Hello all,

I am researching gear cutting, and I am thinking about doing it my self. I am woundering who out there had done it the single point method. Any tips of how to grind the tool? How successful is this method.

Thanks,
Jose.

Normally you use gear cutters, they come in sets of 8. The method gives "approaching" gears, they are noisy above a low (lowish) rpm. This method is inferior to the evolving milling method used in the making of industrial gears. I made several times a gear without a gear cutter, just by grinding the bit till it fitted in the tooth. Perfect? No. Every imperfection disturbs constant velocity and it will never wear in. But for low rpm replacements, why not?

Carel

Jose,

while not a form cutter, here's an idea for a home made cutter to for gears. Peter Harrison's site gives a very good description of what I call faceted hobbing. Its not really hobbing but it is a very cool way to make your gears and cutters without requiring true hobs, a swiveling mill table etc., or form cutters As this needs is a lot of back and forth stuff/index repetition. As Carel said, form commercial form cutters are also only an approximation - so lacking gear generation equipment, this might be as good as form cutting? haven't had a need to cut a gear since i saw this, but it looks to be worth a try

http://homepage.ntlworld.com/peter_...tting/index.htm

link does not work

This one does though....

http://homepage.ntlworld.com/peter_...tting/index.htm (http://homepage.ntlworld.com/peter_harrison/workshop/gearcutting/index.htm)

The cutter is a whole lot of single points and the gear is a worm gear but I though I would show that you don't always have to use conventional equipment to do something. This is a converted benchtop lathe and to date it has generated about 400, 4" diameter 60 tooth wormgears from a 1-1/8" -6 acme tap.

Wow, that link is pretty interesting. Looks considerably difficult to make the cutter though. I think I'd just buy an involute gear cutter (McMaster page 2395 toward the bottom).

Jose, do you have a CNC mill? Though limited in how small a gear I can cut, I've done several using Rhino+free plugin and cut with regular endmills. I'm also limited in the types of gears I can cut (ie: not worm) but that should be solved with a 4th axis indexer.

JR

Just a thought, but has any body ever heard of a carbide insert that has a true involute shape. I think it would the way to go for making gears the single cutter method.

If you want to make a range of gears between 15 and 136(rack) you would need 136-15 = 121 cutters, that have a true convolute shape. Because this is a little bit over the edge, they divided this over 8 ranges. Take a look at a gear hobber and try to figure out, how these machines make with 1 mill per modula, perfect gears. Try to figure out the difference between the mill in the link (incorrect) and Geof's hobber mill (correct). Hint: Every tooth is corrected off-center. After that you will see the unavoidable imperfection of the gear cutter.

Carel

Wow, that link is pretty interesting. Looks considerably difficult to make the cutter though. I think I'd just buy an involute gear cutter (McMaster page 2395 toward the bottom).

Sanddrag,

Does McMaster have a web site?

Sanddrag,

Does McMaster have a web site?By all means yes (http://www.mcmaster.com)

Google (http://www.google.com/search?hl=en&q=mcmaster) is wonderful thing.

With the exception of food, there are very few things I've found that McMaster does not sell. That place is wonderful. They are one of the largest industrial suppliers around.

The cutter is a whole lot of single points and the gear is a worm gear but I though I would show that you don't always have to use conventional equipment to do something. This is a converted benchtop lathe and to date it has generated about 400, 4" diameter 60 tooth wormgears from a 1-1/8" -6 acme tap.

hey geof did you make the mating worm shaft as well? and if so could you post a picture?

I also noticed your using a smaller gear to drive the bigger gear, did you need a different ratio? and if so was there just a straight math ratio calc on the size to tooth count?

By all means yes (http://www.mcmaster.com)

Google (http://www.google.com/search?hl=en&q=mcmaster) is wonderful thing.

With the exception of food, there are very few things I've found that McMaster does not sell. That place is wonderful. They are one of the largest industrial suppliers around.

Whoa, They aren't cheap are they? But they do have a great selection of just about any ger combination you might want or need. Thanks!

hey geof did you make the mating worm shaft as well? and if so could you post a picture?

I also noticed your using a smaller gear to drive the bigger gear, did you need a different ratio? and if so was there just a straight math ratio calc on the size to tooth count?

The application is a hand operated mechanism that is very low load so the worm is just a short segment of 1-1/8" - 6tpi ACME.

The smaller gear was something I just had in my pack-rat-pile and it just happened to have 60 teeth. I just cut a custom acme thread to drive it then used a 1 : 1 ratio.

It was amusing how things fell together designing this worm gear system; it worked out that the pitch diameter of the gear is 3.94" or something like that, I was able to buy 4" diameter leaded steel and I had a machine big enough to part off the blanks with a 1.500" bore. I guess the planets were lined up correctly or something.

Every once in awhile a blue moon happens and you get lucky.

I wish those kinda things happend to me more often. Although as a rule my luck is pretty good too.

whats the aplication for the worm gear? Something cool that you have pictures of?

.....whats the aplication for the worm gear? Something cool that you have pictures of?
Didn't have pictures earlier. Don't know if it classifies as cool; it is for an tilting front surface on an adjustable computer desk we make that is used in rehab centers. The pictures show half the worm gear attached to the stationary frame (the desk surface is removed); the worm screw climbs around the gear when the crank is turned and can tilt the table surface back about 20 degrees and forward up to 90 degrees. The keyboard is held on with velcro. The idea is to make the keyboard accessible to someone with limited arm and hand mobility or even place it almost vertical so it can be used with a pointer held in the mouth.

Thats cool. Even cooler if you "invented" it.

I always get the most satisfaction coming up with an idea and seeing it used by someone else. Well as long as their not cussing and cursing when using it anyway! :D

Thats cool. Even cooler if you "invented" it.

I always get the most satisfaction coming up with an idea and seeing it used by someone else. Well as long as their not cussing and cursing when using it anyway! :D

Gee, I'm cool! Who'd I thought it. Everything we make are my designs; and sometimes I do get the cussing and cursing but they are more or less equalled by the people who express compliments.

WAIT JUST A MINUTE! lets not get carried away now!

Dont go putting words in my mouth, I think I said "Thats cool" not to be confused with "your cool". :D

ouch!

But hey your shop is cool so some of that must be you. right? ;)

:cheers:

WAIT JUST A MINUTE! lets not get carried away now!

Dont go putting words in my mouth, I think I said "Thats cool" not to be confused with "your cool". :D

ouch!

But hey your shop is cool so some of that must be you. right? ;)

:cheers:

Boy talk about flying high, coming down with a thump and then getting a little rebound. Ouch indeed!

The shop credit I have to share; I have a couple of 'Production Managers' (that is what it says on their business cards) who are pretty good and my guys over the years have come to take pride in a tidy place.

thats ok.

we still love you man! Even if your not that cool! ;)