[willheg]

Hello everyone

well firstly if your reading this thanks for doing so and i hope you can help me

sorry if i ask in a round about way but i'm not to good and putting questions into words but hope you can help

i have not so long ago purchased 4 stepper motors and a motor to drive the spindel but i have a few questions

1st one is would anyone have any idea on the best power source for these motors, the steppers are rated 18-60vdc and a rated current of 4.2 amps and the spindel motor is rated 36vdc but will handel 48vdc, running at 12 amps and 350 watts, looking at running them all on 36vdc to there rated current but wondering on what to use (i.e. tranformers and everything) and where to get it all from

2 is what board should i use to drive the steppers as i'm tight for cash i was looking at building my own and wondering if anyone had plans or could put me onto somewhere to find something cheap to run these, i have plans and will attch and if these are ok could someone let me know only thing is i need to run current limiting resistors i think. the board would be running 1x 4030, 1x 4027 and 8 Mosfets or transistors to handel the power and 1 board of this per each stepper motor

anyway thanks for reading and hope people can help

Cheers
William

[irving2008]

That stepper driver design is fine for baby steppers up to maybe 1/2A per coil and 20volts supply voltage but wont drive the 4A units you have. You need a much more functional driver with a chopper current control. Current limiting resistors with 4A motors is just not going to be efficient or cost-effective, not to say HOT.

Stepper motors aren't normally rated at those sorts of voltages, typically they would be rated at between 2 and 5v - they are normally overdriven voltage wise (typically 10 - 20 times the coil rated voltage) using a chopper current limiter to control the coil current and prevent overheating. Do you have model # or other info on the stepper motors?

[willheg]

thanks for the reply so quickly, the information i have on these motors is:

Step Angle (deg) 1.8
Motor Length (mm) 112
Rated Current (A) 4.2
Phase Resistance (ohm) 0.9
Phase Inductance (mH) 3.8
Holding Torque (N.cm Min) 280
Detent Torque (N.cm Max) 12
Rotor Inertia (g.cm²) 800
Lead Wire (No.) 4
Motor Weight (g) 1400

i was told by the supplier they can be run from 18-60vdc so i'm taking they have done the figuers allready to get these numbers thats why i'm looking at running 36vdc because of my spindle motor and to try and keep things simple

on another note while i'm here what transformers and other stuff so i use and can anyone recommend anything to use to get the numbers i require

i'm also looking into another controller i have found in a data sheet which i have attached and wonder if this would work ok to drive the steppers i have choosen just wonderin also what resistors and caps to use and stuff

i value other peoples opitions as i'm new to this and usally many heads are better than 1

cheers for any help

[MrWild]

Go to www.Pminmo.com for all sorts of good driver schematics, PCB layouts, and parts lists. Many drivers to choose from. Or you could just buy a Gecko G540 and take the easy way our.

[willheg]

thanks for the reply i've been looking there but didn't know which driver would suite the motor but i'm keen to try and build it myself as money is tight these days and just want the whole thing of, i did it myself, it may not work out cheaper this way but it will be easyer to buy parts one by one and build up slowly

but if anyone could help me on which driver will work i would thank you very much and also i'm after help on the power supply

i have almost everything else worked out it is just these little nigley things that are getting me, as i'm not to flash at electroinics but want to give it a go like i said before to say hay i did it even with the help of others on the way

Cheers
William

[TOTALLYRC]

Not to disuade you from doing it your way, but if the electronics is not your strong point it will be alot easier to save up and buy a driver ready to go. It will also be a false economy. I am so so at electronics and the thought of making a GOOD driver scares me. If you want to learn electronics I would say that the stepper motor driver is not the best place to start, especially if you want the drivers to run a machine tool.
Do some searching of the forums and you will find a lot of data on drivers and power supplies including recomended suppliers.
Mike

[willheg]

cheers for the reply mike

all i really need is the secmatics and i'd go from there, i'v edone some looking around but there is to much information and not enought time to read it all and then i read one thing but look at something else which either confusses me or makes me think in a bad way and yeah that is why i decided to start me own question to see what information i got back but i guess if i need to sift throw the weeds on here then so be it but i'd just like to get on and start building the rest of my project cause currently i'm on hold till i sort out power supply for the motors listed below which again is 4 x 4.2 amp steppers and a 12 amp spindel motor all running at 36vdc and also the driver boards for the steppers

but your help is thanked and if anyone else could help with my search in controller boards and what sort of power supply it would be of great help

Cheers
William

[TOTALLYRC]

cheers for the reply mike

all i really need is the secmatics and i'd go from there, i'v edone some looking around but there is to much information and not enought time to read it all and then i read one thing but look at something else which either confusses me or makes me think in a bad way and yeah that is why i decided to start me own question to see what information i got back but i guess if i need to sift throw the weeds on here then so be it but i'd just like to get on and start building the rest of my project cause currently i'm on hold till i sort out power supply for the motors listed below which again is 4 x 4.2 amp steppers and a 12 amp spindel motor all running at 36vdc and also the driver boards for the steppers

but your help is thanked and if anyone else could help with my search in controller boards and what sort of power supply it would be of great help

Cheers
William

The formula that I found on the forums is amps/stepper x number of steppers x .6 or .65.
Which is about 10 - 11 amps. That is if your drivers a capable of putting out that much. Max motor voltage is the square root of te inductance in mh times 32. About 62 volts for your motors. If you go 36v you will be somewhat above 1/2 max voltage will get somewhat more than half speed form the motors. Depending on the gearing it might be more than enough for you.

I haven't heard of anyone using the DC stepper power supply to drive the spindle also, but I assume it is possible. However you are looking at 22 amps (12 spindle + 10 Steppers) minimum plus startup torque for the spindle. You would end up needing a 30amp? power supply, not cheap unless you find a nice 36v battery charger with a nice big amp rating. All the fall swap meets are coming up and maybee you could find something there.

It might be easier to find a 110v Ac powerd DC motor supply and just turn down the maximum speed setting so as not to overvolt the spindle motor. Ebay is a good source as well as Craigslist and backpage.com..
I have bought several for $30 on ebay.

I can't help on the driver boards for the steppers unless you want opinions on ready to go stuff. Don't forget, whatever boards you go with, you really need a breakout board to protect the computer/pport.

Best bang for the buck is stil the G540. read the manual and see what you get for $299. Hard to get all that for less even if you build it yourself.
I will get of my soap box now.
Mike

[irving2008]

cheers for the reply mike

all i really need is the secmatics and i'd go from there, i'v edone some looking around but there is to much information and not enought time to read it all and then i read one thing but look at something else which either confusses me or makes me think in a bad way and yeah that is why i decided to start me own question to see what information i got back but i guess if i need to sift throw the weeds on here then so be it but i'd just like to get on and start building the rest of my project cause currently i'm on hold till i sort out power supply for the motors listed below which again is 4 x 4.2 amp steppers and a 12 amp spindel motor all running at 36vdc and also the driver boards for the steppers

but your help is thanked and if anyone else could help with my search in controller boards and what sort of power supply it would be of great help

Cheers
William

I don't know of an open-source design that will handle those steppers, you need something capable of controlling 6A at 50v to get the best out of them. The second diagram you found is good for no more than 3A in practice at 30v. You could build it but you'd have to be careful not to overload it and you'd get nowhere near the rated torque from the motors. Also building from a schematic isn't practical at these current levels... you need to pay very careful attention to layout, current routing, etc.. or it simply wont be reliable... unless you have considerable experience laying out high-current 2 or 4 layer PCBs you want to be buying something that is known to work... else it gets very expensive very quickly..... have a look in the open source drivers forum for some info...

[willheg]

thanks for the replys people

this information is starting to make sense

the problem on the boards is i live in new zealand and yeah the cost of buying the boards is really expencesive for me at the moment not to say the freight cost hense mhy i'm looking to build the boards myself but it's looking more like i'll have to spend the dollars and buy a gecko maybe the 201, cause the other thing is i'll need 4 motor drives as i'm running a 4 axis machine and finding help or people in NZ is so hard that is why i'm asking here

the question i also have is wouldn't i just need a board per motor rated at more than 4.2 amps at around 60vdc yet the power supply would need to run 60vdc at the 10-11 amps posted before

and another question i have is how is it worked out that the chips will only run 30v 3a, i read they are rated 52v 5 aamps max but if i used that i would look at maybe 40v at the 4.2 amps max which should be fine i thought on the L6023 or is that 30v 3 amp the limit on the L297?

once again cheers for the help it is all useful and i'm so thankful and hope i can help others someday once i get my machine done and work out all these things

William

[irving2008]

....the question i also have is wouldn't i just need a board per motor rated at more than 4.2 amps at around 60vdc yet the power supply would need to run 60vdc at the 10-11 amps posted before

the power supply would be need to be rated at typically 67% of 6 x phase current (for 3 axis, 8 x for 4 axis - remember there are 2 phases per motor), so you are looking at 4.2 x 6 x 67% = 17A capability (3 axis) or 22A (4 Axis). Voltage would be around 60v max. to get the best out of the motors, which means you are looking at 80v drivers - obviously you can run a lower voltage but you'd probably not want to go below 40v. For these currents/volts you might be better looking for a pair of supplies or even one per motor.

and another question i have is how is it worked out that the chips will only run 30v 3a, i read they are rated 52v 5 aamps max but if i used that i would look at maybe 40v at the 4.2 amps max which should be fine i thought on the L6023 or is that 30v 3 amp the limit on the L297?

Sorry, my typo on the 30v... L6203 chips are rated 52v 5A absolute max but you wont be able to run them reliably at that level... 40v and 4A is pushing the limits (see several threads here where others have tried it with varying degrees of success). The 6023 is very finicky about layout and needs big heatsinking and careful thermal management to get anywhere close to those numbers - reality is nearer 3A in practice with any degree of success. You cannot run these chips at max voltage as you have to take the back-emf of the motor into account and the reverse energy dumped into the power supply on deceleration - this raises the supply volts well above the norm unless you have very high stability switched mode power supplies which will be expensive or some other energy-dump circuit. As I said before, if you have a trusted off the shelf PCB layout it might be worth considering building your own but if you are planning to lay it out yourself then expect to go through several chips to get it right...

William, see my comments in-line above

[TOTALLYRC]

Hi William, I skimmed thru this but can't seem to find what type of machine you are controlling.
It will have a big impact on everything else down the line.
A small mill and a small router could both use those motors but you could power them very differently. Those motors look to be nema 23 double stack. If you are putting them on a large mill they probably won't work.

Depending on the machine you are controlling they could be completly useless and I hate to see you by all of the controls and then have the wrong parts for the wrong application.

Michael

[willheg]

hi michael

thanks for your interest, i'm looking at building a custom mill for pretty light work i've got plans in my head and was recommend by the supplier of the motors that these should work fine

it will have 4 axis x,y,z,a and mostly cut alloy if i do it right i hope, hope i havn't jumped in the deep end and brought rubbish

but yeah i'm starting to get really lost as i'd like to build the controller boards myself because 4 geckos to drive this plus the freight to New Zealand i don't think will be cheap

yet again the time and money in making my own will probly be just as easy to buy the geckos, but don't know which ones of those either but any help would still be thanked

William

[irving2008]

William,

The motors you have are certainly good enough for such a job but it is important to look at the system as a whole - the design of the machine, the axis and drive mechanisms and the loading, performance, friction, efficiency of those will determine motor requirements and the electronics. All have to be married together to produce an effective whole. Too big a motor on too flimsy a design is as bad as too small. Even a big motor on a poorly designed axis may not achieve the transport speeds necessary to get a clean cut. If you start with the motor then you will have to determine what mix of loading, friction, speeds, etc. are appropriate so you assess what can be achieved in reality against the 'plans in your head'. If you don't know how to work these out then there are lots of people here who can help. It may be for the design you need the motor requirements are relatively lightweight and these motors could be used with lower current and cheaper electronics, but until you know what the design requirements are you cannot make that assessment.

You say money is tight (as it is everywhere in this time of credit crunch) and the old maxim of measure twice, cut once applies now more than ever. You need to do a lot more planning, drawing of designs, working out the parameters, before jumping in to purchasing the expensive electronics.

A 4 axis machine is a big undertaking for a starting project. Maybe you have the skills and experience elsewhere - we simply don't know, so apologies if this seems a bit patronising. Most would start out on a small MDF-based router design, like one of the Rockcliffe designs, which are known to work well and then progress from there. A machine to cut light alloy effectively needs at least one order of magnitude of accuracy and rigidity over an MDF-based solution, probably constructed out of ally or steel. As such there are greater weights, momentums and forces involved, bigger and more expensive rails, leadscrews, etc.

None of which is meant to dissuade you, but you need to go in with eyes open as to what can and can't be achieved with the funds, skills and experience available to you and where best to apply those. You may be a great mechanical engineer but if you aren't an expert in designing/laying out PCBs, building your own drivers from a schematic for a requirement you don't fully understand will be a expensive and potentially disappointing exercise.

So start with a more detailed description and ideally some drawings of what you want to achieve, sizes etc., what linear mechanisms/rails etc. you plan to use. Start a build thread in the appropriate forum for comment and advice and get the fundamentals right... the rest will get worked out on the way...

[TOTALLYRC]

hi michael

thanks for your interest, i'm looking at building a custom mill for pretty light work i've got plans in my head and was recommend by the supplier of the motors that these should work fine

it will have 4 axis x,y,z,a and mostly cut alloy if i do it right i hope, hope i havn't jumped in the deep end and brought rubbish

but yeah i'm starting to get really lost as i'd like to build the controller boards myself because 4 geckos to drive this plus the freight to New Zealand i don't think will be cheap

yet again the time and money in making my own will probly be just as easy to buy the geckos, but don't know which ones of those either but any help would still be thanked

William

Hi William:wave:
From your earlier post.

Step Angle (deg) 1.8
Motor Length (mm) 112
Rated Current (A) 4.2
Phase Resistance (ohm) 0.9
Phase Inductance (mH) 3.8
Holding Torque (N.cm Min) 280
Detent Torque (N.cm Max) 12
Rotor Inertia (g.cm²) 800
Lead Wire (No.) 4
Motor Weight (g) 1400

With a current of 4.2 and an inductance of 3.8 (60volts max) these will run
Well on the G540 platform (3.5amps and 50v max).
They will be well suited for a Taig sized mill or so.
If your Z axis is particularly heavy and the motor has trouble lifting it,you can always gear down or use a belt reduction.
In my never to be humble opinion, the amps are more important than the voltage. I would shoot for a 10 -12 amp power supply and at least 40v. The closer to 50v, the faster the rapids.
Of course these motors on a 4th axis (rotary table) are overkill but since you own it use it.

You can send your supplier of choice an email and get quotes for shiping to New Zealand. I am lucky because shipping around here,while not free, seems to be a lot less expensive than anywhere else.

For a small mill on a tight budget, the Xylotex board will work (35V and 2.5 amps Max) with a 30v power supply. It does have speed problems especially on a fine pitch screw.

There are of course other suppliers but I have no experience with them.

Like I told somebody else the other day.
1. Come up with a budget.
2. Blow your budget out of the water.

You could probably sell a kidney to help pay for all of this, but due to the economic troubles world wide, kidneys are down 45%

[willheg]

hi guys

thanks for the posts don't really have the time to read them right now but thought i would reply to say i'm still looking here

will check tomorrow to what you have to say and will post another reply then

cheers for the help and good to see there are some caring people out there willing to share there knowladge, veiws, experinces and thoughts

thanks once again and catch you all again soon

William

[willheg]

hi again

in reply to irving2008, thanks for the insite once again, basic specs i have thought of is building the table out of 40x40x3 RHS steel tube, rails where going to be home made, tube over steel rod with 3 bearings offset around the outer tube at each end, if you get the drift, for the drive i was thinking of some sort of chain drive instead of lead screw as i'm looking for demensions of hope fully 2000mmx1350mmx500 on z axis, with travel of 1900x1200x350 roughtly so quite a big machine and maybe i should give up as it is sounding like a big task for a fisrt time

but hope that is a bit more help but will like you said post elsewhere to see what other people say, cheers

in reply to Mike/TOTALLYRC :wave: hi thanks for letting me know you think these motors will be good, one thing you say is to use the Xylotex or simaler board but one question i have to this is that it is rated at 2.5 amps you say but what i want to know is is it ok to run the motors i have which are 4.2 amp on a 2.5 amp board, wont that blow the board??

anyway i'm thinking about just getting geckos but am undecided on what model, does anyone know the difference between then, or could someone explain it for me, cheers

William

[TOTALLYRC]

hi again

in reply to irving2008, thanks for the insite once again, basic specs i have thought of is building the table out of 40x40x3 RHS steel tube, rails where going to be home made, tube over steel rod with 3 bearings offset around the outer tube at each end, if you get the drift, for the drive i was thinking of some sort of chain drive instead of lead screw as i'm looking for demensions of hope fully 2000mmx1350mmx500 on z axis, with travel of 1900x1300x350 roughtly so quite a big machine and maybe i should give up as it is sounding like a big task for a fisrt time

but hope that is a bit more help but will like you said post elsewhere to see what other people say, cheers

in reply to Mike/TOTALLYRC :wave: hi thanks for letting me know you think these motors will be good, one thing you say is to use the Xylotex or simaler board but one question i have to this is that it is rated at 2.5 amps you say but what i want to know is is it ok to run the motors i have which are 4.2 amp on a 2.5 amp board, wont that blow the board??

anyway i'm thinking about just getting geckos but am undecided on what model, does anyone know the difference between then, or could someone explain it for me, cheers

William

It is OK to run a 4.2 amp motor on a 2.5 amp drive. The drive is the limiting factor and will only put out is max and not blow up. That said a 4.2 amp motor on a 2.5 amp drive will only put out 2.5 amps of power. The Gecko G251 or G540 will go up to 3.5 amps/50v and be closer to the motors max. If you want all that the motor can give the only way is a g203v or simliar that will go up to seven amps. You just set the max current to 4.2 amps.

The lower the amps the less power/torque and the lower the volts the less speed. You may not need every ounce of power and speed the motors are capable of but you will want to be close or you will most likely be dissapointed.(This is the voice of experience speaking.)

As an owner of both the xylotex and the Gecko products, I would hands down go with the Gecko if it fit the design parameters. If you compare the price difference between the G540 and a 4 axis Xylotex the cost is not very different, especially when you consider that the G540 has a built in breakout board and has the ability to drive a vfd and charge pump capabilites.

The few dollars that you spend now will save you hundreds if not thousands later just from a time of machining standpoint. Like I said before to somebody else, it is real easy to setup the g540 to run more than 1 machine. Seeing as how the current setting resistor can reside inside the db connector, just use different wires for each machine with the current limiting built into the cable nd away you go. I was considering using a A-B switch but I am not sure if it will work. I think that they are available in db9 configuration, But you would have to check the current handling abilities. You would also need on for each axis plus something to switch the rest of the I/O. With careful planning it would be fairly easy to do.

Many people will say speed is not important but after awhile it is annoying to go slow.

That is an awfully big machine to cut anthing besides wood on. Flex and vibration are what kills a machine's ability to cut aluminum. Thse motors may not be up to driving something that large IMHO.

Large machine on the cheap that cuts aluminum well are as rare as hens teeth
. I guess if your are just engraving, it might work as the cutting forces are fairly small
I don't know about chain drive. If you need screws just turn the nuts instead of the screws and you won't have any whipping problems.

[willheg]

thanks for the reply so fast, that has given me some insite know as i may look at just building the mahine and running a build your own board for now to get me going, then later on upgrade to something like the gecko

i was thinking of just useing the G201 but wondering what one everyone else would reccomend, like i said money is the key but yeah i guess it's only for me around about $1000 just for the drivers, motors only cost me $350-400, but yeah oh well you live and learn i guess

anyway might need to think some more and start a new post or something once i have done this and yeah

looks like i'm going for more than i can chew but thats nothing new for me

anyway thanks for the help

catch you again sometime probaly
William

[TOTALLYRC]

G201's are fine, the 203v's are much less prone to accidental damage and they will turn you motors faster at the same voltage due to the drivers morphing from micro to full step on the fly.
Best of luck
Mike