On 2012-04-12, F Murtz wrote:
DoN. Nichols wrote:
On 2012-04-10, F wrote:
This question will be a bit hard to answer.
With a smallish lathe (600 mm centre)and a small drill mill which module

Is that "center height", or "between centers"? It makes a big
difference in the size of the lathe. :-)

cutter set would be the best to to cut the sort of general purpose
gears? not tiny ones for model making.
one instance would be a gearbox to turn a pig on a spit.
maybe the gears on the end of a sheet metal roller or a swage& jenny
machine,or replacement thread turning gears for a lathe.
Module 1 or 1.5 or 2 etc?

Well ... I'm not really familiar with the module gears, but in
Imperial ones, for the first task (the pig on a spit) I would probably
of with something like 32 DP (Diametrical Pitch). (I've made such gears
for repairing a piece of electronic test equipment.)

[ ... ]

By consulting a book like _Machinery's Handbook_, you can
convert one system into an approximate size for at tooth thickness (not
width) at the pitch diameter, convert that into the other system, and
find what is the closest standard size in the new system.

[ ... ]

FWIW -- I have a full set of the 20 DP cutters (for my lathe's
gears), and only one of the 32 DP ones, as I only needed to make one
size of gear.

the lathe is 600 mm between centres 320 mm swing (160 mm high)38 mm
spindle bore.

O.K. Then for that size, (a bit over 6" swing), I would
probably go somewhere closer to the 32 DP (again in Imperial than the 20
DP. Perhaps 24 or 28 DP (I should to look it up to make sure that
those are standard sizes, but they could be, and would be pretty good
choices for that size lathe. :-)

If my guesses about the size ratios is right, 32 DP would be
about module 0.80 , and 24 DP would be around module 1.0. So I would
say that your module 1.0 would probably be a good choice for most
things in your size range.

My question was not so much that I need any of the things that I
mentioned, just an indication of the size that I may want in the future,
I was just thinking of getting a set of cutters so that if I got a bee
in my bonnet in the middle of the night I could set to making something
and I was just trying to get an idea of which set of cutters would be
the most useful to have on hand.

O.K. Do you have an index head for dividing the gear? Three
dividing plates and a 40:1 ratio are what I am familiar with. It *can*
be done with a rotary table, but without dividing plates and sector
arms, it is rather error prone.

If I had a special job which would
require matching I would probably have to get cutters specially.
If you were making the whole set of gears you are not restricted to matching

Understood. When you mentioned change gears for a lathe, I was
thinking in terms of replacing a few missing ones.

FWIW While I got a full set of 20 DP gear cutters to match my lathe,
the first gear that I actually *cut* required ordering a
separate cutter -- different DP, and different pressure angle
(PA) as well. :-)

Good Luck,
DoN.

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