Thread: Ready Steady Eddy
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...
The Following User Says Thank You to kingcreaky For This Useful Post:
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 ?
2. If so, we are now relying on the repeatability of the switches for machine accuracy.
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 ?
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.
The Following User Says Thank You to Ger21 For This Useful Post:
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 01:54 AM.
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.
Surge protectors here, the one with RJ45 support. Though allot are wifi''ing it up now days.
"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.
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 09:33 AM.Spelling mistakes are not intentional, I only seem to see them some time after I've posted
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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