1972 Mazda Rx2- Moves to a new home

Yes,one piece cranks could be made pre Cnc.

The construction of a Rotary engine is such that it easy to add rotors and increase its capacity. However. Every new rotor you add ,needs a stationary gear to rotate around. The way you assemble a rotor motor with its seals etc,dictates that the maximum number of rotor journals you can have solid on a shaft is two. So when you start looking at multi rotor engines,you will see two fixed journals. In the case of a three rotor,the journal for the front rotor slides on,locating on a key and a taper. On a four rotor, rotor journals two and three are machined onto the shaft,with rotors one and four again,sliding on,keyed and tightening on a taper. Six rotor,? 1,2,5,6 slide on ,splined and taper with journals 3 and 4 machined onto the shaft

If you look back at that animated video posted a couple of days back,you can see when the shaft is put through the centre / intermediate plate,you can see it being wiggled to get it through. That's why it's a maximum of two fixed journals.Rotary engine does indeed have counterweights on the eccentric shaft,just they are fitted afterwards,once the rotor chambers are closed up,there is a counterweight either end. Front one just keyed. Rear one keyed and tapered. Rear one can be built into the flywheel ,or a separate item in the cause of an automatic transmission car. Aftermarket flywheels designed to bolt onto counterweights normally used for an auto,just unbolt the flex plate and bolt the flywheel on. I need to make new counterweights for the three rotor,as they need to be in different positions compared to a two rotor. Not difficult to do,just another type of machining I havent tried before. But how hard can it be? 😂

^^
Yep. You are lucky if they don't bend. All you can do is take all the precautions and find someone you can trust to do the final heat treatment.

Got a response couple of days later along the line of "cannot be done. Would need a cadcam programme to write tool paths". Not what I had expected. Yes ,I did have a cadcam programme,but the 4 axis programming option wasn't something I had. Don't tell me can't be done. I sat down and started brushing up on. G code....

And so it began, the beginnings of a 4 axis milling programme to mill the journals on the shaft

^^
Meh...Just started the 12 days of Christmas

" On the first day of Christmas, my true love gave to me, a healthy chunk of En40b". 🤗

I can fully understand the response I got,in that they are busy supplying a service to their customers who forget to put decimal places and feedrates into programmes and then blame the machine 😉 Anyway ,rather say "we don't know" ,rather than,"It can't be done". So, back to pulling my hair out.....

For those who would like a bit more of an insight on gcode,here goes. Take a look at this programme ,that was just a test to see if I could get machining an arc in the right plane.


G0 is a rapid movement,in a straight line. No federate required.
G54 is the workoffset. Very important as it tells the computer exactly where your part is situated relative to a position it knows(G53)
G53 is where the machine references to when you start up,so basically it's home address.
G1 is a feed,and thus needs a federate added for it to work. In this case it's F500 which equates to 500mm per minute. This feedrate will stay set,so after the first use ,it will stay set,so no need to keep putting it in,unless you want to change it.
G3 is also a feed rate,but in a circular motion,not a straight line. If you don't specify a feed,it will be the same as G1
I,J and K define the centre of the arc you want to mill using G3
S is a speed. Spindle speed,and in this case 1909rpm
M3 denotes spindle roatation clockwise. M4 would be anti-clockwise.
G17 and G19 describe the plane you are machining in. Most run of the mill stuff is in G17, but in this case we do change into G19 whilst using the 4th axis,because that's the plane we need to machine the arc in.
G90 is absolute programming. So everything is relative from the zero position/ datum set in G54
G91swops into incremental programming,so any figures entered in will be from where the tool is now,not from the zero position. Very handy when changing planes. You can see we swop from G17 using G90 to using G91 when machining in the G19 plane
A is a radial position measured in this case degrees. The 360 relates to the forth axis. So,once we have positioned the tool and want to start machining the arc,we now have told it,to now move the A axis 360 degrees. It's in incremental programming,G91, so the part will be rotated 360 degrees from where it is now, with a feed of 500mm per minute, as that was what was specified for both G1 and G3

So that's all luuurvely. And does it work? No. Bucking Fastard thing. Stupid machine....
Three days later I have it sussed. Schoolboy error. Remember me saying a Cnc machine only does exactly what it is told to do? Well that's exactly what it was doing. The position set for the centre of my part ,in G54 ,was X0,Y0,Z0,A0....So,with me saying to it move to A360, it did nothing. Why? Because A360 and A0 are the same place.It was just one of the little quirks of Cnc programmes that you sometimes come up against. With it being in incremental programming,G91, I would have thought it would have just moved 360 degrees from there,but it didn't.  Quick cheat and use A359.999 and hey presto it mills the arc

So the fundamental move for milling the arc is sorted out. Couple of days later a very composite programme running part Siemens Sinumerik with patches of g code plugged in,and it all works. Couldn't resist sending it back to tech support.....

Right. That should have put the insomniac's to sleep 😂

So basically it's like the BBC micro turtle that schools borrowed in the 1980s except instead of felt tip pen it's got a cutting device of some kind...

Or a big trak...

If you're a different vintage to me you might not know what I'm on about!

Either way there's something deeply satisfying when you program machines using direct code like that and actually crack a problem like your 359.9999999r instead of 360.

^^
Pretty much. 😂
Most Cnc. Machines today still run gcode. Most of the cadcam packages will output gcode too. Very often I write a program offline in Mastercam,then,seeing I have a basic understanding of the gcode it generates,I go in and edit bits to suit my needs. So, I am grateful for the time I spent right in the beginning on the big old mill in g code because it gave me an understanding of gcode many do not have...

I've just been on line and learned double dutch ,,,,it was easier than trying to understand ,G..code ,,,ps still loving the thread tho

Yep I have felt like that over Christmas as well - fecking mince pies.