Master + Slave motor axis homing

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Master + Slave motor axis homing

Postby maker44 » 05 May 2017, 16:24

I've seen a couple of forum posts from a few years ago on homing Master + Slave axes.

Generally people were requesting a function to do this with 2 separate limit switches so that the motors would adjust independently and the result would be a perfectly aligned axis. (For example both ends of the Y axis on a CNC router.)

What's the latest on this?

What's the best procedure for homing with limit switches a 2-motor Y-axis CNC router?
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Re: Master + Slave motor axis homing

Postby maker44 » 09 May 2017, 16:07

There must be somebody out there with two Y-axis motors on their CNC router.

How do you manage that with just 1 limit switch?

Or have you found a workaround so that one can use 2 endstops, 1 for each motor?
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Re: Master + Slave motor axis homing

Postby Support » 17 May 2017, 09:16

Auto squaring is not supported and two limits per axis are not supported.

One user did manage to solve this problem for himself: viewtopic.php?f=18&t=1631
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Re: Master + Slave motor axis homing

Postby maker44 » 18 May 2017, 18:36

That's a neat electronic solution from a user.

Thanks.

What I'm really interested to know is what is recommended.

1) Do we convert a 2 Y-motor design to a 1 Y-motor design ? (Anything is possible when you make your own machine!)

2) Do we continue with 2 Y-motors but use some kind of manual adjustment to both ends of the gantry perfectly aligned before homing with one limit switch? If so, what kind of adjustment procedure do people recommend? How often is it necessary to do it? Once a day, once a month... only after crashes?
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Re: Master + Slave motor axis homing

Postby JerryBurks » 19 May 2017, 20:14

Probably not what you are looking for but I have force synchronized the x-axis stepper motors with a timing belt. Once aligned it stays aligned and usually I don't ever bother to home the machine. I just set x/y-zero wherever needed on my work piece.
It does however require tightening the belt pulley set screws with both motors "in phase" so that they don't work against each other
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Re: Master + Slave motor axis homing

Postby maker44 » 20 May 2017, 17:31

Thanks @JerryBurks, that's actually super-interesting.

Since there were no replies in this thread, this week we took off one of our Y-axis motors and moved the other one to the centre of the gantry (this is a router). Timing belt down to a new rod that runs from one end of the gantry to the other (it's about 1.5m long) to turn the cogs at each end. Increased the current in the NEMA23 from 4A to 6A.

So far seems to be running pretty good but might be interested in moving back to 2 Y-motors in due course since this is an all-steel construction, pretty heavy and I just can't believe it wouldn't benefit from the extra power. So eager to hear how other people are doing. Thanks again!
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