Looking for the Barber Colman gear ratio book

# Thread: Looking for the Barber Colman gear ratio book

1. Cast Iron
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## Looking for the Barber Colman gear ratio book

I am trying to locate and borrow the Barber Colman book of 95,000 4 gear ratios. This book is over 500 pages of gear ratios to set up there gear hobbers. Let me know if you have one to borrow or even sell. I would like to buy it or make a duplication of it. I will make sure you get it back undamaged. I am learning gear hobbing using the BC #3 and this info would help me out. I know there are computer programs out there but I would like to learn the long hand calculation. I have talked to Terry at RPI and he only has one.

Thanks,Cory

2. Diamond
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How many gears do you physically own?

Get a TI 30X calculator for about \$10 and punch in the numbers, it will do it all in fractions.

The part that YOU need to do is decide what problem you are trying to solve that day.
Once you lay it out, lay it out as fractions and see if you have gears to match.

A book of 95,000 gear ratios that you don't have anyway won't do much to solve our problem.

What you really need is to start with what ratio you need for That gear, and see which gears that you own to achieve that ratio.

3. Cast Iron
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Ok I spoke to Terry at RPI and he explained how to find the gear ratio for spur gears. He also said you will need that book or a book like it or a computer program to help figure HELICAL gears. I am trying to cut HELICAL gears and having trouble with the whole fraction deal and using a calculator to figure my change gears. I shopped for a new calculator and found nothing that would change a decimal to a fraction.

Please explain in writing or a picture of how you get your answer on how to set up a #3 gear hobber to cut this gear:

20dp
50 teeth
45 deg helix
.040 feed rate

Thanks,Cory

4. Diamond
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I shopped for a new calculator and found nothing that would change a decimal to a fraction.

I am gettintg Sofa King tired of typing --> TI 30X
"What we have is a failure to communicate"
"Some people you just cannot reach"

Please explain in writing or a picture of how you get your answer on how to set up a #3 gear hobber to cut this gear:

20dp
50 teeth
45 deg helix
.040 feed rate

Once YOU describe the problem... YOU will have the answer.
You need to drive the Hob and the blank and the advance.....

Type out the operating manual for the hobber, that describes the ratios that you need, since I don't have the manual, but you do.

5. Hot Rolled
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Originally Posted by 3t3d
I shopped for a new calculator and found nothing that would change a decimal to a fraction.
My HP 35s will do it on the fly. Decimal to Fraction and back again

6. The old Sharp calculators were really nice, but nobody carries them anymore. Their new ones are even better and for a lot of power (and fractional capabilities) check out the EL-W516B.

CH

7. Cast Iron
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Ok Problem: How do you figure the change gears for cutting a HELICAL gear.
How do you figure the feed gears for cutting a HELICAL gear.

Without using a computer program.

Gear to be cut:

20 dp
50 tooth
45 deg helix
C=6

The pictures might be hard to see so here are the formulas:

Index gear formula:
18 x C
-------
(N x C) - 1

Change gear formula:

Normal Circular pitch
--------------------
C x sin angle x .075

Thanks for you time and help!!!
Cory

8. Diamond
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I have a #3 BC as well, and a Adams #3, and gleason #3 bevel. I asked the local gear shop about cutting a helix on the BC. They asked if I was crazy!

They cut spurs on a fellows. ( I have the helix guides but no fellows, but want one) And helix on a CNC (gleason I think) They explained that it was difficult to cut a helix but could be done.

Do you have the manual? If I remember correctly it is not much help on helix. What about colvin and stanleys book "gear cutting practice" or the B+S "treatise on gear cutting"?

9. Cast Iron
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I do have the manuals and they are hard to understand when cutting a helix gear. I have already cut a helix gear but I had help from another member. He gave me the gear ratios. I am looking for some help to figure them not just the answers.

Thanks,Cory

10. Diamond
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I'd probably be looking for a book of ratios if I had a hobber, because given the final ratio (as a decimal) it doesn't help much (if at all) to convert that to a simple fraction, and certainly not every calculated ratio has an exact fractional equivalent (within a fixed set of change gears), (although every set of change gears does work as an exact fractional ratio), so it is great to have a chart with ratios that are possible with the standard change gears, so that a person can decide which set is close enough.

Is there an online version of these hobber manuals? Might make for interesting reading

11. Diamond
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Originally Posted by HuFlungDung

Is there an online version of these hobber manuals? Might make for interesting reading
Is this close?

12. Stainless
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Cory,
Did you get the scans in the PM I sent you a few weeks back?

They have the method for calculating the gear trains from basics.

13. Cast Iron
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Alpacca,

I did get the scans. I will have to reread them again.

Mebfab,

I do not know why your gear group frowned at cutting helical gears. These machines have been cutting helical gears for a long time. My current machine was made in 1919 and with the help from a member I did cut a 50 tooth 30 deg helical gear. The trick is to set up the change gears correctly.

Everyone keeps telling me I need a calculator but I am not sure a calculator is the answer. I only have change gears from 21-100. So if the calculator gives you some number that is out of the range of my change gears I am back to more figuring.

I appriciate all the help and feedback that I am getting but I am not sure all the members that are replying have setup a BC number 3 gear hobber. Also I am new to gear hobbing and most likely not explainig myself clear so someone can help me. I have spoken to Terry Mcdonald at RPI who was the BC service manager for 35 years and now sells parts to keep these machines running. He told me that it is very difficult to figure the ratios for helical gears without that book that BC put together (95,000 four gear ratios)

14. ## Stick to your guns, dude

Originally Posted by Cory
...I only have change gears from 21-100. So if the calculator gives you some number that is out of the range of my change gears I am back to more figuring.
...
I appriciate all the help and feedback that I am getting but I am not sure all the members that are replying have setup a BC number 3 gear hobber. Also I am new to gear hobbing and most likely not explainig myself clear so someone can help me. I have spoken to Terry Mcdonald at RPI who was the BC service manager for 35 years and now sells parts to keep these machines running. He told me that it is very difficult to figure the ratios for helical gears without that book that BC put together (95,000 four gear ratios)
He is absolutely correct. Figure the decimal ratio and instantly look up that change gear train in the book. End of problem, no fooling around, no mistakes. The next closest combinations are shown immediately before and after. Sometimes one of those will be within the limits of accuracy for the job you have to do. You will find the book a great convenience.

It's really funny that somebody with a Fellows shaper would tell you you couldn't do a helix with a hobber. Colossal bullsh*t. The hobber is made to do helical gears. If you want to do a helix on a Fellows you have to change the fixed guides, which is so much trouble it's easier to buy another machine.

15. Diamond
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I'm not a spreadsheet wizard, but there are probably guys around here that are. Would it somehow be possible to make a spreadsheet, that writes out the various 4 gear combinations (given a certain range of change gears, and whether or not there are any duplicates available) and calculates the resulting ratio? Then, sort the ratios from smallest to largest?

And, not have to do this one line at a time in the spreadsheet? <----that would be the hard part for me.

Cory, you might even repost this topic with a title something like "Need spreadsheet help for gear ratios" to get some new attention.

16. Stainless
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The current issue (No 170) of Model engineer's workshop describes the calculation process and also a spreadsheet for calculating the correction gearing for helical hobbing.

The author gave his email address for anyone interested in the spreadsheet to contact him. I'm not sure about posting it in open forum, but if anyone is interested, give me a PM and I'll pass the address on.

17. dp
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Originally Posted by 3t3d
That book is well worth the price just for what is on pages 7 and 8.

18. Diamond
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Personaly i would secound the spread sheet, so easy to do. Only shows the combos for the gears you have. Doing that on a calulator is positifly darft, a spread sheet will work out every line for you in tiny fractions of a secound.

With that many gears there will be a lot of common setups to get the same result, hence calculating around your gears would be a very good head start. Whats more every time you add a gear you can darn near instantly update it for the new few hundred - thousand combinations it adds to your overall capability.

19. Cast Iron
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I have had luck finding a Barber Colman gear ratio book from 1910. It has I think 20,000 ratios. I aslo found a Pfauter gear ratio book. I may still have Terry copy the BC 95,000 four gear ratio book that he has. This sounds like the missing link in helping me cut helical gears.

Can the spreadsheet be made up for two sets of gears (4 change gear ratio)? I guess it would probably come out looking like the BC book I am looking for. Maybe it would be easier to have a copy of the original.

So all this nonsense about getting a calculator to change a decimal to a fraction to help me with cutting a HELICAL gear is over rated. Unless you are telling me that the calculator can be programed to solve my decimal to 4 change gears within the limits of my change gears are possible.

Please share the model number of that calculator.

Thanks to all that have replied. Little by little I am getting closer to making helical gears easier to cut.

Cory

20. Stainless
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Originally Posted by Cory
Please share the model number of that calculator.
It isn't so much the tool, as the knowing what to do with it.

I'm guessing that a good proportion of visitors to this board started working before the price of a simple calculator with square and square root as its fanciest functions, dropped below \$200 in the mid to late 70s.

The log and trig tables used in the calculation of the change wheel tables were themselves calculated with pencil and paper by teams of human "calculators".

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