[mmukhaizeem]

Hi,
This is my first post on this great forum, and I want to say Hi everybody ,

I have been reading and reading for years now, I have built a CNC router long time ago which was bad in all aspects, bad structure and wiring,

although I have good motors, BOB and of course geckos, the result was I lost confidence and lost interests for some time.

Now, I have a lot of space in my new home workshop and have been dreaming of a CNC router and inspired by the Madvac CNC, I want to be back but there is one problem, I am soooo confused about the electronics things, I have managed the power supply needs for my motors but regarding fuses, emergency switch, precharge resistor, diodes, solid state relay, pole switches ….. I am totally lost!


what I have now is a custom transformer 240v/50v 1500VA , 3 Nema 34 1200 oz stepper motors, Campbell BOB, and 3 gecko drives, 85,000uf 100v cap.

My plans are full size steel structure CNC router, and without your generous help and advice I am sure I will not achieve that goal.


Thanks and appreciate your input.

MSD

[LeeWay]

You will need a multimeter and a box to mount the electronics in. It can be pretty much anything as long as it's large enough. Leave plenty of room around the components for wires and fans.

That will get you started.
You will also need a computer.
What software will you run on this computer?
You have to make some type of decision here first.

[mmukhaizeem]

I do have large electrical box, a multimeter, and a PC, I am considering mach3 to run this machine.

Note, I have disassembled may first machine and electrical enclosure just to start all over again right.

MSD

[LeeWay]

That is a good start then.
I concur with your Mach 3 choice.
It is wicked for the price.
Does your computer have a printer port?

Download and install a trial of Mach 3 and get it set up to that printer port and then run a driver test.
You will find the driver test in the Mach 3 folder.
Just double click the file and hold on a minute or two to see the results. Only maybe 10 to 20 seconds actually. Look for spikes on the graph.

[mmukhaizeem]

i have desktop computer with two printer ports, the test is smooth with a couple of small spikes.

FYI, English is not my native language so I may ask stupid Qs that's because I did not understand all what I read.

Thanks

[LeeWay]

Your english is fine. My Arabic is non existant, though I do speak German as a second language.
No worries about stupid questions. Asking questions is a smart thing to do.

I am hoping some others here will chime in. I am no pro at this either, but I have been down the road with it a few times now.

I think the driver test is fine for now.

Tell us which Gecko's you have and which BOB.

[mmukhaizeem]

I have combo board from Campbell designs and 3 X 210 and one 212


My concerns are:

I do want to put fuses between cap and drives, but what type of fuses - fast or slow blow- and how to determine the amps of those fuses?

do I need charge pump, precharge resistor or pullup resistor, I even don't know what they are!

emergency stop! what type if there are types?

I do want shield twisted wire! 18awg and 4 core is my best for all 3 or 4 axes?

what about the bare wire (the fifth wire in case of 4 core shielded cable), is that right? how to ground it? both ends? where?

one end should be grounded to gecko drive body?terminal? what about the other end! just leave it untouched and just cover it?


I am soooo confused


MSD

[LeeWay]

It can be overwhelming at first. Just relax a bit.



You are now getting to the root and asking some of the right questions.

I don't have any experience with any of your electronics. I use C10 BOB's and Gecko 201's and 203V's.

They should be similar enough though I think.

Here is a link to the 210 PDF.

The 212 here.

Someone more familiar with those drives will have to give you clues on fuses and setup options for those.

Bob has more than 1 board available. Specifically which do you have?

Your wire choice sounds fine. The 5th wire is your ground or sheild wire. It should only be connected to the ground at one end. The cse ground that the gecko's are mounted in. Just leave it disconnected at the motor end.

I use 5 amp automotive fast blow fuses between my power supply and my Gecko's. Not had any issues with those.


We will get to the charge pump later. For now, just skip it.

An Emergency stop can really be just about any type switch.
U use a simple mushroom switch that is momentary. In other words, it activates when I push it and deactivates upon release.
Lots of guys use the twist lock switches.

http://homanndesigns.com/store/index...bbd8ab73e4945a

Even the switches on the Chinese made mills and lathes would work okay.
I actually use a machine toggle switch on my lathe.

I have combo board from Campbell designs and 3 X 210 and one 212


My concerns are:

I do want to put fuses between cap and drives, but what type of fuses - fast or slow blow- and how to determine the amps of those fuses?

do I need charge pump, precharge resistor or pullup resistor, I even don't know what they are!

emergency stop! what type if there are types?

I do want shield twisted wire! 18awg and 4 core is my best for all 3 or 4 axes?

what about the bare wire (the fifth wire in case of 4 core shielded cable), is that right? how to ground it? both ends? where?

one end should be grounded to gecko drive body?terminal? what about the other end! just leave it untouched and just cover it?


I am soooo confused


MSD

[DaveKennedy]

Hello, This is my first post too. I have just aquired my stepper motors and bits for the first time. Nema 34s 4.2 Nm.

I have it all on my desk top and it's working with Mach3.

I used car inline fuses with the common blade type fuses found in cars. Each driver has it's own fuse of 15Amps. Don't know if it's right, but it works.

The wire I used I striped out of a standard 3 core electrical wire.. the type you have on a kettle or washing machine or.... no shielding.

Then I followed those great videos on http://www.machsupport.com/videos/

and I'm off! building a frame and fitting linear rails and ballscrews is easy for me and I now treat that mass of wires as a package to be used to drive the mechanics.



I can order 2 glasses of white wine in Greek, but that's not much use

[DaveKennedy]

It can be overwhelming at first. Just relax a bit.



An Emergency stop can really be just about any type switch.
U use a simple mushroom switch that is momentary. In other words, it activates when I push it and deactivates upon release.
Lots of guys use the twist lock switches.

Hi LeeWay,

Our good friend Art says use 'normally closed' switches, because Mach3 can tell you if there's a break in your circuit. If you use a 'normaly open' switch Mach 3 thinks all is well when there is no current flowing. So if you get a break in your circuit Mach 3 thinks all is well, even when the limit switch/ emergency stop is pressed. Using a 'normally closed' switch makes sense to me. I'm no expert.

[LeeWay]

Right.
That is the best practice. Wire it so that the switch is closed at rest and active when open. Some switches like some limit switches can be wired either way.
This is the switch I use on two machines.
http://www.surpluscenter.com/item.as...tname=electric

[srcmadison]

If you choose a momentary e-stop button like the nice one suggested by LeeWay, you will need a relay to cut the motor power when the switch is activated, otherwise the power comes right back as soon as your hand leaves the button. Your drives may have an internal circuit which does this for you but the safest bet would be to use a maintained switch or a relay circuit so that you are sure that the motor power is off when the switch is pressed in.

[LeeWay]

Actually it puts Mach 3 into a Reset condition. No power will be allowed to return on unless Machs reset switch is hit. If the computer has a crash, here would be a good place for a charge pump. It would not allow the absense of a special Mach driven frequency and thus no power to anything without that.

I don't use charge pump circuits yet, but I fully intend to do so in the future.

[bobgerman]

A charge pump is a must when using a PC to operate a dangerous machine. I have had several occations where the charge pump saved my machine from self distruction. They are quite simple to install and inexpensive. Plus they serve as a good point of connection for your E-stop circuit. i.e. you can share a common port pin for both. Plus, it can be used to disable certain break-out boards; adding to the over all emergency safety features.

[DaveKennedy]

Well a charge pump sounds like a good idea, I can just imagine coming to the end of a 2 hour routing job and the computor glitches and smashes the work piece. I'm still celebrating seeing 3 motors dance on my desk at the moment but I shall look into charge pumps.

[Al_The_Man]

The important thing is to not rely entirely on software or on-screen buttons for E-stop.
An external hardware E-stop circuit should be in place.
A charge pump, or more precisely, a Watchdog Timer can be made from a 555 timer that runs around 50¢.
Al.

[donald_ortega]

donald O
Re: if you want a good solid ground, see if their is a water pipe close by and connect the ground wire to a water pipe. Do not connect to any gas pipe!!!

I have combo board from Campbell designs and 3 X 210 and one 212


My concerns are:

I do want to put fuses between cap and drives, but what type of fuses - fast or slow blow- and how to determine the amps of those fuses?

do I need charge pump, precharge resistor or pullup resistor, I even don't know what they are!

emergency stop! what type if there are types?

I do want shield twisted wire! 18awg and 4 core is my best for all 3 or 4 axes?

what about the bare wire (the fifth wire in case of 4 core shielded cable), is that right? how to ground it? both ends? where?

one end should be grounded to gecko drive body?terminal? what about the other end! just leave it untouched and just cover it?


I am soooo confused

MSD

[Ed VanEss]

External e stop switch should be wired to a relay that cuts power to your incoming current on your power supply , not between power supply and drives. Also , mount your Geckos on a heat sink plate with cooling fans. 12 v fans from old computers work great. Remember , heat kills electronics. keep it COOL.

Ed V

[LeeWay]

In my way of thinking, with steppers, a simple estop will suffice for hobby machines. Unless the machine is paper mache', steppers won't do any damage if they do happen to run away. They would stall or skip steps at the end of the axis provided good stops are in place.

The cutter, however can do damage to fixtures and itself as well as the part.
Servo's on the other hand are capable of wrecking a machine. With those, a charge pump is a must. If you have a stepper system that is often running long programs, then do the charge pump.
My machines have been running for years without one in a semi production mode and are often left alone to do what they do. I have had only two crashes. Once was a power black out and the other was when I was just setting up my laptop. It still had some hibernation feature working.
Once I got the computers reliable, there have been no issue.
Since mine are semi-production though, I do want to add the charge pump.
It is cheap insurance.
They are not crucial to a hobby cnc machine though.

[mmukhaizeem]

I have this combo board but not rev.5, I bought mine two years ago. I believe I have read some where that it contains a charge pump!! please correct me.

I have an emergency stop switch similar to the one in the link http://homanndesigns.com/store/index...bbd8ab73e4945a but not sure NC or NO, I should check it once I get back home. the circuit is my concern.

so,

The shielded wire in 18awg in my last post is fine.

I need fuses to protect my drives, also I read that some type of diodes are used in this case!! what are they?

Don't you thing a 15A Automotive fuse is too much! the drive may get fried b/c the fuse is too big!

I do need a charge pump if my BOB doesn't have one. where do I find it, any websites?

I will posting some photos of the steps I would like to provide max benefit to those are like me.

MSD