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[routercnc]

From your introduction it sounds like you want to make a wood cutting machine and have fitted 4off Nema34 stepper but are loosing steps. Couple of things:

Nema 34 sounds a bit overkill for a wood machine - I've seen them specced for lifting the knee on a mill, but for a wood cnc machine you can lift a lot of weight with a Nema 23
Nema 34 needs lots of voltage to make them work. It is possible you are under driving them. I've seen them specced on this site to run at 70V DC minimum, with a preference for direct mains drivers.
Stepper motors can be wired in different ways (series, parallel) to change their output but only if the drivers can take the current

So without jumping to conclusions too early, I think the collective wisdom on here can help you out if you provide:

1. Stepper driver make, model, and most importantly voltage being used on each axis
2. Drive system - all-thread, trapedoizal screw, ballscrew, rack and pinion, belt, other
3. Linear motion - skate bearings, v-bearings, supported rail, linear profile rail, other

Also any photos of the machine, particularly the Z axis will be a great help.

[shipper506]

I'll answer the questions as best i can first, then the upgrades I've made, then pictures (if I can figure out how to add the pictures-including some of that Florida sun I promised)

[jamesgates1000]

Hi welcome to the forum, I have been a member for a while but only just started using it. The really knowledgeable people on here have been a great help to me so far.

[shipper506]

STEPPER DRIVER
1 pc Four-axis Driver Board HY-TB4DV-M (TB6560), 3.5a, 16 micsteps

STEPPER MOTORS
Nema 34 stepper motor 878oz.in bipoler - step angle 1.8, Rate voltage 6.4, Rate Current (A) 2, Phase Resistance 3.2,Phase Inductance (mH) 15, Holding Torque (oz.in) 878, Rotor Inertia (kg.e?) 1.7

DRIVE SYSTEM
Lead screws are 1/2 " 8 starts 1 turn=1"

Anti back lash on all axis

LINEAR MOTION
skate bearings

WIRE
18 gauge wire from driver board to stepper motors and 22 gauge wire to limit switches/e-stop

POWER SUPPLY
350W 36v

[njhussey]

Well the first 2 lines says it all....TB6560 (by the way you're brave running it at 36V, surprised you've not had the magic smoke from it yet at!!!!) and Nema34 motors.

See this thread...http://www.mycncuk.com/threads/1373-...ghlight=TB6560

You're never going to get any sort of performance running Nema 34's with a TB6560. Nema 34's need 100V plus to get any sort of performance.....

[shipper506]

Im confused, you say im not going to get any type of performance out of the 34's because they need 100v however they are not rated that high voltage and all but "Z" was working fine.

The upgrades consist of new limit switches/E-stop, rewire from 22 gauge to 16 gauge on the stepper motors, and new connectors between the two modules, what i call the brains (computer and breakout circuit (software)) and the working module (Stepper motors X Y Z and limit switches (hardware)).

[routercnc]

The rated voltage is much lower than the voltage you can actually drive them at using pulses (ie what the stepper driver voltage is)
I'm afraid Neil is correct and you have built a mismatched system. 36V is way too low for Nema34. You can either accept that or wait for someone to post the technical reasons why.
You are also running lead screws not ballscrew and have anti backlash. This all adds to the friction when lifting the Z axis. To add to it further they are on skate bearings although that should be a minor factor in terms of allowing a smooth lift.
The cheapest way to stop loosing steps would be to swap out the Nema34 on the Z to a Nema23, and probably turn the voltage down a touch to be kind on the chips. Keep the acceleration and velocity at modest levels and you should avoid loosing steps.
If your leadscrew pitch is 1" per turn then I think you would also benefit from a 2:1 pulley on the Z

[shipper506]

If i wait for someone to post the technical reasons, I probably wouldn't understand the post anyway.
I will go with the Nema 24 on the Z. for now.
Could you expand your thoughts on the pulley? Are there any pics of this system?
If i continue using Neman 34 (thinking about expansion) what would you recommend?

[routercnc]

Just noticed that I've typed Nema 24 where I should have said Nema 23 on my posts - corrected. I should also add that you need the lower inductance ones -I'm away from my computer but remember somewhere around 2-3 mH being a good choice. Hopefully someone can post up a good spec.
If you look through the build logs here you should see some of them using pulleys. Your screw pitch is very high putting a lot of load on the motor so the pulley ratio will give the motor more torque with less chance of stalling

If you want to stick with the 34s then you need to buy 4 separate stepper drivers and a break out board. This will be a lot more expensive than your current board and it's all because of your choice of motors which are a bit big for the machine you describe.
When I'm back at my computer I'll try to find the ones most people use. I think Kinko do some mains powered ones which will really make the best use of them.

This thread talks about using 34s
http://www.mycncuk.com/archive/index.php/t-8248.html

[JAZZCNC]

If i wait for someone to post the technical reasons, I probably wouldn't understand the post anyway.
I will go with the Nema 24 on the Z. for now.

I'll give it in simple Technical terms. Large motors have more Inductance or think of it as Resistance to flow of current thru it's windings and Current gives us Torque.
Then think of voltage as the force pushing current thru the motor windings.
So with higher inductance you need more Push to achieve the same speed as motor with lower Inductance. Then because torque mostly comes from current and your struggling to Push the current thru the windings then Torque is also lower.
Think of it as trying to drive a manual gearbox(don't think you have many of these in US . .Lol) Car Slow in too high gear!! Because your speed isn't enough then Motor stalls.

Now you have the worst mix match of components because Nema 34 motors have high inductance but you have Low voltage. Made worse by Drive/s that don't allow higher voltage and like has been said your very lucky you haven't fried them already running so close to there Max voltage.

Unfortunatly it gets worse when it comes to speed because you have high friction linear components in the form of Lead screw and Skate bearings.

This translates into Driving Car Slowly in high gear with the brakes Sticking and the end result motor stalls at lower speed.!!