Raised Y Axis Plywood CNC Router Vol.2

[mactec54]

Hello everyone!
There still seems to be some slight disagreement whether a VFD spindle works or not haha
I'm still not decided yet. Will continue my build and get back to thinking about the spindle further into it.

Today I started to cut the 32mm plywood I had laying around. Front and back covers as well as X Axis main plate are cut, just finished the ball screw bearing holders today after buying a sliding mitre saw to get proper perpendicular cuts $$$
Unfortunately, I know I will be a few cm too short of the 32mm ply to make all necessary parts. Really annoying. So will have to rethink which of the parts I need to glue together to make 2x15mm = 30mm thickness instead.
Tuesday I will be getting the 15mm plywood sheets and a 19mm MDF blockboard for the spoilboard/wasteboard.

Will utilise my tax return refund to buy all the hardware - quite convenient timing!

Cheers
Dan

Why so thick 32mm is not going to make the machine any better than using 15mm /19mm, with ribs Etc. where needed, you only have a small spindle so won't have a lot of cutting force to worry about.

Don't be confused, VFD Drives work very well on Single Phase, you just need the required input Mains Power Supply to have the capacity (Amperage) to support the Motor size being driven

[OZ_Dan]

Hi Mac!
There are only like 10 out of about 100 parts which are 32mm plywood, the rest is 15mm with bracing and ribs etc so all good

You said earlier that my single phase 10A 240V will not be enough to power a 1.5kw spindle, but Pete himself is running one of those without issues on single phase 10A 240V. This has me confused. But all good now - won't poke around in this topic any more. Will get some more information later on.

Cheers
Dan

[mactec54]

Hi Mac!
There are only like 10 out of about 100 parts which are 32mm plywood, the rest is 15mm with bracing and ribs etc so all good

You said earlier that my single phase 10A 240V will not be enough to power a 1.5kw spindle, but Pete himself is running one of those without issues on single phase 10A 240V. This has me confused. But all good now - won't poke around in this topic any more. Will get some more information later on.

Cheers
Dan

10A can run a 1.5Kw spindle, but you will have to restrict it to 5A output in the VFD Drive or it will overload the 10A circuit, why can't you run a 20A circuit then you will have enough for the whole machine, this is what is normally done, Pete if he has not restricted the Amp output in the VFD Drive his circuit will overheat if he is doing any heavy cutting

[peteeng]

Hi Dan- Like any electric motor the spindle current is proportional to the load on it. So if its lightly loaded it will run from a 10A GPO no issues. I am reviewing my power circuits at the moment. It's the same as your stepper motors you may have them set at 3A or 4A but they won't draw that unless loaded appropriately. I'm looking to get an amp clamp at the moment to learn more about actual conditions... Peter

[mactec54]

Hi Dan- Like any electric motor the spindle current is proportional to the load on it. So if its lightly loaded it will run from a 10A GPO no issues. I am reviewing my power circuits at the moment. It's the same as your stepper motors you may have them set at 3A or 4A but they won't draw that unless loaded appropriately. I'm looking to get an amp clamp at the moment to learn more about actual conditions... Peter

You need to know more than trying to use an amp clamp, you can't read the output of a VFD Drive with an Amp clamp, or any regular meter, it will give you a false reading, the output of a VFD Drive is not a normal sine wave so needs expensive meters Etc. to be able to read the output

Most VFD Drive have the Amp reading right on the Keypad just select the amp mode and you will see what the spindle is using, whatever you see on the screen X that by 3 gives you the total amps the spindle motor is using it's very simple, your spindle full load should show 2.3A on the screen the input on the service will show 14A at that reading

[peteeng]

Hi Mactec - Thks for the heads up on the amp meter. But I can measure the input amps to the inverter and thats the important bit? Peter

[OZ_Dan]

Hi Mactec - Thks for the heads up on the amp meter. But I can measure the input amps to the inverter and thats the important bit? Peter

Hi Pete,

I chatted to someone at CNC3D.com.au here at the Gold Coast yesterday about this topic. Should've taken a screenshot... Anyway, I asked how much the inverter from a 1.5kw spindle draws from a household power outlet (240V 10A) and they said, depending on load, anywhere up to 800W - so like 3A only. They also said it's simple math for the spindle power draw from the inverter. 1500W spindle / 240V = 6.25A at max. I just leave this here with no further comment.

https://www.cnc3d.com.au/product-pag...pindle-vfd-kit


Other than that, some more progress has been made


Cheers
Dan

[mactec54]

Hi Mactec - Thks for the heads up on the amp meter. But I can measure the input amps to the inverter and thats the important bit? Peter

The input won't give you a totally accurate reading of what the spindle is doing the VFD Drive readout and the input combined will give you a better idea of how well the spindle is doing

So, if you were to see 2A on the readout this then should show close to 12A on the input supply

[mactec54]

Hi Pete,

I chatted to someone at CNC3D.com.au here at the Gold Coast yesterday about this topic. Should've taken a screenshot... Anyway, I asked how much the inverter from a 1.5kw spindle draws from a household power outlet (240V 10A) and they said, depending on load, anywhere up to 800W - so like 3A only. They also said it's simple math for the spindle power draw from the inverter. 1500W spindle / 240V = 6.25A at max.

I just leave this here with no further comment.

https://www.cnc3d.com.au/product-pag...pindle-vfd-kit

Cheers
Dan

There are some dreamers around, you are missing the point you are using Single Phase Supply the Spindle is 3 Phase, so your Single Phase has to have extra current to make up the required 3Phase to run the spindle, the basic laws of physics at play, you can't get / make more from a lesser supply, just (2) things you have to remember Single Phase to 3Phase

That is correct the spindle will be anywhere from 6A to 7A that would be normal for a 1.5Kw 3Phase spindle, so just remember this is 3Phase output at 6A to 7A so how is the poor Single-Phase supply going to make up the 3 Phase this would be magic if this could happen that the output could be the same as the input

[OZ_Dan]

Hello everyone,

Finished cutting all the 32mm plywood parts - such a breeze working with a table and sliding mitre saw compared to cutting each piece by hand with a circular saw. Well worth the investment
Will get the 15mm plywood on Friday, currently working on nesting all the parts on 4 sheets in Solid Works and try to make it easy to cut. I also bought a drilling block and 3D printed a guide for drilling holes into the sides of the parts. Will post a pic when I use it.

Cheers
Dan

[OZ_Dan]

Hello peoples!

Another update - Nesting is finally done! That took a while... Also had to split the machine bed in 3 parts so will have to make sure it's super flush and properly bonded together. Otherwise I'd need one complete sheet for one small piece and that doesn't fit in the budget!

Cheers
Dan

[mactec54]

Hello peoples!

Another update - Nesting is finally done! That took a while... Also had to split the machine bed in 3 parts so will have to make sure it's super flush and properly bonded together. Otherwise I'd need one complete sheet for one small piece and that doesn't fit in the budget!

Cheers
Dan

You should not worry too much about a budget, as that can be a variable when building a CNC Machine like this.

[OZ_Dan]

Hello everyone!
I got all the 15mm plywood sheets and the 19mm blockboard as well. It is laminated on both sides which is great as it is very flat and straight - perfect for building the torsion box on it!

I need to ask some electrical questions as I'm not too familiar as a mechanical engineer

- Power supply: Is a 48V 10A enough to run 4 NEMA23 steppers and drivers with it? The steppers are the 4A version but they won't all draw that at the same time I reckon. I know the steppers could go higher voltage but it's hard to find a suitable PSU.
- Wiring: Recommended wire mm2 for steppers and drivers? AWG20 / 0.5mm2 enough considering the lengths? Are you guys using any fuses?

More plywood cutting and pics tomorrow!

Cheers
Dan

[peteeng]

Hi Dan - I have used 10A PSUs on a few machines and all good. 4x4A=16A but they do not draw that all at same time. I recommend when you are starting up that you cut the amps back on the drivers so if things go bump they cut out. Their happy to run on 2A for instance. Then when your confident everything is good crank up the amps. I use AWG18 speaker wire works well. The motors have AWG20 on them.
Pro Audio Speaker Cable - 4 Core - Sold per metre | Jaycar Electronics Peter

some of your components may need 24V? If so run your Z axis on 24V and the XY on 48V then you have heaps of AAAAs for everything...

[OZ_Dan]

Hi Pete!

Alright thanks for confirming. Then it will be a 48V 10A PSU. Will cut the stepper drivers down to 2A as you suggested. Where am I doing that? in Mach3 or the drivers itself?
The breakout board needs 24V. I thought of either stepping it down from 48V or get an extra 24V power supply which is probably the right(er) choice. A 24V 3A power supply should be sufficient.
Wouldn't the Z Axis motor run considerably slower when running on 24V?

Cheers
Dan

[peteeng]

Hi Dan - I have had 48V systems and 24V systems and can't detect a difference on smaller machines with hobby level electronics. You can use advanced electronics and go much faster and then you have to balance voltages, drivers and controllers to get that speed. say 10-20m/min (again general statement)

The system voltage does not absolutely set the max speed (general statement) there are several things to consider if you are aiming at "high" speed or accelerations. Using a high voltage is the easiest way to overcome the back emf created as the motor moves, especially at speed. If you are doing big jobs with lots of rapids then the XY axes will need speed if you are trying to make $$$. If its hobby level then you just let the machine run for however long it takes. Most hobby level drivers are rated at 50V so go 48V. You can go to 100V+ if you get the right drivers and power sources etc etc....

If you consider steppers can run from 0-1000rpm then less than 500rpm back emf is not a problem. The driver has smart electronics that deal with mid range instability so around the 500rpm mark the internal harmonics of a stepper are poor and the electronics deal with that. Then above 500rpm back emf starts to be an issue and the driver deals with that as well. But the speed will flatten as the back voltage and drive voltage start to equalise. So the 48V helps with this issue. Steppers use electromagnets, high frequency AC currents, so harmonics and inductance are big issues in driver performance

The Z axis being very short does not need a lot of speed (and it does not have enough time/length to get to high speeds anyway, unless your aiming at ultra high accelerations to operate; hence a 24V system for Z is fine. There are PS with 24V 12V and 5V outputs, these can be useful as you may need 5V as well.

The drivers have settings for microstepping, amp limiting and idle currents. Usually 8 dip switches to deal with.. read the manual . Peter

[OZ_Dan]

Hi Pete and everyone!

Thanks for the explanation. For ease of use and installation wouldn't it be better having 48V for all steppers opposed to running an additional 24V circuit just for one axis?

Let's summarise:

- 240V mains for PSU
- 48V for stepper motor drivers
- 24V for breakout board only?
- 12V anything? Maybe LED lights?
- 5V?

Tool setters and handwheels plug in directly into the breakout board I think.

Other than that, I ordered X and Y Axis ball screws from Ali yesterday Most expensive things I ever bought from there. Let's see how we go!

Cheers
Dan

[peteeng]

Hi Dan - 48V vs 24V up to you. To answer your Q no. You need 24V for the BOB, you can use the 24V for the control circuit vs 5V if you get drivers with 24V control (same cost just a switch look at DM542) I use a 24V brake on the z axis so it does not fall (have you considered this? brake springs rubber bands to stop it plunging into the machine when power goes down) so 24V is a good thing to have and a 24V high amp PS is not expensive vs a low amp one , If you use this BOB you will also need a USB 5V input for the isolation side of it. Peter


Digital Stepper Driver 1.0-4.2A 20-50VDC for Nema 17, 23, 24 Stepper Motor - DM542T STEPPERONLINE (omc-stepperonline.com)

[mactec54]

Hi Dan - 48V vs 24V up to you. To answer your Q no. You need 24V for the BOB, you can use the 24V for the control circuit vs 5V if you get drivers with 24V control (same cost just a switch look at DM542) I use a 24V brake on the z axis so it does not fall (have you considered this? brake springs rubber bands to stop it plunging into the machine when power goes down) so 24V is a good thing to have and a 24V high amp PS is not expensive vs a low amp one , If you use this BOB you will also need a USB 5V input for the isolation side of it. Peter


Digital Stepper Driver 1.0-4.2A 20-50VDC for Nema 17, 23, 24 Stepper Motor - DM542T STEPPERONLINE (omc-stepperonline.com)

Just a heads up, the 12v to 24v supply for these Breakout Boards is best to keep it at the 12v the 24v can cause some overheating and Board failure, some work fine with the 24v some do not

[OZ_Dan]

Thanks everyone!

It will likely be the red breakout board:
https://www.ebay.com.au/itm/30460439...frcectupt=true

Will step the voltage down from 24V to 12V+ to be safe.

Are you using any fuses in some places?

Cheers
Dan