1/4 scale Porsche 917 180 degree V12 Build

[steamer]

Thanks Mike!

Dave

[Vixen]

One fulĺ depth pass then a spring pass.
Mike

[steamer]

One fulĺ depth pass then a spring pass.
Mike

That's the plan

[steamer]

Gonna put a footstock on it though

[Vixen]

Gonna put a footstock on it though

Tailstock???

[kuhncw]

Allways climb mill gears
Mike

Mike, what is the reason for climb milling gears vs conventional milling?

Chuck

[steamer]

Gonna put a footstock on it though

Tailstock???

Cylindrical Grinders AND Dividing heads it's called a footstock

On a lathe it's a tailstock

I didn't name them.......

Dave

[steamer]

OK    good evening  it'

I was able to cut the teeth....not without incident, but I guess I'm not surprised as it's the first time cutting gears on a CNC mill.

I've cut many gears on manual mills , like my #12 Van Norman mill....and it was ALWAYs  conventional cut always towards the dividing head.   That is not an option with my software on a CNC mill as far as I can tell.   But no matter it climb cut quite nicely.   CNC is always better as climb milling.....it's just not my experience ....so I got nervous....but there was no need.

300 rpm was just fine, and I think with the mist coolant that I could safely go to 400 without any problems
What I did wrong, was set the center of the cutter on center with the work piece quite precisely....which is what I would do with my Van Norman or my F1....there was the rub!    Zero on the program is the bottom edge of the cutter, not the center...so it cut low by half a cutter thickness....  Once I got that sorted out I started making decent teeth!   but of course the damage was done.

The mill doesn't have the snot to run at 3 inch/min at that speed....2 in/min is just fine.    I'm not surprised as the spindle will run happily at 10,000 rpm so as a belt drive machine, Im not at all surprised.    I can work with it, as the gears are small, and I don't suspect I'll need to cut anything of bigger DP than Mod 1 or 32 DP.

So I'll make up another blank and have at it....this week I think....we'll see what work brings to my desk...

I have a BS1 dividing head....I think a BS0 might be better given the table size....  I'll look into that

Thanks for following along......

Dave

[john mills]

climb milling is always better than conventional milling  but only on machines rigid enough and no backlash preloaded ball screws and the work must be held  to control the cut .  at apprentice school they had a good big heavy horizontal mill with back lash eliminator but
when they tried to show how it worked it picked up the vice and threw it over the end of the table it was a good big solid vice firmly held with 5/8" bolts so they put it all back making sure it was done up tight and tried again same thing so they didn't try again.whith good cnc machines with preloaded ball screws  and good spindles i always climbed mill unless the set up was likely to be a bit springy .
good you have the gear cutting working.
  john

[steamer]

YUP   35 years turning cranks and now slinging pixels!.......designed quite a few of them too....just never got a chance to run CNC myself till I got my mill....it's a bit of a learning curve...and you have to learn to trust the machine and change your work methods....

[steamer]

Case in point

https://www.modelenginemaker.com/index.php/topic,649.msg6073.html#msg6073

[john mills]

your little mill with high spindle speeds carbide end mills should love climb milling  when you start with larger end mills in cnc machines
plowing into tool steels is something to think about but it works and you quickly see it works i started more than 40 years ago but
i had to wonder on old machines that have long seen there best but never had any trouble i didn't climb mill holding tough steels in a indexing head and using larger cutters where the setup needs to be rigid .
John 

[Vixen]

YUP   35 years turning cranks and now slinging pixels!.......designed quite a few of them too....just never got a chance to run CNC myself till I got my mill....it's a bit of a learning curve...and you have to learn to trust the machine and change your work methods....

When you convert to the CNC way: you must trust your machine and trust the drawings.

Mike

[steamer]

YUP   35 years turning cranks and now slinging pixels!.......designed quite a few of them too....just never got a chance to run CNC myself till I got my mill....it's a bit of a learning curve...and you have to learn to trust the machine and change your work methods....

When you convert to the CNC way: you must trust your machine and trust the drawings.

Mike

t
Yes you do!   I set the center of the cutter at the center of the gear.....of course the software set zero at the bottom face of the cutter set to cut the bottom face of the gear tooth slot.....so half a gear cutter thickness low....once I convinced myself that I set it on center....like 4 times....it dawned on marble head that the software wasn't reading my mind...    I say I sack the software!!!!

Dave

[Vixen]

I set the center of the cutter at the center of the gear.....of course the software set zero at the bottom face of the cutter set to cut the bottom face of the gear tooth slot.....so half a gear cutter thickness low....once I convinced myself that I set it on center....like 4 times....it dawned on marble head that the software wasn't reading my mind...    I say I sack the software!!!!

Dave

There is still a lot of merit in using less sophisticated CAM software than Fusion 360 and the like.   

OK, you may have to do more of the work, but the lower level of automation leaves you, rather than the software, in command of the process.

   I say I sack the software!!!!

Dave

Yep, I go along with that as you must also trust your software or have software you can trust

Mike