missing steps with a "low" feed

Hey guys, i am having some trouble on missing steps with my cnc machine,it have 3 axes, 23nema stepper motor, tb6560 driver board and mach3 to run, so i have been reading that this driver board is very problematic, poor engineered, so i am getting missing steps when using a feed of 1000mm/min+ (40ipm+), i am using the 1/16 microstep setting, 50% decay mode and 75% of current, one guy i know recommended to me to use a power grid stabilizer of 2kVA that it would up the feed a good amount, but i am not very confident to it, so i am thinkin to buy a gecko driver board because i have seen some video and threads saying its a good board to get speed and use a usb-to-parallel cable to connect to a laptop that have a lot more processing power than the cpu that its currently running, what you guys think ? i am not an expertice in eletronics so all that capacitor thing its out of my league

Missed steps is normally caused by overpowering the stepper motor. Microstepping is to be avoided if at all possible. It is a torque robber. It could be that you just have too much mass to move with too small a motor. How big is the machine? What kind of linear bearings? What system for converting rotary motion of stepper to linear? Normally it is not the computer but it could be noise in the conductors. You say that you are running a laptop. That is specifically warned against in Mach3 documentation. Are you using a USB smooth stepper? Home If you are using a usb to parallel converter for printers that could be a problem as they usually are not buffered.

no, currently i am using a desktop cpu, i was thinking to get a usb to parallel because the laptop could get a pulse rate much greater than the desktop that only gets 23khz~, so, i am using couplings and the machine is about to 1,5m x 85cm and about to 25 cm in Z, and the linear guide is that one on the photo and my machine is that one in the other photo, ok so without a microstepping setting the precision is 0,015 mm with gives about a 0.000590551181 inch precision, i think that its ok to wood work right ? but what if taking out the micro step out and it still continue to miss steps, it could be the computer ? in the future i am thinking in get a bigger machine, so would be the gecko drivers be the right driver with a new computer ?

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I am not familiar with your driver board but from the chatter on the web your problem appears to be congenital with that board. I was never convinced that a single board could do everything including driving the motors. I prefer an optoisolated BOB and separate motor drivers.

could u give me a hand and tell me what is that BOB and where i can read about this ? would be a good help, thanks a lot man

I apologize for using acronyms. A break out board (BOB) is the interface between the computer and the motor controllers/limit switches/etc. It protects your computer from being fried by the high voltages o stepper motors (high for a computer). Some contain relays for starting routers/power supplies/ what have you. If you are running motors at 72V DC and are using 24v DC power to control spindle speed then the computer is just waiting for a release of smoke if you do not protect it.

Are you running from a laptop? Mach doesn't like that much.

Another thing that will cause missed steps is mid-band resonance. In this case you are in a range where the motor still has sufficient torque but unexpicalbly stalls out. It is fine if you go faster or if you go slower. On a machine without a lot of reserve power, it will lose steps or stall otherwise will be noisy and vibrate some. Well designed drives will compensate for it..

I have no experience with the board you have but from what I have read here it is problematic. A Gecko G540 with a suitable power supply might be a better choice. Do you have the specs for your motors? Whatis the current rating and what is the inductance? There are plenty of threads here that talk about matching motors and drives. Search for and read a few of them before spending your hard-earned money.

bob

hi, i am using a desktop cpu at the momment, i am thinking in get that bob with 3 stepper motor drivers 3 axis Stepper Motor Driver 0.2-5A controller & Breakout board for CNC Router, this bob has a better price than the gecko board and have about the same specs, and buy a new psu with a 2kVA power grid stabilizer, and does the wattage power of psu matters in this problem ?this bob need a 5v dc power supply, does the psu i use in tb6560 works in that bob ? i have no experience with eletronics, i am currently studying mechanic technician, and just entered in eletric machines subject in school

You may be jumping ahead of the game. Windows® steals a lot of power that is need to run the parallel cable. Before spending any money make absolutely certain that no other programs are running when you are running your router. Turn off any routers, modems, anti virus software, etc. DO NOT try to open another program while running the router. The problem may be in your computer and the way that it is running.

That said, if you are going to build a bigger machine in the future a bigger amp rating on motor drivers might be money well spent. Otherwise 2.5A should be sufficient for your situation. I have never been a fan of those 3-axis all-in-one units. It is like those old Christmas lights. If one goes out they all go out.

Bob

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i am thinking in get that bob with 3 stepper motor drivers 3 axis Stepper Motor Driver 0.2-5A controller & Breakout board for CNC Router, this bob has a better price than the gecko board and have about the same specs,

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You get exactly what you pay for.

ok guys, yesterday i had a chance to play a little bit with the machine and i changed the micro step to 1/2 and the feed was running smooth at 2000 mm/min, i didnt tested further than that, so if it went smooth it must be the computer velocity, and all the runs i made sure that all the processing power robbers were closed in task maneger, to get a better velocity should i buy a usb smooth stepper to use a faster pc or get a parallel board to desktop cpu

The primary limitations to velocity in a stepper system are your screws (coarser ones go faster), the torque curve of your motors (they need to deliver enough torque at a given speed not to lose steps) and the power put out by your DC power supply (more power means more speed, up to the point your driver blows up or the motors can't use any more). Changing your computer won't help much unless its a problem with throughput that's limiting your speed. So if you've got lots of tiny directional commands, adding the smoothstepper can help speed things up, but not for long linear moves.

By micro-stepping you lose power. It is a bit complicated to explain here. If you can get the resolution you need without micro-stepping do it. Also, as speed increases, power drops off. Steppers do not like to run fast as the stator coils do not "pass off" the rotor as in a regular motor but grab it from the last one as it releases it. That can only happen so fast.

Microstepping also gives much smoother motion, and minimizes resonance. My recommendation would be to always use microstepping, either 1/8 or 1/10. With better drives, the benefits far outweigh the negatives.
Over the years, it seems like people that get better results without microstepping are almost always using cheap drives.

hey guys, sorry for reviving, just want to give some feedback, so, today i can go almost 3000mm/min ( ~118 IPM ), i think its pretty good for a TB6560 axis drivers, but i want to sell this machine and build another one with a better structure, but i have to change the drivers, thinking about getting a BOB with separate axis drivers and 15A power sup to at least run at 118IPM with a good torque

IMHO, if you really want a powerful machine you need to upgrade your electronics package. I would recommend a Ethenet Smooth Stepper, C32 BOB, separate drivers for each motor, 20 amp 60 or 72 v power supply. Motors and drivers would depend on size of machine but this setup is sufficient for a large format high speed router. 120 ipm is nothing to write home about. Routing requires cutting speeds upwards of 200 ipm and rapids up to 1000 ipm. Anything less would burn bits and waste time. Unless you really want the experience in building the cost will begin approaching the cost of a Chinese import. Good luck on your sale and new build.

Bob

thanks man, but for know i dont wanna invest in so much velocity because if i do i will have to change the leadscrew to a ball screw or ratchet (rack), just want to go 5m/min in rapid moves and 2,5m/m or 2m/min in cuting move

If cost is an issue, and you can solder / have time to build a kit, take a look at my THB6064AH kit.

i have noticed something annoying now, the x and y motors have almost zero torque, if i use my hands to try to stop the motors its stalls, but the z axis have a bigger torque, than i noticed that the cnc is losing steps (stalling because of the lack of torque), could that be a problem in the configuration pins of TB6560 that its not setting the 100% current on those axis ?

There are a number of causes of low torque unrelated to motor size.
1. are the motor drivers set to the proper amp rating?
2. are you micro-stepping? Microstepping seriously reduces torque.
3. Is there sufficient current? Volts * Amps = Watts. Watts is power. Motor drivers limit the amps so putting more voltage to your motors will increase the power.
4. Mechanical friction. There is a fine line between tight enough and too tight.

Bob