The Craftmans Shop > New from Old
The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
awemawson:
Using the (new to me) PLC ladder testing approach is both swift in some ways, and mighty frustrating in others. Although I reckon that I have the majority of the logic 'nodes' (ie inputs outputs and flags) named so that I can find my way around, inevitably I end up in a bit of logic where I've not yet been able to plant signposts :scratch: I reckon I've still 102 out of 490 nodes to name and identify the purpose of
Today I found out that one of the pressure switches that monitors chuck clamping was permanently 'made' - entirely by following the ladder logic, but the frustrating thing is that either they have been wired wrongly, or the circuit diagram is wrong. They are pretty well impossible to get at and determine which is which - certainly can't at the moment as still in Sunday Best :palm: - a job for tomorrow slackening a hydraulic fitting and see if clamp or unclamp covers me in oil !
Hopefully I can pull it out and re-work it as I very much doubt that they are a shelf item any more - have a picture.
I'm also attaching the latest .pdf version of the annotated PLC program for those of you that can't get to sleep at night :lol:
WeldingRod:
Ugh. I hate pressure switches! Just a time bomb ticking off till failure.
Sent from my SAMSUNG-SM-G891A using Tapatalk
awemawson:
Taken a bit of time off to sort out some tooling cabinets for the Beaver TC-20 lathe - Versatool ones like I used for the Traub - details here:
https://madmodder.net/index.php/topic,8741.msg152687.html#msg152687
awemawson:
Major break through today in the hunt for the M19 Oriented Spindle Stop problem that has been eluding me for ages.
In desperation I have typed into the 'Machine Data' for the controller the values of parameters for Spindle Data from the TC-10 back up that I obtained, where they differ from mine. And guess what, the servo loop IS closed, and the spindle rotates to approximately the programmed position but then oscillates around that position never completing the command. Parameters changed are:
#4010 Drift Compensation (Spindle) was 2 now 6
#4270 Cut Off Speed M19 Gear 1 was 5 now 10
#4350 Gain for M19 Gear 1 was 2000 now 7000
#4430 Positional Limit for M19 was 2 now 1
#4500 Set Reciprocation Speed was 100 now 0
So I conclude that the spindle positioning servo loop parameters need tuning. I have tweaked all these values up and down a bit but not yet found any one that stops the hunting.
Bear in mind that the other lathe is different. It only has one gear whereas mine has two, so parameter #4350 for instance where the servo gain is very different (7000 as opposed to 2000), in fact mine was originally 7000 for Gear 2. Also my main spindle motor is significantly bigger than the TC-10 one.
Need to research servo tuning, but what amazes me is that with my original values there was no apparent servo action on the spindle at all - very odd.
But this IS another major step forwards :clap:
seadog:
The gain would be the obvious choice to prevent hunting. I can just about recall this was fairly critical when I was playing with feedback on RF frequency synthesizers.
Perhaps the drift compensation is damping. (Then again, perhaps it isn't)
Well done!
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