SMC mod for single cable end stop sensors

Here's a picture of my modification to use a single RJ-45 cable for the minimum and maximum end stop sensors.

It allows the use of the unused orange wire(pin 2) to carry the opposite signal sense. As you can see from the picture I made use of the signal pad for maximum and soldered it to pin two of the RJ-45 jack.

From ExMrClean

While you are at it might make since to do the same going the other way so if you want to reverse your axis direction you would simply move the plug from the minimum jack to the maximum jack and turn around the motor plug on the other side of the board.

Also a quick picture of the 7404 inverter chip that I inserted/hacked inline to reverse the logic level from my hall effect sensors so that it matched the optical end stop polarity.

From ExMrClean

Hall Effect Sensors

Since my X & Y stages already have endstop sensors that are already mounted and take in account the space needed for the folding shields I most definately want to reuse them. Also since the opto sensors are the wrong physical layout to insert in their place, it makes even more sense to reuse them.

After my shopping trip to get more Allen wrench sizes I start taking off the old end stop sensors and what the heck they are magnetic, not optical!

Hmmm at least they have part numbers on them, time to Google them to figure out what the heck they are. The only hit is for a store for obsolete parts and they want $80.00US apiece for them.

No Matches for technical data so I keep shorting the part number until I finally get some hits as a family of parts.

Turns out they are Honeywell Hall Effect limit sensors, that takes another half a day goggling before I find a circuit to wire them up, which turns out to be simplicity in it self.

From ExMrClean

After a bit of experimenting it is determined that the devices I have are active low. Until the metal vane on the movement stage moves into the sensor zone it is conducting current and illuminating the LED. When it kicks over it stops conducting, which in this case if you monitor signal of the output lead from the sensor it goes from a low to high value.

In examining the standard RJ-45 color code/pin out and how it is mapped into Opto Endstop RJ-45 connector I determined that one of the four pairs of wires is unused.

Since one of my stages has a DB-9 connector for the end stops. I decide to use a single RJ-45 cable for both signals back to the stepper motor board.

In the color code the blue, white-blue is the positive connection. Brown, white-brown is ground. The Green wire is used for the end stop signal and the Orange wire is un-used.

I make a quick mod to the stepper boards to add a jumper from the max optical input pad to pin 2 of the minimum RJ-45 jack. Then at the end of my single Ethernet cable that I have hacked the end off of I wire the minimum output pin of the DB-9 to green and the maximum output pin to the orange wire.

The other stage (Y) used to have a connector but it had obviously failed at some point and to repair it they had fished out the wires and solder new ones directly to it. So for that stage I put the parts onto a small chuck of prototype board and hot glued it in place.

I now had all my end stops working and created a quick exerciser program that cycled all three axis’s between the end stops, counting the steps it took to go from end stop to end stop and let it run for 24 hours.

After looking at the G-code program sketch it has support for active or active low signals from the end stops, but not having mixed values on the same machine!

Since my hall effect sensors are backwards from the normal signal from an end stop, I add an inverter section out of a 7404 chip so it gives the same output as the standard Optical end sensors that we use.

Where to put the need inverter chip? I could have dead bug glued it next to the Sanguino, but elected to install them inline with the cables using plenty of hot glue to encapsulate them and to electrically insulate them.

Rethinking the solution:

I should have simply used the end stop kit from the store and had the LED side of the optical sensor powered via the hall effect sensor.

Initial flurry of activity

DAY 1

Was spend unpacking everything and mounting the first two stepper motors to the X & Y stages. Put aside the electronics control box that came with my stages as I am going to use RepRap electronics.

From ExMrClean

Day 2

Build of the electronics, Sanguino goes very rapidly! Next board is the PWM driver which goes ok. Time to tackle the driver boards, RRRP store link directs me to V1.1 rather then V1.2 drivers, all three driver boards are missing the same components by the V1.1 info.

I follow the v1.1 instructions and am highly unsatisfied with the build progress as it wasn’t like the Sanguino where the installation and soldering was lowest profile component to highest component which make it easy to insert, flip and solder!

Day 3

Was missing components from my driver boards so visited the rat shack for resistors and capacitors to finish my drivers. Researched on how the steppers would be wired up and solder necessary wires together to get down to the four needed to attach to the driver board. Then wired up the remaining stepper for the Z axis to a plug for testing.

Realized that my Antiono breakout board was useless for the Sanguino board! Read that Sanguino was designed to plug into a bread board.

Finish all three boards and then I finally notice the URL reference on the static wrap that lists a link to the instructions for my V1.2 boards!

In the meantime I had fired off a QA report to Zack suggesting better build procedure of lowest to highest that was fairly much reflected in the actual build instructions once I found them, missing components are actually optional opps! Sorry Zack!

Day 4

Purchased breadboard for Sanguino on way home, scavenged a couple of AT style power supplies from the IS department at work along with old Ethernet cables. During the day printed out diagrams for recommended Arduino wiring and Sanguino pin outs on works color printer.

Assembled the breadboard and find that Sanguino doesn’t fit the rat shack version! Sanguino design assumes standard IC width between the rows, not rows that are butted together.

Figuring out what wires of the ribbon cable are for what for getting the Z axis stepper motor to spin, ten wires are present but only five of them are in use counting the ground wire.

Wiring on the ribbon cable from left to right with red strip on the left is:

1. No Connection
2. Ground
3. Step
4. Direction
5. Enable (tied high to VCC via a resistor so not used, so effectively no connection)
6. Minimum sensor line
7. Maximum sensor line
8. No Connection
9. No Connection
10. No Connection

Solder wires to some header pins to plug into breadboard, decide to reinforce with hot glue to turn into mini plug.

Discover hot glue gun must have been left on for months at low heat, filled with dry brown gunk; after poking various gauges of wire up nozzle finally get it to flow. It takes quite a while to flow and most of a long white glue stick as it flushes out the old stuff before it turns white again.

Make handle with painters tape and hot glue and burned fingers; I guess I will have to predict a lot of this with this project?

Test power supplies; second power supply I grabbed just in case is the one that works.

Hook up stepper boards one by one and observe that the LED’s work. Followed by hooking up the Z axis stepper which gives a little scratchy noise on power up as it jumps into phase/step.

Use screw driver to momentarily ground step line and watch the motor step and the step LEDS change colors as it moves from phase to phase.

Day 5

Figured out how to compile a sketch and upload it to the Sanguino, did the blinking led test.

Then I ran my first stepper test with the motor waving the tape flag! Opp’s half of one of the drivers board is not working, must be a bad L298N. Though interesting enough it will step at some speeds but not others!

Experimented if we could drive the motor faster than the lower 600 value in the stepper motor test, no luck.

Day 6

Started wiring up the steppers for the X & Y axis’s and laying out the wiring on the breadboard for my repstrap!

Assembled the X&Y stages by stacking the Y stage on top of the X; quite a chore to get them to snug up together over the registration / alignment pins.

Given how tight the tolerances are I have a very high confidence that it is square.

Started figuring out how the desk is going to look and how I want to route the wires.

From ExMrClean

Day 7

Need to figure out what the wiring is for the limit switches that are on the stages, do not have a Allen wrench that will fit to take off the old sensors so off to the tool store (Harbor Freight ) to buy more tools, end up spending most of the morning wandering around shopping!

Finished wiring up the breadboard and the stepper motor to driver cables. Time for some movement!

I am kind of worried that since these stages are fairly massive that it will just sit there and groan.

X stage starts right up, takes a while for me to realize that it is actually working right off the bat, no complaints!

It goes though the speed tests and doesn’t like 750 or 600 values of the stepper motor tests.

Now since the X stage is carrying the Y stage around with it I assume that the Y stage will move better, wrong guess. Y stage for some reason 900 and below it moves one direction but not the other; might a resonance thing?

Manually centering the stages before running the tests and it is getting closer to a limit with each failed movement and I have no limit switches wired up or software that is testing for them since I am using the stepper motor test program.


Day 10

Time to tackle the Z stage which has a Pittman motor on it which is not a NEAM mount. Pulled up the engineering diagrams for our stepper motors and make multiple attempts to figure drilling dimensions for the center of the Pittman motor which has an offset center for the shaft; to the NEAM 23 mount.

Doesn’t work out until I actually measure my stepper motors! Lots of tiny drill marks that are thankfully hidden by the stepper motor once I get it mounted.

Work kicks into high gear with massive overtime so I have been stalled for a while!

Things learned:

1. Sanguino is still the new kid on the block so not to order the Arduino bundle. (Store now has a Sanguino Breakout Shield Kit, so will place another order.)
   
2. The stepper motors selected for our projects actually have some fairly good strength.
   
3. Electronics are fairly advanced; almost turn key, great work everyone!
   

Work still to do:

1. Get Hall Effect end stops wired up and tested.
   
2. Test Z axis now that the stepper motor is mounted.
   
3. Mount the Z axis.
   
4. Figure out how to calibrate everything!
   
5. Start thinking about the extruder!

EBay Purchase

After waiting a bit for my xy table/slides to be motor freighted to me, it finally arrived on a Monday.

Picked up the XYZ stuff from the shipper at lunchtime so I could draft an employee to carry it into my place once we had broke it down on the shipping pallet it had arrived on.

Gloated over my massive hardware! (Ok someone with a CNC mill would not think it massive.)

Electronics and stepper motors also arrive from the store; box is almost totaled on one corner but everything appears to be ok.

That evening I started unwrapping everything to figure out what I had, found out the XY stage had servo’s rather then steppers motors.

My question about how many wires coming out of the motor was answered by the number of the pins on the connector; which was four and turned out to be two for the motor, ground and an unused pin!

Dumb luck aside the old servos were NEMA 23 mounts, the same as the stepper motors from the store! Good thing I decided to order the steppers motors from the reprap store!

But hey the old servo's are NEAM 23 mounts, so I rapidly mount two of the steppers!

Needed to slightly drill the coupling plastic in the center to make the motors fit as the shaft is a bit longer on the stepper motors. Fifteen minutes of work and my X&Y stepper motors are mounted!

In looking over the electronics portion that I had brought from Ebay it was very interesting and told me a bit about its history.

From ExMrClean

Look at that locking emergency stop button!

First off it wasn't recent hardware as the PC portion of the main control unit did not have a PS/2 style keyboard connector and most of the boards plugged into it are ISA style. (Still haven't fired it up to see what was on it, suspect DOS).

From ExMrClean

Another big clue is as clean as the electronics are it had to have spent it's working life in a clean room, (not a speck of dust on any of the four fans) so the dust shields on the mechanics where more and likely to protect what was being handled verses the mechanics them selves.

So I suspect given that the control box also had pneumatic valves and that only the X&Y connectors are wired and the Z electronics were unused that this was a part of a semiconductor manufacturing line.

From ExMrClean

Ah the easy clean life of your first career is over, your new name is ExMrClean!

Given what I know now, should have told the vendor to keep the electronics and just shipped me the mechanical components. That way they could have been shipped UPS, rather then on a crate via motor freight.

From ExMrClean

From ExMrClean

From ExMrClean

EBay Lessions Learned:

1. Pure dumb luck that my stages arrived in NEAM 23 format, should have queried as to the actual model number of the motor. My Z axis had a Pittman GM9000 series motor so was enough real estate on its mount to overlay a drill pattern for the NEAM 23 format.
   
2. E-Bay XY stuff is more in likely for fine positioning rather then motion control (CNC) for handling semiconductor masks in IC manufacturing. Very precise stuff; but analog which doesn’t fit our model. I could have avoided truck shipment of the package as the electronics module is what put it over UPS standards.
   
3. Might have been able to re-use the servo motors by buying Gecko G320 drivers for them, but then would have also needed a higher voltage power supply. Motor’s are brush driven, might have needed new brushes, etc.

E-Bay Adventure

Hi Everyone

First off I would like to thank everyone who has gone before and contributed to this project!

I now have my repstrap moving in all three axis’s and figured it was time to start blogging about. Sort of the job is not done until the paperwork is!

I bit the bullet and ordered the electronic kits and stepper motors from the online store. My initial order was for the “Complete Arduino Electronics kit” and the Sanguino processor.

The original plan was to build the electronics first and then work on the mechanical. However the store was back logged on deliveries; so after reading a lot of blogs and forum entries I decided to follow NopHead’s example and start with a XY table.

So off to Evil-Bay I went!

Given the cost of a gold reprap kit I knew I could spend a fair amount of money and still have something that would give me a good quick start.

Since I am thinking of subtraction processes like milling a bit more robustness would be a great plus. (Great to see NopHead now has a mini mill, how long before he drives our solutions to be more universal? I personally can not wait.)

E-Bay search terms that I evolved to look for something usable are: xy stage, xy table, linear stage, linear slide and linear actuator.

Anyway after loosing a number of bids in the ball park of a Gold kit I managed to get an XY table and another slide to use for the Z axis for about $400.00 plus shipping.

Here’s the picture that enticed me as it already had the dust shields for milling.

From ExMrClean

After questions to the vendor the question that I posed was how many pins on the motor cable? The answer was four which I assumed was a stepper motor (opps more on this later)!

So I placed my order, contingent on the vendor throwing in the Z axis stage, which he accepted.