Shaped, Tangental, Rooting & Root Wall

[Hwingo]

Good Evening to All,

1. When simulating a straight spur gear, it would appear that Tangental, Rooting, and Root Wall cuts (when all three are activated) will clear away all material as the gear is cut and finalized. Stated differently, though it may be wise and good shop practice, it?s not necessary to perform a Shaped Tooth cut. Is this fundamentally correct?

2. This brings me to the Shaped Tool button. While quickly going through the 4th axis tutorial, the thrust of what was gathered seems to be, ?the purpose of the Shaped Tool cut is merely to remove (clear away), at the onset, excess material thus reducing wear on the tool and reduce accumulative lateral forces that may takes its toll (over time) on the machine?. Is this a fair statement?

3. Assuming it to be proper protocol and wholesome shop practice to first begin with Shaped Tool cuts, am I correct in assuming that this is a totally separate G-Code *program* that?s generated first and put into operation first, and then a second program is generated using the remaining three, i.e., Tangental, Rooting & Root Wall all of which will be used to cut and finalize the gear in a single, second program?

4. The reason I ask the question immediately above is, the Tangental, Rooting & Root Wall buttons can be activated independently or simultaneously and shown to operate either independently or simultaneously in simulation. Conversely, if one attempts to activate the Shape Tool button (with the other three highlighted), the remaining selected button(s) will no longer be highlighted and simulation will only display a Shaped Tool cut. If so, this would mean that in order to use Shaped Tool cut, it would be necessary to generate G-Code for Shaped Tool cut and then return to the screen and generate a second G-Code for Tangental, Rooting & Root Wall (all three acting as one G-Code program). It would then make sense that the first program to be called up would be the Shaped Tool program. Let that program run to completion and then call up the last program which would cut and finalize the gear. I assume, with little effort, the first program could be easily incorporated into the second program making the two seamless. Is this correct? Please correct me where I may be missing the mark.

5. The last question relates to time. On the left of the screen, when all three buttons are highlighted, it will state a time, e.g., say 15 minutes. If you select, singly, Tangental then time changes considerably; select another and again time changes again, etc. So I assume that when all three buttons are selected, time-forecast is a total time to cut the gear. Is that correct?

6.  Where I am going with this is, Shaped Tool cut is not a component of Tangental, Rooting & Root Wall cuts so one will need to add the time of Shaped Tool cut to the sum of the other three to get a more accurate time-for-completion forecast. Right?

In passing, has anyone noticed that if you separately add given times for each of the three cuts, the sum of the individual numbers do not equal the total time shown if all three cuts are made using one single program?

Harold

[ArtF]

Hi Harold:

>>1. When simulatin g a straight spur gear, it would appear that Tangental, Rooting, and Root Wall cuts (when all three are activated) will clear away all material as the gear is cut and finalized . Stated different ly, though it may be wise and good shop practice, it?s not necessary to perform a Shaped Tooth cut. Is this fundament ally correct?

    Yes. I assume by shaped tooth cut you mean an involute shaped bit? The theory here is to use a mill bit instead, and to first rough ( which is the equivalent of rooting", then finish ( the equivalent of tangental), and finally make good corners on the bottoms of the roots( the rootwall phase). You dont always need all 3, and some shapes should only use rooting.. ( like a pulley), but the putpose of the 4th axis is to either do passes in one spot with an involute cutter, OR to do any or all of 3 replacement stages with a milling bit.


>>2. This brings me to the Shaped Tool button. While quickly going through the 4th axis tutorial, the thrust of what was gathered seems to be, ?the purpose of the Shaped Tool cut is merely to remove (clear away), at the onset, excess material thus reducing wear on the tool and reduce accumulat ive lateral forces that may takes its toll (over time) on the machine?. Is this a fair statement?

  No, the real purpose of shaped tool is to allow a ground tool ( one ground to the tooth  shape put out in the DXF's of the gear) , to be used  instead of end mills.

>>3. Assuming it to be proper protocol and wholesome shop practice to first begin with Shaped Tool cuts, am I correct in assuming that this is a totally separate G-Code *program* that?s generated first and put into operation first, and then a second program is generated using the remaining three, i.e., Tangental, Rooting & Root Wall all of which will be used to cut and finalize the gear in a single, second program?

  Its really either or. The "shaped tool" simply means you have a tool of tooth space shape. We also put out the shape required to do this. This makes the cut much faster of course as you only need center line passes to generate the full gear.


>>4. The reason I ask the question immediate ly above is, the Tangental, Rooting & Root Wall buttons can be activated independe ntly or simultane ously and shown to operate either independe ntly or simultane ously in simulatio n. Conversel y, if one attempts to activate the Shape Tool button (with the other three highlight ed), the remaining selected button(s) will no longer be highlight ed and simulatio n will only display a Shaped Tool cut. If so, this would mean that in order to use Shaped Tool cut, it would be necessary to generate G-Code for Shaped Tool cut and then return to the screen and generate a second G-Code for Tangental, Rooting & Root Wall (all three acting as one G-Code program). It would then make sense that the first program to be called up would be the Shaped Tool program. Let that program run to completio n and then call up the last program which would cut and finalize the gear. I assume, with little effort, the first program could be easily incorpora ted into the second program making the two seamless. Is this correct? Please correct me where I may be missing the mark.

  As above. When you select shapd tool, the others turn off as being unnecessary, as one runwith a shaped tool and the gear is complete.

>>5. The last question relates to time. On the left of the screen, when all three buttons are highlight ed, it will state a time, e.g., say 15 minutes. If you select, singly, Tangental then time changes considera bly; select another and again time changes again, etc. So I assume that when all three buttons are selected, time-forecast is a total time to cut the gear. Is that correct?

  The time shown is an approximation of the total of all toolpaths. This is simply done as total motion divided by the various feedrates involved and then corrected with an approximation of typical acceleration on a machine. Gearotic doesnt realy know your machine so it
uses some approximations , it isnt accurate but gives an idea as to length of process.

>>6.  Where I am going with this is, Shaped Tool cut is not a component of Tangental, Rooting & Root Wall cuts so one will need to add the time of Shaped Tool cut to the sum of the other three to get a more accurate time-for-completion forecast. Right?

No, you wouldnt do both shaped tool and any other process, so its one or the other( the other being up to 3 different operations in total)

>>In passing, has anyone noticed that if you separatel y add given times for each of the three cuts, the sum of the individua l numbers do not equal the total time shown if all three cuts are made using one single program?

    There shouldnt be too much variance, but Gearotic is trying to be cute in its asumptions of extra time involved in coordinating all three
options. But dont put too much store in numerical accuracy on machine time, as I say, Gearotic doesnt know your machine. Its guessing on time.

  Im assuming after typing this that you have a different meaning for "shaped cut" than what is meant. What is your meaning Harold? It may help me to understand any other issues.

Hope it helps
Art


Harold

[Hwingo]

Hi Art and Good Morning!

It?s 0443 hrs (Zero Dark Thirty) as I begin replying to your post. You know, the ?Early Bird Get the Worm?. Like a child on Christmas Morning, anxiety over-powered my Circadian Rhythm triggering this early morning response. Reveille sounded early and I am ?up & at?em?.

Wow, your reply causes this subject to take on an entirely different complexion. Gee, I was totally ?off base? with regard to my thinking and I?m really glad to have broached this subject early in the game.

I knew, from a brief exchange with John S., that it was entirely possible and well within reach to fabricate a ?shaped tool?, e.g., a ?shaped cutter? from a blank lathe-cutting-
bit, and a good place to start was with Gearotic2. He sent a drawing as an illustration.

It never once crossed my mind, although it should have, that the Shaped Tool button, was to be used with a ?shaped cutter? (one such as that which John S. wrote about) *rather than* the small diameter end mill cutter. Well duh  ?? I mean DUH!!!!

So, in one respect I was somewhat, maybe sorta on the right track (if you stretch it a wee bit). I am offered the choice of using a bit that has been shaped and designed for use in a fly cutter (as an example), or I can use a small end mill and either use one of the three remaining options or all three at the same time. Boy I hope I?m now on the ?straight and narrow?. In retrospect, my folly came from seeing the end mill cutter being used when simulating the Shaped Tool process and I simply connected this as a means of quickly clearing away ?real estate?.

Thanks Art.

Harold

[ArtF]

Harold:

Your now bang on. I dont show the shaped cutrter as yet, but it is on my list to create it on the fly for display.
I think you have the full of it now though.. one, two or all three types of passes add up to the gear itself..or as close
as I can come using this type of graphical analysis to generate the path..
  It does have the advantage of all being pretty intuitive and one can figure out what the end will look like
from the stages it will perform. :)

Art

[Hwingo]

Art,

In the legend, at the left of the screen, one finds various useful information. One piece of information that I find useful (I hope) is the maximum size of the end mill cutter, which should not be violated, when cutting the gear. If using one, if not all three available options  (Tangental, Rooting & Root Wall), is it safe to assume that if I don?t exceed the maximum diameter of cutter, even when populating the *Maintain Depth* box, that the cutter WILL NOT cut away material that?s needed to properly fabricate a gear?

Harold

[ArtF]

Harold :

  Yes, thats true. It comes with a BUT however. Always run the simulator to see if it looks as if its gouging.
Its a function of statistics that you cannot be sure something works properly until a set number of tests
are done. As the number of actual users cuts in this process increases, the confidence in the probability
thats the process can fail lowers. This is an exponential function e^-n, but it means I need to know a lot of cuts have
been made. Ive seen many examples of good cuts with this module, Ive seen very few bad ones, and usually
have found the issue ( rotation backwards..etc..).  At this point Im fairly confident of the results. Should
you cut a gear using this module, please post it or at least post a note that you were happy with the results
or less than amused. :-)

    When Im asked how well a module works, I modulate my reply based on my own knowledge of results
across the spectrum of users.

(Sorry for being so verbose, every once in a while I like to remind people to at least let everyone know
results , if not to show them . It isnt for vanity or just to brag, the results play an important part in the game
of confidence I play with the dozens of code modules I often tweak to get better results from. :)

Art

[Hwingo]

Thanks, Art. I think the next move is to get licensed so that I may give this a go.

Harold