Machsupport Forum
Mach Discussion => Mach4 General Discussion => Topic started by: Flying Scot on March 13, 2020, 06:39:51 PM
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I have just finished a router with Nema 23 motors driven by Gecko 251 drivers controlled by an ESS with MB3 breakout board with Mach4 running on 24v.
In motor settings I have steps set to 250/ unit , acceleration 60 and velocity various settings right up to 3000mm/min.
Dimensions are accurate for the 8mm leadscrew
The highest speed I can achieve on all axis is about 500mm/ min.
Should I be able to get any higher speed with this setup?
Maybe it has been a poor choice of steppers and drivers.
Art
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Try upgrading your power supply to 48 volt. Best case your maximum velocity could almost double.
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Hi,
I agree with Steve, use the highest voltage power supply your divers will tolerate. Geckos have a superb reputation for
reliability, if they say 80V...then use 80V.
What model steppers do you have? In particular do you know the inductance? It is a little understood fact that the inductance
of a stepper determines how badly the torque will degrade with stepper speed.
Most stepper manufacturers make high holding torque (desirable) steppers but with commensurately high inductance (highly
undesirable) because they can make them cheaply and thereby appeal to first time buyers.
If you absolutely require the fastest possible axis speed then you will probably have to replace your steppers with the
LOWEST POSSIBLE inductance. This might mean that a (say) 300 oz.in stepper of 1mH inductance is a better choice
than a 600Oz.in stepper but 6.8mH because the smaller stepper will still have useful torque at 1000rpm whereas the bigger
one stalled at 300 rpm.
Craig
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Thanks for your replies.
Raising the voltage to 48 volts has made no difference to the speed. The inductance of the motors are 3mH and they are 2.8A motors. I have them set to 2.7A as I only had 2.7k resistors.
Maybe I am expecting too much but looking at some videos of similar machines on youtube my machine seems much slower.
Art
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While 3 mH is not great, neither is it that bad. With your setup I would expect 1000mm/minute or better, possibly even 2000 mm/minute.
When you state that 500 mm/minute is the best that you can get, do the motors stall or simply refuse to go any faster? If stalls are the issue, try running the motor with it not mounted to the machine and see if it will go faster unloaded.
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Hi Steve,
They just refuse to go any faster. They are very smooth no skipping steps or stalling.
I remember setting up my mill and lathe on mach3 many years ago you could make them skip and stall but that was a very different system.
The machine is a workbee router but I decided not to use the duet controller. I did see that with the duet a rapid of 2000mm per min was possible.
Art
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If the motors keep running at 500 mm/minute but do not stall, then I suspect a configuration error, possibly in your ESS setup.
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Hi,
the ESS plugin has the ability to assign motors to axes and output pins of the ESS but it has NO motor tuning
features, motor tuning is the sole responsibility of Machs Control plugin.
Craig
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I must admit to not being very familiar with the details of setting up a SmoothStepper, especially with Mach4.
There was an option for "Controller Frequency" in the configuration menus for the Mach3 plugin and that could influence how the SmoothStepper generated pulses. It seems that is no longer present in the Mach4 plugin configuration, so it should not be an issue.
I am still curious if Mach4 thinks it is moving the motor faster than 500 mm/minute. In Mach3 there was an on screen DRO showing the current instantaneous velocity. Is there an equivalent in Mach4 that I am overlooking?
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Hi Steve,
In Mach3 there was an on screen DRO showing the current instantaneous velocity. Is there an equivalent in Mach4 that I am overlooking?
Yes, there is, see attached.
I think your suggestion is good...to OP: MDI some commands, for instance g0 x300 (assuming mm units here) and observe the feed rate
DRO. Does the DRO show what you believe to be the correct G0 rate?
How about MDIing g1 x200 f300....does the feed rate DRO show 300mm/min. If not, why not?
Craig
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Dang it, I had assumed that DRO showed the requested feed rate, not the actual. 8-(
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Thanks Steve and Craig,
Using MDI and using G1 x200 f100 the speed is about 100 but the dro is random numbers.
Increasing the feed to f200 the speed of increases but dro still random. This can be done up to f500 with speed increasing to 500 but when f is increased to 600 or higher there is no change in speed dro still random.
Art
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I could not figure out what was happening so I decided to hook up the router to the pc driving my mill on mach 3 which has been running well for over 10 years on xp.
After configuring and setting up only 1 axis on mach3 to test I can push the motor to just under 2000mm/min on 24 v and 3700mm/min on 40v. Feed dro quite stable.
It would appear that it is mach 4 problem as this was with the ESS. Only other difference is mach4 is running in Windows 10.
Any idea where I could be going wrong?
Art
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It is probably time to ask Andy from Warp9 to connect into your Mach4 system using remote access and maybe he will spot what is wrong.
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Hi Steve
The machine on mach3 can now feed up to 8000mm per min now.
My mach 4 machine only has a single ethernet port and no internet access in the workshop. I will drop him an email
Art
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Okay nearly there.
I have reinstalled mach4 and ess using the SCU Application tool on the Warp 9 website with the latest versions of Mach4 and ESS plug in. All motors are now behaving perfectly up to 2000mm / min on 24v. (I may increase the driver voltage to 48v later)
The only problem remaining is the feed dro is showing random numbers but on mach3 it is steady.
Art
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Hi,
the feed rate DRO should be an accurate representation of the current actual speed but may not, in fact seldom is, the same
as commanded speed.
If I commanded a g1 of 1000mm/min I would expect that when the axis reaches constant speed, that is after the acceleration phase,
that the feed rate DRO would display anywhere between 950 and 1050 mm/min say.
Craig