[bevinp]

My question relates to using Gwizard interpolation calculations to determine a safe feed rate for hole/curve machining where the end mill radius is close to the radius of the hole/curve. Gwizard requires the user to input a limiting value of acceleration. Does anyone have any idea what would be a safe limit to set for the Tormach 1100?

I emailed Bob Warfield with this question a few days ago, but he might be too busy to provide any advice.

I have a tight inside corner in a profile that I would like to machine with full axial DOC, small radial DOC and high feed rate. I know there are other combinations utilising smaller diameter tool, slow feed, etc but I would prefer the HSM style.

Any advice re 1100 acceleration limits?
Bevin

[TurboStep]

Mach3 for Tormach is configured with a standard acceleration limit of 15in/sec/sec (see attached image). This equates to 0.0388g or 0.381m/sec/sec. I have GWizard set to 0.05g because this is the lowest value that it accepts!
Maybe I’ve been doing something wrong, but I couldn’t make any sense out of the values generated by the acceleration limiting feature when GWizard was set to metric. I tried setting GWizard to inches and I got roughly the values that I was expecting. Maybe I need a holiday
As I would expect Mach3 to take care of the acceleration limit I wouldn’t have given any further consideration to acceleration at all. Am I missing something?

Step

[BAMCNC.COM]

That 109 should be ATLEAST 150 (if series 3)

(Did you read their white paper on the new drivers/steppers)

[bevinp]

Step,
Thanks for the info.
What software provided that time/speed graph? Tormach's Mach3 doesn't seem to have that feature.

No I don't think you are missing something. All controllers must have an acceleration/deceleration setting to ensure motion will not lose steps. So the only thing that needs to be considered when milling an inside corner is the sudden increase of radial tool engagement that might overload the tool, cause major vibration or the stepper to slip. And I assume that is what GWizard calculation seeks to provide.

In regard to its output differing when changing to/from metric, I think some of the parameters may not get converted. For example, the Max Rapids on the Set Up - Basics screen is not converted and while this is not a parameter used, it does show at least one conversion is omitted.

Anyway I will do some manual calcs and just experiment with machining my inside corner to get to where I want to be. It's all learning.

BAMCNC,
Thanks for pointing me to the Series 3 whitepaper. What a great testament to the research Tormach does in designing their products. Excellent. It makes me want to spend the money to upgrade my Series 1 steppers.

And the whitepaper on the selection of the camera used in the Scanner is another example of thoroughness and quality examination of performance before selection.

Perhaps all those posters to this forum, who seek to impress with their self-proclaimed wisdom, expertise, and unchallengeable opinions, and who belittle others, should read Tormach's Engineering documents to re-calibrate their inflated egos.

Bevin

[BAMCNC.COM]

I agree, and as for that graph, look around in your mach folder... You will find another version of Mach, unlocked...

[TurboStep]

Bevin
Sorry but the values shown by the dialog are for the series 3. If you haven't upgraded to the new motors then the values will be different. Unfortunately I don't seem to have an old series II installation anywhere.
I'm not sure where BAMCNC found a separate Mach executable but I have both the Tormach and standard Mach3 applications installed on the same machine. Just copy the xml file across to the Mach3 installation and you have access to the locked parameters. There's no need to bother with the license if you don't actually use it to run the mill. The parallel driver will probably get overwritten so you could install it on any other, non controller machine if this bothers you.
If you're contemplating the series 3 upgrade then I can only recommend it. I was really shocked at the vibrations/resonance from the series II motors and I ordered the update based purely on the aforementioned white paper. I wasn't disappointed. The increased speed is nice but not amazing and I didn't use the series II motors long enough to judge whether the results are better, but it makes the whole experience much less painful But then everyone has decide where their own personal priorities lie.
Step

[BAMCNC.COM]

I did the same as you at first, but the unlocked mach file is there, its just named something else, but still in same folder as the stock mach.exe.

[TurboStep]

What's the name of this executable?

[bevinp]

Thanks Guys,
I will have a look for the accel for my Series 1 and post it if I find it. Maybe I will just ask Tormach... what a great idea !!!

In regard to the new steppers, I will be pressing my nose to the window for some time yet, hoping that one of mine fails preferably without breaking a tool or ruining a workpiece... hoping I am not asking too much from the CNC God. Perhaps we should ask the new Pope to give us a Patron Saint of CNC operators.
Bevin

[dbrija]

That 109 should be ATLEAST 150 (if series 3)

(Did you read their white paper on the new drivers/steppers)

Why do people think this is a good idea? You are pushing the machine beyond what Tormach considers safe and reliable, and for what.. To shave 2 seconds off your total program time? Rapid moves are a tiny part of a typical program.

[David Bord]

Tormach gives that file name in good faith with an agreement of losing your claim warranty rights. Posting it, or passing it on would be... well, not the right thing to do.

If you want to mess with your settings, give Tormach a call. They'll give it to you if you are willing to sign the agreement. If you need the acceleration numbers for the calculator, Im sure they would pass that along.

David

[BAMCNC.COM]

Why do people think this is a good idea? You are pushing the machine beyond what Tormach considers safe and reliable, and for what.. To shave 2 seconds off your total program time? Rapid moves are a tiny part of a typical program.

I'll take that as you didn't read those papers, please read them before you claim I'm pushing it beyond the limit, I'd appreciate it.

Also all of my Acceleration settings are "15"

[SCzEngrgGroup]

I'll take that as you didn't read those papers, please read them before you claim I'm pushing it beyond the limit, I'd appreciate it.

Also all of my Acceleration settings are "15"

Did you read the footnote on page 6:

"2 The curious observe might wonder why we didn’t stay with 375 lbs reserve and increase the machine speed even further. The answer is that higher speeds, in the vicinity of 130 to 150 IPM, approach mid‐band resonance frequency. Mid‐band resonance is a subject beyond the scope of this paper."

On top of all the other valid justifications they give in the paper for their choice, this seems to me like a very good reason for setting the limit where they did. Mid-band resonance can easily cause a stepper to miss steps, or even stall, when it would appear, on paper, to have plenty of reserve torque. It's a very common cause of unreliable operation in poorly designed stepper systems, and it appears you're putting your rapids right in the middle of that range. Simply passing through the mid-band resonance range, on the way to higher speeds, can easily cause lost steps. Operating for any length of time in that range is especially risky from a reliability standpoint.

Regards,
Ray L.

[David Bord]

Good point Ray. Tormach is also a company that puts stone cold reliability ahead of squeezing everything out of the machine.

I was speaking with one of the Tormach engineers a couple days ago, and it still blows my mind the level these guys to make sure the product is well engineered and every stone is un-turned.

I work for one of the largest and most succesful hi-tech companies in the world and Im used to dealing with smart people in engineering. Tormach has the same level of commitment to producing world class products that we do.

David

[dbrija]

I'll take that as you didn't read those papers, please read them before you claim I'm pushing it beyond the limit, I'd appreciate it.

Also all of my Acceleration settings are "15"

I have read the white paper, and I understand why Tormach made the choices they did. I was approaching this as more of a "return on investment" thing. You can test and tune to try to max out rapid speeds, but what is the real net gain (both immediate, as in speed, and long term, as in driver or stepper failure)?

This is not an industrial class machine, so maxing things out really does not make sense (to me at least), even if you are doing production runs. I am perfectly happy to make chips at 110IPM rapids and not worry about lost steps...

BTW, I wasn't picking a fight. I was genuinely curious why folks choose to push to the edge on rapid speeds (i.e. do you do long 3D program runs, large part volumes, or just to tinker..):cheers:

[BAMCNC.COM]

No problems as of yet with 150, I've went to 180 with no noticeable difference in sounds or lost steps, but I'm not manly enough to run at that speed with a .03" clearance plane, just yet.


Rapids play a HUGE part in anything I do with multiple tools, as I have the ATC the Z has to go all the way up to change a tool. I can make better parts using more tools, so any extra rapid speed helps A LOT more than you would think. If I didn't have ATC then your right, its kind of a waste of time.