Thread: Tassie Build

wow very nice.

Just curious as to what the teknomotor spindle set you back? I've been looking at the Colombo spindles myself but they are a little pricy at ~1K landed for a base model.

That is one beautiful machine Kym. It reminds me a lot of Rod's machines. And for somebody who doesn't know about electronics, you do seem to have done a remarkably neat job on them.

As to the Estop, it doesn't HAVE to be 24 volts, it is just that this amount of voltage is less susceptible to noise than the 5 or 12 volts are. So, 24v is better but 12v or 5v will do, so long as the environment isn't too noisy.

Very nice indeed. First Tassie build I've seen mentioned..
What's its cutting area?

Interesting collections of patterns/templates on the wall too.

Reply to questions above:

2 KW Electro Spindle.. 24V DC Fan...778 EUR
Delta VFD-E...279 EUR
VFD Brake Resistor...31 EUR
Shipping...90 EUR
Aus customs AU$300
From www.damencnc.com

Thanks Bob your posts helped me along the way.

Cutting area approx 900 x 700...Z 170
Jigs are for Grand Father clock and Wall clocks ...Spindle molder.

Thanks Kym.

That is one nice build, really like the base cabinet, well done

Looking good Kym.
David

Originally Posted by Kym A

Hello Forum,
I am getting to the completion stage of my build and am wanting to thank the forum members who have helped with information, during the design and sourcing of components for the build.
You are a good bunch!...
I am able to grasp the mechanical side of the build, but have struggled with the electronics side of it. ...Fortunately I have managed to get it up and running.
I still have to rework my E-Stop, as I have just been informed that it needs to run from 24V DC...I have set it up in the incoming 240V...I am also going to have one on the front and other side.
I am not running Limits or Homing at this time.
I have just heard about Dampers recently, are these recommended and do you build them yourself?

Pictures attached, may have to send in multiple posts.

Cheers,
Kym

Hi Kym,

How you arrange your EStop depends on all sort of things, mainly to do with the size of machine, how it is constructed, etc.

Looking at your Photos, you have a purpose built enclose with the EStop on the front, and you plan to put another on the side.

With EStop, keep in mind that it's primary purpose is to stop the motion (including spindle) by remove power from the drives quickly and reliably. On some syslems, the EStop also applies safety brakes as well.

There is a common misconception that all you need to do is feed a signal into the control software and let it handle the EStop. The problem with this is that you may have pressed the EStop because the control software has screwed up and just ignores the logic signal fed to it.

When removing power from the drives via EStop, you need to do that on the AC side. If you cut the DC power to the stepper drives that you have, there is no where for the energy stored in the stepper motors to go, so it get dumped into the Gecko drives, and can destroy them. So you need to cut the AC power to the power supply.

I'm not sure why you have been told you need to change the EStop to 24Vdc. If you are planning to use a handheld pendant with an EStop button on it, yes it is not appropriate to run 240V through the pendant. You would normally have 24Vdc through that switch that in turn controls a contactor or relay that breaks the 240Vac supply.

In your situation I see no problenm with running the 240Vac supply through the EStop switch(s) that you have as they are built into an enclosure, and in the end it is no different to the ret of the 240Vac wiring in your enclosure.

If you want to have other EStop switch that are in pendants or mounted on the machine, etc, then you will need to use a safer voltage on them to switch relays as mentioned above.

If you look at this engineering note you will see that in the schematic, the Estop cuts the power to the G540 drive supply
http://www.homanndesigns.com/pdfs/EN010_V8.pdf

Although you are using individual Geckodrives probably wired up similar to the engineering note below, wire the EStop similar to the G540 schematic.
http://www.homanndesigns.com/pdfs/EN012_V4.pdf

Note: Do not have the EStop cut power to the 5V BoB power supply, as you may want the BoB inputs to still work.

Basically the EStop should cut AC mains power, to;

• Stepper drive power supply
• Relays that are switching Mains power
• Supply to the Spindle controller.

Every machine is slightly different so you need to have an EStop strategy that will reliably make the machine safe when activated.



CNC control software cannot be part of the EStop system. If you want, feed a signal to the software to inform it that an EStop has occurred, but remember this is just to be polite so that the software can stop wasting its time generating motion control unnecessarily.




If you want to put another switch on the side of your enclosure, wire it in series with the first switch.

I hope this helps.

Cheers,

Peter.

Originally Posted by Kym A

Hello Forum,
I have just heard about Dampers recently, are these recommended and do you build them yourself?

Cheers,
Kym

Hi Kym,

By dampers presumably your talking about stepper motor dampers?

As you are using Geckodrives, dampers are totally unnecessary as the Geckodrives have anti-resonance circuitry built in which is what the dampers are designed to combat.

Furthermore, the dampers would most likely interfere with the Geckodrive anti-resonance circuitry defeating their benefit

Stepper motor resonance occurs at 2-3 rps. The motor's rotor starts to oscillate and if not controlled, will grow and may eventually stall the motors. One reason the motor stalls is that the resonance is consuming power, reducing the steppers output. One way to combat resonance is to use microstepping but it does not eliminate it completely and has other undesirable effects such as limiting the top speed of the motors. This is what the Chinese Stepper drives do, and why their performance is inferior to the Geckodrives. That said dampers may help the Chinese drives.


Also Gecko drives morph from microstepping to full-stepping after the speed gets to around 6rps where microstepping is no longer of use. The microstepping provides smoother motion at low speeds.

To see the resonance in a stepper, drive it at around 2rps. You will hear the pitch of the motor change and it will make a growling or rough sound. On Geckos drives you then adjust the trimpot to minimise this by tuning the anti-resonance circuitry in the Geckodrive.

Cheers,

Peter.

Hi Peter,

Thank you for the info.

I had the impression that all E Stops needed to be wired with low voltage to be legal.
So I thought I had better change my setup incase the machine was ever sold down the track.
I will introduce other E Stops around the machine so that they can be reached incase of the need.

Thank you also for the info on dampers and that Gecko drivers already compensate for the resonance problems.

Cheers,
Kym

Kym,

That's a real nice unit you have made there, very professional.
Q1. Did you fold the gray panel doors yourself or acquire them from something as I need to look at this detail next to finish off my unit.

As for E-Stop, its not a commercial machine so I am unaware that we would have to ensure compliance to that regulation??

RodM uses dampers on his unit, but he seems to find these things on eBay without issue, but i cant seem to locate any. They are supposed to improve performance - Rod?? any feedback?

/M

Mike,

I have a sneaking suspicion that those doors, and the drawer fronts, are MDF or similar, but I could be wrong (it's been known to happen)

Edit:

Actually closer inspection seems to show that it is a steel door on a metal cabinet

its hard to tell whats size steppers your using
but your using separate PSU for each gecko so must want some amps
your geko's look well " pasted " to the aluminium sheet

just keep an eye on the temp of the sheet , it looks like you have a fan behind the sheet ?, but i cant see another air "port"

i used a Jaycar heat sink 250mm long , Diecast Heatsink - 200mm Long - Jaycar Electronics , and 4 PC chip fans ,too mount the gecko's
not saying to do it this way , just the way i did it
cheers ken

The Drawer fronts are 18mm prefinished (melamine) MDF, silver colour.
The door on the power box is spray painted silver....sourced box from recyclers.

I have 2 x PS-01 MeanWell 48Vdc 7.3A Power supplies powering two 201 Gecko Drivers each.
570 oz in Stepper motors.

Fan pushes air against the 6mm aluminium plate that the stepper drivers are mounted on....The air escapes at the bottom of the power box.

Thanks for the interest.

Cheers,
Kym