Divider head question.

jarhead jim · Feb 5, 2021

Making my first spur gear on an ancient Putnam #2 horizontal mill. Trying to make a 52 tooth 12DP gear but none of the numbers on the 3 different plates will compute. The numbers are as follows...16, 18, 24 28 30 34 37 38 39 41 42 43 46 47 49 54 58 62 and 67.... What do I do?

jariou · Feb 5, 2021

39

Sent from my SM-G986U using Tapatalk

jariou · Feb 5, 2021

Let me elaborate a bit.

You need to figure out how many turns of the crank to get a full turn of the spindle. It is possibly 40, but it might be something else, like 60.

Let's assume it is 40. If you have a 39 holes indexing plate, it means that 40 x 39 holes will cover a full circumference. Divide that by 52, and you get 30. So you mill a tooth and move the crank 30 holes. Repeat.

Good luck

Jacques

Sent from my SM-G986U using Tapatalk

John Garner · Feb 5, 2021

If I remember correctly, and your dividing head has a 40:1 wormgear ratio, you would need to turn the worm handle 40/52 turn for each tooth of the gear you're cutting. The fraction 40/52 = 20/26 = 10/13. None of your indexing plates has a 52 hole pattern, a 26 hole pattern, or a 13 hole pattern, but it DOES have a pattern having an integral multiple of 13, as 3 x 13 = 39.

Since 10/13 x 3/3 = 30/39, you should be able to cut your 52 tooth gear by advancing the worm 30 holes on the 39 hole circle for each tooth.

jarhead jim · Feb 5, 2021

Thanks fellas. I re read both of your posts and have NO FRIGGIN idea how you came up with 39. I’ll post the results.

Phil in Montana · Feb 5, 2021

Count holes not turns...Phil

jariou · Feb 5, 2021

You were looking for 52 = 4 × 13

The 4 comes for free because of the nature if the indexing head.

Looking for 13, we found 39 = 3 x 13

Play with your indexing head a little, it will become obvious quickly.

Jacques

Sent from my SM-G986U using Tapatalk

johnoder · Feb 5, 2021

You could look in Machinery's Handbook in the Milling Machine Indexing section - it agrees with 30 / 39 - for 52 teeth

HuFlungDung · Feb 5, 2021

Phil in Montana said:
Count holes not turns...Phil

Count spaces not holes

John Garner · Feb 5, 2021

Or to make the same point a third way, the indexing pin is in hole zero when you start counting.

jarhead jim · Feb 6, 2021

This was the result. What did I do wrong?

jarhead jim · Feb 6, 2021

whoops, wrong picture.

jarhead jim · Feb 6, 2021

In the first picture I used the 39 hole and advanced 30 each time. At 90, 180, 270 and 360 I ended up in the 39 hole so the indexing was spot on. The only thing I screwed up on was the diameter of the blank. It was supposed to be 4.500 and I turned it down a smidge more to 4.490. Would that be enough to screw up the whole setup?

johnoder · Feb 6, 2021

Makes it tough to have two threads on the same thing

Divider head question.

have fun

TGTool · Feb 6, 2021

jarhead jim said:
In the first picture I used the 39 hole and advanced 30 each time. At 90, 180, 270 and 360 I ended up in the 39 hole so the indexing was spot on. The only thing I screwed up on was the diameter of the blank. It was supposed to be 4.500 and I turned it down a smidge more to 4.490. Would that be enough to screw up the whole setup?

The diameter change has no effect. You're dividing a full circle into equal parts, or at least that was supposed to happen. If you had divided the circumference as a linear measurement, then changed the diameter, you'd see an error.

A best guess would be bumping the sector arms somewhere so it altered the divisions. You might look carefully around to see if there's also a tooth that's too narrow. Another possibility if the indexing holes checked out by returning to zero, is that the blank slipped on the mandrel at some point.

elwinbender · Feb 6, 2021

I am considering adding a microscope to my home shop and was wondering what would be recommended for mounting on a lathe for machining very small parts and setups on a tool grinder and inspecting tooling for wear. I know there are a ton of different types for all different uses. I'm thinking something compact enough to mount on an indicator base and easy to move around with a screen large enough to easily see what's going on with possibly some measuring capabilities. Maybe capable of plugging into a tablet to use as a screen.

Sent from my SM-T510 using Tapatalk

eKretz · Feb 6, 2021

What the literal f. :toetap:

jarhead jim · Feb 6, 2021

Tried again and still f’d up!!!!!

Assuming my math is correct..... Was very careful to make sure I was indexing and hitting every 30th hole. This is starting to piss me off...... The gear was spot welded to the shaft so I know it didn’t slip. The divider head is in perfect working order. Used the #39 hole to start with..... Cut out a round piece of 1” thick steel plate, turned down and bored in the lathe to exactly 4.500 OD like the math said to do..... This is pissing me off almost as much as the election! Does anyone know what the f—— I’m doing wrong!?!?!?!?

Red James · Feb 6, 2021

Your PICTURE in post # 11 shows a 38 hole pattern. Use a plate with 39 holes.

johnoder · Feb 6, 2021

jarhead jim said:
View attachment 312919 This was the result. What did I do wrong?

Like the man said - its stamped 38

I made it a bit easier to see

Divider head question.

Aluminum

Cast Iron

Cast Iron

Titanium

Aluminum

Stainless

Cast Iron

Diamond

Diamond

Titanium

Aluminum

Aluminum

Aluminum

Diamond

Titanium

Plastic

Diamond; Mod Squad

Aluminum

Stainless

Diamond

Similar threads