Created Date: March 22,2013

Created by: Adisharr

Personally, I don't being held to some arbitrary 100 word limit plus ASCII can use a lot of words. If you have the option of using a stepper controller/drive that supports ASCII then I would use the Click. The software is well done, it's free, the ASCII support is good and it's easily expandable.

Consider using sensors to detect that you actually fed a part into the carriage - also a sensor to make sure it's clamped. Depending on your clamp, you may be able to use one sensor to do both of those things.

2. Clamp on/off (clamps the part - pneumatic) - additional sensor to determine it was actually clamped / a part is present

5. Stepper motor for feed (ASCII)

Consider a watchdog timer for the cycle to make sure things happened in a certain amount of time. What about an E-stop? Fault light? Is this saw dangerous? Is there a guard? What happens when it's off - can the machine still operate?

Safety should always be a big concern. If you 're going to go through the trouble of automating a machine it should be made as safe a possible so that someone completely new can operate it without instruction and not hurt themselves.

Created Date: March 24,2013

Created by: ironband

Thanks Adisharr!

Originally, I was thinking if I used the DirectLogic 05, I wouldn't need to use ASCII, but then I realized that I would need to add a CTRIO unit which would add another $200 to the price tag. Of course, I just realized that I will need to buy the more expensive advanced driver to be able to do Click ASCII, but it's still cheaper than going the DL route. Click it is!

Thanks for the safety reminders as well. I was already thinking that a check on proper loading and clamping would be a good idea. The saw does have a guard and is pretty small - one would really have to try to injure oneself seriously on it. Still, better safe than sorry!

Andre

Created Date: March 25,2013

Created by: Adisharr

Thanks Adisharr!

Originally, I was thinking if I used the DirectLogic 05, I wouldn't need to use ASCII, but then I realized that I would need to add a CTRIO unit which would add another $200 to the price tag. Of course, I just realized that I will need to buy the more expensive advanced driver to be able to do Click ASCII, but it's still cheaper than going the DL route. Click it is!

Thanks for the safety reminders as well. I was already thinking that a check on proper loading and clamping would be a good idea. The saw does have a guard and is pretty small - one would really have to try to injure oneself seriously on it. Still, better safe than sorry!

Andre

Sounds good - glad I could help :)

Created Date: March 26,2013

Created by: Philip Potts

A question for Ironband

Ironband,

Why are you going to use a stepper motor? A stepper motor is generally used for precise positioning of a part or something. If I understand your description of the equipment and it's operation correctly, you are cutting pieces of metal to length. The carriage moves the piece forward through the saw blade until it hits a stop, at that point the piece is removed and the carriage travels backwards to another stop. I think a basic AC motor with a variable frequency drive would be sufficient for your needs.

But, you know your device and the design you have in mind much better than myself so I'm curious about the stepper motor.

Thanks,

Philip

Created Date: March 27,2013

Created by: ironband

Philip,

Thanks for asking - My needs as far as the feed motor are as follows:

1. Needs to have sufficient torque at low speed to push the part through the saw

2. Needs to be reversible.

3. Needs to be able to return at high speed

4. Needs to be consistent enough to stop in a target area at each end of the lead screw to allow for loading and unloading of the part clamping fixture.

If I am over-speccing with a stepper, I'm happy to entertain lower cost alternatives which are easily controlled. My current manual machine uses an AC gear motor as the drive, and I manually return the carriage by way of a push button quick-thread nut.

Is an AC motor with a variable frequency drive going to meet my needs? Seems like it would save me over a hundred dollars ($99 controller + $143 motor vs. $199 driver + $37.50 motor + $120 power supply) to go that route.

I'm interested in anything anyone has to say on the topic...

Created Date: March 27,2013

Created by: Philip Potts

Ironband,

I'm not sure how much torque you will need to turn a lead screw. A gear box would be good but will add a couple of hundred dollars to your project. If you connect the motor shaft to the lead screw with a chain or timing belt you might be able to reduce the speed by half. This is assuming you have the room to mount sprockets or pulleys large enough to achieve a 2:1 ratio. If you used a 1800 rpm motor this would give you 900 rpm to the lead screw. You would then have to set the VFD to about 10% to get the 100 rpm you want. I really don't know if this would provide enough torque for your project or not. I have a machine about 20 ' long that pulls cardboard boxes in, glues the box, folds it and then runs the box through a "compression " section that holds the box closed until the glue sets enough to hold. It has a 2 hp 3 phase motor with a Leeson VFD. The motor is attached to a gearbox and I run the motor at about 30%.

You said, "4. Needs to be consistent enough to stop in a target area at each end of the lead screw to allow for loading and unloading of the part clamping fixture. "

You will have to mount a prox switch or a limit switch to signal the PLC that the end of travel has been reached and the PLC can, in turn, tell the drive to stop.

You have lots of choices here. Let us know how it goes.

Created Date: March 27,2013

Created by: ironband

Let's see - the gearmotor I am presently using is rated 4 in-lb of torque at 200 RPM and has been running well for over 10 years. I'll have to take a look at the available motors and run some calculations, as well as look at my design to see what I could do with timing belts for speed reduction. In any case, this now has me thinking about my saw drive, for which originally I was going to use a repurposed treadmill motor and control for, but now I'm thinking one of the larger AC motors with a VFD might be nice and I could write programs for different materials (saw speed and feed speed). Definitely gives me some things to think about while I prototype the clamping fixture with my existing tool.

Thanks for the food for thought!

Created Date: March 22,2013

Created by: ironband

Hi all,

I'm new to the PLC game and very excited about a machine I am building which will use PLC to automate its operation.

One function of the machine will require a stepper motor with a lead screw to move a carriage holding a workpiece through a saw - it's a fairly light machining operation, but one I wish to automate.

It appears that if I'm only using one stepper in my application, then I should be able to control the driver using ASCII commands using a Click PLC.

But from what I 've been reading and watching on YouTube, it appears that perhaps a DirectLogic (like a DL05) might be a more robust choice.

Considering that the Click would run me $79 plus $30-40 for the power supply, while the DL05 would run around $140 and includes a power supply, the price differential is fairly negligible with regard to the hardware.

But the software has me a little worried. Apparently if I keep my instructions under "100 words ", there is a free version of the DirectLogic software I can use. On the other hand, the Click software appears to be completely free no matter what I write into it.

So I'm wondering how much mileage I can get out of 100 words, since I haven't done any ladder programming...yet.

I expect to have inputs as follows:

1. Start button

2. Carriage home sensor

3. Carriage end sensor

4. Hopper sensor

5. Stop button

Outputs will be

1. Hopper actuator (loads a part - pneumatic)

2. Clamp on/off (clamps the part - pneumatic)

3. Saw motor on/off (electric)

4. lubricant pump on/off (electric)

5. Stepper motor for feed

6. unload actuator (unloads a part)

The jist of the program will be

When start button is pressed and parts are in the hopper

- carriage goes home

- part is loaded

- part is clamped

- Saw is turned on

- Lubricant is turned on

- stepper feeds the carriage loaded with the part through the saw (slow rate)

When the carriage reaches the end limit

- Saw is turned off

- Lubricant is turned off

- Part is unclamped

- Part is unloaded

- stepper returns the carriage to home position (fast rate)

When the carriage reaches the home position and parts are in the hopper, the first sequence is repeated.

When the carriage reaches the home position and parts are not in the hopper, the program ends.

When the stop button is pressed, the program ends.

So, for those of you with some experience, does that sound like a "100 word or less " program to you? And, all things considered, anyone have any recommendations as far as which way to go on my PLC?

Thank you in advance for your assistance as I learn this stuff...

Andre