Hello Guest it is March 28, 2024, 11:32:52 AM

Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.


Messages - nicad

Pages: « 1 2 3 4
31
Mach3 and G-Rex / Re: Mach4 - couple of quick questions for Art.
« on: March 07, 2006, 02:27:19 AM »
Hello...?
Can any one answer the vectoring question?? it is the main deciding factor on purchasing a Grex...

32
Mach3 and G-Rex / Mach4 - couple of quick questions for Art.
« on: February 15, 2006, 04:47:21 PM »
Art-
As I understand it, Mach4 outputs "curves" at a rate (1/64 sec?) that results in prominent vectoring of the curve at anything above a slow feedrate. If I am post-processing all my curves into very short line-segments (~0.002"), will Mach4 + Grex be able to output this smoothly at a quicker rate?

Also, The Grex has a USB and an Ethernet port. The USB is for flashing of the firmware only and the ethernet is for motion control commands (correct?). Will this always be true? It would seem that a direct USB link would be more "fail proof" than an ethernet network.. but I am just thinking out loud here.. :)

Thanks-
Colin

33
G-Code, CAD, and CAM discussions / Re: M98 & 99
« on: February 14, 2006, 12:40:33 PM »
I have seen this same thing in Mach3. It will not show or get to the last line, which so far has always been M99 or M30.
One time I simply edited the code and put a couple of <enters> after the last line, and that actually fixed it.
Other times it still ignored it.
It also seems to make a difference in how you start the program.. but I haven't nailed it down yet.

34
Art-
Good to hear that Mach3 does function this way. Was starting to think I might be a mad man out yelling in the streets.. :)

But there is still something awry causing the slow accel.
Feedrates are reached fine-- it is the acceleration that is dragging.

Example-
I want to cut a spiral on a cylinder that has a pitch of .1" for 4 revolutions.
Code: [Select]
N1 G0 X0 Y0 Z0.5 A0
N2 G1 X-.4 A1440 F20

If I had to guess I would say it takes about 3-5 seconds to get up to the 20ipm on this cut (N2), then another 3-5 seconds to slow down to a stop at the end.
If I were to run A from 0 to 1440 by itself, it would take off quickly like normal. Likewise, moving the X axis from 0 to -.4" at F20 would be a snap.

It happens with both G0 and G1 commands (These are the only commands I use for mixed A-axis and X/Y/Z axis moves).

Another example-
I cut a lot of contoured work on the rotary axis.. some of it roll-cutting (A-axis rolls while Z-axis contoures, then after 360*, X axis steps over a slice and then another roll of contour cutting). Some of it gets very complex with many many lines of points to hit per roll, and every time the Z axis changes directions, the Z and A slowly grind to a halt and then slowy take back off. Doing this a couple thousand times on one part can add an hour of slow accel times.
Rough example:
Code: [Select]
N1 G0 X0 Y0 Z1 A0
N2 G1 A10 Z.9 F50
N3 A12 Z.7
N4 A15 Z.69
N5 A20 Z.8
N6 A26 Z1

N1: prepair to cut
N2: slow accel of rolling A and lowering Z
N2: keeps speeding up with the rolling A and lowering Z
N3: will probably be slowing back down by now
N4: has slowly ground to a halt
N5: slow accel of rolling A and raising Z


last example I can think of for now- rapids for positioning:
Code: [Select]
N1 G0 X0 Y0 Z2 A0
N2 G0 X5 Y1 Z2 A0
N2 G0 X10 Y2 Z2 A20

N1: set the stage
N2:  All axis accel rapidly and move to destination.
N3: All axis take many seconds to accel up to full speed, and likewise to accel back down to a stop.

This is on a MaxNC machine (dont laugh, its been modified beyond its wildest dreams! :) ) and in no way do I think that its old software is better than Mach.. but It did handle A+X/Y/Z motion with out this slow accel, So I know it can be done (and you would be the man to do it!).

Any ideas? :)
Thanks

35
Art-
I have asked about this in the past via email... You had made a "change" to one of the mach2 6.11x versions, but it didn't help any.

The problem that I see is that Mach is calculating accel rates based on a unit/sec^2, which is fine if all of the axis were the same units.
Yep, you guessed it. I am talking about simultaneous  rotary + linear motions accelerations.
If Mach calculated accel rates based on STEPS/sec^2, it would remove units from the equation.

my setup:
X/Y/Z axis resolution: 16,000 steps/unit (unit = INCH)
X/Y/Z axis accel: 17 units/sec^2

A axis resolution: 400 steps/unit (unit = DEGREE)
A axis accel: 500 units/sec^2

When a move involves both the A and one of the linear axis, I know mach defaults to the slowest accel on all the axis involved. This results in ~ 30 TIMES slower accel on all axis (500 is used in place of 17 to be "safe"). I agree with the "safe" algorithm, I do not agree with the numbers it is looking at.

IF Mach used steps/sec^2, I would have:

X/Y/Z axis resolution: 16,000 steps/unit (unit = INCH)
X/Y/Z axis accel: 272000 STEPS/sec^2

A axis resolution: 400 steps/unit (unit = DEGREE)
A axis accel: 200000 STEPS/sec^2

This is the exact same config, but using steps instead of units (same accel and resolutions). The accel calcs would operate properly all the time. (272,000 is VERY close to 200,000) Which would perform as it should.

This is killing me. It it taking at least 10x longer time to cut the same part because of it.

Please help! :) :)



(yes I have set my "rotation diameter".. it does not fix it) :-/

36
General Mach Discussion / Re: Angular axis A
« on: February 13, 2006, 04:39:07 PM »
I would not trust G92.. I have had it ignored once too many times at random in code that works most of the time.

Acceleration rates are being calcualted based on a unit/sec^2 scale.. It causes problems when simultaneous angular and linear axis moves are made. Mach needs to calculate acceleration in STEPS/sec^2, like I other control software does. take units out of it...
The way it is now, you woud have to have ~115" diameter object in your A-axis (pi*115 = ~360) for "units" to be the same...

But alas, I will make another thread about this and see if I can get Art to change it.... after asking many time before.. :)

37
G-Code, CAD, and CAM discussions / Re: G92 does not always take.. why??
« on: February 06, 2006, 12:46:05 AM »
Art-
Nope- always on its own line.
It works most of the time.. but every now and then it won't. same code, just random.
here is a segment of the exact code (beginning of the program) where it happened today:

Code: [Select]
G40G49G80G64G90
G0 Z1.5
X0.125 Y0 Z0.86
G1 X-1.2 A2520 F90
A2880
G92 A0
X-0.0059 F80

After this, A may still be 2880, or it may be 0.
If I run it step-by-step mode, it will always work correctly.
When running through normally is when it might ignore it.

I have also had this happen in the past on a Y axis re-setting to 0 (in Mach2 V6.11)

Any ideas?? :)

38
G-Code, CAD, and CAM discussions / G92 does not always take.. why??
« on: February 05, 2006, 05:56:47 PM »
I have observed this problem in Mach 2 6.11 and now just happened to me today with Mach3.

G92 command randomly gets ignored. G92 should change the designated axis to the value given (no movement).

Example:
G0 Z1
G92 Z0

Most of the time Z will be 0 after this, but sometimes, randomly, Z will still be 1.

why??

39
General Mach Discussion / Re: Angular axis A
« on: February 03, 2006, 02:22:26 PM »
That sounds right.. mine also keeps going. Most of the time I want to know how many times I have revolved anyhow.. rolling from 359 -> 0 would loose that information.

now, the way Mach treats degrees as a unit does not seem right (feedrates, acceleration, etc..). but I can live with it for now (Grex.. muahaha!) :)

40
General Mach Discussion / Re: How can I adjust the speed of Jogging ?
« on: February 03, 2006, 02:18:55 PM »
I do not know what version of Mach you are using, but I believe at least on all of them, if you goto the Diagnostics screen, it will have the jog speed listed as a percentage (of your max speed). you can change this by either clicking the buttons with the mouse or hitting the "[" key.
The "]" will increase the jog speed.

on a side note, holding the SHIFT key while jogging will override to full jog speed. Make sure you shift key is not stuck (has happend to me in the past-- got another keyboard!!).

Pages: « 1 2 3 4