CNC Controller

[picks27t]

Cnc Kit 3 Axis Tb6560 Stepper Motor Driver Mill Router Nema 23 Motor 24V10A Psu From Frist-Supply on E-Bay New 3 Axis TB6560 Driver Controller Board

1/16Microstep, 12-36V, 1.5A-3A

3 x New 57BYGH56-401A Single-Shaft Stepper Motors 1.26Nm/175oz-in 2.8A


1 x New 24V 10A power supply
$208.00
Would this be a good start
From Company called Frist-Supply

 

[ninefinger]

If this is for your 8520 mill then I would say no because of the motor size (too small). For a really small mill its a maybe but even then the TB6560 driver boards have a VERY bad reputation for dying / burning up etc so I would stay away from it on that count as well. If your really interested in CNC conversion I would suggest a visit over to CNCzone is in order and have a look at the Benchtop Machines sub forum as that seems to have the highest number of home converted machines. You can also search the site for 8520 mills and its comes up with a number of people who have or are contemplating converting.

There is lots of help to be had. CNC conversion isn't for the faint of heart though - its a long process with lots of learning and at the end you still don't have a push a button get a part type machine (but it sure is better than hand cranking IMHO!)

Mike

 

[Tin Falcon]

IIRC TB6560 Driver Controller Board is a low end control well known for releasing magic smoke if the voltage goes over 24 volts.
in cnc voltage == speed. a system that will allow for higher voltage will give better performance. Also the 175 oz in motors are on the small side.

read my getting started in CNC thread. it will give parameters for what you need. Your requirements will be based on the part of the machine the motors need to move . so a heavy mill table with a vise and part bolted down needs a bigger motor than a lathe with a smaller saddle and just the tool holder.

What machine are you trying to convert.???
Tin

 

[dman]

while the driver listed may be adequate they can be unreliable. as tin said voltage doesn't equal speed necessarily. speed is directly regulated by step frequency. however there is still a relationship to voltage. it's somewhat counter intuitive. to maintain full torque as long as possible some drivers are current regulated. as speed increases effects of inductive and electromechanical reactance come into effect and the impedance may rise so the voltage rises with it to maintain current till you reach the voltage limit. so voltage effects torque at speed.

driver manufacturers have rule of thumb type formulas on voltage required often based on inductance of the motors. but low voltage will not hurt the low speed performance.

as for the motors the torque sounds low unless its a small machine with linear bearings and ball screws. I'm not really sure of a good method to choose motors yet. but you probably don't want to cut corners here.

as far as cheap alternatives for a ~100w setup you can look at the linistepper kits. something I'm considering myself.

if you decide 100w isn't enough power for the feeds you want and table weight go with a more commercial driver than a linistepper kit board. gecko boards are fairly affordable. I haven't looked into anything else yet.

 

[picks27t]

How about this on my Taig Lathe

 

[lensman57]

Cnc Kit 3 Axis Tb6560 Stepper Motor Driver Mill Router Nema 23 Motor 24V10A Psu From Frist-Supply on E-Bay New 3 Axis TB6560 Driver Controller Board

1/16Microstep, 12-36V, 1.5A-3A

3 x New 57BYGH56-401A Single-Shaft Stepper Motors 1.26Nm/175oz-in 2.8A


1 x New 24V 10A power supply
$208.00

Would this be a good start
From Company called Frist-Supply

I have 2 of these drivers, a 3 axis that I have used for my home made X1 cnc and a 4 axis that I use for my Taig cnc mill, as Tin mentioned, these are budget low end kits that are restricted to a max of 24V, remember this if you don't want to fry it. I set the current at 75% and microstepping to 1/16, and I have used 1.8 N/M and 3.1N/M motors connected so that I'd only draw 2.1 A max. Forget the 3.5 A claimed stuff. I mostly use the mills with a hand operated pendant to jog along so I don't have to crank them all the time. Forget rapids and all that, the motors inductance will not allow it with these drivers. I have used the wizards from MACH3 and NFS at times and if the software is set up right it does work but with limitations, expect missed steps if you push the machine hard .

Regards,

A.G

 

[Tin Falcon]

How about this on my Taig Lathe ??

Should work fine . If I were you check power supply voltages. Make sure the power supply is putting out 24 volts. before you hook it up. I work with electronics and have seen PS vary several volts plus or minus of rated values.
I would not expect high performance from a cheap cnc package but to learn cnc on a small lathe it should be fine.
Tin

 

[aarggh]

I would highly recommend a Gecko G540 for cnc'ing just about anything. The 175oz/in steppers you listed really need around 48v to get full torque. This will be the problem you'll have with any of the TB6560 based kits, apart from generally being garbage most of the time, and ignoring the earthing/noise issues, and common faulty design resulting in invalid power up/down sequences that tend to blow the driver IC's, 24v just isn't enough to power any but the smallest of steppers efficiently with reasonable torque, ideally NEMA17's which run around 40-60oz/in usually.

I have a similar board on my tiny circuit board cnc machine, and that works fine, but it's slow and low load. The G540 however on my bigger machine is just awesome.

280-380oz/in steppers with as low an inductance as possible, around 2.3-2.8uH is the sweet spot, and a 48v power supply will happily run quite large loads.

cheers,
Ian

 

[Tin Falcon]

I would highly recommend a Gecko G540 for cnc'ing just about anything.

I agree I have a G540 a solid unit. IIRC running 36 volts on mine.
but a 540 is 300 plus three gecko motors at 52 each and another 50 for a ps
so about $500 total and you need to throw in another 50 to 100 for misc items .

Build quality if you can afford it but if his budget will only alow for the low end deal it will allow him to get started in cnc.

thanks for the input please post an introduction in the welcome area.
Tin

 

[dman]

http://www.mycncuk.com/forums/faqs-...t-size-stepper-motor-do-i-need.html#post10046

for motor sizing follow this link ^^^ this helped me to see my knee mill will need individual gecko boards @ 7a and 80v despite the rough estimations i have seen that 100w could push a heavy table as fast as i need it, once rotating inertia and drag come into play the results are totally different. but a small lathe will need much, much less and a g540 will almost certainly work. a set of 3 linistepper kits may also work if you want to be really thrifty.

read it for some understanding and use the calculator linked to at the bottom of the post. the calculator will help you see how things need some balance. also remember the math isn't absolute, for instance what acceleration rate do they assume is acceptable when they calculate torque requirements for inertia? with proper cnc software you could set acel/decel rates so maybe with some fidleing you can make it work with less... playing with the calculator can show you that big motors can have no benifits on high speed systems as they need to overcome there own inertia, but if a lot is required to drive things constantly like the assumed cutting load is large or the friction is too much would you want a smaller motor even though the speeds work out? you can also see that low screw pitches can make no difference despite more equivalent torque to drive the table because the motor has to overcome it's own inertia at a higher rate. the calculator also shows the motor rpm and assumed corner speed of the torque curve (based on inductance) so you can see how much room there is to play with. say you want 100ipm rapids and need more torque available, if the rpms is 500 on a 5tpi leadscrew and the corner speed is 400rpm based on inductance and you need more torque simply choosing a similar motor with lower inductance will improve results but the effect diminishes after you the corner speed becomes higher than the required rpm, while going with a higher torque rated motor can have negative results if the mh or inertia is also greater... all a big balancing act...

http://www.mycncuk.com/forums/attac...t-size-stepper-motor-do-i-need-motorcalcs.zip

 

[Tin Falcon]

Gecko drives has lots of info on there site about motor sizing etc. And IIIRC at lot of this mentioned in my getting started in cnc thread which is a sticky in this sub fora.
Tin

 

[lensman57]

Hi,

If oyu can afford a Gecko and the matching motors go for it, it is about the best for the money, if you have it.

It is not necessarry for the motor to pull 48 Volts for max torque.
If you connect the poles in series the motor actually gives its max torque at the lower speed end and with that Tb driver 24 Volts is the Max that it can tolerate but you do get most of the torque. If you connect in parallel then you'd draw Twice as much Amps and the driver is not capable of supplying it. If you need to do rapids ( proper cnc ) then you have to connect in parallel, twice the Amps but 1/2 of the inductance and then if the power supply and the driver are up to it 48 Volts will give you max speed at the expense of some lost torque. You can look up the graphs of V and A and make deductions youself. Tb 6560 based boards are just not capable of dealing with more than 24 V and high amps.

I would also add that unless your machine is equipped with good quality ball screws most of these arguments are just academical as ACME screws are not that great in either transmitting torque or repeatable accuracy.

Given a machine like a Taig or a Sherline a small motor with lower inductance and torque may actually out perform a larger motor even with a TB6560 driver, again due to the lower inductance, inductance is what I call the enemy of performance.

Regards,

A.G

 

[picks27t]

Thanks for all your help yes my i am new to cnc have been reading cnc cookbook and i am going to leave my 8520 alone but am going to play with it on the Taig lathe. hobby zone has a kit board about $85.00 i can get a PS $50, am using Alibre cad will need Cam what steeper's would you guys use will be working with Lot off 6061 AL i am a hobby engine builder and RC Cars Thanks again for all your help.

 

[Tin Falcon]

I used these on my small lathe.

Vexta PK266-02A

data sheet here:

http://www.interinar.com/public_docs/PK266-02A.pdf
I would think you should be able to find them for about $25 - $ 27each
Tin

 

[dman]

Thanks for all your help yes my i am new to cnc have been reading cnc cookbook and i am going to leave my 8520 alone but am going to play with it on the Taig lathe. hobby zone has a kit board about $85.00

can you give a link to that board? is it for unipolar or bipolar steppers?

i can get a PS $50, am using Alibre cad will need Cam what steeper's would you guys use will be working with Lot off 6061 AL i am a hobby engine builder and RC Cars Thanks again for all your help.

with some details we can plug numbers into the calculator and i can say what is minimum requirements in each area but from searching the taig lathe all i see is a micro lathe and i feel most any nema 23 or maybe nema 17 stepper will do as long as the inductance is low, high inductance will need lots of volts at high speeds and have no torque at speed. the fine pitch the leadscrews have will likely mean the motors will turn a decent rpm.

some info i would need if you want to be precise on motor selection is how many graduations are on the hand wheels and is it a 2/1 or 1/1 lathe? ie if you dial .001 does it take off .001 or .002 from the diameter? or if you happen to know it, what is the thread pitch on the leadscrew? what leadscrew do you plan to use for the z? or will you use the rack gear? how many divisions are on that hand wheel if you want to drive it with the rack gear?

my recommendations may end up being overkill because it will likely be impractical to cut al at the mathematical speed recommendations because of rigidity limitations. al has a high sfpm which translates to high rpm which the lathe is apparently capable if and that means fast feeds. but there is no reason you have to go that high. you can go much slower as long as you bring everything down in scale to each other to maintain chip thickness.

below is a link to the linistepper kits, interesting concept, not a perfect design due to heat but at your scale it may be the best implementation for the money. the kit board you found may be as good. these could do 2 axis for ~$75 total + power supply

http://www.piclist.org/techref/io/stepper/linistep/index.htm

 

[picks27t]

Man i cant believe it but got motors ruining and watching some Gcode go through its thing. Still long way to go to parts.

 

[picks27t]

Trying to get Steps per for motor set up I am useing 10 lead screw direct to Z axis with a 200 steps per motor 200 x 1 lead rev. = .100 in will be useing 20 tpi in X axis any help would be nice.
Thanks

 

[RonGinger]

If the motor needs 200 steps to make one rev, and the lead screw needs 10 turns to make one inch then its 200 x10 or 2000 steps per inch. BUT, we need to know what kind of stepper driver you are using, because that adds another factor. If you are using a full step driver, then 2000 is your answer, but I would get a better driver- one that does some microstepping. If its a gecko the microstepping is 10, so the steps per inch becomes 2000*10 or 20,000.

 

[picks27t]

I have 1, 1/2, 1/8, 1/16 microstep settings ?

 

[dman]

I have 1, 1/2, 1/8, 1/16 microstep settings ?

there is a tradeoff here but it might not matter depending on how fast the computer can generate steps. more microstepping is more precision but if your velocity and precision requirements add up to too much step rate the computer may not be able to keep up.

i don't know if you are using an external step generator like a smooth stepper but if you are step rate might not be a problem. if you are using a parallel port then you'd have to check with someone with mach 3 experience to find what the max step rate is.

basically with full steps you are getting 1/2 thou precision. you probably want at least .0002" and 1/2 will get you close. there is no 1/4 in your list but 1/8 will get you 62 millionths.

you could probably use 1/2 steps or 1/8steps, i'm not sure if on that lathe you could see the extra precision of 1/8 steps but it would make it so changes of 1/10ths in the offsets would be more consistent. with 1/2 steps adding .0001 at a time will do something 2 out of 5 times. adding .0002 will do something 4/5 times, otherwise it may or may not do something as multiple increments will round the same. it takes away some predictability in adjustments unless the microsteps either precisely add up to the scale you are working with or the micro steps are significantly smaller than the smallest value you'd adjust by.

so it's up to you. 1/2 steps give .00025 precision with some wonkyness if you want to adjust less that .0005 (unless mach has a 10s of millionths place and you keep the offsets reading in increments of .00025) and 1/8 steps will give you precision and consistentcy but you'll need 27khz step rate to go 100ipm so you'll have to check out step rates for your application and how fast you need it to go.