New Build 1000x600x200mm (newbie)

**Noplace** · 08-11-2015

Originally Posted by CharlieRam

Yes. You would have to spin the ballscrew twice as fast as a 1610 to achieve the same linear speed

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yes machine is already setup to just do that, as I mentioned speed is fine, motor stalls If I increase acceleration to higher than .5m/s^2 range

**Jonathan** · 08-11-2015

Originally Posted by Noplace

yes machine is already setup to just do that, as I mentioned speed is fine, motor stalls If I increase acceleration to higher than .5m/s^2 range

If you take the belt off the Z-axis and give it a slight push, does it start moving down by itself due to gravity? If not then your ballscrew and or rails may not be aligned well.

To increase the acceleration capability the easiest way is to change the drive ratio. Make the pulley on the Z ballscrew larger, or the motor pulley smaller. The torque required for acceleration is proportional to the inertia reflected to the motor. This inertia scales with the drive ratio squared, so if you make the ballscrew pulley half the size, the motor will see about 1/4 of the inertia as before and the torque goes down by the same ratio. It's not quite as good as that as the larger diameter pulley will have a higher inertia, but you'll also reduce the torque required due to friction and lifting the axis (though that is already small).

Once you think the motor tuning is correct, I recommend running random g-code rapid moves for say half an hour, as that will stress the system to give confidence that the machine will not stall. I've made a spreadsheet here to do it:

http://www.mycncuk.com/threads/5843-...g-motor-tuning

**Noplace** · 05-02-2016

Guys quick question, filling up the steel tubes, is it worth it? can I use normal concrete for that? any disadvantages?

**JAZZCNC** · 05-02-2016

Originally Posted by Noplace

Guys quick question, filling up the steel tubes, is it worth it? can I use normal concrete for that? any disadvantages?

What's in Concrete that doesn't mix well with Steel.?? . . . Neil's suggestion is spot on and yes it's worth it.

**njhussey** · 08-11-2015

I'm questioning why you want all that speed on your Z? I've got my Z at 7m/min and its plenty fast enough. What are you doing that needs more speed?

Ps I've got a 1605 ballscrew on mine.

**Noplace** · 08-11-2015

no I don't need that speed at all, sorry I'm talking about the acceleration here mostly, I was just wondering how to achieve higher acceleration without stalling.

**CharlieRam** · 08-11-2015

But because the motor is spinning faster it will have less torque than the same motors in the other axis

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**Noplace** · 08-11-2015

Originally Posted by CharlieRam

But because the motor is spinning faster it will have less torque than the same motors in the other axis

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thanks that makes sense! but makes me sad haha

**njhussey** · 05-02-2016

I think kiln dried sand (as used for block paving) is the preferred thing to fill with for resonance. That way if you put bungs in you can empty it should you wish to move the machine...

**Lee Roberts** · 05-02-2016

Neil is correct, problem with creat is it can become brittle and brake up/crack, when that happens you end up with "lose" in your tubes and so on.

We used to call it silver sand back in my paving/block driveway days, think there is a difference between it and kiln dried, silver being a finer grade as it needs to work it's way into all the joints on the blocks.

.Me