504,336 active members
4,273 visitors online
IndustryArena Forum > MetalWorking Machines > Benchtop Machines > CONFUSED... Where to home too... Help! where should my home switches be.

# Thread: CONFUSED... Where to home too... Help! where should my home switches be.

1. ## CONFUSED... Where to home too... Help! where should my home switches be.

Very Confused about where to mount my home switches...

I put my Z at the top of the column so I would assume it would home in the + direction.
I put my X at the left side of the table which would home in the + direction
I put my Y in the front (closest to me) and it home in the - direction.

What I would like to know is the left front corner the place to home? and if that is so the when homed the X can only go in the negative direction and the Y only in positive right?

2. ## Re: CONFUSED... Where to home too... Help! where should my home switches be.

Is there some reason why you can't locate the home position as you describe?It appears to be logical and the positive direction of travel for X would be to the right and for Y it would move front to back.Having z homed at the top is also logical and you should generate a homing sequence that has it as the first axis to home.When machining you can locate the part datum and orientation to suit I would imagine.

3. ## Re: CONFUSED... Where to home too... Help! where should my home switches be.

The home position really doesn't matter. It is only a reference position only. You can put the home switches wherever you want or where is most convenient.

4. ## Re: CONFUSED... Where to home too... Help! where should my home switches be.

Originally Posted by routalot
Is there some reason why you can't locate the home position as you describe?It appears to be logical and the positive direction of travel for X would be to the right and for Y it would move front to back.Having z homed at the top is also logical and you should generate a homing sequence that has it as the first axis to home.When machining you can locate the part datum and orientation to suit I would imagine.
I guess that was my question...Does it matter?

Since I am new to this just wondered? I assume you would home the machine then mount your work and locate the work coordinates to somewhere in the middle of the X and Y travel right?

Correct me if I am wrong but when the X axis MOVES to the right it is a positive direction correct... and Y is postive going away from you toward the column correct?

Thanks!!

5. ## Re: CONFUSED... Where to home too... Help! where should my home switches be.

Originally Posted by truckeic
Correct me if I am wrong but when the X axis MOVES to the right it is a positive direction correct... and Y is postive going away from you toward the column correct?

Thanks!!
Here is the normal layout for mill axes, home position can be anywhere that you want it.

Unless your home switches are very accurate, it is better just to zero off of the part that you are working on. There is really no need for a home position unless you have a tool changer. I don't have home switches on my mill, but I do have the ability to set a floating ''parking position'' to move the Z and table to a convenient location for tool and part changes that is invoked on a tool change command or program end. This is set per the job on the table.

6. ## Re: CONFUSED... Where to home too... Help! where should my home switches be.

Originally Posted by truckeic
Very Confused about where to mount my home switches...

I put my Z at the top of the column so I would assume it would home in the + direction.
I put my X at the left side of the table which would home in the + direction
I put my Y in the front (closest to me) and it home in the - direction.

What I would like to know is the left front corner the place to home? and if that is so the when homed the X can only go in the negative direction and the Y only in positive right?
If that is where it works best for you then that is where you want them to be, Home switches double as limit switches also and is what soft limits are associated with so are an essential part of any CNC machine operation

7. ## Re: CONFUSED... Where to home too... Help! where should my home switches be.

There is really no need for a home position unless you have a tool changer.
While it is true that you can get by without home switches, they are very useful for not having to zero every time you turn on the machine. For example, 90% of my work is referenced to the fixed jaw of my vise, which is keyed to the table. I never have to zero the Y axis on power-up because I can just home the machine and it is set to within 0.0005" as the jaw offset is retained. Likewise if I am working on a part and don't finish it, I can just power down the machine, and when I power-up the next time simply home and the zeros are all set and ready to go. Without home switches you are required to re-zero every time you power up or reset the controller.

8. ## Re: CONFUSED... Where to home too... Help! where should my home switches be.

Originally Posted by 109jb
While it is true that you can get by without home switches, they are very useful for not having to zero every time you turn on the machine. For example, 90% of my work is referenced to the fixed jaw of my vise, which is keyed to the table. I never have to zero the Y axis on power-up because I can just home the machine and it is set to within 0.0005" as the jaw offset is retained. Likewise if I am working on a part and don't finish it, I can just power down the machine, and when I power-up the next time simply home and the zeros are all set and ready to go. Without home switches you are required to re-zero every time you power up or reset the controller.
You turn your machine off? I just move mine to 0,0 and hit the E-stop.

9. ## Re: CONFUSED... Where to home too... Help! where should my home switches be.

I home mine to the table centre and top of the column.
I don't use limit/home switches just the software limits.
Couldn't be bothered to fit any as soft limits works for me, can be a pain though to get machine co-ordinate 0.0 back exactly if it does go out.

At days end with Mach3 I send machine home G28 and turn off. Next day I turn on and just hit ref all home button and good to go. It's stayed in position.

It would be easier to go to a corner but my Y axis overhangs the base and I don't like to leave it in that position for any length of time.

In my view having a machine home position is important because when G-codes start G28 G91 Z0 it will send the machine home first. If home is incorrect it can cause damage if you have no physical limits unless you change the G28 lines.

10. ## Re: CONFUSED... Where to home too... Help! where should my home switches be.

There are two main purposes of limit switches.
1- In the case of any sort of malfunction the limit switch at the end of a travel will be triggered before one part of the machine crashes into another part of the machine. For example, If you are using Mach3 and disable Soft Limits and jog the X or Y axis till it reaches the end of the travel and the motor starts stalling makes noises...this is bad...don't do it, avoid it! Well if you had a physical electrical switch at the end of the travel, it would be tripped/triggered and stop the travel even if there were instructions to keep going, Its a safety mechanism.

2- limit switches allow the machine to get a rough idea of where it is. If you program your machine to know a switch is at 30 and you trigger the switch, well you just told the machine it is in fact at 30 and not -5. This is a referencing function. But it may not be as precise as you need to machine. So the limit switches may give you a position +/- .5 accuracy, but your machining operation may need +/-.01. So it will be good enough to avoid crashing and maybe rough machining but if you have a jig, you may have to reference off the jig also!

To be honest I don't have limit switches, Soft Limits in Mach3 are good enough for me.

11. ## Re: CONFUSED... Where to home too... Help! where should my home switches be.

Don't confuse homing and limit switches. The OP asked specifically about homing switches and where to home. Home switches can serve double duty as limits, but can also be totally separate and independent switches.

A good homing switch will have good accuracy. I use proximity switches for homing and have tested them to be accurate to within 0.005" (0.01 mm). I have also tested mechanical switches and the ones I tested were only a little worse (0.001" or 0.02mm) accurate. A lot is dependent on the homing sequence and what the homing speeds are set to.

Saying a switch can only be used for the machine to "get a rough idea of where it is" may be true for a crappy switch, but is totally false if using a switch that provides good repeatability.

12. Thanks for all the great info and replies. This forum is indeed great..

Sent from my XT1635-01 using Tapatalk

Page 1 of 4 123