Tangential Saw shaving 4th axis

[David]

Hi Art

Thank you for your Sterling efforts and magnificent support.
It is midnight here in the UK, so will have another trial tomorrow.
At present I am using old saws and any scraps for blanks whilst I learn the program, so no real damage done!
I  will be intrigued if we can get this working for clock gears because the availability and cheapness of narrow slitting saws makes it a very attractive proposition.
This is only a hobby, going from large scale steam to full size steam cars to large scale steam to small scale steam to maybe clocks, oh and I broke my neck somewhere around steam cars  :)
it would not be fun if there was no challenge and we rely on people like yourself to make some of it possible.
You may like my steam car site locomobile dot plus dot com
David

[JustinO]

"...because the availability and cheapness of narrow slitting saws makes it a very attractive proposition."

Have you tried flycutter/gearcutters? With simple flat edges on a single point, you can generate involute toothed gears.

[David]

Hi Justin0

I know, but you do not need 4 axis CNC or this program to do that.
I can make and use single or multiple tooth involute cutters, but it is one or several cutters per module or DP
My idea is to be able to use essentially a simple saw and let the computer do the work.
Given my limited mobility it is easier and more productive to let the CNC work whilst I get on with another component  :)
Kind regards
David

[ArtF]

David:

Well, for my part Id just like to know the routines work. Weve all seen nice examples of the flute cut tangentals, but I havent
seen any by saw. This is a good way to get rid of bugs and to learn a bit more about changes I need to make in the next iteration
of the 4th axis code. The code I checked tonight made much better sense, I couldnt understand why the Y was moving in and out,
took me awhile after this hiatus to figure out it thought the saw was on top. :)

Anyway, we'll figure this one out and hopefully by start of next year we'll have a graphical way to simulate the damn things..that
will save us all a bit of head scratching, and will allow us to experiment more on bevels and such..

Thx
Art

[David]

Hi Art

A rather frustrating day, did not get to my workshop until after 6pm today  :(
Tried another simple gear; 22 teeth 2mod using a 0.016" thick 2.75" diameter saw and a 1.85"blank
Not a great success, cuts a number of slots above and below Z zero ending in a rapid 90 degree A and a full depth Y fortunately just missing blank above and beneath.
No Z or A movements were cut with saw in work.
Then proceeds to cut away almost all material of some teeth. I think 16 thou should be thin enough and no warnings given in Gearotic.
Attached gth tap screen shot and picture
Thanks but I am not longer sure if this a program error or my own stupidity!
David

[ArtF]

David:
 
  I ont think its you, the numbers seem deeply wrong in the Gcode, but I cant make head nor hair of it. Its one of those things
that unless Im doing it myself, someone elses number mean nothing. Leav it until I can check to see whats going on internally, and that may take
a few weeks from where I am. Sorry for the screwyness, I cant see where its coming from but Im sure I latch onto it..

Art

[ArtF]

That depth per pass looks awful high though doesn't it?

Also, can you verify for me that your A axis rotates CCW when you move it A++, when viewing it down the X--.

In other words if you look down the X-- axis towards the A axis chuck, does it rotate CCW when you do positive rotation?

Thx
Art

[ArtF]

David:

  Other than checking rotation is good, coudl you do a run if you get time or feel inclined, with tangental turned off, and just rooting turned on? Turn off "Root wall" and just try a rooting. The code I created for mine looks very good in the rooting and Id like to know if perhps its just the tangental thats screwy in the saw routines..

( Actually, its al one routine, but conditioners rotate the path for the saw.. Ive cut many normal tangentals, so perhaps its just the rotation
of the tangental path...)

Thx
Art

[JustinO]

David,
I don't think you understood my post.

[David]

Hi Art

I will check A rotation direction this evening
You ask I turn of tangential not too sure what you are asking me to do.
As far as depth of cut, from the user guide it states it must be a positive number, I think I have taken this to mean a positive integer.
Should I put the actual depth of cut I would like there, I was thinking it might be a percentage or ratio.
Regards
David

[ArtF]

David:

Sorry, Im confusing myself at this point... lol

OK, first, the depth is fine, its not used at all in 4th axis. It will be removed in 4th axis during this years recoding.
Second, The process of cutting the teeth is 3 steps of code. (If their all selected).

You have selected "Tang. Saw", this is the tangential saw rouine, turn it on and off and you can see this is the actual
tooth shaving. This tangental work is done last. The first thing the software will put out is the Rooting phase.
With a saw you may not need this phase, but Id like to see what happens if you do. At the end of this phase which is
done with no rotation you should see a roughed out tooth.

  Then, if you selected "Root Wall" the blank will rotate so the root below the base is tangent to the tool and will take one slice on each flank. This is just to straighten just the walls of the root area beneath the base circle. THEN, finally the system will do the tangental shaving.

  What Id like if you can is to let it do the rooting, then stop it and see if the tooth actually looks proper. You can turn off root wall as there isnt much root below the base in your example. Heres a snapshot of what mine shows when I set up to do your gear for example.. If you turn off toothing by unchecking it, you wont get shavig at all, just thge rooting..


Art

[David]

Hi Art

Thanks for your help
Attached is a picture with two arrows to show direction rotation of chuck when A increases (more (+) which I think is counter clockwise
Attached is a picture of a part cut blank. One side shows the slashing cuts with toothing on. The other side shows a part cut "gear" with just rooting on, you can just see 1 under first tooth 7 under last and the direction of rotation arrow all in pencil, looking good.
I notice that with toothing off depth of cut does work and these teeth are cut in depths of 0.05" no finishing cut.
As soon as toothing checked everything goes haywire, results as described in previous posts and depth of cut does not work cuts up to 0.20" can be seen
Hope this helps
David

[ArtF]

David:

Well, those rooting passes look good. The depthperPass is used to set only the root passes, and is used if toothing is on or off. A saw has so much power you likely dont need it, but keep it in mind to flute work. The teeth are shaved in a number of "Segments" and thats what the segments box sets.. You might want to invert your direction bit for the A axis to see if shaving then works...its odd to me its that far out..

  The shaving looks good numerically, so it will take me a while to dig deeper. It may be the rotation backwards on my end.

Art

[SkyMoBot]

I'm pretty interested in you all getting this to work.  Bigger gears work great with endmills, but once you get into small clock gears you had better be purchasing tiny end mills in bulk on EBay.

I start off cutting air, then mdf, then acrylic, then if I have any end mills left, brass.  I'm thinking a .25mm saw is going to last a whole lot longer than a .25mm end mill.

[ArtF]

I agree, a saw would have much greater staying power...
We'll definitely get it sorted out.. :)

Art