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Mach3 Major Bug?
« on: June 21, 2015, 08:30:31 PM »
Hello all,
I am trying to pass a value from a script to Mach3. The Value is 13.846153846154. However, instead of passing this value it passes 13.8567. The value is the actual position that Mach will go to based on the Steps per Unit defined in the Motor tuning section. Now the issue is, this would be fine if it was a one off amount and wasn't used in additive functions or for that matter any arithmetic based function in your program. I use these passed values in a number of intense mathematical on the run equations that are duplicated upwards of 3-400 times per program.
The error that is generated due to this incorrect passing of value gets to the point that Mach3 is becoming useless as a program in any real accurate program cutting of parts.

My Question is.... Is this the correct way Mach3 passes values? or Am I missing something in the setup or the script writing in passing Values.

I use a few of the included Wizards to generate internal Polygon Shapes and have found that theses also generate the error in accumulated movements.
And No backlash has long since been eliminated ;-)

Wes

Offline BR549

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Re: Mach3 Major Bug?
« Reply #1 on: June 21, 2015, 08:39:51 PM »
SO lets see your script. It all depends on what you are doing in the script and HOW you use the values.

NOW can you measure 13.846153846154 to insure that it is accurate ?? Can your machine CUT it to that degree ?

Remember that Mach3 is a $150.00 DIY controller running inside of windows (;-) There are concession that were made to make it all possible. ONe of those is accumalative moves. IF mach canot make a small move that is LESS than a single step then it adds it to the next move in the que and so on.

What is the minimum resolution of a single step for your setup ?

Post your script for review.  

(;-) TP
« Last Edit: June 21, 2015, 08:43:43 PM by BR549 »
Re: Mach3 Major Bug?
« Reply #2 on: June 21, 2015, 09:12:52 PM »
Hi TP,
Not trying to be nasty, just asking for an answer to a basic flow process of Mach3.
The GCode and Script can be found here - http://www.machsupport.com/forum/index.php/topic,29895.0.html.
The measurement of 13.84615 or 13.8462 is actually degrees, and as I indicated it actually goes to 13.8467(hence the steps per degree is 355.5555555556). That in itself is not the issue. the issue is the accumulated effect of adding this value around the circumference of a Circle. This value is for a 26 Tooth gear, when you process this to a 233 tooth gear the amount in accumulation is quit high for practical use. When you pass the 13.84615 value around it remains within tolerance.

Wes
Re: Mach3 Major Bug?
« Reply #3 on: June 21, 2015, 10:55:00 PM »
I think I may have found a work around.

At this point in the Macro

Dim Gear1 As Double
Dim AxisCut As String
Teeth = Question ("How Many Teeth on the Gear?")
Gear1=Val(Teeth)
SetVar(6,Gear1)
Gear1 = 360/Gear1
Print Gear1
SetVar(1, Gear1)

I changed it to this

Dim Gear1 As Double
Dim AxisCut As String
Teeth = Question ("How Many Teeth on the Gear?")
Gear1=Val(Teeth)
SetVar(6,Gear1)
Gear1 = 360/Gear1
Gear1= Round(Gear1,4)
Print Gear1
SetVar(1,Gear1)

Basically rounding the value down to 4 Decimal places gives me 0.003 of a degree maximum variation. Im thinking it might be a rounding issue or not being able to handle large value decimals in the Variable.
Your Thoughts?

Wes

Offline BR549

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Re: Mach3 Major Bug?
« Reply #4 on: June 21, 2015, 11:45:37 PM »
I did not take it as nasty(;-) I just needed a bit of perspective as to how you were using the values.

 SOMETIMES I get a question like this and they have build a presicion CNC out of 2x4s using threaded rod for screws and complain about not getting 0.00000000001 accuracy cutting nylon and they know it for sure because they have a $5 plastic caliper and the part is not coming out to the .0000001 in a shed that is at about 200deg F and 96% Humidity. (;-)

YEP you found one of the answers the other would be to use format . The actual values that mach3 use internally are very large decimal wise. TO use them with YOUR accuracy you have to intervene and set the needed resolution or limit the rounding as you did. Otherwise Mach may just rounds UP to the DRO display resolution.

To be sure I would round to the 5th instead of the 4th. GEARS need to be precise.

I like your thinking (;-)

(;-) TP

Re: Mach3 Major Bug?
« Reply #5 on: June 22, 2015, 12:11:54 AM »
Thanks TP.
I did try the format function first, however the results were unpredictable. May have been the Format is was using (I think ##,##00).
I will try the 5 digit and see if it makes any appreciable difference. I initially used 4 as that was all the DRO's show.

And yes I can appreciate the $5 dollar caliper standard. I actually had a customer complain about a job i had done for him because his Calipers(yes they were Chinese plastic ones) indicated I had machined a part over 2mm Larger then he wanted. Stupid me, i should have used his calipers to make it ;-).

Wes
Re: Mach3 Major Bug?
« Reply #6 on: June 22, 2015, 01:03:16 AM »
Ok Final Test.
Changed the 1024.set A Axis DRO to 6 decimal points and the Round function in the Macro to Match.
on a 705 mm Dia Gear with Mod 3 gear cutter at 2214.822821 mm Circumference, each tooth is accurate to .012 mm max( In theory)

I believe the rounding is the way to go on this one, and i will leave the 1024 A Axis set to this so i can verify as i cut
on the smaller 1-300 mm gears.

Thanks for the inspiration TP, sometimes we just need to step away from these things for awhile and the answer will be there when we get back.

Wes

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Re: Mach3 Major Bug?
« Reply #7 on: June 22, 2015, 10:08:24 AM »
HIYA Wes, I am glad you got it sorted out. Mach3 was built for the general DIY users and there are many things based on general DIY CNC knowledge. BUT mach3 is capable of PRECISE ACCURACY if you know how to extract it.

Good job on the gear work.  Have you tried Arts Gearotic motion program ?

(;-) TP
Re: Mach3 Major Bug?
« Reply #8 on: June 22, 2015, 08:15:08 PM »
Yes, I have had a look at it. Some of the information and design features are brilliant, however not having tried the cutting function I would be remiss in passing judgement.
I would think it would be great for small RC gear cutting and GoKart gear boxes and such, and certainly for low production 1 off assemblies that don't require low noise gears.
And as you can see, I am only looking at it from my background in engineering.

As to Mach3/4 being DIY, I believe those days are gone, as I am seeing more and more Taiwanese, Chinese, American, and Australian products brought of the shelf incorporating Mach3 as the Control software. Even a lot of the questions on these forums relate back to store bought Mach3 configurations. It is a problem with Good after market software, eventually it gets used in commercial stuff, and the robust nature of its design come to the fore. From that stems the inevitable intellectual/legal lock down of the software.

Also TP, I put up a macro used while trialling the Number features of Mach Cypress Basic. It becomes quite interesting when you put in large decimal place numbers.
I.E. what rounds up and down and where the cutoff point is.

Wes

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Re: Mach3 Major Bug?
« Reply #9 on: June 23, 2015, 12:33:44 AM »
HI Wes,  The problem with Mach3 as a Commercial contoller is there are a good number of bugs and odd things left in Mach3 that can ruin parts and break tools and tear up hardware.

Tool comp has problems, Subs have problems G2 and G3 CAN have problems . The Z is know to run away from time to time(;-)

AND it will never be fixed (;(

There are also OEMs packing up and leaving Mach3 because there is no hope for it to ever get fixed. In mach3's  idles years the competition Zoomed right on by .

SO I leave it classed for simple DIY users (;-) , There is does well.

(;-) TP
« Last Edit: June 23, 2015, 12:47:00 AM by BR549 »