Homing-TouchPlate Issue

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  • December 16, 2015 at 4:25 pm #9150
    leversole
    Member

    Back up and running! (thanks Riley)…anyhow, I am about to scrap the idea of ever having limit swithes work correctly…either I am stupid or overlooking something simple…

    I have attached the config in MM for anyone to take a look at…here is the problem and it is repeatable…

    With the limit switches (Xmin, Ymin, and ZMax) enable as 1, homing only, homing works perfect every time, the problem is when I use the touch plate feature in Chilipeppr

    Here is the scenario…
    Fresh boot on the tiny G, JSON server and chilipeppr starting from scratch.
    Home the machine G28.2 Y0 Z0 X0 – works great
    Switch to inches, (or not, doesn’t matter for issue)
    Jog the machine z+ 1.9 (to get it closer to touchplate
    Then use touchplate, which is
    G21 G91
    G38.2 Z-20 F50
    G28.3 Z6.5
    G91 G0 z2

    The machine will ALWAYS go in the WRONG DIRECTION (z axis up) the first time! I can manually trip either the touch plate sensor OR the Z limit switch and it will stop and set the z to 8.5mm (as it should)

    If I run the touchplate routine again without ANY moves/changes, it will go in the correct direction (down) and touch off on the plate, but usually screws up the Z coordinate (not 8.5 anymore, some random value)

    As a further test, I went and disabled all of my limit switches then restarted everything. No the touchplate routine operates correctly…

    Am I missing something here? Surely you can run the touch plate AND limit switches?!?

    Thanks

    TinyG MM Config

    December 16, 2015 at 9:35 pm #9152
    cmcgrath5035
    Moderator

    I don’t have a working setup to experiment with, so am just reading and trying to understand what you are doing

    Sidebar comment – Chillipeppr seldom starts from ‘scratch’. You may want to flush browser cache as well, but not at all obvious that has anything to do with your issue.

    If your first step is to home the machine, setting Z=0 at the top limit of Z travel, why do you say jog the machine z+ 1.9 to get closer to the touch plate? seems z-1.9 would move down closer to the touchplate. If in fact z+1.9 moves down, I have to wonder if your polarity is reversed.

    Also, your Gcode snippet G28.3 Z6.5 yet you say “and it will stop and set the z to 8.5mm (as it should)”. Doesn’t the command say set it to 6.5mm?
    I assume 8.5(or 6.5) is the thickness of your touch plate?

    Your Parameter file looks mostly OK. Your jerk homing settings are very low (typically 2 x the jerk maximum settings. e.g. $xjh=10000)

    Also,, at the point you created the $$ file All Limit switches were disabled and Soft limits disabled. Not clear where in the timeline that occurred.

    Any of these observations make sense?

    • This reply was modified 8 years, 11 months ago by cmcgrath5035.
    December 16, 2015 at 10:14 pm #9156
    ril3y
    Keymaster

    Great to hear you working again. Ummm you perhaps I am missing something but you have your switches set to normal closed. The cp widget probe tool has to be NO to complete the probe when touched. I think you are confusing tinyg as you start a cycle with a limit in the open position ?

    ril3y

    December 16, 2015 at 11:09 pm #9158
    leversole
    Member

    You may be on to something Riley…I bought NC switches because I read everywhere that NC was the way to go to prevent false trips from noise…I guess TG doesn’t like the fact that the touch plate is NO…

    There was a section in the wiki that pointed to an article on using the touch plate but it was empty…If I keep on the way I am going I’ll be an expert!

    I guess I have to order new switches, as mine are NC only…

    Carl, the touch plate is 6.5, but the tool moves up 2 more mm for clearance…for a total of 8.5mm, also, I meant LOWERING the z 1.9!

    • This reply was modified 8 years, 11 months ago by leversole.
    • This reply was modified 8 years, 11 months ago by leversole.
    October 19, 2017 at 10:01 am #10635
    kenmoberg@gmail.com
    Member

    Although this is a pretty old issue, I thought I’d add what happened to me…. the probe was working fine until I realized I was getting shocked by my ungrounded Chinese spindle. Once I grounded that, the touch plate started running in reverse. I found out that I had wired my touch plate backwards so it was applying the 3.3 volts to the bit, closing the switch so it was always closed after I grounded my spindle. After I reversed the wires on my touch plate, so the clamp was ground along with the spindle, things started working as expected again. Hope this helps someone.

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