[How-To] Rank beginner question on cutting gears

BS-0 came in from PM. Undamaged. The packaging was better, although the factory box seemed identical. This BS-0 seems for the most part, a lot nicer than the other one. It had a couple more accessories. The internal packaging was significantly better and fit the box and parts well. The manual was a little printed booklet, rather than over-xeroxed pages. Made a much more favorable impression. It felt like a first run set of parts, rather than the reject grade unit I first received. Oh, it turns 10 x smoother, and has hardly any backlash out of the box. That makes me happy. :) Still a couple of things that need some cleaning up, but much higher quality than the original eBay reject. If I touch the degree marks, they are rough, but at least they don't cut me, like the last one did. Although it probably would benefit from a teardown, it works well enough that I have no good reason to do so. For now, it will stay intact. Have a couple of questions.

Are there any surfaces that one can indicate on? How do I know it's even level? I'm not trusting the marker on the side. Right now, 0 degrees doesn't line up with the line. This unit has a 5" 3 jaw chuck and a MT2 dead center. I'm guessing that the 3J doesn't have the lowest TIR. For indicating would one use a spindle mounted "Indicol" holder? Are the $15 eBay ones ok, or do I need to pony up for the real Indicol holder? How does the Indicol attach to a DTI?

The C-clip that is used to hold on the indexers, looks like it was designed to lacerate unsuspecting fingers. On mine, the tips point up, also the tab at the back isn't bent correctly and has really sharp edges. Can one bend these clips much, or is it better to try to find a new one? For instance, the back tab is bent maybe 10 degrees and should be closer to 90 degrees. Also the clip is putting a lot of tension on the indexers, so they are very hard to move. (When the indexers are locked to each other) Would stoning the top and bottom surfaces of the indexers to help this? The indexers seem to be cast and have a somewhat rough surface.

On my dividing head, the chuck was attached to the backing plate with SHCS. Of course there's no way to remove the chuck from the plate without spinning off the backing plate. There's no access to the socket heads. On the eBay BS-0 they used hex head bolts. When I first saw the new BS-0, I thought, why would one make a design like that? It was simple to open up the jaws off the chuck a little and tapped with with a brass hammer and spun it off. I've left the chuck attached to the plate for now.

Should the TIR of the chuck assembly be poor, what are the options? Not really sure how one would shim a 3J. I see one can get a MT2/ER32 collet. I have an ER32 set for my lathe, so I could commandeer them. I tried fitting a MT2 dead center and it seemed to fit well. Apparently that is almost the same as B&S-#7? The dead center that I received from the BS-0 has some burrs on the machined taper, how do you fix them? Fine diamond hone? How do you do it without damaging it?

There's a plate with a hole and two slots in it. Is this to engage a lathe dog? I don't understand why they supplied so many bolts for it, there were 5 with my kit. One to attach to the dead center, one to capture the dog leg, what are the other ones for?

Apparently there are some keys supplied for the head and tailstock, but they don't fit my table. They are 16mm wide and the table has 12mm slots. And the counterbore is 10.6mm. Seems like the keys would be a pain, as the units would never sit flat off the table. For a hobbyist, do the keys help?

Eventually want to make some gears for my mini-lathe. But before I do that, are there some sort of beginner's exercises that make sense? I'm really starting from the beginning here, so if you know of a few things to try first to build gear cutting skills, please let me know.
 
Indicol Holder: I have a cheap one, not worth it's cheap price! The plastic washers allow it to slip slide around. Been meaning to replace them with something better, what? I don't think scroll chucks are ever dead on if you move anything. You will have to re-center the cuck after mounting the work. You need to center the rotation of the table first. How to tell if it is level? Use an indicator on the rotating table before mounting the chuck or if the chuck is good, on the face of the chuck. That doesn't mean the jaws are holding the work vertically! For that indicate a round rod near the bottom, then near the top while rotating the table. If there is no wiggle on the indicator it is running pretty true vertically.

I have a Vertex 8" rotary table, so different from what you have but this may apply. The bottom of the table has two slots with bolt holes in them. I machined two keys with one side fitting the table slot and the other fitting the T slots on my mill table. Very close fits. So each time I mount the table it is oriented true to the X travel. Allows the RT to be removed and replaced and the scales to remain the same in rotation relative to the X travel of the table. My RT seems decently made. I can adjust the backlash to near zero but it doesn't matter much since you always approach a settings from the same direction and always lock the table rotation before cutting.

Are you using expanding mandrels or making tapered ones for each job?
For practice use some plastic to make some change gears. Allows you to test results and they may even be at least a good as what some mini lathes come with. I made a couple of aluminum change gears as tests and put them on my 1440 lathe that has 3 hp and they have been running fine for nearly 2 years. Still have the steel ones. I think S. Bend lathes used zinc alloy change gears.

BTW your experience in buying from eBay or PM shows what a minor difference in cost makes in the PIA factor.
 
@Larry$ thanks for the cheapo indicol review. Was wondering about them. Hope to find something more than $15, but less than $125 that isn't junk. I'd rather spend less, than more, but don't want to be stuck with poorly made junk.

You have touched upon what I was wondering about the initial setup. I need to make a checklist to make sure I don't miss anything - so I end up with something exactly perpendicular to the mill spindle. In the beginning it's real easy to think you got it setup right, when it isn't.

I'm laughing, at your question, what am I using? Nothing, I've never done this, ever. So I'll probably have to make some mandrels, or buy them. At least I know what a mandrel is - 6 months ago, I didn't. At the moment, I want to cut a gear, it doesn't matter what it is. Then make another, and have it mesh. As for materials, I'll start with something cheap, as I'm pretty sure the first gears won't be HM worthy. Haven't seen much plastic that is cheap and machinable, at least compared to metal. If you know of a cheap source of machinable plastic disks that would be good. Otherwise, maybe I'll practice on some 1" rod 6061 turned down to the right diameter for a mod 1 gear. Beats me how many teeth that is - I'll have to go calculate it.

If I'm going through the effort to cut a gear, it might as well be metal. Not saying that as a I hate plastic statement, but more of a "the task is mostly labor", why not make it out of some more robust material.

I didn't want to believe there would be a big difference between buying between eBay and PM, (for the same item) but at least in this case, the difference was pretty stark. If things go wrong, eBay will eventually come through, but you are right, it was a total PIA and the turnaround time took longer than it should have. With PM, I just put in the order. When nothing happened for a few days I sent an email. PM answered quickly and the minor issue was fixed immediately. Got the dividing head a few days later. The PM BS-0 I got was clearly set up better, it turned very freely, but tight. The BS-0 had PM's name plate attached, and the standards do seem higher. I do not regret getting this dividing head from PM one bit.
 
WobblyHand said:
Haven't seen much plastic that is cheap and machinable, at least compared to metal. If you know of a cheap source of machinable plastic disks that would be good.
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Dollar store or even yard sale cutting boards are one source of plastic.
Good for practice and even low-speed bearings.
Cut out discs with a hole saw, or even band-saw then mount and turn the OD.
-brino
 
Very early in this thread I asked about holding the gear blanks. It was suggested I turn between centers using a nut mandrel. I think I understand that, but when faced with the actual hardware I have, I'm failing to imagine how the lathe dog is turned (securely) by the dividing head. The lathe dogs that I have just have a bar sticking out radially. The divider head has an adapter with u slots that attaches to the dead center. The missing link is the piece that drives the lathe dog. What does this piece look like? I'd imagine it would be different for gear making than just using a lathe. For a lathe all you need is a pin. For gear making doesn't one need to prevent the blank from rotating (relative to the pin)? How is that done?

Some googling showed a couple of pictures, enough to cobble something together. Still not sure what such a device is called. I'm envisioning a rectangular piece of stock with a hole in it to accept the lathe dog post. Then maybe a slit and a bolt to snug it. The other end would go in the u-slot piece. Lot's of fixturing, just to get started. Need to make this gizmo, the nut mandrel and the gear cutter arbor. That will keep me busy a bit.
 
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Sounds like an H-shaped dog to me. I made my gear without a dog. I used a mandrel.
 
WobblyHand said:
For gear making doesn't one need to prevent the blank from rotating (relative to the pin)? How is that done?
Click to expand...

Metal Planer Restoration 44: Cutting Gear Teeth, Keith Rucker @ about 8 minutes. ​

This shows how I've seen it done. The mandrel is driven by a chuck, either a jaw type or collet. Could also use a face plate or jaw chuck & dog clamped (trapped) to prevent movement. Holding the mandrel between centers would be preferable to holding it with a (3 jaw) chuck.
 
Sort of stuck on the dog problem... Think I have a way out of it. Getting kind of weird, have to make tooling for the tooling so I can hold the work so I can make a gear. Here's what I'm thinking of: milling machine driving dog. It's more complicated than necessary right now, but it is slightly tolerant of alignment. I think making it is within my capabilities.

This isn't as easy as the videos make it look like! They have all this tooling in place, me, I don't even know what I don't know! (Like I needed to make a holder for the driver to the holder of the mandrel (that I needed to make) to cut a gear.) Can't even express that correctly. I need to make a mandrel for the gear blank, a gizmo to attach to both the dividing head driver and the dog, and the offset dog itself, before even getting to the gear. The videos don't show any of that... Building your own infrastructure seems to be the dues one needs to pay. So I'm in, but this is going to take longer than I naively expected. Rank beginner indeed.
 
WobblyHand said:
What does one look out for in a dividing head? Is the smallest one available a BS0? Can one fit an ER32 chuck to it? Or is a 4 Jaw better? TOT shows an adjustable pair of arms that help one index the number of holes, is that a standard thing?
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As with any machine tool, there are a number of points to keep an eye out for. As you discovered with an eBay unknown vs Precision Matthews. There are better but WAAYYY outside the hobbyist budget confines.

There are many smaller dividing heads, actually small 90:1 rotary tables fitted with fraction plates. That's what I use for my model building, in 1:87 scale. For doing gears and splines, I use a B&S-0. I dedicated one 4" table to dividing and mounted a 3 jaw chuck from a mini-lathe with semi-permanant clamps. Centering it to the rotation was a bear, but finally got it right.

The big advantage there is that my lathe(s) have a threaded spindle, 1-1/2X8. As does my BS-0 dividing head. (Grizzly, I think) Work is taken from the lathe to the dividing head by moving the chuck with the work. That reduces a source of error. Not all of them but a major one.

On dogs, the dividing head requires a little "tighter" control than on a lathe. If I'm thinking right, the dividing head should have included an "H" shaped dog drive device. There will be setscrews in each leg of the "H" to lock out backlash. Using home made dogs on occasion, it sometimes is necessary to "get creative" with tooling. If the setscrews aren't there, drilling and tapping is just a few minutes work.

Just as a reminder, your mini-lathe probably has M1 gears. Modulus 1. . . The 127 tooth is a prime number, not available on any straight indexing heads. I use a spin indexer with my mini-lathe gear keyed as a stepper. That's how I made a 16 DP gear for the Atlas / Craftsman 12 inch machine. Out of cheap plastic. . . If it were used more often, I would use a dime store cutting board. But change gears don't see a lot of load, they are only for indexing with threading.

Just my comments on what looks like a beginners job. You'll find the rabbit hole has a side passage for making gears. Once you're hooked. . .

.
 
@Bi11Hudson my BS-0 has the same 1-1/2x8 thread. My mini-lathe does not has a threaded spindle. Currently in the figuring out the "home made dog" mode, as well as the make my own mandrels, etc.

I've purchased the M1 gear cutters. I have to re-read the threads here on HM on doing the calculations. The booklet that came with the dividing head is less than clear. I've seen it spelled out before and it didn't seem too hard. I like to be able to calculate the values rather than using a table. The formulas are rarely wrong, the tables are known to have some issues.

The cheap cutting boards I have in the house aren't worthy of spending time on. Too flexible, too thin. I'll have to look around for other candidates.

I'm already hooked on the capabilities that having just a few machines can bring. Just a little bit taken aback by the amount of auxiliary stuff that's often needed. When I make some of that tooling it will get a little easier. After I can do this, the next project will be slightly easier, not because of making a simple gear, but more of retraining myself to think about mechanical problem solving more efficiently. More practice will make it easier. Only have another 9850 hours to go before I'm almost good at it...
 
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