Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: studysession on January 23, 2011, 12:27:55 AM
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I understand speed of the motors are controlled by velocity and acceleration. How do I make my motors go faster without them stalling on me? I see other machines cut really fast and mine seems slow in comparison when I see machines in videos.
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Lots of ways and all will depend on what you have but bigger motors, higher voltage if your drives allow, less gearing between motor and screw, bigger pitch screws are a few of the ways. Servos however may be the only way to get real speed, depends on what machine you have whether it would be justified.
Hood
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Hood,
Think you meant to say smaller motors ;)
Dan
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Have a look at the motor curve....if one is available for your particular motor. It will provide a torque to motor pulse /rpm curve based on some voltage and also for different wiring of the stepper.
From that you pick where you will have the most power or where you will be on the curve. That tells what can be expected in terms of torque to motor rpm. You need to relate that to your intended use of the machine. You have what you have and cannot compare to someone elses machine and can only do so much. Speed is useless if there is no reliability.
Now if you were starting from scatch, you define the intended use of the machine and design accordingly.
IE; - define the desired axis feedrate / IPM
- define the desired resolution
- define the cutting that will be done
- find a motor which can provide for the above ( a stepper may not work and you need to go to a servo )
- based on the above, check that the other parts of the system ie; computer, power supply and drive are correct for the application
All the above may not work so it becomes a compromise of them all.
Have a look at this for a flavor of the above:
http://www.machsupport.com/forum/index.php/topic,12484.msg80824.html#msg80824
There is nothing wrong with duplicating someone's machine that is very similar to yours but one needs to understand any differences between the machines and how it
may affect your outcome.
RICH
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How do I make my motors go faster without them stalling on me?
As Hood says, the only way to make the motors spin faster is to use a higher voltage.
But, to get the machine to move faster, the drive system needs to be designed so the motor spins SLOWER, where it will have more torque.
Can you tell us what pitch screws your using, as well as drives. power supply, motors, and maybe a pic of the machine?
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Hood,
Think you meant to say smaller motors ;)
Dan
Not at all Daniel, could be either just depends on the machine and the motor now. Smaller motors will rotate faster but they may need more gearing, larger motors will rotate slower but may not need any gearing.
The question asked is really meaningless without knowing the setup and type of machine.
Hood
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Here is his machine and some more info:
http://www.machsupport.com/forum/index.php/topic,16875.msg114422.html#msg114422
RICH
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Attached is info on the motor but no curve that i could find.
RICH
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Doesn't say what drives he's using, but the real killer is the 1/2-10 acme. Switching to 1/2-8 2 start or 1/2-10 5 start will give much greater speeds. I can get 190ipm with 1/2-8 2 start and 24V with a Xylotex, with slightly smaller motors, on a bigger machine.
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how are the motors wired?, what's the drive current set to?, what motor voltage are you using?
T curves for your motors attached.
Ian
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WOW! Thanks for all the replies!
I have the 2x3 gantry router from here:
http://www.finelineautomation.com/
I am using Acme 1/2-10 screw with NEMA 23 BIPOLAR STEPPER MOTOR 425 oz-in KL23H286-20-8B motors on all three axis.
http://www.kelinginc.net/NEMA23Motor.html
I have everything setup as direct drive. They are wired as bipolar series on the PDF file.
http://www.kelinginc.net/KL23H286-20-8B.pdf
The velocity is set to 10 and acceleration is set to 7. If I go to much higher meaning 12 or 13 it stalls.
I am using this 3 axis board and it is currently set to 1-full step
http://celticmachining.com/2x3-machine/mach3-settings.htm
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Right now everything is running really wel and accurate - just very slow. :)
Thanks for all the help!
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Currently I am using this power supply
http://www.radioshack.com/product/index.jsp?productId=2103959
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My thoughts
Using a voltage nearer the 36 volts max of the drives should help a lot,
Setting to 8 microsteps should help smooth things out.
The power supply you are using is a bit on the neat side for current, would be better another amp at least I would say.
Screws with more pitch/starts would also help.
Hood
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Your biggest problem by far is that power supply. You should be up around 30-35V for best performance. Your drivers are limited to 36V, which is kinda low, but you want to stay a little below that, for safety.
Regards,
Ray L.
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BTW, with better drivers, like Geckos, and a higher voltage supply, you could almost certainly go much faster...
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Thanks!!!
I am saving for a Gecko 540 and better power supply.
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yep - you're in all sorts o doodoo with your combination of things. If speed is your quest then for starters you'd be better off wiring parallel. For 3 such motors as the KL23H286-20-8B in parallel you want PS and drive setup capable of around 5.6 to 6A (total). @ around 83V.
Driving them in serial - waaaaay undervolted is not going to get these puppies singing. BTW your KL23H276-30-8B motors (pictured in your other thread) are more beefy but no way you're going to drive them with your current setup. Just mentioning that so if you decide to up your PS/drivers - personally I'd go with these other motors instead.
Ian
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Current plan -
Rewire for parallel instead of serial??
Future plan to increase speed
Gecko 540 and what voltage/amp power supply using the motors I am using??
These are my beefiest motors. I don't have motors any bigger than these.
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THANKS EVERYONE FOR THE HELP!!!!!!
:) :)
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As Ian says, you've got a bunch of bad performing parts that can't work well together. You'd need to change at least 2 of the 3 to get decent performance. I'd change all 3.
1) 1/2-10 acme - Requires the motors to spin too fast, where they have little torque. Best case with 1/2-10 acme is usually 80-100ipm max.
2) The 425oz motors are very poor performing at higher speeds, unless you can provide a LOT of voltage to them, like 72V from a Gecko G201. According to Gecko's power supply formula for maximum performance, those motors need about 80V when wired bipolar parallel,, and 160V when wired bipolar series. Even a G540 will only give you half the performance the motors are capable of. I'd recommend new motors to go with the G540.
3 )From what I've read, those drives are cheap, but not very good, unless you have a small, slow machine.
Bottom line.
The G540 will help, but the combination of those motors and 1/2-10 screws will still result in about 100ipm speeds. Changing to 1/2-8 2 start might double that. Changing motors to these http://www.kelinginc.net/KL23H2100-35-4B.pdf might get you 300ipm, but you may reach a point where the screws start whipping, which would require switching to 1/2-10 5 start screws to slow the screw rpm down.
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Your motors are also rather high inductance, which will affect speed. Particularly with the G540, you might well be better with lower torque motors that have lower inductance, like one of the 2mH-ish 380 oz-in motors. The ones you have would work best on a much higher supply voltage, which neither your current drivers, nor the G540 will drive to their best performance.
Regards,
Ray L.
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These are my beefiest motors. I don't have motors any bigger than these.
This is a case where bigger isn't better. Most smaller Nema23 steppers will have more power at the higher rpm's you're looking for.
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When wiring motors -
When do you wire parallel or serial? I just rewired for parallel instead of serial on my Y axis and I can change the velocity and acceleration a bit faster and not have it stall. :)
Thanks
To change everything to 5 start instead of single start seems to be the most expensive upgrade. I think I am going to start small and work my way up. Gecko 540 & Power supply first and then 5 start and then the motors? Or maybe motors and then 5 start.
:)
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Current plan -
Rewire for parallel instead of serial??
You can't - you don't have the amps
Future plan to increase speed
Gecko 540 and what voltage/amp power supply using the motors I am using??
These motors are not good - if you're going gecko and a new PS - do them justice - get "better motors".
These are my beefiest motors. I don't have motors any bigger than these.
In your OP here http://www.machsupport.com/forum/index.php/topic,16875.msg114422.html#msg114422 (http://www.machsupport.com/forum/index.php/topic,16875.msg114422.html#msg114422) you have a picture of two motors - they are very different. The KL23H276-30-8B is the beafier one I was talking about. Totally different and much better spec.
When wiring motors -
When do you wire parallel or serial? I just rewired for parallel instead of serial on my Y axis and I can change the velocity and acceleration a bit faster and not have it stall. :)
See above - you don't have the amps for parallel
But to answer your question: Generally speaking serial gives more torque at lower speeds but it soon falls off with speed, parallel gives less torque at lower speeds but extends the torque into higher speeds.
Meanwhile with your current kit: You could try changing from serial to single coil - your specs are still not good but single coil should beat serial hands down.
Ian
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Ian -
What is single coil?
Let's assume I have the money to do all three at once (which I don't it will take a while) -
If I got the Gecko 540 (I want to add a rotary axis so figure this would be a good choice being 4 axis). power supply and new motors. What volt/amp power supply should I get with what motors? I want something that will be good and fast. Just have to budget for it.
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On my current driver board posted above -
What is "Decay Mode Setting"? Not sure what this means or how it effects things.
Thanks
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All the advise you've received is really great. No mistake about that. But.....
I would have to echo what Rich stated in his first reply.
define the intended use of the machine
IE; - define the desired axis feedrate / IPM
That right there, is really the key part of information you should be concerning yourself with. If you define the desired speed, everybody can give you a more accurate detail of what you should do. If you don't really know what speed you want, tell us what your going to be cutting, and the people around here will know what speed will best suit your needs. "Speed" is a common pitfall of 99% of beginners. "Most torque at cutting speed" is what you should be after, not how fast you can zip around the table. If all your wanting is to go faster, my spidey senses tell me your going to be right back in the same boat your in now, with a whole lot less money, and a whole lot more aggravation....A machine that does not do what you desire.
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I am using the machine to cut various woods for guitar bodies or sign making.
here is what I cut out last night
http://celticmachining.blogspot.com/2011/01/here-it-is.html
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If you don't really know what speed you want, tell us what your going to be cutting, and the people around here will know what speed will best suit your needs.
I do not understand enough to state what speed I really want. How ever the sign in the link I gave measures approx 10 x 20 inches and it took a few hours to cut. I would like to keep the accuracy and quality I have up till now and maybe improve as I go but also speed it up to where that job might of taken an hour or hour and half instead of 3 - 4 hours.
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And I do understand that I need to upgrade some components which is why I was asking. I can now start making a list of what I need compared to what I have and start budgeting for better quality parts. :)
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You really need to start by defining what performance you're looking for, then characterizing your machine to determine what's needed from the motors/drives to achieve that. In other words, you need to actually DESIGN the machine, not just bolt and wire together a bunch of random parts. You need to know your max desired rapid speed, your max desired cutting speed (which is heavily affected by cut depth/width/material), and you need to MEASURE the torque required to move each axis, and the calculate or measure the inertia of each axis, when carrying maximum load. From that you can calculate the required motor performance, which allows you to select proper motors, drivers, and power supplies to achieve the desired result. Simply bolting on parts without doing this design work is not likely to do much more than waste a whole lotta time and money. There are no shortcuts to getting a reliable, high-performance machine.
Regards,
Ray L.
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Ray -
I understand there is no shortcut. I have been focusing on the machine build and take advantage on what electronics I had first etc... I have a really nice build that I am happy with and now I am ready to try and upgrade to better electronics.
And YES I do need to plan it etc. but at the same time I am asking the questions so I can figure that part out now. I am ready to figure out what I need to get the performance I am looking for, but need help on helping me understand on how to do that.
Even though I have been experimenting with CNC for a while does not mean I understand everything or even much at all. I need help understand how to plan for what I want so I can effectively do that. I need to figure out what I need so I can figure out how much will it cost so I can save and eventually get those higher quality items.
Thanks!!!
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Thanks to everyone for all the help!
With everything I learned so far and still have a lot to learn to go. I made some changes to my settings and did improve the travel speed of the x and y axis. I am now cutting another sign and this time the cutting time has been improved and no burn marks in the wood. With the cutter moving as slow as it was before I kept getting burn marks.
http://www.youtube.com/watch?v=FyqJJrzqzFI
THANKS!!!!!! :)
Now I need to figure out what I need in better quality electronics and motors and get to that next level of happiness with my machine. :)
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Ian -
What is single coil?
It's where you just use one coil from each phase and ignore the other, rather than connect the two coils in series or parallel. However I just re-checked your PS specs and I'm afraid you don't even have the amps for that! (never mind the volts). It would have given you kind of mid-way performance between serial and parallel if you like. But - as I say - you can't even do that with your setup.
I agree with everything that's been said here. In brief, I'd be looking at new screws (higher lead), new PS, new drivers and new motors.
Sorry
Ian
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That's ok though. that's why i am posting - I am ok with replacing those items it's just getting and understand what I need so I do it one time and not multiple.
For when I do upgrade -
How would I hook the motors to be single coil?
I am making notes of all of these things.
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I want to add a 4th axis so that is why I figured the Gecko 540 was the better choice for me. If there is something else I should consider, please let me know.
with that said what should be the minimum power supply requirements should I be looking into?
Everyone has posted me upgrading my motors to something other than keling. What should I be saving for and should I go with Nema 34's instead of 23's?
Thanks
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Another example of what type of cutting I am doing -
http://celticmachining.blogspot.com/2011/01/cnc-inside-sign-finished.html
:)
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That's ok though. that's why i am posting - I am ok with replacing those items it's just getting and understand what I need so I do it one time and not multiple.
For when I do upgrade -
How would I hook the motors to be single coil?
I am making notes of all of these things.
Don't. Pick your motors and drivers, and design your power supply, so you can run bipolar parallel. If you do it right, that will give you the best overall performance.
Regards,
Ray L.
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Thanks!
What motors and power supply should I get to go with the Gecko 540? And should I look at Nema 34's instead of the 23's or are the 23's fine?
Thanks!
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The one mistake that i didn't make was a puny power supply. Got 30 amps available at 36 volts so i can have use max amp out of the Geckos i use for 4 axis.
Only had to buy once which was cheaper than buying twice. Or said a different way, like a big motor in the car, power available should i decide to use it later.
Here is the problem with all of this. To design your system you need to be able to relate each of the pieces to the intended use.
What system you end up with willl only be as good as the weakest link . There are books written on each system piece.
RICH
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I read a lot of books - but still need help understanding this stuff. :) Thanks
It's ok to have more amps because the system will only draw what it needs, right?
Do you have a link to power supply you have? I have another coming because I needed the 12v power supply for another project. I have a 36v 10 amps coming and another 12v power supply but not the radio shack model coming.
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It's ok to have more amps because the system will only draw what it needs, right?
Yes
Do you have a link to power supply you have?
Bought them from Camtronics a long time ago but suggest you shop around.
RICH
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Thanks
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For when I do upgrade -
How would I hook the motors to be single coil?
This was not suggested as a recommended starting point for a new system, this was to try to improve what you have already but see my previous post as to why you can't even do this.
Re: your motors, I'm still not clear on which motors you have or are using. In your first post (december) you said you were using the 276's but you attached a photo of two - the 276 and the 286. In this post you say you're using the 286's. These are quite different motors with very different torque curves (which I attached) - until you understand what these motors can do and what their strengths and weaknesses are - I'd not go out and buy any more.
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You don't need more than 10 amps if using a G540
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Thanks!
What I am going to start saving towards -
Gecko 540 and cables
Power Supply -- Assuming 36v and long as it is at least 10 amps???
And eventually change everything over to 5 start screws instead of the single start I am using now.
Still unsure if my current motors are good enough. I have the 286's currently mounted but I also own from a previous build the 276's.
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Thanks!
What I am going to start saving towards -
Gecko 540 and cables
Power Supply -- Assuming 36v and long as it is at least 10 amps???
And eventually change everything over to 5 start screws instead of the single start I am using now.
Still unsure if my current motors are good enough. I have the 286's currently mounted but I also own from a previous build the 276's.
I guess the advice about designing with purpose and not just choosing kit at random just went out of the window then... shame.
Ian
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I guess the advice about designing with purpose and not just choosing kit at random just went out of the window then... shame.
Ian
I must of missed something. I posted what I am using the machine for - And I want to upgrade to a 4th axis for a rotary.
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I must of missed something. I posted what I am using the machine for - And I want to upgrade to a 4th axis for a rotary.
OK let's take your proposed PS as an example in combination with your proposed G540.
Take a look at the specs of the G540. What Vdc can it handle? 50Vdc right? but you're going to limit your system to 36Vdc - why? You don't even know what motors you're going to be using yet because...
Still unsure if my current motors are good enough. I have the 286's currently mounted but I also own from a previous build the 276's.
Have you looked at and understood the torque curves I posted yet? BTW- Hint - there's info missing - what don't they tell you?
Ian
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Still unsure if my current motors are good enough. I have the 286's currently mounted but I also own from a previous build the 276's.
Have you looked at and understood the torque curves I posted yet? BTW- Hint - there's info missing - what don't they tell you?
Ian
I am not 100% sure what those charts mean.
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I am not 100% sure what those charts mean.
Then I'd have to say your nowhere near deciding on a PS or drivers or anything else yet.
I'm not trying to be difficult here - believe it or not I'm trying to save you wasted money and another disappointing system. Why not read the whole thread again - there's a lot of good stuff in it about where you should start.
Ian
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Thanks Ian - will do.
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I understand speed of the motors are controlled by velocity and acceleration. How do I make my motors go faster without them stalling on me? I see other machines cut really fast and mine seems slow in comparison when I see machines in videos.
If you don't have resonance dampeners installed you might want to look here (http://www.machsupport.com/forum/index.php/topic,9943.0.html) and here (http://www.cnczone.com/forums/showthread.php?t=32284).
I made and installed them for each axis and the difference is night and day.
Vogavt
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I read through that first link - a lot of great info. Will have to try the other later, can't pull up cnczome.com at the moment.
THANKS!!!
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Thanks for all the help folks....
I have learned a lot and now realize I have a lot more to learn. Before posting this I did order a 37v 10 power supply and that did arrive today. So that will be nice.
Everytime I learn something I always find there is something else I still need to learn.
Thanks