Uneven spacing, when direction is reversed, points to mechanical flex or slack.

Gerald,
I thought maybe one of the pinions might be loose. Is it possible that A is not activating at the same time as X even though they are slaved? I can not find any flex anywhere and only a slight amount of play in the servos but they all have the same amount. I know when it is running PhotoVCarve gcode I swear I can actually see it move off position before it is has lowered the Z to the cut point. I had not noticed it before but it is possible it was doing this with my 3d carvings. What about the tension holding the motors? Could too much tension cause this?

Thanks in advance.

yes it can be the tension on the motors I added tension to my slave motor and everything worked fine a wile ago.

al

Al, the springs I am using were based on posts by Gerald and specs from the plans. However it does seem like a lot of tension. I called Oriental Motors to verify the backlash in the gearbox which is 1 to 2 degrees. With lines only 0.040" apart, this may be leading to the problem. I will still try to fix this

First ran 6 inches to and fro in the X and Y multiple times. Dead on every try. Made a simple program with parallel lines at 30° angle using the original start and end points of the line from the VCarve generated file. Ran with good spacing. Now I have no idea. Will have to try another PhotoVVarve imported into Aspire again and see the result.

Also check the following:
- pivot bolt for the motor plate, make sure it's not to tight, but allows movement
- spring pressure even on motor plate
- pinion's tight
- pinions fully seated in rack and not meshing at an angle.

Sean

- tension the z-slide rollers with the eccentrics

I have looked into most all of those. Something I have noticed. If I set the speed at 10 to 15 in/min you can see the X is always moving before the Y starts moving. It just looks unsync'd, not jerking just starting motion not at the same time. I might see if I can borrow the Scopemeter from work and see if this is the case that the signals are not happening at the same time. In which case this would point somewhere else all together. Is there something in Mach that maybe I don't have set correctly?

On another subject. I was looking at changing from a router to a water cooled spindle. What capacity tank would you need for a 2.2kW? I am using a PDMX134 and 126. I assume you need another board to set the freq with Mach. Is this correct? I see there is a lot of problem with noise and recommend an isolation xfmr, ferrite EMI cores. Any other recommendations? Radiator Mount on car or at tank? etc...

Thanks

I use a 10L tank filled with coolant without radiator, no problems on the long run.

This is how I control the VFD from mach3

http://www.mechmate.com/forums/showthread.php?t=3411

Danilo, thanks for the info. I read your post before but forgot all about it until you posted the link. How do you control the microorganism growth? I have read that antifreeze does nothing, that biocides are not 100% effective and stabilizers are a 50/50 based on comments.

I've been using 50/50 anti-freeze as coolant, don't know what micro organism you are talking about but if you are talking ablout the slimy thingy in the pipe, I don't have choking issue with it. & no effect on my spindle temperature, (at least my IR thermometer said so).

Upgrading to Water Cooled 2.2kW Spindle
 

Thanks Ken.

Anyone with any info on how to set up mach to set an estop condition based on an input. I would like to use a water flow sensor to have mach activate the emergency stop if the flow drops below a given setpoint.

In monitoring water flow you are monitoring a secondary parameter not the primary one.
The spindle temperature is what you need to monitor, not the water flow or the water temp.

Good design is no accident while overly complex design is an accident waiting to happen.
Why trigger and Estop, potentially loose steps and stop a perfectly good job when the spindle itself has not altered a single degree in temp.
Put a paddle wheel visual flow indicator in line and relax a bit, it is not a microsecond critical parameter.
Water flow monitoring just seems wrong thinking to me once the machines operation is considered holistically.

Regards
Ross

Ross,

My experience with paddle wheels is they leave a lot to be desired. I work on $1M sintering furnaces everyday. The water flow principal is basically the same, monitor the flow and if the flow stops for x amount of time it shuts down the system. Originally they were designed with paddle wheels and flap sensors. Even with water constantly treated and controlled, the flappers and wheels would not work as well or even just stop even with good flow present. Flow sensors on the other hand give a very accurate reading as they work on the temperature of the water. Effectively indicating the temperature of the device being cooled. Understand that a spindle is not furnace but does that mean you should not thing about safety? So my line of thinking was to monitor flow of the water with a sensor, once it quit for any reason (pump failure, collapsed line, etc...) the sensor would activate a timer and audible alarm, this would give me time to diagnose the problem or stop the program that is running, if I was unable to solve in a given time and the machine is still running the timer would send the signal to mach3 to immediately stop the machine. Since wood is cheap when compared to the worst case scenario (a fire) I would say that machine and life protection is worth the risk of ruining a piece and a $300 sensor. I have not purchased a sensor yet and maybe I don't need one. I have read in the past couple days online of the spindles burning up because of water flow failure. This led me to this question. I am trying to cover all basis to help make a wise decision.

Hi Pete

The water wheel was just to give you something to look at, an unimportant and mentally soothing detraction for the complusive water monitors in the MM crew :)

You still debate around my significant point that is ... monitor spindle temp not water.
All your other logic regarding alarms, timers etc is fine.
Not picking on you here just trying to promote the message about monitoring the actual device rather than monitoring an ancillary process.
So far I'm having no luck in getting others to make this shift.
My only consolation here is knowing I'm right :D

regards
Ross

Ross,

I agree with you that monitoring the temperature of the device is the key. But the accurate way to monitor it would only to be to place a thermistor or thermocouple inside the unit to receive an accurate reading because the chamber would skew the temperature reading from the outside. If your water flow rate is controlled then the temperature of the device is accurately shown through the water temperature fluctuation. This is the way most industrial machines I have worked with have been set up. Robotic welders, Process furnaces of every type and even industrial lasers (not steel cutting type). Have they all been this way, no. Do they all have a long standard of performance in their fields, yes. Yes some units are sensitive to temperature and use a refrigerant based cooling system but I am not speaking of those. I just don't see how you can accurately monitor the temperature of the bearings from the outer side of the cooling chamber with a medium present(water, oil, coolant, etc) or not present (air). A handheld temperature sensor should not be used with a reflective surface (water, polished steel, etc) Reflectivity and refracted light give inaccurate readings. The only device I would trust would be a FLIR but I can not afford one of those. We only have a the low end model where I work and the cost of it was 2k. More than my pocket book can handle. However I have seen the 80k unit with thermographic scans and they will show you every detail of whatever it sees. That will open your eyes to how much heat affects the smallest detail.

Back to the original question, can Mach be set up to active an estop from an input (oem trigger) or is it not worth the hassle? Most of you make your living from these machines, so I do trust all of your opinions. This is my specific purpose then hobby machine. Mine is run maybe 20 hours a week at the max so I ask you all that run the guts out of these what is the best avenue to travel? Monitor or not?

Thanks

Not picking on anyone or intended to do anyone any harm but just laying out a real life operation scenario.

Visual monitor,
General monitoring, Look for turbulence in the translucent PE coolant reservoir, water will churn when the pump is switched on.
For a closer monitoring, observe the out flow from the returning pipe. If you wish to measure the flowrate, just time the duration to fill a pint glass..... In my case, I keep an empty 500ml mineral water bottle for the job.


Contact monitoring,
I frequently touch the spindle body during operation to ensure the spindle doesn't approach total melt down. When I'm really bored, I'll point my IR thermometer at the black part of the spindle (which happens to be where the bearings are mounter)
When I'm bored to my bones, I'll touch the coolant reservoir, the pump, the motor or even dip my fingers into the coolant....

Audio Monitoring
Listen for the coolant motor humm (which is actually overwhelm by the vacuum pump, dust collector fan & cutting noise)

All these seems like too much chore, but when you are cutting a batch of a few hours, they give you something to kill time...

PS,
In a few occasions, I forgot to turn on the cooling pump & went on cutting for 1~2 hour. but the spindle kept its cool with the residue coolant within the system & lived....

Even though I do not agree to complicate simple thing like looking at the reservoir tank, with sensors, writing code, complex electronics, Siren Alarm, Light Alarm... I'll tag along for the spirit of trying.

I believe if you know Mach3 well enough you can program it to fulfill all your desire, but since there are limited I/O point on a parallel port, you need to re-think your pin usage strategy, maybe additional parralel port; if you go this way.

I would suggest to leave the Mach3 alone. Instead, wiring up a complete microprocessor based spindle coolant monitoring & control system with any monitoring sensors of your choice.
This is how I would do it::-, decide on the type of sensors, monitor points & whatever siren, whatever warning light etc.... Mount them as you desire, feed the signal to a micro processor as input. write some code with a forest of "IF" & "ELSE" to set the conditions which you desire. There is only one output which will turn on/off a relay which you will add-on to the existing Estop circuit loop. Activate or de-activate this relay to "kill" the Estop circuit.

Paul

Last dig before I direct you to what you want:)
I have a senior executive friend that goes to great lengths to explain why things can't be done.
One day he explained to me why it was impossible to put more than 10% ethanol in fuel ... impossible.
His explaination ranged from production capability, cost, transport, storage bottle necks etc.
He used all the big names and quoted mega dollar amounts.
He was flabbergasted when I told him about E85 or 85% ethanol fuel already being used in Brazil.
Moral of the story is he was so tangled up in the orthodoxy that all other options were closed to him - despite their actual existence !!

The forum user "Skippy" has some detail in his build thread of a flow monitor that you might like to use.
I believe he monitored temperatures in 4 places, included a LCD read out and has an Arduino Uno as the processing brains.
The flow monitor is a paddle wheel design that outputs a signal and PWM is also used somehow.
According to Skippy some massaging of the sensor signal is needed for the Arduino to cleanly trigger Mach3.
You might wish to read the thread and contact him directly for more information about the sensor and the Arduino sketch he is using.

Mike Richards has also mentioned the use of the Ardunio over recent time so he has some very good knowledge in this area as well.

Regards
Ross

Really, microprocessor isn' that hard once you have Arduino at your disposal. :D

I made some cool stuff with it, namely PWM DC motor speed & direction controllers, ambient temperature activated fan (activate the fan when ambient temp is above 32V & deactivate when its below.)... etc & my favorite is a High Tension mouse trap which detect the present of mouse on a steel mesh with a IR sensor before delivering 10,000 Volt zap to send the rat to its end :D but it killed more cockroaches than mice...

Ross and Ken,
You both make very valid points and I very much appreciate both of your time. Please try to understand I have not ran these before. Obviously I to not want a money investment to be tossed out the window by my dumb mistake or the pumps failure. Now that I know that you can run more than a hour without cooling and not damage the unit, that is different. The internet is a great tool for information. However, I have also noticed that most reviews on products are written by only those who have problems or a life changing event.

A very crude approach, but would work is a series of switches and/or sensors assembled in a and/or logic pattern that would only use up one input pin on the BOB.

It would be a lot like your limit switches that use 4 limit switches, but only one input.

If you were to look at the following:
- thermocouple with form c contact out (either NC/NO)
- flow valve with form c contact (either NC/NO)
- pump on/off with parallel contact for monitoring of the assumed power state.

etc. etc.

With a little relay logic, you could do the same thing if you didn't have the access / or resolve to tackle the microprocessor route.

The adrinuo family of processors is cheap and will do all the same function as a relay logic layout with far more options. I agree with all that the microprocessor is gaining popularity as a replacement of smaller simple "brick" PLC's and perform complex functions.

For the MM - it comes down to time, cost and effort. Pick which one of the parts you have more of and go that route because you usually only get 2!

It has been several years since I played with a mcp. I will think a lot about what you both have written and review what you have suggested. Ross, I was trying to convey my thoughts and put them into words. Sometimes I have a hard time doing that and have argued with people for hours just to find out we were heading in the same direction toward the same end result. Again thanks for the info and great stuff from both of ya.

Sean, Ross and Ken, I have 2 parallel ports I am using with my BOB. I have more outputs than inputs left. I have a spare AB plc laying around somewhere for a project that went nowhere. I have been itching to use it for something. But using it for this logic would but a great under utilization of that piece of equipment. Has anyone burn up a spindle from water flow issues?

IF water flowing is your only real failure concern, then I would just focus on the simple solution so your machine won't start cutting unless water is flowing.
That could be a simple as a flow alert valve (like in fire sprinkler systems) or quick a/c motor sensing switch (like used to verify your home stereo, projector or other is powered on. These send back a 12vdc signal that would need to be resolved with a relay and then close the input on your bob.

...just need a simple contact closure to verify that fluid is flowing. Add as many checks in the system until you feel comfortable. A simple "idiot light" might even be the answer wired in parallel to the pump motor.

Good luck with your choices!

I agree with the PLC being way more expensive and overkill use for such a simple monitoring solution.

Heck, you could even wire the switch inline to your ESTOP circuit and that wouldn't allow the machine to start without verification of pump flow.

Spindle Upgrade
 

It is not my only failure concern but it is the easiest one that can be prevented. I was opting for a flow sensor because just because a pump is on does not mean it is flowing. However it does seem to be that these units are made rather well. I am used to a product failing if cooling is lost even for a minute when be run at there maximum capacity. For the statements above this does not seem to be the case. The concerns I have are for preventative costs and downtime both of which is a high dollar item even for a hobbyist especially when it could have been prevented. I would like to have mach not start if the water is not flowing but this seems a mute point based on the discussion and information all of you have provided. Plus the interfacing seems a lot for the reliability of the unit. More concerning to me is safety of changing the bits at a tools stop. This to me is the most dangerous portion of the process. I will be tying i a disconnect to make this portion as safe as possible. I remember when I set up mach that you can set a time to m3 for delay. I need to refresh a little on that as well.

you can put a switch on the Car switch box, wired to the VFD "enable" signal next to it ... a red light lit when its active, so when you change a bit you know it won't start and there is a red light if its active.

this way also you can wire a flow sensor to the green light on it to indicate the flow is present.

Industrial machines have all these signals wired and put out an error number corresponding to the error signal. So you can input everything into a Mach to deal with errors (not a problem but in case of some electrical noise use 24V relays and filter the interference) OR rely on yourself to interpret the signals.
Great deal of us who built and work with these machines choose to deal with troubleshooting themselves as we have little time to build a real industrial system and test it, instead we need these machines to work and be as simple as it gets.

Danilo, I know that you can kill the enable feed but personally prefer a dead motor. I was going to kill the enable and use a relay to open the uvw leads all controlled by a single bat switch. I would just like to build a little safety into the machine to protect not only the person but the components of the machine. The machine is a simple machine with amazing performance. I was only trying to enhance the features of it.

Just skimming the above discussion, I think detection of loss of coolant flow is quite valid, but it shouldn't trigger a stop....it should just give an early warning, by audible alarm or flashing light.

Don't kill UVW ! if you need a dead motor then mount the switch on phase inputs to VFD

I am assuming to minimize the risk of switching off the vfd prior to it spinning down and possibly frying the vfd.

Here is an in depth discussion - http://www.practicalmachinist.com/vb...er-vfd-102341/

Short answer as a stand alone means of cutting power to the spindle switching the feed wires to the spindle = not a good idea.
The longer answer is basically what Danilo says, then you can put a switch or contactor between the VFD and the spindle if you want after that.

Regards
Ross

I thought that de vfd have some electronic protection for power cuts. mine its a cheapi cheapi ls vfd and says power low for a while when i turn of the machine. i will add the contactor to the spindle for shure after reading this.

A vfd does have protection in case of total power loss but there is the possibility of problems with opening the uvw when it is decelerating or running. However this may happen it, I have never seen it. I have seen two legs open on a motor before and only have the vfd go into protection mode. As with most things, it depends on the manufacturer and quality of the vfd. I know AB, Woods(now Vacon) have this protection but I do not know about Hitachi, Delta or some of the others used with these spindles. If in doubt contact the manufacturer technical department and they will let you know for sure.

Another Electro-Mechanical tech I work with, his brother was working on a vfd controlled motor. When someone hit the reset he lost three fingers and part of his hand. Some things you can not replace or wish later on that you took more time or precautions. Obviously my router had a kill switch on it that I always used. I will let you know what Hitachi advises on their drives. I have seen disconnects placed before and after the vfd. Is it a good practice, as Ross and Danilo have both said, No. But sometimes it needed.

For the time being I think I will break the drive enable circuit. You can break the output of a vfd at idle. The problem comes if someone does it when it is running or decelerating. If I broke the enable but had deceleration setup the output is still energized. Since I am the only one using the machine, I did not see this as a problem but what if.... Someone else may not understand how this works and could possibly damage the unit. At the very least I would have to disable drive then break the output if and only if the drive was set to coast to stop. Not very feasible.

When you command a VFD to stop, it ramps down or breaks in seconds
when you kill the enable while its spinning, the spindle will keep free rotation until it looses its inertia, same with breaking the drive circuit.

So in emergency its better to use a VFD STOP input so it breaks and not freewheel.

Alright, talked to Hitachi about my drive. It is a WJ200. It has a the capability for a safety circuit to be added. It uses GS1 and GS2. From the manual..."By pressing the emergency stop button, the current to GS1 and GS2 is shut off, and the inverter output is shut off. By this, motor is free-running. This behavior is according to the stop category 0 defined in EN60204."

Since this is the behavior I am looking for this will be the direction of approach. You have to use a reset to enable the drive. Since this is to be used at a tool change the deceleration has already occurred so the free running aspect is not an issue.

Upgrading to Water Cooled 2.2kW Spindle
 

Have all the parts except the spindle mount and one relay for the alarm on the water flow. Machinist is busy. Well I can start the wiring and try to figure out the modbus and mach3 settings. Probably will not have the mount for another week but I do have a nice mount for a PC7518 now.