[RCaffin]

Reverting to the original request:
I can't really see any problems. I have made gears using three different methods.

The first laid the blank flat on the table and milled out the teeth with a fine end mill. The method is suitable for clock gears etc.
I can't find any photos of this.

The second used a custom gear hob in the spindle with a simple rotary table.
Attachment 492446

The third use the simple rotary again and milled out the tooth profile using a ball end cutter.
Attachment 492448

Mostly these were making GT2- compatible pulleys, which were used to drive the Z axis.
Attachment 492444

If you want a helical gear the third method will still work fine: you just need a little more programming.
Incidentally, the cutter in V3 was a 1.1 mm ball end spinning at 3000 rpm, with MQL mist spray. Movement (feed) was a shade slower than normal (I wonder why?). Apart from a simple good rotary axis, nothing special was needed.

Yes, I know this may not be how gear hobbing is done conventionally, but so what?

Cheers
Roger

[joeavaerage]

Hi Roger,

Yes, I know this may not be how gear hobbing is done conventionally, but so what?

I've been called many things but 'conventional' does not figure on that list. I say good work to employ a method to exploit the capability you do have....and 'devil take the hindmost'.

Craig

[keitholivier]

Reverting to the original request:
I can't really see any problems. I have made gears using three different methods.

The first laid the blank flat on the table and milled out the teeth with a fine end mill. The method is suitable for clock gears etc.
I can't find any photos of this.

The second used a custom gear hob in the spindle with a simple rotary table.


The third use the simple rotary again and milled out the tooth profile using a ball end cutter.


Mostly these were making GT2- compatible pulleys, which were used to drive the Z axis.


If you want a helical gear the third method will still work fine: you just need a little more programming.
Incidentally, the cutter in V3 was a 1.1 mm ball end spinning at 3000 rpm, with MQL mist spray. Movement (feed) was a shade slower than normal (I wonder why?). Apart from a simple good rotary axis, nothing special was needed.

Yes, I know this may not be how gear hobbing is done conventionally, but so what?

Cheers
Roger

Roger, I will be making gears that need to run at 120+hp sustained with input shaft speed of up to 5800rpm. So the gears will need to be hobbed in a pretty rigid setup with minimal lash and then hardened and tempered etc. Depending on how loud they are, may need to be ground or shaved after heat treatment when the surface hardness is in the 58-60Rc range. There are likely to be splines on the input and output shafts too, to accept input and output flanges.

[RCaffin]

Roger, I will be making gears that need to run at 120+hp sustained with input shaft speed of up to 5800rpm.

All this on a hobby machine?????

I believe that some commercial CNC machines have been converted to Mach3 or Mach4, but by people who really understood what they were doing. I can't see why that should not work fine, as in many ways even Mach3 has capabilities NOT found in slightly older large commercial machines. Older commercial CNCs often ran a subset of NIST g-code; some older ones even required a many k$ extra PCB to handle G2 and G3. The difference is that those older CNCs had controllers built with discrete TTL chips - lots of them, on big PCBs, while modern CNCs use GHz processors and very powerful FPGA accelerators. A world of difference!

The more modern Mach3 and Mach4 (and the Linux equivalents) are able to handle 6 axes or more, in full sync, because they are just software running on those GHz processors. Even so, they offload the time-critical stuff to external motion controllers (such as the ESS) which use FPGAs running and hundreds of Megahertz. However, while those old controllers cost a small fortune (complex limited volume PCBs), modern stuff like Mach3 &4 are just software, running on a stock desktop of laptop machine. Cost of reproduction is 0.1%.

IF I had to do that job, I would have to start with a physical machine large enough to handle the parts. The teeth are likely to be much larger than mine, so you should be able to buy suitable hobs. I would not hesitate to use Mach3, which is what I use today. Then I might run the gears together for a few hours with some polishing paste on the teeth. I don't mind cheating if it works! I might repeat the polishing after heat treatment too.

Splines: I chose to use taperlocks instead. Commercial ones (eg Fenner) are B I I I G, too big for my jobs, so I machined my own. But at that horsepower and shaft size you should be able to have a sales engineer sort you out. A good taperlock fitting, done up tightly, is not going to shift.

Cheers
Roger
PS: yes, I use an ESS, with the latest driver. It threads well.
PPS: to the best of my knowledge, Mach3 (under an earlier name) more or less started the transition.
PPPS: Chinese clones are crap. They can do G0 and G1, and sometimes G2 & G3. But the doco is (not).

[keitholivier]

Roger, Im not sure you would regard a 3500lb universal mil as a "hobby machine". They are routinely used for high precision prototype/toolmaking work. They are equipped for manual operation although they usually have power feed on all axis including the knee. Not the bolt on sort of power feed, this is all geared of the main spindle motor, ie the horizontal cutting axis.

All this on a hobby machine?????

I believe that some commercial CNC machines have been converted to Mach3 or Mach4, but by people who really understood what they were doing. I can't see why that should not work fine, as in many ways even Mach3 has capabilities NOT found in slightly older large commercial machines. Older commercial CNCs often ran a subset of NIST g-code; some older ones even required a many k$ extra PCB to handle G2 and G3. The difference is that those older CNCs had controllers built with discrete TTL chips - lots of them, on big PCBs, while modern CNCs use GHz processors and very powerful FPGA accelerators. A world of difference!

The more modern Mach3 and Mach4 (and the Linux equivalents) are able to handle 6 axes or more, in full sync, because they are just software running on those GHz processors. Even so, they offload the time-critical stuff to external motion controllers (such as the ESS) which use FPGAs running and hundreds of Megahertz. However, while those old controllers cost a small fortune (complex limited volume PCBs), modern stuff like Mach3 &4 are just software, running on a stock desktop of laptop machine. Cost of reproduction is 0.1%.

IF I had to do that job, I would have to start with a physical machine large enough to handle the parts. The teeth are likely to be much larger than mine, so you should be able to buy suitable hobs. I would not hesitate to use Mach3, which is what I use today. Then I might run the gears together for a few hours with some polishing paste on the teeth. I don't mind cheating if it works! I might repeat the polishing after heat treatment too.

Splines: I chose to use taperlocks instead. Commercial ones (eg Fenner) are B I I I G, too big for my jobs, so I machined my own. But at that horsepower and shaft size you should be able to have a sales engineer sort you out. A good taperlock fitting, done up tightly, is not going to shift.

Cheers
Roger
PS: yes, I use an ESS, with the latest driver. It threads well.
PPS: to the best of my knowledge, Mach3 (under an earlier name) more or less started the transition.
PPPS: Chinese clones are crap. They can do G0 and G1, and sometimes G2 & G3. But the doco is (not).