Hello everyone - My OX experiences over the past week or two I am

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Hello everyone - My OX experiences over the past week or two

I am very new here and there are many of you that have more knowledge than I, but I wanted to share some information that I have put together in hopes it will help guide some of you to better “OXing”.

I have an OX machine driven by TinyG which is in turn connected to my laptop via USB and running chillipepper. I placed my TinyG, the spindle speed controller and the two power supplies in an old desktop case and then configured a cabling system to go from the cabinet to the CNC machine using some click connect connectors and shielded cable. Seems to work fine. My CNC machine sits on a cabinet I made (with wheels for movability.

In my first post many of you offered suggestions an I hope I have included all of that here - Thanks!

The main problem I was having is that during machining, OX would simply stop, sometimes and at different places. Always the stop was associated with the TinyG blinking it’s Spindir LED. I noticed the stop always occurred at a corner either when creating a pocket or cutting out the work piece. In addition, I noticed my z-axis stepper (NEMA-17) was extremely hot.

So I did several things. first I addressed the hot motor by adjusting the motor pot on the Tinyg board according to TinyG instructions This change seems to have cured the hot motor. While OX was down, I looked at my limit switch cabling. Remember that this cabling is all shielded. I bring the motor and spindle shielded wires into a terminal block near the motors and then connect the motors to the terminal block. I noticed that one of my z-axis limit switch cable (shielded) was zip tied to the shielded spindle cable and to the unshielded z-axis motor wire. So, taking advice from this group, I cut the zip tie and moved the sensor wire. While I was at it, I noticed a similar situation on one of my x-axis motors and moved that signal wire as well.

I have had three glorious day’s running several different work pieces thru OX without any problems. probably running three or more hours a day.

So, I believe that I had a signal crossover problem at the junction of the shielded signal wire and the Z-axis motor wire (unshielded).

I must say that I was convinced that this signal wire problem could not exist on my shielded wire system. I am now a believer!

One last observation that has to do with one of the work pieces and feeds and speeds. I wanted to drill several round bottomed holes in the board and purchased a core box bit router bit the right size. After experimenting, I found that a plunge rate of 75mm/minute combined with a spindle speed of 8,000 RPM produced the desired holes with very minimal edge problems. This is working with soft Pine.

So I’m sorry for such a long post, just wanted to get things out here in case it would help someone else.

Thanks for reading.

Ted

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Great post @Ted_Ellison ! Thanks for being a contributor. I have long avoided limits. My first experiences were similar.

I was wondering, do you have a drain or ground wire on your limit switch wires?
Is your machine and control system grounded together?
Are you running all limits at NO or NC (normally open or normally closed?)

I never had the opportunity to really test all these variables. But do know running NO solved my issues.

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NO or NC? Conventional wisdom is to use NC as an NO line acts like an antenna and picks up radiation for nearby signals.

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Thanks for the feedback. There are lot of guys out there that are much smarter than I about all of this, I’m just a Jack-of-all-trades and know just enough about a lot of things to be dangerous.

My switches are set as Normally closed So that should minimize the exposure, but it sure did happen to me, at least that’s what I see so far. I’m wondering if the heat stress put on the z-axis stepper caused additional radiation and that was picked up by the signal wire being tie wrapped to it?

Brandon, I wish I could answer your question regarding machine and control system grounding but that’s terminology I just don’t understand.

As to the drain system I guess you mean is the shield itself grounded? And no it is not.

Really would like to see a SIMPLE diagram showing where to ground the shield and also would be good to visualize the control and system grounds. Perhaps I would have a chance of understanding it.

For me the frustrating part is people making guesses about why the TinyG light flashes. I realize that it’s complicated and each machine is a little different, but there must be some way of quantifying - it this then that…

I sure do find this both fun and frustrating… I’m learning a lot, but then the head get’s sore pounding against the wall…

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My understanding is that you want the grounds to be in a star configuration. For the shields, if you have a metal case for the controller, then the shields should be connected together at the metal case and not connected to anything at the sensor end. Connecting the shields at both ends can lead to ground loops, which you don’t want.

The case ground would then go to the earth ground (i.e. the ground on the 3-pin 120VAC power plug).

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@dhylands agreed, however. I was told at one time though to run all mine in NO. On the unit I was testing it cured all issues. TinyG/OX.