I suspect you mean gear cutting as to do hobbing properly you really need a gear hobber, it can be approximated with home made tools but you would also need a lathe to do that.

An idea of the size (diameter and tooth size) of the gears as well as what material you want to make them from would give members a better idea of what machine to suggest.

You will almost certainly need some form or rotary table or dividing head to increment the blank around 1 tooth at a time so allow 250-300 euro for that. And easily the same again for some other basic tooling to go with the mill such as an arbor to hold the gear cutter, the cutters themselves, measuring tools to set the job up, etc.

Welcome!

If you are going in for gear manufacture, do buy Ivan law's book on "Gears and Gear Cutting" No.17 in the "Workshop Practice Series", as Mike Hurley has already recommended.

You will find it a great help. Study it well before starting to cut metal.

If need be make your mistakes on some trial pieces, to gain experience, before embarking on the final product,

It may help to bear in mind that gear cutters are numbered in the reverse order between Imperial (DP ) gears and Metric (Module ) gears.

You are also going to need a Dividing Head or Rotary Table, (With Tailstock ) and a 4 jaw chuck to hold the mandrels on which the gear blank will be mounted for machining.., The mini lathe will come into its own to make the mandrels on which to mount the gear blank

I prefer using Division Plates on a Rotary Table, to calculating the angular divisions and setting them on the vernier scale.

Since gear cutting involves a heavy cut, although at a very slow feed rate, you will need the Tailstock to support the mandrel on which the gear blank is mounted.

This also implies that the milling machine needs to be fairly substantial and rigid, if your gears are going to be made from steel. You can do small work on a large machine, but not so easily the other way round.

A larger, heavy machine will be more rigid, so an aid to quality, so buy a little larger than you initially anticipate

New machines will be Metric, so you will need a calculator to make the settings for Imperial gears…

If you do not have it already, you will need measuring equipment to measure diameters, and to ensure that the work is held concentric in the chuck.

Howard

if you do indeed mean radius rather than diameter then you will struggle with the smaller mills. certainly a (mini-mill) won't do it and even the Sx2P sized machine will struggle This is because you can't bring the table far enough forwards to get the cutter into the right position behind the gear blank.

Even the next sizes up like the SX2.7 and SX3 size machines will be hard pushed to accomodate a 200mm dia gear and rotary tables for that size will be a lot more than the figure I mentioned earlier, you could possibly get away with a 6" rotary table packed up but front to back movement may still not be enough.

A DRO is nice to have but may be more economical to buy separately and fit yourself. Power feed less so

As for measuring tools a half decent 150mmdigital calliper will do to start with and cover most of the gear sizes you are thinking of. Dial test indicator and a magnetic base will get your work and th rotary table set true and an edged finder to locate the work

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Dare I suggest that you might convert your sucking Chinese mini lathe into a wheel-cutting engine ?

Have a look at J. Malcom Wild’s masterwork for inspiration : **LINK**

http://www.j-m-w.co.uk/contact.html

MichaelG.

Neither, but it will be tricky. it is normal to cut gears (at least in ME sizes) in one pass per tooth space. That means the cutter is working on a long mean path. So machine rigidity is your friend. With a 200mm diameter gear on a vertical mill the cutter will be sticking out about 100mm. That is an open invitation to chatter, which will get worse as the number of teeth get smaller and hence the spaces get bigger. What DP or Mod will be the largest you'll cut?

Of course gear cutting can be done on a vertical mill but it can be problematic. For manual spur gear cutting I prefer a horizontal mill. Far more rigid than a vertical mill and the arbor is supported at both ends:

Total cost of the setup above was less than half the stated budget, including a universal dividing head not shown above.

Andrew

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… Just realised that I had made an unjustified assumption when suggesting conversion of the lathe

At those diameters, it would never enter my head to try cutting coarse gears in difficult materials on a ‘mini’ machine.

… I was thinking of clock wheels in brass

MichaelG.

Just to say that if you want to make larger gears for "small mechanical follies" then you could consider using CNC. Small gantry CNC routers are not too expensive and the better ones have ballscrews etc for better precision. You can make quite large gears up to the max size of the router table and down to whatever the precision of the machine permits by profiling them out of flat material using small milling cutters. There are quite a few links on the web to people making wooden clocks who use this approach. The main limitation is that the smallest practical cutters are ~1mm which limits the minimum gear module to a bit over M1.

The g-code to drive the machine can be generated by free or quite low-cost CAD/CAM software. For example, this web page: **LINK** * – will generate the dxf file for a cycloidal wheel and pinion; and this: **LINK** – can convert the dxf to g-code. Or you spend a little money and get a general purpose CAD/CAM package like CamBam that can do the dxf-gcode bit and also allow you to do involute gears and design other bits. There's lots of other free CAD packages – look at recent threads here for more information.

*Security concerns have been expressed about this as it uses WebGL but these may be overplayed – anyway with your background you will be in a good position to judge.

I'm in the process of learning to make gears using these methods albeit on a conventional CNC mill.

How do you get that with the OP wanting gears of 100 -200mm dia That is going to need 2.5Mod for 80T on the 200mm dia which is a considerably bigger bite to expect a minimill to take.