Thread: Making a new CNC machine

It happens in Australia too Bob. I have a computer that has been sitting in Aitkenvale PO for a week.

You are talking about a failure of the Post Office though Rod, rather than a supplier.

Are you sure that the computer is actually at the PO, because if it is then a strong complaint would be in order. Their rules (Service Level Agreements) require them to deliver that parcel within a certain time frame, and that is (from memory) within 4 days of their having received it.

A phone call to the manager of your local Mail Centre should get some fast results, or at the very least they could put you on to somebody who could get you results. There is no excuse for this sort laxity unless they are having a strike or floods etc.

Bob

Edit: Just checked their web site and they say 7 business days.

In preparation for the installation of the new PSU I have installed the Gecko 203V (for Vampire) driver.

I then spent the next few days wondering why it didn't work. Had I done something wrong? Surely not. Well, maybe just a little bit not quite enough reading.

The 203V requires a common NEGATIVE (-0v) to work properly at all. and the C10 that is sold by Keling comes with instructions on setting it up with a positive (+5v) common terminal. OK, simple thing to change, just move the supplied jumper from the present location of pins 2 -3 to short the header pins 1 -2 instead and voila, we now have a common negative instead positive.

Fire up the computer and turn on the power to the CNC and Yahoo, X moves again. But then Boo-hoo, Z and Y have lost the plot. (Subtle joke there, you may not get it, most people fail to understand my sense of humour.)

Turn off the power to the CNC and start figuring out the rewiring.

Turns out that Pin 4 now goes to Pul +5v
Common to -Dir
Pin 5 to +Dir
And then jumper -Pul to -Dir

Using that as a base, it is easy to work out how the next axis is wired as well.

During this, I also decided that I should use a different wire for the signals between the K4030 and the C10. It is all low power stuff and all it needs is a bit of ribbon cable to carry the 5 volts signals. I removed about a kilo of HD wiring and replaced it with 200mm of 3 strands from an old hard drive cable.
Pleased to say that all axis are now working again. Hurry up with that PSU.

I see your problem - you should have hooked up to Youtube instead of Yahoo.

I was having a bit of fun in the previous post as I knew you were in the PO when you worked and had free time.

Originally Posted by rodm

I see your problem - you should have hooked up to Youtube instead of Yahoo.

Originally Posted by rodm

I was having a bit of fun in the previous post as I knew you were in the PO when you worked and had free time.

Damn. Hook, line and sinker.

Originally Posted by Bob Willson

Damn. Hook, line and sinker.

Just like a dead rat

Don't worry Bob I'm sure they think I am sick with some of the silly quips I throw up here.

Sounds like the service i got from Antek, took a few extra days to see it through usps too. Good news is when it does arrive and you see it, you'll forget about the delay. I found mine very well spec'd and good quality. You will need to check ripple under load as i have heard of one person having issues with it as the capacitor had issues somehow. Word of wisdom though and not sure if i mentioned it already, but if your PSU is supplied with a 5v daughterboard DO NOT use it as your logic supply. I found mine very unreliable...spent quite a while trying to figure that bit out.

Daniel

Wahoo. It finally got here at 12:15pm today.

Detailed Results from USPS

Out of Foreign Customs, September 29, 2010, 3:45 pm, AUSTRALIA
Into Foreign Customs, September 29, 2010, 3:27 pm, AUSTRALIA
Arrived Abroad, September 29, 2010, 3:27 pm, AUSTRALIA
Arrival International Dispatch, September 25, 2010, 10:25 am, FOREIGN CENTER, JERSEY CITY NJ 099
Electronic Shipping Info Received, September 20, 2010


Australia Post still don't even have it registering on their site yet.

Now to take it downstairs and quickly (yet skillfully and eptly) wire it into the setup.

Roadrunner - take cover!

Can't wait to see what you've been doing with it already. Look forward to the great projects i'm sure you have planned for it already.

Well things have not been going well again. At least, not as well as I had hoped they would.
The new PSU arrived and I wired it in to the Gecko G203V for the x axis and thought that this would make a difference now. How could it fail with 3 times the torque and twice as many volts and a Gecko controller. But fail it did.
Sean came over and we had a look at everything for several hours. Sean thought that I might have had some misalignment in the bearings and the nut. So we took it all off and measured everything. It all seemed to as accurate as needed ie +/- 0.5 of a mm. So we bolted it all back together again and greased it all up.
When we tried to get speeds of over 5metres a min it immediately started to lose steps. It appeared that the shaft had some flex in it when we tried to drive it at speed. Sean thought that he may have mis-advised me when he suggested that I only needed to use 25mm screws over a 2 metre length as his had been 16mm over 1.5 metres and he easily achieved speeds of 6metres a minute with much smaller motors that I was using.
He suggested that I beef up the cross member underneath the gantry table. I did this by bolting and screwing two pieces of 25mm RHS along the front and rear of the lower cross member. It is now absolutely rigid. That rigidity has removed almost all of the flexing that I had been getting in the screw but it still failed to improve the speed. This leads me to the conclusion that Sean did not give me bad advice when he suggested the 25mm screw.
Does the BOB make much of a difference where number of pulses is concerned? Would it make a difference if I were to use a smooth stepper?

Bob Willson

Further to the above, or at least, relating to the power supply, I need some advice from someone who knows about transformers and such like.

The Antek PSU that I purchased has 5 pins for connecting the output wires to.
First pin (1) is +
Second (2) is +
Third (3) is C (I assume this means centre or maybe common)
Fourth (4) is -
Fifth (5) is -

Measured DC voltage with nothing connected is:
1 - 2 = 0 volts
1 - 3 = 37.3 volts
1 - 4 = 75.4 volts
1 - 5 = 75.4 volts
2 - 3 = 37.6 volts
2 - 4 = 75.4 volts
2 - 5 = 75.4 volts
3 - 4 = 37.9 volts
3 - 5 = 37.9 volts
4 - 5 = 0 volts

I connected the Gecko driver to pins 1 and 5 and it works fine.
I then connected the other two Keling drivers (which need a lower voltage) to pins 2 and 3.
When I then measured the voltage at 2-3 the voltage was only 4.9 volts.
Can anyone tell me what I am doing wrong please and if possible, the correct way to do what I want to do. (If it is possible)

Bob Willson

Hey Bob,

Sorry to hear your having issues. From memory, and it is hazy, but i was told not to use the centre as the C terminal is for 'centre' as it is apparently a centre tap for the torroid. From what i remember It is possible to use a centre tap but not when using the outer as well, as the load is uneven across the torroid. I would recommend not using it as all information i found back then from other people said not to use it.

Our drivers should be run from the + and - terminals (made easier as there is 2 for each). This presents an issue with your keling if they require less voltage then your PS supplies.

One other thing to check also is the Kernal speeds (drop back or ramp up) and your logic supply (what are you using). The 5v logic must be regulated and very close to 5v. As the drivers start pulsing more it uses more logic and thus has more load on the logic supply. Either of these could result in lost steps as it struggles to keep up. The 5v logic was what caused many issues for me.

Daniel

BTW, copy profile, make the gecko drive setup to run your gantry axis through ports and pins. Disconnect power to other drives, test that out and see if the gantry stalls where you had issues before, if it works change it to another axis, you will soon see if its your setup or mechanical.

As a side note, did you calculate the steppers and such to suit. A larger stepper does not always mean faster. More voltage helps, but the inductance, mH rating of a stepper, decides final speeds. The lower the inductance, the quicker it can accept the new signal as it is not held back. I have seen an identical setup run with 2 305oz/in steppers. One had a higher inductance and it was noticable in speed.

Remember a stepper runs at about 800RPM at best(Theoretically and about 300RPM in most routers). Using this calculate your max speeds using your pitch of screws and any pulleys.