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Messages - Sherwood

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81
General Mach Discussion / Re: Looking for good DIY controller kit supplier
« on: November 24, 2020, 08:43:20 PM »
Test run not successful for X Axis

The A axis and X axis pin numbers were swapped in Config - Ports and Pins - Motor Outputs. The X axis now has Step Pin 2 and Dir Pin 3
I entered the updated Motor Tuning values with X and Y veloc as 2000 and Z veloc as 4000.

X axis does not function, Y and Z axes function well. Nil smoke, nil motor heating

Is there another setting in (maybe) Ports and Pins that has to be altered?

82
General Mach Discussion / Re: Looking for good DIY controller kit supplier
« on: November 24, 2020, 08:33:43 PM »
Let's try

83
General Mach Discussion / Re: Looking for good DIY controller kit supplier
« on: November 24, 2020, 08:18:41 PM »
will do all that.
Following the same rationale, could I set the Z axis speed at 4000?

84
General Mach Discussion / Re: Looking for good DIY controller kit supplier
« on: November 24, 2020, 05:42:46 PM »
I'll reset the stepper values and set the max speed at 1000 as you suggested and re-assemble the machine for a trial run. I'll follow up all your suggestions. Dave was not able to give me the info required so I'm flying blind on original feed specs.
Will let you and TPS know how things went.
Much thanks and appreciation.

85
General Mach Discussion / Re: Looking for good DIY controller kit supplier
« on: November 24, 2020, 04:57:35 AM »
Aaaaah, MN300, just got educated on thread starts .... thanks for that. Took the other 2 motors off and lead screws out and had a look at the ends of all the lead screws. Both the X and Y lead screws have two thread starts and the Z lead screw has 4 thread starts.
So the steps per mm for the X and Y axes are 200/2.54=78.74 divided by 2 (thread starts) = 39.37 steps per mm.
For the Z it is 200/1.6=125 divided by 4 (thread starts) = 31.25 steps per mm
Fairly close to the present profile figures.

So X and Y speeds double and Z speed quadruples.

How should I configure the axes motor movement profiles; just enter the steps per minute as calculated?
And what velocities and accelerations would be best; tune them so that the motors and gantries run smoothly?
Are there other config adjustments to be made?

Now to Feed Rate; once again a steep learning curve. Please correct me if I'm wrong.
So the G code for Feed Rate is F, say F20, F60, F1500 etc, and the F value is always per minute: i.e. in my case F60 is 60 mm per minute or F125 is 125 mm per minute etc.
Is that correct?

So I can set the Feed Rate (F value) to reflect the speed my motors can handle and that is why you are questioning which max speed they can handle .... is that correct?

86
General Mach Discussion / Re: Looking for good DIY controller kit supplier
« on: November 24, 2020, 02:20:14 AM »
The 78.---- value makes sense. I've only been playing with roadrunner.tap, the file that comes with Mach3. I am so far not up to speed with what the codes mean. There is an F60.000000; would that be it?

87
General Mach Discussion / Re: Looking for good DIY controller kit supplier
« on: November 23, 2020, 10:53:38 PM »
I only noticed a hot X axis motor the last time the TIP blew up. The Y and Z motors were cool. I did not feel the X motor temp the first time the TIP blew up.
All three motors measure a resistance of 1.4 ohm across 5/1, 5/2, 5/3 and 5/4. So if the X motor is shorted, then the Y and Z would be as well ..... I hope not.

I have sent another email to Dave, but he seems very reluctant to give specifics on this motor as it is a proprietary product. I have asked him for the name of the manufacturer for whom they manufacture this product, hope he'll give it to me.

Yes, I was confusing the TIP120 with the PIC16F84A-201/P. Good to know I could still swap the TIP120 with a 122.

The motor settings have always been a mystery to me. How is it possible for instance for 200 steps (1 full revolution, 360 degrees) to move the X axis 2.54 mm (screw pitch) and yet the 'X Axis Motor Movement Profile' states that the 'steps per mm' is 39.2343239, which is approx 5.1 mm per full revolution. I've always just accepted it as a Mach3 internal mystery. Now if, as TPS says, the settings are not 'real' than the velocity, acceleration and other settings would also be unreal. What are the generally expected values in motor tuning; how do I arrive at correct values?

Unless you have real misgivings and would like me to check the resistances or anything else with a different instrument, I will assume that the motors are still functioning normally. So then the only issue to be resolved before I 'fire up' is the speed; maybe in the Motor Tuning setting ...... I need help there. The 'steps per (mm)' in the 'X Axis Motor Movement Profile' window are arrived at automatically by 'Calibrating the Axis' under the 'Settings' tab in Mach3.  I follow the steps after activating the 'Steps per Unit' button, and the calculator inserts the 39.---- value. I do this a few times to reduce the error as far as I can and then tweak the acceleration and velocity till the gantry movement is smooth. Is this the correct procedure; could there be an error elsewhere in the settings??

And then there is the 'working' speed' ... it seems so very slow. Is that because it is a unipolar slow machine?

88
General Mach Discussion / Re: Looking for good DIY controller kit supplier
« on: November 23, 2020, 08:15:56 PM »
Dave from Lin Engin confirms what we know so far but adds that 'If the motor windings get overheated the insulation on the windings can begin to break down over time leading to shorting or performance issues'. Could be possible that has happened since the TIP120 burnt out; but the motor ran cool before that. What is 'shortening'?

I have averaged the Z lead screw pitch over a few distances and come 1.606 mm, so 1.6 mm is not too far off. This lead screw has the smallest diameter.

MN300, 1000 mm/min travel, should that be 100 mm/min? TPS looked at this issue on a different post and we tested the metric distance travelled against the line  G1X100 F100 starting X at 0; 100 mm or 10 cm took exactly one minute. I must say that I do not really understand the issue with the Mach settings, would either of you please explain them to me.

If the required pulse is determined by the PIC120, would replacing it with a PIC122 change the pulse duration and strength? How would that affect the motor?

89
General Mach Discussion / Re: Looking for good DIY controller kit supplier
« on: November 23, 2020, 06:14:26 AM »
The lead screws are directly attached and in direct line with the motor shafts so one turn of the motor (200 steps) is one turn of the lead screw. The X and Y lead screw pitches are 2.55 mm each and the Z pitch is 1.61 mm. There is some error in this reading as my calipers are quite cheap and loose. The error may be 0.05 to 0.1 mm. I will reduce the error tomorrow as lighting is not great in the shed at night.

90
General Mach Discussion / Re: Looking for good DIY controller kit supplier
« on: November 23, 2020, 01:13:41 AM »
Much to learn.
Originally, the CNC was built to be run on a Mach version called MaxPath42 but I installed Mach3 instead. The machine has never been used to do a job as I was learning to understand the processes. I got as far as setting up the configs, motor tuning, jogging, setting Soft Limits, loading up G Code and "Cycle Start' dry runs in Mach3. It was then that the TIP120 burnt out ......smoke galore. The X Channel had only 3 out of 4 TIP120 installed as the 4th one was loose in the circuitry box. We installed both the loose and a replacement TIP120, tried again and after some 4 hours the same thing happened ..... again plenty of burning plastic, with a very hot X axis motor. The Y and Z channels and motors were fine.
The machine jogged at what to me was a good speed, but when in 'Cycle Start' mode, at an absolute snail's pace.
I have emailed Dave from Lin Engineering to see if the readings are within specs and for more info on motor characteristics with this wiring configuration; I expect an answer hopefully by tomorrow. It'll be interesting to see if the motors are functioning within specs.
So what I understand you are telling me is that with these readings, the motor would draw a current that can not be met by the circuitry without causing some damage to the TIP120 unless the pulse length is controlled. Would that be a circuitry function or an original setting in the MaxPath42 config, which I may not have picked up in the Mach3 settings? If circuitry, no wonder MaxNC went bust.
Heat build up could be a problem with temps here in the good land of Oz reaching the high 30s Celsius, so opening the box an applying more airflow can be arranged.
Limiting or reducing speed further than it already is in 'Cycle Start' mode would maintain a snail's pace or bring it to a virtual stand still. This issue may be related though to the issue TPS has just raised yesterday re the Motor settings not being 'real'. Could we go into that further, TPS?
I would prefer to wait with the trial run till I've received all info, just in case I blow the A Channel now used as the new X Channel up.

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