Z axis error woes

[Swarfing]

Grand job Hank and good to see you are on your way again. Well done

[HankMcSpank]

Thanks guys....would you believe that since my last "solved" post - my problems (missing steps) moved to my Y axis!!

Basically, to solve the former Z axis problems I put in place a chinese TB6560 board...it transpires the 6 way DIP switch (ie the one that sets the current, decay & micro-stepping) for the Y axis was faulty & therefore some of the individual DIP contacts weren't making properly - the outcome being my Y axis was actually only running at 25% current...which made my Y Axis lose steps, which wasted a lot of my jobs (not to mention a couple of days lost time!) ...the solution was to hard wire (with little strips of wire) across the contacts on the base of the DIP switch!

Should anyone be misfortunate enough to hit a similar 'missing steps' problem with a TB6560 board ...if you've the same issue as me it's actually easy to diganose (in hindsight!), the swishing sound made by your stepper changes if your press down on the overall DIP switch! (the switch itself is a nasty bit of manafacturing....I can see a lot of these giving problems)

An unbelievable bad run of luck - & speaks volumes for the importance of using good stepper drivers - that's two consecutive boards that have bit me in the arse in short order!

Mishinh' Shteps.....Shteppersh, schmeppers.... [to be muttered under your breath in a Muttley style]

[JAZZCNC]

Well hate to say it. . .BUT . . . Did say Scrap em and start again. .

Pleased you found it quick this time thou because it would have been hard for Epoz and me (Edit:Oh and musn't forget Jonathan.!!) to scrap over what this one was.!! . . . Sure we'd have made something up thou.:rofl:

[HankMcSpank]

Well hate to say it. . .BUT . . . Did say Scrap em and start again. .

Indeed you did...but that was related to the first board - not the replacement! (that I thought had solved all my problems...whereas in fact it solved the Z problems but introduced Y problems)....I was tempted to post here & pretend it's not sorted just to give you all a reason to squabble! :-)

. Sure we'd have made something up thou.:rofl:

& such is my present fragile state of mind with respect to CNC machines - I'd have certainly bought it!

[Swarfing]

Still think your wrong, you know dam well its the widgets and bodgets at fault.....LOL!

[HankMcSpank]

Talk about a bad run of luck ....first Z woes - I replaced the stepper board which sorted this aspect ...but then Y axis woes, which I had thought was down to bad A3977 IC holder missing steps ...swapped out the IC holders which was no mean feat...these Allegro A3977 IC holders are QFP44 & soldered in on both sides of the board ......top tip- use bismuth rich solder - I bought some here a couple of years a go http://www.carnmetl.demon.co.uk/ (he makes it manually himself!) ...this type of solder stays molten long enough to flood all 44 pins - also I put a hot air gun perched above to help keep it molten... yank out the IC holder then clean up the pads with copper braid & liquid flux (consider this method a cheapskates hot air rework station!)

But after swapping out the IC holder, my Y axis was *still* missing steps! Seriously, I was getting zany 'all over the shop' results when moving back/forth 5mm on the Y axis.

The cause?

The grub screws on the motor coupling weren't quite tight enough ...which meant the Y stepper motor was occasionally slipping vs driving the leadscrew (which I guess is a mechanical version of 'missing steps'!) ....after tightening it up, now I've got superb repeatability at least (as measured on a dial gauge)

So a warning - if you buy/own a Sabel 2015 or Panther 2015 (same machine...there are a few variants out there) ...make sure all the motor coupling grub screws are nice & tight...prefereably with thread lock applied!

Also I've now got rid of my Chinese TB6560 board ...so finally feel that the my CNC demons - for now - have been exorcised!

[JAZZCNC]

:dance: . . . Congrats Hank pleased you've finally tamed the beast . . . Happy PCB'ing . .:dance: