why does centroid never remember its coordinate/home

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ShawnM
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Re: why does centroid never remember its coordinate/home

Post by ShawnM »

If you use the default "park" macro before you shut down the machine it'll take less than 5 seconds to rehome any machine at startup. Maybe a few seconds longer for any paired axis/auto squaring router. :mrgreen:

If you park the machine elsewhere you do know that you can manually jog any axis BEFORE you home the machine, yes? (be aware that no limit switches will work when you do this so you can crash your machine before you home it, you've been warned) ) I operate a 6 foot by 12 foot router and I have the "park" position at the opposite end of the table (X .25, Y 143.5, Z .25) so the extra large gantry is not in the way. When I power up the machine, BEFORE I home it, I press the Y- button on the VCP and the gantry moves towards Y0 at the fast jog rate. It takes about 5 additional seconds to jog the gantry to within about an inch of the home switch, the X and Z are already within 1/4" of their respective switch, then I press cycle start and the machine runs the cncm.hom file. Maybe a whopping 10 seconds to home a 6x12 router. While it's homing I'm doing other things anyway and the machine is homed before I know it. I only imagine it takes quite a bit less time to home smaller machines. I don't see what all the fuss is about. :shock:
vw_chuck
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Re: why does centroid never remember its coordinate/home

Post by vw_chuck »

Well if they could fix the jumping shit at startup and add a battery that would be sweet. Industrial controls are so archaic. The shit that is being done with controls nowadays is crazy. Most of this technology in CNC is like 30 years old or more at this point. Maybe it is time to think outside the box. Maybe just a little.
ShawnM
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Re: why does centroid never remember its coordinate/home

Post by ShawnM »

vw_chuck wrote: Wed Jan 19, 2022 10:50 am Well if they could fix the jumping shit at startup and add a battery that would be sweet. Industrial controls are so archaic. The shit that is being done with controls nowadays is crazy. Most of this technology in CNC is like 30 years old or more at this point. Maybe it is time to think outside the box. Maybe just a little.
None of the 4 machines I operate (or numerous ones I've retrofit) with the Acorn controller do any "jumping shit" when I power them up. Some of the machines don't make any noises and I wonder if they are even on and ready. So it's not an Acorn issue, it's a wiring or component issue. :mrgreen:
Last edited by ShawnM on Wed Jan 19, 2022 11:07 am, edited 1 time in total.
martyscncgarage
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Re: why does centroid never remember its coordinate/home

Post by martyscncgarage »

CNCMaryland wrote: Wed Jan 19, 2022 10:45 am
vw_chuck wrote: Wed Jan 19, 2022 10:33 am I have said the same thing in the past. The board needs a battery and some memory so that retains it's position from the last session so it thinks power was never turned off to it. Then you wouldn't have to rehome and set your part zeros and such. It would save a massive amount of time for us hobby guys. I would even pay like 50 bucks for a board add on to accomplish this.
First off, no machine is able to do this unless it has absolute encoders. Once you turn any machine off and then on, the motors jump to some degree (.01mm perhaps).

Secondly, if you have good home switches, all you need to do is home the machine at startup. If the home switches are accurate, all your WCS are just as accurate.

Third, you can go into system Parms and turn off the need to home at startup.
He basically wants to keep Acorn powered up...
Open loop systems are NOT conducive to what they are asking for.
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
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suntravel
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Re: why does centroid never remember its coordinate/home

Post by suntravel »

vw_chuck wrote: Wed Jan 19, 2022 10:33 am I have said the same thing in the past. The board needs a battery and some memory so that retains it's position from the last session so it thinks power was never turned off to it. Then you wouldn't have to rehome and set your part zeros and such. It would save a massive amount of time for us hobby guys. I would even pay like 50 bucks for a board add on to accomplish this.
for homing once a day ?

Get an Oak board, glassscales, or servos with absolute encoders and you can save one minute a day for 5000 bucks :D

Uwe
Sword
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Re: why does centroid never remember its coordinate/home

Post by Sword »

I'm sorry, but I just don't get this desire/mentatity to not have to home your machine upon power off/on of the controller. As far as a battery, you would also need to have one that would be set up to keep power to your drivers to keep the motors locked in. Why not just leave it powered up 24/7 then?! On my router with rack/pinions, when I shut down for the day, the Z axis is free to slightly fall from the weight of the spindle etc. Because of this, it's mandatory that I home the machine upon restart. I or someone could bump the machine when it's off and slightly change it's position, thus requiring it be homed to be accurate again. If you kept Acorn alive to keep values and didn't keep the motors powered up, you couldn't really trust that some outside force didn't change the machine position (bump or turn a handwheel a little etc. Are we just too lazy to install and properly set up some proximity switches!?

Acorn does not lose it's park or part position values (G54, G55, ....). If your Z moves down when parking, you don't have your Z axis set up properly and/or you edited your park macro incorrectly. If the machine is properly homed, all part locations (WCS locations) will be accurate.

As far as saving time, because your not utilizing proper homing, it's wasting you much time. I park my 96" x 48" machine at zero for all at the end of the day and it maybe takes all of 10 seconds to run the homing routine. Once done, all my previous work coordinates are dead on from the day(s) previous.

"Is this just a hobby controller?" No, it's a professional controller in a DIY package. The Y stands for YOU. This means that it's up to you to set it up properly with the help of documentation and the forum. A hobby controller would be something like the deadware called Mach3 and some others that never required homing. For those that didn't require homing and the DRO's kept the previous values, are you sure a gremlin didn't come in and mess with you overnight? ;-)

As far as jumping, along with what others have said, I have had Mach3 and UCCNC on two different machines with open loop steppers and they both jump when locking in. I'm sure that there's something electrical that could be done to soften the sound of it happening, but the motor is still going to fall on one side or the other of a detent. Because I had/have proximity switches on each, a quick homing of the machine eliminates all doubt.
Scott
CNCMaryland
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Re: why does centroid never remember its coordinate/home

Post by CNCMaryland »

Sword wrote: Wed Jan 19, 2022 11:46 am As far as jumping, along with what others have said, I have had Mach3 and UCCNC on two different machines with open loop steppers and they both jump when locking in. I'm sure that there's something electrical that could be done to soften the sound of it happening, but the motor is still going to fall on one side or the other of a detent. Because I had/have proximity switches on each, a quick homing of the machine eliminates all doubt.
Thank you for saying this better than I did. When I said "jumping" earlier this is exactly what I meant. The locking and unlocking.
cad cam man
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Re: why does centroid never remember its coordinate/home

Post by cad cam man »

Absolute encoders . You can't buy cheap stepper motors and expect them to work like a machine with servo motors i mean come on anyone with any sense knows you get what you pay for . A battery really??? Buy real servo motors and not "hobby" motors then you can expect no homing , and no jumping at start up
vw_chuck
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Re: why does centroid never remember its coordinate/home

Post by vw_chuck »

This isn't a real issue with a mill I guess but with a lathe if it knows where it is from the last time you ran a part you wouldn't need to home and then make a cut to calibrate your X axis. It is quite a bit of time and potential error and wasted metal on a lathe.
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Re: why does centroid never remember its coordinate/home

Post by suntravel »

vw_chuck wrote: Wed Jan 19, 2022 4:27 pm This isn't a real issue with a mill I guess but with a lathe if it knows where it is from the last time you ran a part you wouldn't need to home and then make a cut to calibrate your X axis. It is quite a bit of time and potential error and wasted metal on a lathe.
When power is down and axis are moved, no way that Acorn could know the right position...

But I you like to gamble set P5 to 1

Otherwise get an Oak board and absolute encoders for all axis.

I have absolute Scales and a DRO besides Acorn and home after power up, double check if the DRO is 0 on all axis to be shure homing is precise...

Uwe
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