handle it. The head has the capacity for such a large plate. Tedious for sure, but so will be cutting 247 teeth. I ordered a 9" x 3/8 HRS plate off ebay. For the price I couldn't drive around the few suppliers that will talk to us hobbyists, find the scrap, and then make it round.  

Right now I'm more concerned with holding things. Holding the blank. The head has a keyed 1 1/16 hole at one end, a #10 B&S taper at the other, and a 5" three jaw over the taper.  I'm thinking I will attempt to just the taper first. If that fails, choose one of the others. Holding the cutter at the needed height will also require making something. Remember "normal" would be able to use the gillion R8 arbors on ebay. Not this Cinci.

I have two dividing head apps on my phone. One you program in all the the plate counts you have. then it tells you which combinations work for your target pattern. The other you give the target pattern and the worm ratio, and it gives all results that work from 10 to 99. I'm going to ping the author and see if he can make the upper limit adjustable. 

Tonight I set up the chainfall and hoisted the head up onto the mill table.  The spindle center is exactly 5.25 above the table. I will have to shim it  I single 1/8", such as a parallel, will give me 10 3/4 swing. I need 10 9/16+. Tomorrow I will do some indicator work to check runout and parallelism.


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## Bi11Hudson (May 21, 2020)

For what it's worth ~~~ Just to throw my two cents in. I normally use a Craftsman 12X36 but have a Grizzly G1550-9X19 as a back-up machine. The Griz has Modulus 1 gears(25.4 DP), the Craftsman has 16 DP. The few gears I make for the Craftsman are both with the indexing head *and* the spin indexer. 

I have the spin indexer modified to accept the metric gears from the Griz. Including the 127 tooth metric transposing gear. I don't have any plans, just cobbled something together to take the metric sized gears. I haven't made a 127 yet. I haven't found a piece of aluminium big enough as scrap. I'm allergic to sales reciepts. . . It will requite riser blocks, no big deal. When I need 'em, I'll make 'em.

The key being the Grizzly 127 tooth gear and the spin indexer. Cheating??? Well, yeah. What the hey?

.


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## silverhawk (May 22, 2020)

silverhawk said:


> I think both options should work. If you can use the bolt circle function on the dro, that will make it easier. Use that to make a new index plate.
> 
> If you can't get the dividing head onto the mill, though, that's a problem. In that case, the 127 tooth MGB flywheel will work if you can key your blank to the flywheel and lock them together. Then just lock a vertical shaft to the mill table and a way to index off of the flywheel. You would need an adapter for the flywheel-to-blank. It should work well enough.
> 
> joe


Just to revisit the thought of direct drive using a gear to index, if you are using a vertical mill, you probably can't arrange it vertically. You would need to possibly arrange the gear hanging off the side of the table, keyed to a shaft with the blank and run it horizontally. 

joe


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## RandyWilson (May 23, 2020)

I gained a few experience points today.  The first time using the taper attachment. And the first time cutting 4142 in earnest.






 Last to first. Top is the gear cutter arbor. Right side is turned to 1", as it's a convenient size for the Cinci mill and the largest 5C collet I have for the lathe.The cutter end is cut down to 22.1mm and a random depth. It will be finished off when the Chicom cutters arrive. I was finally getting the hang of cutting the 4142, speeds and feeds.  .010 made birds nests. .020 made very long stiff tight spirals.... maybe .200 diameter by 3-4 feet long. Still more controllable than the birds nesting. .025 started making decent chips. And .030 was more than the 5C collet could hold against.... shoved the work right back into the headstock, it did.

 Middle is the dividing head arbor to hold the gear blanks. Right side is cut to a B&S #10 and drilled and tapped for a draw bar. This was the first time using the taper attachment, and at a really odd setting. 1.232 degrees / 0.5161 in/ft.  The taper blued up... okay first try. The left end is cut to 7/8" by .950 with a 3/16 keyway. It's done. I cut the taper on the lather, and roughed in the gear end. Then I installed it in the dividing head, and spun it against an endmill to finish. It took a few tries to get it to cut square. The divisions on the Dividing head are about a 1/4 degree off, it seems. We'll see how well it's trammed in when there is a 10" gear blank  chucked up.

Next up will be one little arbor to hold the gear blanks in the lathe for initial sizing and truing. Then it's wait until they frisbee in my 9" steel plate so I can drill a few dozen holes...


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## RandyWilson (Jun 4, 2020)

My frisbee arrived. I learned something, again. A36 is not the most friendly stuff to machine. Stringy, gummy, with chunks of glass tossed in. I eventually got it cut down to size and trued up.  then I proceeded to drill the 127 hole pattern.  And I learned something there, too. When you instruction this DRO to put 127 holes on a 360 circle, it does exactly that. Hole #1 at 0 degrees, hole #127 at 360 degrees.  Grumble.

 So I redrilled the 127, then moved my clamping so I could drill a few patterns on the inner part, and also to final bore the center to 1.750. I need 42 holes, which is on plate 2 for my dividing head, I don't have plate 2. So I started drilling the circles until I was getting close to my clamps and blocks again. 38, 42, 47, and 49. 





Final score, Harbor Freight 1/8" drill bit, 429, plate 0. I bought a 5 pack, and am shocked that the first bit is still going strong after all of that.


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## RandyWilson (Jun 6, 2020)

And mounted with arbor installed. The dividing head is ready. That's a 9" OD plate, and I have room for bigger still.





 I hit it with a scotchbrite scruffy, looks like I used 10 grit in the pic.


The cutters aren't here yet, of course. But there is still lots to do. Next up is one of two projects.  I've been pondering how to cut the 3/16 keyways in the stud gears. I had resigned to cutting a start with a 3/16 end mill and then hand-filing square. But I had vague memories of a keyway broach coming in a lot of used endmills I bought at auction a year or two ago. What are the odds it's 3/16? Turns out, 100%. And it's brand friggin new.  So I need to make a 7/8" guide bush for the broach.  And ponder what material to use. I have aluminum bar, which might be good enough since I'm cutting aluminum. I also have more of the 4142, but.... whine.

 The other objective is to cut the blanks to size.  I mis-mathed above. I gave pitch diameter rather than OD. OD is 10.75.  So I need to turn these roughly 14.5" to 11" and 10.5  for the 127 and 120, then bring them to final size in the lathe.   I made an arbor to hold them that fits the biggest collet the lathe has, a 1" 5C. I've tried a wood bandsaw. A jigsaw. A cutoff saw. None showed much progress, and most didn't have enough control. I'm trying not to waste stock as I will be needing a 3.5" piece for the 40 tooth stud gear later on. Yes, I could just chuck them up in the lathe and chip-ize 160 cubic inches of aluminum.  But that would be too easy. An wasteful. And I'd have to buy more stock to make the 40 and 28.

 So then I look at that old rotary table. It's a 12" table, and I"m working with 14.5" blanks. And I want to offset the cut. So no. But... wait. What size taper is the center hole? It's full of crud and goo. A bit of clean up, and I find it's not tapered. It's 1". Exactly 1.000 inch. My lathe arbor from above is a light press into it. Bingo.  Hold it on the table with that arbor, get some jacks under the perimeter (may have to make some short enough) And then just play merry-go-round. Uggh.  How many passes, 2? 3? 5? 90:1 worm in the table. Add fabricating a way to drive the table crank with my drill to the list.


 But first, I need to clean up all the swarf from that hideous A36.


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## RandyWilson (Jun 7, 2020)

Today I cleaned up.


Then made an even bigger mess.  OMG


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## RandyWilson (Jun 12, 2020)

The two big blanks are cut. I still have to do the two little ones. 


 But the cutters arrived!!!


 Question. How much TIR is acceptable? Right now, on 6 inches of arbor stickout, I have .002.  Part of me is panicked, the other part is Meh, it's likely the least of my precision issues.


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## Lo-Fi (Jun 12, 2020)

I cut some pretty good gears with a spindle that was running out 15 thou. I was assuming (wrongly) the cutters were at fault when it was actually my mill needed fixing... Don't worry about it! The form cutters only cut an approximate tooth profile in an ideal world anyway.


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## RandyWilson (Jun 13, 2020)

Thanks. Yeah, logic dictates that the .002 is nothing compared to the deflection that's going to happen in the arbor, the unsupported gear mandrel (no tailstock) and the 10" diameter gear blank itself.  The gears will be low speed. 800 RPM lathe, and threading will be a lot less than that.


 Onward, trusty steed!! We have chips to make!


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## RandyWilson (Jun 16, 2020)

First gear. Well second. I had a failed blank... I tried to get 3.5 diameter out of a 3.42 piece, that I used for a practice run. Good thing too. It seems I have trained myself to the pattern of unlock axis, move axis, relock axis as a single two-handed process. But here a I need disengage power feed, crank table back 2 inches, move dividing head to the next index, engage power feed. Several times I followed the unlock-move-lock pattern with the table feed. Then tried to re-index only to discover the table moving. So now it's disengage power feed, stick right hand in pocket, crank table with left hand....







It is amazing how light scratches look like gouges in the pictures.  Those are file marks from knocking off the burr from the keyway broaching.


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## RandyWilson (Jun 21, 2020)

And..... we're done. *








The four gears I need to cut the metric threads I'll actually use are made. The final was the 127






I needed to cut a tooth every 40th hole around the 127 hole plate, for 42 laps around the dial. Since my sectors aren't big enough for the circle, and I didn't feel like counting off forty 127 times, I counted off and marked 40 three times. Then I made 3 piece of mechanics wire that spanned 39 holes. Thus you had 39 spaces for a wire, an empty hole for the index pin, another 39 wire, another empty hole, another 39 wire, another empty hole. And from there it should be 7 holes back to the start point.





I developed a pattern where I would advance the sector to the next hole and start the cut. While the cut was progressing, I would move the just-left wire to the front, leaving the empty hole and then making sure there were eight empties (one plus 7) between it and the currently trailing wire. Thus I always had a wire either side of the sector pin, and moved the wire so that next point was surrounded, if that makes sense. That way I had double references in case a wire got bumped out of place.

 Next up is to figure out how to pin the double idler together and bore and install a bush.


* I'm thinking about remaking the 120 tooth.  I had the mandrel drawbar lightly nipped down, which worked just fine for the smaller gears. But the larger 120 tooth put up enough cutter vibration that it worked loose. It took me a bit to realize why I had picked up more vibration / wobble in the blank... a few teeth are a bit wonky.  I did remake the drawbar as a stud and nylock nut before doing the 127.


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## silverhawk (Jun 21, 2020)

It looks fabulous. Now you get to try it out. Why the two smaller gears?

joe


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## RandyWilson (Jun 22, 2020)

The stock Southbend set includes something like 8 stud gears to be able to do all known plus a few theorized metric pitches. 26, 28, 32.....46. This is on top of the stock 24 and 48.  The 120/127 with the stock 24 stud converts the 8TPI setting to the metric 3.0.  From that you can reach 1.50, 0.75 easily with the first tumbler, and 6.0 with the 48 stud. I need to be able to do 0.80, 1.00, 1.25, 1.50, 1.75, and 2.75. I did a chart of all the combinations of stud gear and tumbler settings, and found I could get to everything I need with those two added gears. I don't have the charts in front of me. As I remember, everything I wanted except one could be done with one gear in addition to the stock 24. The other gear is only to do 1.75.


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## RandyWilson (Jun 22, 2020)

Okay, at home with the notes. The nice thing about this lathe setup with the 120/127 is the math is really really easy. Number of teeth on the stud gear  divided by the indicated TPI on the gearbox gives the metric pitch.  While Southbends charts only use positions 1 and 3 on the right tumbler, there are many ways to get to most pitches.  The 40 tooth is to do 1.25 (40 / 32tpi). The 28 tooth is to do 1.75  (28 / 16 tpi)  1.0, 1.5 etc can be reached with several gears. 0.8 I figure I can do with a die. And that covers pretty everything you'll see in automotive apps.


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## RandyWilson (Jul 5, 2020)

When you take the most obstinately prime number, and marry it to an extremely anti-prime number, being divisible by 2,3,4,and 5, you get this hybrid








Together they go out to bridge the communication gap[s and attempt to unify the engineering world








And everyone lived happily ever after.



 (yeah right)


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## bac1972 (Jul 14, 2020)

In case anyone was curious....this is a factory dual tumbler set for a 16” SB . It also has a specific banjo that goes along with the kit.


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## RandyWilson (Jul 14, 2020)

Yes, thanks for that. That's the first picture I've seen of the big lathe version.  It verifies what I suspected SB had done with the banjo. I"m still considering two different paths to get more stability on the banjo. And the 64 tooth.


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## bac1972 (Jul 16, 2020)

If memory serves me well, the 13” and 16” South Bend standard end gears are 14dp. The factory  transposing gears, including the set I have are 16dp. I believe that the quick change gearbox gears are all 12dp. At least they are on my spare 16” gear box that I have access to. I’d have to assume the 14.5 is similar. It shares some same parts as the 16.

The factory South Bend transposing set, in my opinion, is one of the neatest ways to get the metric pitches easily. I really admire what you have done with your time and skills!!

If you need a factory SB metric chart, Grizzly still has them available. I can look at the part # on mine if you want one in the future.


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## RandyWilson (Jul 16, 2020)

Thanks, I'm good on the chart. The math is easy and I have a limited range of needs; Automotive. No heavy equipment, no watchmaking. The math is number of teeth on the stud gear divided by the indicated thread pitch on the gearbox gives the metric thread pitch. Many pitches can be achieved by several combinations. The South Bend chart sticks to tumblers 1 and 3.  I can get to some of the needed ones other ways and reduce the number of stud gears on hand.


 The internet wisdom is that you remove the 64 gearbox gear, put a spacer on and reinstall the 64 to mesh with the outer 120 tooth idler. I noted a problem with this on my gearbox. The input shaft only has a keyway in the inner position. The outer gear is un-keyed. I see from your picture that they supplied a 64 tooth with an extended boss such that you just flip it over. 
 I first thought about  keying, either with a dowel or a real key, the outer section of the gearbox shaft. But the potential for screwup dong it in-situ is extremely high, and I really don't want to strip the gearbox to do it in the mill. So  I'm going to make a keyed hub and pin/bolt it to the existing 64 tooth.  Or I may just make a new 64 and leave the original undisturbed.


  Again, the internet wisdom was you just reposition the banjo to hold the bigger gear. This banjo  is held by the bolt in a cross-slot at the top with limited range, and a grub screw at the gearbox boss end.  If I had looked at it in the beginning it would have been obvious that the slot wasn't long enough (this I suspected) and would be inaccessible, totally covered by the 127 gear (didn't think of that). Right now it's being held by the grub screw only. But that is not a long term solution. I'm either going to extend the banjo and make a new slotted support point, or if the proper sized stock presents itself, duplicate the split clamp  like in the picture.

 And one more thing I see. There must be a longer banjo bolt and bushing not pictured. That 120 gear isn't hollowed out to match the original bolt/bushing length like I had to do.  That would supply better support for the gear. But I'm not terribly worried about it. The only time there will be a cantilevered load from using the outer 120 gear would be low load low speed thread cutting.  



 But in the mean time, off to the next project. The wife needs a die to cut foam pads. Seems the embroidery machine supplier wants $6 (+S/H) each for a 70mm x 12mm circular foam pad... and there's 15 of them. So I get to whittle up some more 4140. But first, I'll need to make a tool post grinder......


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## bac1972 (Jul 16, 2020)

It uses the same banjo bolt/spacer. The only thing I saw that stood out was the gears are of different thickness.  I almost purchased a newer lathe because of metric capability but learned of the metric conversion kits. There’s not a lot of information about the metric kits for the larger ones but I just enjoy the simplicity of the older machines.


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## RandyWilson (Jul 17, 2020)

Interesting.  That is the same thickness as the 14DP stud gears that came with my lathe.  Is that a gear from a 14.5 / 16? Or a 13?


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## bac1972 (Jul 17, 2020)

RandyWilson said:


> Interesting.  That is the same thickness as the 14DP stud gears that came with my lathe.  Is that a gear from a 14.5 / 16? Or a 13?



It’s the 120/127 for a 16”


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## RandyWilson (Jul 17, 2020)

If you tell me those gears are 14DP, I'm a-gonna scream. Is the 120 gear a shade under 9", or a shade over 10"? In other words, did the metric conversion kit change the entire geartrain from 12DP to 14DP?


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## bac1972 (Jul 17, 2020)

RandyWilson said:


> If you tell me those gears are 14DP, I'm a-gonna scream. Is the 120 gear a shade under 9", or a shade over 10"? In other words, did the metric conversion kit change the entire geartrain from 12DP to 14DP?



I did the measurements and math. Yes 12dp standard with the metric set being 14dp. I learned something! 120T=8.71” 127T=9.2

The internet information led me to believe that (on larger SBL) the only 12dp gears were the quick change gearbox gears. On the 13”, I have seen more than one thread discussing how they go from 14dp standard to 16dp for metric. I assumed my 16” was the same. 

I’m sure South Bend did this so the gears would fit in and under the factory housing!


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## RandyWilson (Jul 17, 2020)

Sob... whine!!!!



Guess I have a very unique set of 12DP transposing gears.


Although.... I do now have the arbors and dividing head plates... and the 14DP #2 cutter. Just need some blanks to make a SECOND set. And the #3 (??) cutter to make the 64 tooth.


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## RandyWilson (Jul 17, 2020)

BTW, the 12DP set does fit under the cover. It just touches in one spot when swinging open,  so don't open the cover while running.


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## silverhawk (Jul 17, 2020)

RandyWilson said:


> BTW, the 12DP set does fit under the cover. It just touches in one spot when swinging open,  so don't open the cover while running.



My SB Junior also touches when swinging the cover open.  I expect it is a misalignment on the cover, but I don't think it's caused a headache (yet).


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## RandyWilson (Sep 20, 2021)

Just to follow up, a year later. A few months after making these gears, I purchased a 3D printer. I finally got around to designing and printing a 64 tooth driven gear with the extended boss like the factory set, except in my 12DP, last winter  I also carved a new split-clamp style banjo from a 2x4 chunk of aluminum bar this past spring. So now the system is complete. And stable.  And for all of the promises that these were just for metric threading, the aluminum transposing gears and the plastic (PLA at that) driven gear have been in continuous service since day one.


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## Grendel (Sep 21, 2021)

having got a 3d printer, i just print new dividing head index plates all the time, they dont need to be that strong, just register on the holes. I managed to purchase a van norman dividing head, it was listed as a 4 1/2 ", unbeknown to me that was the centre height, it came with an 8" chuck, and was bigger than my milling machine, but i have hopes that if needed it will work on my SB 13"


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## MrWhoopee (Oct 28, 2021)

I can't believe I just read this entire thread, and with interest no less. I may need professional help. Thanks Randy, it was quite a journey. Better you than me.


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## mattthemuppet2 (Oct 28, 2021)

I'm in the same boat, very inspiring!


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