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  1. #301
    Quote Originally Posted by EddyCurrent View Post
    I had to strip it down a bit today because there was still a BK and FK bearing to sort out, both had bearings in facing the same way and no grease, made shims, greased, reassembled.
    More progress, ready to order some energy chain and start wiring and I'm very pleased the panel is already built.

    Attachment 11883

    Limit and home switch for Z axis, there is one switch and two strikers. For the home switches I mounted a piece of 6mm thick mild steel to aluminium angle to act as the target.

    Attachment 11884

    Motor mount for Y axis

    Attachment 11885

    limit switch and adjustable striker for Y axis, there's another striker at the other end of the gantry, so one switch with two strikers.

    Attachment 11886

    Ive been aware of this thread for a while, but tonight, only just read it.

    Nice Design!!!. Must say, hats off to you much better than mine. I think every single thing I wished I did with mine you have done here... Proper Rails, I like the extra plate at the top of the Y carriage (making a figure 8) The X steppers inside the gantry (rather than sticking out). and the general quality of the build looks superb

    Credit to you chap. Got to start thinking about my next build soon...

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  3. #302
    Ger21's Avatar
    Lives in Detroit, United States. Last Activity: 8 Hours Ago Has been a member for 5-6 years. Has a total post count of 483. Received thanks 63 times, giving thanks to others 0 times. Referred 1 members to the community.
    Quote Originally Posted by JAZZCNC View Post
    Ok Both motors drive upto first switch then both back off then Slaved motor drives upto it's own switch while Master stays still then backs off.
    Sorry my friend, but that is not correct. I didn't think so when I read it, so I just went out to the garage to check. My machine has a lot of flex, so I can easily rack the gantry one way or the other. I have dampers on my steppers, so with the power off, I can move one side by turning the dampers.

    First I moved the master side about 3mm away from home, then powered up the machine, and homed the X axis. The slave axis hits the switch, and backs off, while the master keeps moving to it's switch, then it backs off.

    Next, I moved the slave side 3mm farther from home. This time, the master hits the switch, and backs off, while the slave keeps moving.

    Each side of the gantry (master and slave) move independently to their own switches. For all practical purposes, they are not slaved during homing.

    1. Do both X home switches have to set so they both activate together exactly when the gantry is at the physical 'square' position ?
    Yes, but technically, no. The Home position is not set when the switch activates, but when it deactivates as it's backing off. So technically, the switches need to be set so that they both deactivate when the gantry is square

    2. If so, we are now relying on the repeatability of the switches for machine accuracy.
    Yes, but as Jazz said, even cheap switches are quite accurate. The DIY Hall switches I use are supposed to ba accurate to about .01mm or better, and only cost about $3 each to make them. The most important factor is accurately positioning the switches.

    3. Imagine a cutting job has just been completed so that the gantry has been up and down loads of times and it's now out of square. When it comes back to the home position it will hit one home switch first, so then what happens ?
    The side that hits the switch will back off and stop, while the other side continues to it's switch, squaring the gantry.

    Depending on the type of switch, you may or may not actually see the machine back off the switch. On my machine, it backs off such a small amount that it appears to just stop.
    Gerry
    ______________________________________________
    UCCNC 2017 Screenset

    Mach3 2010 Screenset

    JointCAM - CAM for Woodworking Joints

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  5. #303
    Quote Originally Posted by Ger21 View Post
    Sorry my friend, but that is not correct. I didn't think so when I read it, so I just went out to the garage to check. My machine has a lot of flex, so I can easily rack the gantry one way or the other. I have dampers on my steppers, so with the power off, I can move one side by turning the dampers.

    First I moved the master side about 3mm away from home, then powered up the machine, and homed the X axis. The slave axis hits the switch, and backs off, while the master keeps moving to it's switch, then it backs off.

    Next, I moved the slave side 3mm farther from home. This time, the master hits the switch, and backs off, while the slave keeps moving.

    Each side of the gantry (master and slave) move independently to their own switches. For all practical purposes, they are not slaved during homing.
    To be honest Gerry I wasn't 100% sure my self it worked like I said and couldn't can't check as I don't have slaved motors on my machine. Last machine I setup that used slaved motors was several weeks ago and was using the ESS but I'm sure that stopped both motors and backed off then moved slave.? Thou I'd have to check again to be 100%. I don't ever use PP so can't check if it works differant to Motion control cards but I will on next slaved machine I'm building just out of curiosity. Previous machine also used Motion control card but that was Russian PLCM and thought that did the same but again can't be 100%.? Esp as it happens so fast and with gantry being square so hard to see.!

    But more the point was they work together to square the gantry and like as been said if the gantry's setup square to start with and switches located at same point it's a seamless operation and very little twisting forces applied if correctly setup.

    Edit: One other thing for clarity for others (Gerry knows this ).? The speed at which you home makes a big difference to accuracy and how far it over shoots then as to backoff. Thick of it as driving wheels upto a line in your car.! At fast speed chances are you'll over shoot further then have to back up more to put wheels on line. Same principle go slower and chances are you'll hit the line ever time with little to no over shoot.
    Last edited by JAZZCNC; 04-07-2014 at 12:54 AM.

  6. #304
    Ger21's Avatar
    Lives in Detroit, United States. Last Activity: 8 Hours Ago Has been a member for 5-6 years. Has a total post count of 483. Received thanks 63 times, giving thanks to others 0 times. Referred 1 members to the community.
    Homing in motion controllers is done differently than with the parallel port, so you may be correct with the SS. I know it's taken several years for Greg to get slaved homing to work correctly with the SS.
    Gerry
    ______________________________________________
    UCCNC 2017 Screenset

    Mach3 2010 Screenset

    JointCAM - CAM for Woodworking Joints

  7. #305
    Bruce,

    This is the circuit as it is on the machine.

    Click image for larger version. 

Name:	circuit.jpg 
Views:	145 
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ID:	12761
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  8. #306
    Quote Originally Posted by kingcreaky View Post
    Ive been aware of this thread for a while, but tonight, only just read it.

    Nice Design!!!. Must say, hats off to you much better than mine. I think every single thing I wished I did with mine you have done here... Proper Rails, I like the extra plate at the top of the Y carriage (making a figure 8) The X steppers inside the gantry (rather than sticking out). and the general quality of the build looks superb

    Credit to you chap. Got to start thinking about my next build soon...
    Thanks for that, but it was thanks to your initial drawing and design that really took me from floundering to finding a route through it.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  9. #307
    Surge protectors here, the one with RJ45 support. Though allot are wifi''ing it up now days.

    .Me
    .Me

  10. #308
    Quote Originally Posted by Ger21 View Post
    Homing in motion controllers is done differently than with the parallel port, so you may be correct with the SS. I know it's taken several years for Greg to get slaved homing to work correctly with the SS.
    Going back a little here to homing but was looking thru Mach manual today and noticed this in the Homing/limits section.

    "When a Reference operation is performed, then the axes will run together until the final part of referencing, which
    is moving just off the Home switches. Here they will move so that each stops the same distance off its
    own switch. Referencing will therefore correct any racking (i.e. out of squareness) of the gantry, which
    might have occurred when the machine was switched off or because of lost steps.
    "

    So they do a mixture of both really has they are slaved upto point it's backing OFF the Switch.!! Tonight Just checked on machine that is using PLCM-E3 and it works just like this. . . . . . Just thought this might clear any confussion.

  11. #309
    So after that bit of RTFM, here's how I would set up the homing switches;

    Assuming 2 home switches used on X

    1. One switch can be mounted in a fixed position while the other switch needs to be + and - adjustable in the X direction.
    2. Using some form of measuring equipment e.g. large T square, set both switches square to the X axis.
    3. Carry out a homing operation of the machine then using the same measuring apparatus as in step 2. check squareness of the gantry to X axis
    4. If the gantry is not square then move the adjustable home switch by the required amount and in the required direction.
    5. Repeat steps 3 and 4 until the gantry is square to the X axis.
    Last edited by EddyCurrent; 18-07-2014 at 08:33 AM.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  12. #310
    Eddy Spot on, simples, can't just remember if the slave needs to be the adjustable one. I drilled some holes down the x and y then put dowels in then the square against the dowels. then readjusted the switch and tried again. ..Clive

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