Electronic Lead Screw Project

Finally working with no blips!! I fitted the split ferrite collars as suggested but unfortunately no better, I then updated the code from git hub [well my son did] & it's now sorted with no random data changes from the control panel, I think Clough42 lowered the clock speed?

Tony

Tony, glad to hear that. Yes, James says he has lowered the clock speed on the SPI bus which presumably should help noise immunity but still the fact that noise could change the settings dramatically while the spindle was rotating remained. I was seeing the control panel settings being returned as all-1s, which causes the system to go into reverse and enter screw cutting (i.e. usually high pitch) mode. His mods, which prevent changes while the spindle is rotating and check that only one control panel button is pressed at a time, constitute the real protection.

Roy

Roy, even with the new code installed I can change modes with the spindle running so I am confused.

Tony

Oh, I must have misunderstood what he said in his description of the changes. I must have a look at his code. Roy

James has just released another video describing his software modifications. He does now disable all buttons except feed rate settings while the spindle is turning, with a configuration option to disable the latter also. Time to replace my version.

Roy

I'm going to leave well alone atm, if I get a problem later on I will get the change done to the latest update but the control panel is currently behaving itself.

Tony

Grr, installed the TI board etc in it's final location but now playing up with random data changes! I tried to install latest software but I think my micro USB cable is kaput so waiting for a new one so i can flash the board. I'm also going for a CAT5 unscreened cable as per Clough42 installation but my question is how is best to connect the 3 data earths to the board earths, are there any relevant YouTube vids or websites? I've now got a spare keypad on top of the electronics enclosure [cable about 2" long] & all is steady again so it must be the screened cable I'm using?? Can't believe how frustrating this is.

Tony

There is a later video on YT by Clough that explains how he wired the CAT5 and also explaining the software changes.

I confess I ignored James' recommendations and grounded everything to everything via the enclosure connector panel.

Alan

Alan,

Thanks for that!

Tony

Hi Tony, I tried Cat5 cable as suggested on this forum but it performed worse than the screened cable I had previously tested. My control panel is housed in a die cast box so I was able to connect it to earth as well via the screen and it helped. However, I couldn't get the noise down to zero (a glitch every few hours) which is why I was forced to implement the changes to the original software release I have mentioned previously. James has now implemented these changes and more. I regard them as essential for safety. Roy

Thanks Roy, I'm going to update the software asap.

Tony

Problem with ELS

Having set up my hardware on the lathe using a stepper/servo motor and driver CL57Y , the motor encoder resolution being 1000 and the motor to leadscrew drive being 1:2 ratio. Decided to test the set up whilst all the electrical side was still on the bench, with a light cut on scrap went through most of the thread TPIs and feed rates and all seemed well.
Finally finished fitting all cabling and installing in cabinet, upgraded to software version 1.301.

However on attempting to cut a 20 tpi thread it turned out very rough and difficult to see exactly why, so cleaned up end of bar, blackened with permanent marker, changed to 8tpi, put on 0.003" cut and got a perfect first pass, but on second pass with same 0.003" cut was approx 1/16" away and on subsequent cuts filled the bar end. Even tried changing software back to version 1.1 made no difference. See photos
Could this be an encoder or a software problem?
Any help much appreciated.

Thanks Dennis

Are you engaging the half nuts at the correct indicator figure? Try leaving the half nuts engaged and reversing the lathe back to the start as you would with metric threading.

Mike

The half nuts were left engaged and the lathe reversed after backing off the cut.

Dennis

I have zero knowledge of electronics but if you are 100% sure there is nothing wrong mechanically [nothing loose etc. etc.] I would imagine it is the code you put in? I suggest you double check all your parameters & settings & please report back, also check you have got the right lead screw pitch specified.

Tony

Difficult to imagine how this could be caused by the electronics. As Tony says, more likely to be a mechanical issue, e.g. pulley loose on shaft.

Roy

Dennis,

Some thoughts:

1. backlash through the encoder - so when you go from forward to reverse there are a number of missed pulses.
2. stepper missing steps - maybe at the point of reverse direction, maybe during the screwcutting run or when returning
3. noise into the encoder path
4. since you keep the halfnuts engaged, I don't think the issue can be the config settings since errors here should only result in incorrect pitches/TPIs and not a loss in sync

#1 would appear to be most consistent with the reported symptoms - missing pulses to lose the sync between the leadscrew and the mandrel.

#2 again, I can only see this related to the change of direction at each end of the run. Any inconsistency during the cutting run should be visible as a lack of parallelism between the first and second cuts.

#3 same as above...

I can run my ELS by turning the mandrel by hand so in your case, I would:

• put a long throw dti on the bed/saddle junction to see how much the saddle moved when I moved the mandrel by a full turn
• observe the effects of reversing direction

Both observations may shed more light on what is going on and turning the mandrel by hand will also eliminate your motor as a noise source.

Also, check that the various 0V connections are not linked - in particular, the Launchpad 0V and those for the stepper driver - including screen path connections.

Hope this helps, I have had my ELS running for a couple of weeks and it is really good once it is running.

Simon

Thankyou for the replies and suggestions, over the next few days will check everything that I can and report back hopefully reporting a success.

Thanks again

Dennis

Dennis, may be you have your encoders mixed up, the motor encoder 1000 pulses per rev used for tracking missed steps and setting the alarm state via the driver and the spindle tracking encoder, the ones I have is

1024 x 4 = 4096.

#define ENCODER_RESOLUTION 4096

Lofty

Not sure if it is relevant but a good check that all is well would be to set the TPI setting on the control panel so it matches the leadscrew characteristic and then put an optical tacho on the leadscrew and see if it matches the control panel readout.

I put a request into James to have an enhancement whereby there was an ability on the control panel to get a readout of the user settings as feedback that the config was set to what was expected.

I had a similar problem to Denis but not as severe which was a mixture of the slop on the end of the leadscrew and slop on the half nut.

Alan