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General Mach Discussion / Homing operation does not pulls back enough to get away from switch?

« on: March 16, 2018, 01:25:46 PM »

Hello i am fighting a pretty annoying problem on my benchmill i installed a 3 axis kit on , just installed switches for limit and homing

i installed limit switches but they are  industrial NO/NC switches , spring loaded contacts wich have quite a lot of travel in them

 - the machine sees every signals correctly
-the cables are shielded and grounded
- if i disable the limit switches input  it homes and backups fine
- if i disable the home switches pins the limits stops the machine like they should
- if i have all the inputs enabled the machine will home one axis back off and sometimes just not pulling back from the switch enough to bring back the NO switch in open position and then it locks the machine .probably the travel needed times out the homing routine and gets out of the homing operation still on the limit switch locking the machine
-i did install capacitors to clear a potential noise problem but it isnt the case apparently



The axises sometimes clicks and unclicks the switches well but sometimes it doesnt so it is not constant. i can just push a bit on the carriage or the tab the switch sits on and i make it unclick from her activated position so looks like the travel of the homing back off is about a few thousands too short . i tried giving a bit more of acceleration to the axises but it is not helping.


so now i am trying to figure out if there is a way to edit the amount of distance the homing operation has to recognise the home switch click back out ??
tried modifying a few values in the homing setup screen and it didnt helped :-(

2

General Mach Discussion / very slow Feed issues with setup , calculated steps per not working in mach3

« on: January 11, 2018, 01:20:09 PM »

Hello guys , happy to find this community ! i been hitting the forums alot thru google search and i couldnt find a way to fix my problems in Mach3 so i decided to register , will probably be easier to show my problem instead of trying to find someone else's wich match my setup..

I retrofitted a small bench mill to 3-axis CNC


So here we go i assembled a 3 axis kit with  Nema 34 1235oz steppers with Stepper Motor Driver:DQ860MA and 350W 5.8A Single Output Switching Power Supplies

here is the ebay listing from where i bought the kit , the parts are more detailed there
https://www.ebay.ca/itm/US-FREE-Wantai-3Axis-Nema34-Stepper-Motor-1232oz-in-Driver-7-8A-fast-shipping/221683269197?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

so after loosing a whole day trying to figure out why my steppers wouldnt move i found a thread with someone saying he had similar problem and he pointed out a flaw in the wiring diagram provided. i went on LongsMotor webpage and found a 99% similar wiring but it had the ENBL+ pin connected to +5V , the connection wasnt there on the sellers wiring diagram so i made it work.


Then i went on The steppercalc excel sheet i found and with the leadscrew infos , axis and motor teethcount , with the drivers set to 1600pulse/rev it was showing me 640 steps/mm

well it wouldnt move much so i brought up the steps per mm until i got movement then went to Mach3 axis calibration and gave him a movement of X distance ,measures the travel and it corrected it to about 20 000steps per mm wich is waaaayyy out of the 640 range calculated but it now moves 10mm on the table and 10mm on the DRO , i also loaded G-Code i made thru Fusion 360 and cut a part

here it is supposed to be at a feed of 1500 something mm/min

 https://youtu.be/4WImMKD4wv4

here we see the code being worked , FRO overridden , showing 1524mm