GottMitUns

cutting metric threads

Recommended Posts

Lathes are a really good machines for making gears on......... Go on, you know you want to!

Smoggy you sound like my Father when I griped about not having a mill in his shop. I've never thought about cutting gears but can visualize two basic approaches. My lathe is only a 13 swing so I couldn't make blanks for large gears but that'd only mean I had to make more.

Fun Fun FUN!

Frosty The Lucky.

Share this post


Link to post
Share on other sites

My old school teacher made up a dividing head with a spring loaded plunger which was attached to the (external) head stock spindle on a little Boxford lathe. He ground the required tooth vee profile onto a HSS lathe tool  and rotated the tool 90˚ anticlockwise in the holder. He then used the saddle sliding backwards and forwards as a shaper to make the gear...

Alan

Share this post


Link to post
Share on other sites

...an improvement on that method is to make a tool post mounted slotter which will be faster and save wear on the bed and saddle, and will later come in very handy for cutting both internal and external keyways (and you may need one in the back gear) or splines as well as gear teeth,

The most difficult part is indexing the gears, ok most counts are easy enough but a 127 can be a tad difficult without an index attachment.....so probably best make one of them first!

Share this post


Link to post
Share on other sites

I think you are right a powered slotter would definitely be the way forward in the real world.

My teacher's device was to enable us to make a slightly larger than Meccano size brass gear wheel for the steam engine I was making. He stacked half a dozen or so up on a mandrel and cut them all at the same time. Well, he set it up and the three of us making the engines did most of of the shaping.

It is the gear driven by the pinion on the flywheel. The shaft then operated the water pump which pushed the water through the coil boiler.

The photographs show my 45 year old steam engine. They are displayed here because I am still slightly smug that mine was the only one that ever ran first time without any valve modification when tested with the compressed air in the science lab!

Downhill all the way since a sixteen year old!

Alan

image.thumb.jpg.4d909d3697ce775d6a2342c7image.thumb.jpg.11e5ae84e0cb2d8cdb6b4d3c

Share this post


Link to post
Share on other sites

It would have to be powered Alan, a simple hand lever operated slide would speed the job up no end, I'd go so far as to say making a simple slotter (given the stock material being at hand) and cutting the gears would likely take no longer than cutting the gear via the saddle method!

Nice little engine you've made there, about time you started on a full size one to power you're workshop  ;)

 

Share this post


Link to post
Share on other sites

It would have to be powered Alan, a simple hand lever operated slide would speed the job up no end, I'd go so far as to say making a simple slotter (given the stock material being at hand) and cutting the gears would likely take no longer than cutting the gear via the saddle method!

Nice little engine you've made there, about time you started on a full size one to power you're workshop  ;)

 

It would...would not? :)

I was thinking of one of those tool post grinders I think. But I do remember seeing a lever operated thingy in some engineering magazine article now you mention it....Or was it in a Myford handbook?

Alan

p.s. My favourite bit of the engine was filing up the cam follower... Sad life really! :)

Share this post


Link to post
Share on other sites

Typo, Alan *wouldn't* DUH!

Yes I believe Myford did or Myford as is now is do offer one, and there are many other examples, most of which are home built.

Share this post


Link to post
Share on other sites
On 9/15/2015 at 10:12 PM, HWooldridge said:

It's an Imperial (English/American) gear set.  Only way to cut metric is if one of the TPI settings happens to coincide with a metric standard.

Or you'll have to change out one or more gears...

 

The first part is sort of correct. There are no SAE thread pitches that coincide with metric. A couple are very close, but not close enough to match.

The second part is correct. Usually one or more gears can be changed to allow the machine to cut metric threads. You should be able to find that information in the manual for the machine, although it's also sometimes on the inside of the cover on the side of the headstock. It's possible that you could find generic gears(or gear blanks) with all of the correct specs except maybe a little boring/keyway cutting or facing the gear to the correct thickness.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now