Messages

1

SmoothStepper USB / Re: Turning on the lights trips a limit switch

« on: October 19, 2011, 05:42:22 PM »

did you replace the ss usb cable?
Yes, but it did not help. I have read posts elsewhere about USB cables which are too "thin" to carry adequate load. I don't think that was my problem, I am using a separately powered break-out board and the Smooth Stepper has just one port in use at the moment.

I have same problem on z axes... limit switch trips as soon as i jog.

Hmm. I am not sure it is the same problem but it could be similar. Mine originated outside the system. While initiating a jog might be causing the limit to trip because of noise associated with  the stepper motor it could also be something within the control circuits. If you are using a SmoothStepper, does setting a filter delay on the home or limit line in the SS setup have any effect? It has overcome my tripping although, obviously, it has not removed the cause of the interference. In my case a setting of 200 was enough to do the job.

2

SmoothStepper USB / Re: Turning on the lights trips a limit switch

« on: October 19, 2011, 03:09:58 AM »

Thanks Thosj. Filtering certainly masks the noise. I knew that debounce in Mach did not effect SS and had missed the filter section of the window on setup which sounds a bit dumb but I was rushing to get it up and running as one does.

3

SmoothStepper USB / Turning on the lights trips a limit switch

« on: October 18, 2011, 11:38:57 AM »

I have just installed a SS to replace the parallel port connection on a retrofit mill which had been running for 5 years or so. SS installation following WARP9 and Jeff Birt's guides was straightforward (thanks for those) and I have been very pleased with the change. Except that if I turn on a mains neon light or turn off a small machine elsewhere in the workshop I get a "Limit switch tripped" message and flashing red restart button.  What is curious is that it only trips the Z axis and if I disable the limit switch lines in Ports and Pins for the Z axis all is fine.

So, next I swap the Z and Y inputs from the microswitches and still get a Z trip. That seems to tell me that the connection and screening between the microswitch and the control cabinet is OK. Presumably the fault lies between the socket on the control cabinet and the PC.

I use a limit switch circuit suggested by Mark Vaughan in this forum with 24V supply to the limit switches and optoisolators controlling the 5V inputs to my C11 break-out board. This has worked with the parallel port set-up with no problems for some years.

I have rewired all the Z axis part of this limit circuit with new cable, screening grounded at one end to a star connection on the cabinet.

The SS is mounted on an insulated board within the cabinet and connected to the adjacent C11 with the supplied ribbon cable.

I am obviously missing something and would be greatful for any suggestions. Peter

4

FAQs / Re: Losing Steps or something

« on: August 30, 2011, 02:19:11 AM »

Hi Dan,

I think my original post was not as clear as it should have been. The loss occurs repeatably on each of the three axes (but not the rotary table) when that axis is moving but unlike cncnovice's experience it makes no difference whether just one axis is moving or two are moving together; each moving axis displays the step loss. The more I think of it the more I think Rich may be right. I am set up on x,y and z to microstep at 1280 steps/mm which gives 0.00078mm/step which is way beyond what the rest of my kit can approach. Interestingly, the rotary table which does not seem to display the step loss (although I have not done any detailed testing) is on the A axis which is set at a resolution of 300 steps/mm. But then the rotary table only moves in one direction throughout the wheel cutting while the x,y and z axes reverse direction several times for each tooth on account of the four passes used to profile each tooth. Hmm.

I  need to do some more testing with changed microstepping but right now I am very happy to use the SS solution to get on with the job which has been delayed for a good few weeks while I tried to find a way out of the corner.

I am reasonably confident about the wiring which runs through a C11 board which incorporates pulldown/up resistors. But then confidence is only there until you find you are wrong and at my stage of this game that happens quite often.

Thanks for the interest, I'll post again if my further tests show something useful. Regards, Peter.

5

FAQs / Re: Losing Steps or something

« on: August 29, 2011, 02:37:14 AM »

That's a fair point, Rich. I think we can get carried away with the thought that more microsteps must always be better. This can then take us beyond the built-in limits of the rest of the set-up. In my case I was interested by the repeatability of the apparent loss of a step or whatever and was reasonably confident that the source of the problem was outside the ballnut/screw and steppers themselves (I do not have belt drives). It would have been sensible to try varying the step/per mm on the motor drivers as they are set finer than my system needs and maybe I'll try that sometime out of interest. In the short term, however, the Smooth Stepper solution is giving me the result I need. Thanks for the advice. Peter.

6

FAQs / Losing Steps or something

« on: August 18, 2011, 12:18:16 PM »

This follows on from a thread of this title which has been cold for months so I have started a new one.

Hi cncnovice, rcaffin and Dan13,

I know this thread has been untouched for several months but I have a bit to add which may help others. I too had the problem of lost steps: apparently a single step missing on direction change. How did I know? I was cutting a 288 tooth gear by profiling with a 2mm endmill, four passes for each tooth with the indexing by a rotary table on A axis. So the g-code was a set of instructions to cut one tooth. As a result there were around 1200 changes of the direction state while the axes were moving. But when the table had finished its 288 steps I found I had a cut not a circle but a helix with the end point inside the radius of the start point.
I tried all the tests you did, except for the scope which I do not have, and came to similar conclusions. The error was very repeatable which seemed to eliminate noise, it appeared when different computers were running Mach and seemed impervious to any of the changes in motor tuning, ports and pins etc. One difference from yours, however,  was that it appeared on all three axes even when only a single axis was in use.

Eventually I decided that as it seemed to be most likely a parallel port problem (that's how little I know ) I would try a Smooth Stepper which I had been considering since they appeared. The result: 48hours delivery from Minnesota to Devon UK, an hour installation and setup and then.......... no lost steps. As always, you think "why did I not do this before and save the hours of fruitless testing?" I guess the answer is that we are always trying to understand a bit more.

So the point of this post is firstly a big "thank you" for pointing me in the right direction and teaching me a lot I did not know about Mach. Secondly, I wonder how many systems have this error which only appears with multiple repetitions and does not otherwise intrude. I had been using my setup under mach for three years before I stumbled over it.

Cheers, Peter.

7

Newfangled Solutions Mach3 Wizards / Re: Wizard for clockmakers.

« on: May 31, 2010, 01:59:19 PM »

Ron,

I do a bit of work with clocks and the idea of a crossing-out wizard is attractive. I am not sure, however, that scaling the parameters in proportion to the outside diameter alone would meet everybody's needs. The thickness of the rim (outer annulus, or whatever you wish to call it) is often related to the size of the teeth as well as the OD of the wheel. The escape wheel in your picture has quite large teeth in order to do its job while a meshing gear with a high tooth count might be expected to have a narrower rim, not least because the loading would probably be less.

In a similar way, the size of the boss (circle defining the innermost points of the cutouts) would not necessarily increase in diameter in direct proportion to the outside diameter.

This is not intended as a discouraging response, just a contribution to the debate from someone who has so far used CAD only and is intrigued by the thought of a wizard. How hard would it be to design a wizard which allowed the input of the inside diameter of the rim, the outside diameter of the boss, the number of spokes and and the radius of the corner of the cutout next to the boss? Together, of course, with inputs to cover thickness of material, depth of cut etc.

The appearance of clock wheels is quite important and elegance as well as functionality have traditionally been factors influencing quartering.

Hope this is helpful. Peter