MechMate DIY Control box full spec screened spindle 3phase
 

This was the project for today.....

Basically the power supply, parallel connector board and 4 geckos......
.....needed a home.

So we get a metal box....

Also, we need a thermistor relay and 9V transformer for the parallel board....
....and a main switch, a couple of terminals and a circulating fan.

The white plate in the back of the box is taken out for the assembly. The idea is to lift the geckos about 60mm off the back plane and mount them on an alu plate which acts as a heat sink and ground/earth plane.....
......The rail in front is a standard 35mm DIN rail. (Also lifted off the back-plane in case wires/cables need to pass under it.

The fan sucks air from behind the white back plane (which is spaced 15 mm off the back of the box) and blows against the bottom of the alu plate....

More wiring and tidying up to do, and then it can all be dropped back into the "orange" box.

Some more progress this weekend - wiring is about 95% done.......



The last pic is a view looking into the terminals that will receive the cables leading out of the control box.

1. The main power cable, with 3x Line and 1x Neutral conductors feed into the isolator switch with the blue knob on top. The 1x Ground conductor of the infeed cable goes to a point bottom right, on the mounting screw of the white back plate.

2. The outfeed to the VFD for the spindle, 3x Line comes from the contactor to the right of the isolator.

3. The empty terminals further right are for the shielded cables to the E-stops, Z-zero, etc. All Inputs. The shields also have terminals dedicated to them.

4. Nearly everything to the left of the blue-topped isolator is for the spindle. The first five terminals are for the thermistor and cooling fan. (Plus a shield terminal)

5. Then the tall thermistor relay.

6. Next few terminals are the outputs from the PMDX board - some are not allocated yet.

7. The last terminals to the left are for the communications with the VFD. Start/stop of the spindle, Fault at the VFD, Analog speed control via potentiometer.

8. Lastly, each stepper motor (shielded) cable goes directly into its Gecko via the blue terminals at the top of the pic. The shield of the cable screws to the alu plate.

It has since been learnt that the green/yellow ground wire from the PMDX-122 to the top center of the alu ground plate (heatsink) is a mistake - that wire should not be there.

A wiring project like this is a good "kitchen table" project. This is all being done at home, and it is actually fairly relaxing.

(Do you still want a simplified schematic of motors/geckos etc.?)

That orange box got a few holes it, and was sprayed "MechMate Blue" (actually it is standard aerosol "Electric Blue from the local hardware shop)


Then some more wiring......


Until the outside looks nearly finished...

Gerald,
You've done a beautiful job. I wish that my designs looked so good.

If I may make one suggestion, though. You might want to place all switches on a side panel. Even though a door in a control box is rarely opened, meaning that the cables will never be flexed enough to 'crack', there is always the possibility that a cable might get wedged. Of course the ON/OFF switch has to extend through the door so that the door can't be opened while the unit is powered up, but that is usually just the 'handle' of the switch, with the contact portion firmly mounted on the interior of the box (as you have done).

I considered side switches/lights but discarded that for three reasons:

- the box will be wall mounted and the right side is far away from the operator, in a corner. The left side will be obstructed by the VFD.

- the indicator lights need to to be visible over a wide angle, from the front

- the white back panel cannot be dropped in if switches are on the sides.

By the way, to explain the outside features:

- the white rectangles are plug outlets for powering the PC and another appliances if necessary.

- The yellow/red isolator is obvious. Switching that on gives power to everything except the VFD/Spindle and the linear power supply and Geckos. The actual power switched is very low (PMDX, fan, thermistor relay).

- The green pilot comes on when isolator is on.

- the rectangular red/green/pilot controls the contactor that powers the VFD and linear power supply. (The E-Stops, thermistor relay, VFD malfunction, drop this contactor out). Pilot is lit when "drives" are powered.

- silver/grey knob for spindle speed control.

- black button next to it is a detent push-push for starting the spindle for warm-up without starting the PC.

- the empty top section of the front is for the logo decal! :-)

Here is the mounted control box, with the Delta VFD alongside. The "base" of the VFD houses the output line reactor.

what size box and where did you get it?

The box is 550Hx400Wx220D (millimeters) external. Dust proof (door seal), with removable back-plate. Got a no-name brand here in South Africa (part no. HE203 from www.em.co.za), about $150

The COOLING fan system works like a champ! Have been logging internal and external temps over the last 2 months and the max differential was 12 degrees Centigrade. Because the fan does not draw in outside air, there are no dust issues. The box dissipates heat through its surface skin - the larger the box, the better the cooling.

Gerald,
Although I realise price comparisons between countries (even continents), are not necessarily indicative, I would still be interested in the complete cost (including cabinet) of your control box.

..........Mike

Without the shipping costs to get the Gecko's and PMDX here, it cost $970 in materials & components alone. (no labour)

Hi Gerald

I am a newby when you talk about electronics.Can you give me more info on the output line reactor that is in the base of the vfd mount. What is its purpose.

Nice forum you built up....

Thanks
Deon

Hallo Deon daar in PE!

The output line reactor (some people call it a choke) is highly recommended by both the VFD and spindle manufacturers. I didn't want to argue with them. http://www.mechmate.com/Forum/clipart/happy.gif Here is the one that I am using. The stuff on that page explains some of the benefits:

Protect motors from long lead effects
Reduce output voltage dv/dt
Virtually eliminate nuisance tripping
Extend semiconductor life
Reduce harmonic distortion
Reduce surge currents
Reduce motor temperature
Reduce motor audible noise
Improve true power factor
etc.

Anyway, I had heard that VFD's make radios go funny, but so far we havn't had a single issue caused by the VFD in the shop. Maybe it is because we used a "reactor"?

Another reference

Spoke too soon - have just discovered that the VFD is inducing a fake charge pump signal to the MechMate's own controller if the PC is not supplying the real charge pump signal. see this thread. This doesn't make a reactor a bad choice though, I still think it is the very first accessory to consider for a VFD/spindle setup.

People are asking what the following components do.....?




From the left:

1: Thermistor relay. Only used to protect a spindle against overheating....if the spindle has an internal thermistor. If you are using a router, you don't need it. If your spindle does not have a thermistor, you don't need it. (Picture)(Siemens 3RN)

2. Main switch: Operated by the red/yellow knob on the outside of the door. You can only open the door if the switch is OFF. It has 4 poles to break the 3 phases Live and the Neutral lines. You can put your safety switches somewhere else if you want. This is the "export" quality way of doing it. (Ensto - Finland. brochure)

3. Main Relay/Contactor: Needed for the emergency stop circuit so that it can switch OFF all the high voltage when an Emergency Stop button is pushed. Again, this is "export" quality safety - you can decide on your own safety standard. (local source)

4. 9 Volt transformer: to supply the PMDX-122 with power. You can also supply 5V from your PC's USB port, but my PC is old and does not have USB ports. (Picture) I mounted the transformer on the green base.

I was wondering but was timid to ask .
It looks like a nice configuration.

Hi Hugo

I am sorry for my bad reputation which makes you timid http://www.mechmate.com/Forum/clipart/happy.gif

Maybe I must explain why some people get "unpleasant" answers from me at times..... There seem to be two types of people who want to build MechMates - a. Those that like the looks and are too lazy to think and b. Those that want to understand why and what they need to do. I believe that group a. is dangerous and end with the risk of electrocuting themselves - I do not plan to help these guys make accidents. It is easy to identify this group - the first thing they want is a shopping list to start buying stuff! Hugo, you are clearly in the second group - you are trying to find out the purpose of each item before you decide to buy it.

Just think of the implication if I put that Ensto switch on a shopping list..... They are a company from Finland who happen to have a stockist in South Africa. In your country there could be another more economical supplier - remember, it is only a switch. Also, if you are going to use a router, you could use single phase only, so the switch, (and the contactor) can be much smaller.

The title of this thread has always carried the words screened, spindle, 3-phase, "export". People need to realise that their own application could be different and build their control boxes accordingly.

Thanks Gerald.

You can count with a MechMate "beast" done the right way in my country

¿How do you install the 9 volt transformer? It has five legs. ¿How you configured them?

¿Size or capacity of the Main Relay/Contactor? To many questions, but I am making my list for buying all ,and this is my weak area. Thanks

Those five legs on that transformer confused me as well - I had to phone the supplier to find the diagram. Your transformer will be different and it is important only to buy stuff for which you can get information. This mostly means that you cannot buy from the cheapest supplier.

For the "main contactor" capacity you need to decide a lot of things. Spindle or router (and size), how your "safety" standards and plan will work, voltage in your country, etc.

Usually five legs on a transformer means that you have two legs for the primary (input) voltage and three legs for the secondary (output) voltage. The output voltage would have a center tap so that a 9V transformer would produce 4.5V (times 2) or 9V,

Hi Gerald,

Do you have a wiring diagram that would show all connections lets say for example the power supply? Thank You.

I am very nervous about requests for power supply wiring diagrams. I believe that people who understand the risks of working with mains voltages will not need such diagrams.

Ok,understandable. Maybe I'll re-word that question. What I am looking for is something like this.

http://www.mechmate.com/Forum/messages/832/3442.gif

You can use that same diagram for a MechMate.

On the right side, the PARALLEL PORT PINS are all on the PMDX-122 card.

On the left side, the AC PLUG and SPINDLE PLUG is confusing for me. Not sure which is a PLUG or socket, which is the power cord that goes to the wall socket/outlet..... I think that:
- AC PLUG is the incoming power cord
- SPINDLE PLUG is a socket for plugging a single phase router into. (We normally use the term SPINDLE for another type of cutting motor)
- RELAY is standard. We often call it a CONTACTOR, and we often try to break both Live(Hot) and Neutral with 2 poles on that contactor. But if your government/personal laws/standards allow a single pole relay then that is okay.
- S1 & S2 are E-stops contacts or just plain Stop/Start contacts. Not clear how these switches are used.

This circuit will not stop/start the router on command from Mach3. Something more is needed.

We do not use the bleed resistor R1 at bottom left because the 4 Geckos drain the capacitor (C1) quickly enough when the power is cut.

This is the only diagram that I have:




If you look closely, you will see that it does not give the power supply schematic in top left corner. Also, it does not give all the Gecko connections.

I can give a copy of this schematic to people who have purchased exactly the same components (including spindle and VFD).

Subsequent to this exchange, I have ventured into general purpose power/wiring diagrams here

Hi Gerald

Is there a local source of all the components for the control box, also I only want to run single phase at the moment.What is the total cost of building the controller box.

Thanks Edmond

Only stuff not off-the-shelf in Cape Town are the Gecko's, PMDX card, and transformer. Gecko's and transformer ex-JHB. The JHB gecko stockist has an equivalent to the PMDX (www.cncdirect.co.za)(Gecko202 @ $200). Transformer can be ordered via Communica. Most other parts from ElectroMechanica, Bellco and Communica. Total cost depends on where the components come from, whether you import direct and the discounts you can get - my material cost about R6000? (But that could be nearer R9000 with inefficient shopping) ($833 to $1250). Also add sweat & time.....

Gerald

In the old forum on 5 June 2006 you mentioned that you had not made a final commitment to the PMDX 122, after being in use for a year now has it proved itself or would you consider using an alternative?

Has anybody else used a different breakout board and have any comments positive or negative as to their respective choices. I know they are pretty simple devices but there must be differences considering the number of options available (and price range...?)

Hi Alan

Yes, the PMDX-122 has certainly proved itself. I did have a noise problem, and the support from Steve Stallings (the designer/producer) was fantastic. Even though the noise was coming from my spindle drive, he came up with a simple mod (add a resistor) that cured it. Based mostly on the support experience, I would use it again. Until . . . . . .

. . . . . . USB driven "breakouts" are proven. The ncPod is being watched with great interest.

Here is a report on a "CNC Workshop" held in the US recently.

Those guys wiring their control panels . . . . where did they get the idea to put their Geckos up on a plate across the middle of a removable panel from a control box? Wonder if they have fans under those Geckos? :)