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Author Topic: Homing limits and annoying Estops  (Read 3309 times)

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Homing limits and annoying Estops
« on: October 09, 2009, 03:49:36 PM »
I'm hoping some one can help me.

Iv just up dated my Denford triac to Mach the and all was going well up till i got to homing, limits and referencing a long with one other silly little problem.

I can jog my the machine around all day from the key bored with no probelm of sorts but ill come back to that so now i iv gone in to homing and limits to turn my homing switch's on check i have no LED's on and that they light up when i poke one with a finger witch they do next i click on referencing the Z will move say 25mm and zero the DRO (when not even close to the switch)same on the y and I'm Lucky if the X moves at all referencing once more Z Y might do it right second time round if at all and once more x is the same then 1 on 5 goes it will do it all right ? but it gets even better if i go and turn on limits i cant do any ting all i get is Estop's all the time I'm lucky if i get it to start of for 5 secondes turn of the limits and I'm back to how i was just turning on 1 limit will do this never mind all of them.

So what is going off here I'm using pins 11,12and 13 on my break or bored.  is it because I'm using a unlicensed copy of mach3 to set up was just going to wait till i was up and going before doing so is there a few things turned of in my download ?

my next small problem is in jogging the Z i can jog Z- all day but as soon as i try to go back up to the top i cant hold the key down for more than 2 second es before the Z stops moving and i get a very unwelcome sound from the motor i have my motor tuning right down ?


any help please I'm going total mad here

Offline Hood

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Re: Homing limits and annoying Estops
« Reply #1 on: October 09, 2009, 04:09:39 PM »
First problem sounds like noise on your switch, do you have the switch wires shielded?

Second problem is you need to tune your motor, probably too much acceleration. Reason it is working fine in a negative direction is that gravity is helping it and in the positive gravity is fighting it so putting more load on the motor.

Hood
Re: Homing limits and annoying Estops
« Reply #2 on: October 09, 2009, 04:38:12 PM »
Thank you for your reply iv tryed what you have said with my limits all ready with no luck at all but after tinking about it could it be my parallel cabel its home made from a old printer cabel i really am at a loss

as foy my z thank you ill look in to that some more ill slow it down some more
Re: Homing limits and annoying Estops
« Reply #3 on: October 09, 2009, 06:36:36 PM »
as a newcomer to mach 3 and cnc, setting up the machine can be a minefield. There are so many options and cross options it's easy to get confused, so i would watch the first two tutorial videos, they have helped me so much and got me out of some wierd problems.

Take it in steps, get the movements in the right direction first with the dro going the right way, then sort out the home switches. Finally the soft limits, they never seem to work until everything is right.

I've converted a novamill and boxford 260 to mach3 over the last month or so and it's a great feeling when they do what you tell them.

You will get it sorted, and when you do you'll see where you went wrong and think, oh yeh i should have known that.
Re: Homing limits and annoying Estops
« Reply #4 on: October 13, 2009, 05:38:12 PM »
Thanks for the pat on the back i sure do need it to get over this lot but I'm still having no luck i have this gut feeling that its the PC at fault but I'm still not 100% sure. so I'm having a week out to regroup and think on this some more iv got to be missing some thing
Re: Homing limits and annoying Estops
« Reply #5 on: October 13, 2009, 06:16:31 PM »
Could be my old friend, the damp and gummy wires.

See if your breakout board will trigger a limit event with a 100K resistor across the terminals. Also measure the "normal condition" and "triggered" resistance of your home switch circuits and compare results.

A quick way round this is three 5v coil relays arranged to be triggered from the limit switches (or one relay if using a continuous loop). This has its coil driven by a seperate power supply (a phone charger is good) through the home switches, so they only trigger the realy with the sort of current a closed switch can provide, not little leakage currents. The relay contacts drive the breakout board, so it sees either clean, dry open contacts or a dead short - no funny business in between.
Re: Homing limits and annoying Estops
« Reply #6 on: October 14, 2009, 08:15:29 AM »
This is exactly where I was a year ago! My favorite tool for finding intermittent signals and noise became a $3.99 Radio Shack......OH! Excuse me!..The Shack logic probe. It not only showed me good logic-level signals but the nasty bad signals caused by stepper drivers, solenoids and other loudmouth noise generators. It even found a bad power supply filter cap for me when I couldn't even get it to show ground(0). Poor man's scope?
Re: Homing limits and annoying Estops
« Reply #7 on: October 14, 2009, 08:28:01 AM »
Sounds like a clever man's scope, regardless of cost. nice going :)