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Author Topic: Cnc Id od and thread grinder  (Read 19718 times)

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Re: Cnc Id od and thread grinder
« Reply #10 on: August 01, 2019, 09:07:36 AM »
Can a moderator turn that pic over.  I sent it right side up.

Offline Tweakie.CNC

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Re: Cnc Id od and thread grinder
« Reply #11 on: August 01, 2019, 10:29:38 AM »
Looking good (either way up  ;))
PEACE
Re: Cnc Id od and thread grinder
« Reply #12 on: August 21, 2019, 11:49:44 AM »
I have a question for all of you mach pros.  Am i able to define a home, soft limit and hard limit in mach. Soft limit as a stop motion but not a shut down. As an example as I'm trying to home the machine if it hits a soft limit have it turn around and go the other direction to hit the home position.
Re: Cnc Id od and thread grinder
« Reply #13 on: August 21, 2019, 02:41:13 PM »
Hi,
soft limits are effective ONLY AFTER your machine has been homed.

Your description sounds like you want to use a soft limit to turn the axis direction around to find the home switch
ie before the machine is homed. Soft limits are distances from the home position......if the home position is yet to be
defined then the soft limits are likewise undefined.

Craig
'I enjoy sex at 73.....I live at 71 so its not too far to walk.'
Re: Cnc Id od and thread grinder
« Reply #14 on: August 21, 2019, 06:52:17 PM »
What about a physical switch?
Re: Cnc Id od and thread grinder
« Reply #15 on: August 22, 2019, 03:33:39 AM »
Hi,
yes a physical switch would work.

How many axes do you need to do this for?

If you put a home switch(es) at or very near to the end of the axis(es) then you would always home in one direction,
there would be no need of extra switches.

Do you use Mach3 or Mach4? I contributed to a thread where a guy had home switches in the middle of his axes and wanted
some means to always home toward the switch. Using Mach4 there is a way to do so, its not all that straight forward but
it does work.

https://www.machsupport.com/forum/index.php?topic=41636.0

Craig
'I enjoy sex at 73.....I live at 71 so its not too far to walk.'
Re: Cnc Id od and thread grinder
« Reply #16 on: August 22, 2019, 08:09:53 AM »
I'm not set on either mach yet.  I would need to do this on 2 axis.  I'm trying to make this as dummy proof as possible.  If all works well it will be a full production machine for untrained operators.
Re: Cnc Id od and thread grinder
« Reply #17 on: August 22, 2019, 07:27:21 PM »
Hi,
then I'd suggest mounting the home switches at or very near the end of the axes then under almost
any circumstance the homing direction will always be toward the home switches...no guessing.....no extra switches....
no tricky coding.

If you are planning to use this widely then you should consider Mach4 over Mach3 as all development of Mach3 ceased six years ago.
Whatever bugs it has it will always have.

Mach4 is, on the other hand, being actively developed. Additionally the structure, API and Lua scripting language offer very distinct
advantages in terms of flexibility and customisation which would be very appropriate if you were considering manufacturing for
non-expert operators.

Craig
'I enjoy sex at 73.....I live at 71 so its not too far to walk.'
Re: Cnc Id od and thread grinder
« Reply #18 on: August 22, 2019, 08:34:32 PM »
Ok i kindad felt id  go with mach4 . As for home switches I'm planning on the center axis (X) having the home in the center.  If it moves to far in either direction with a piece on the mandrel  it will crash into the grinding wheels.  I will need the room as it dresses so it could create a problem when the wheels are new.
Re: Cnc Id od and thread grinder
« Reply #19 on: August 23, 2019, 03:37:54 AM »
Hi,
OK you have decided on a central X axis home switch then you need to consider how to do it.

Have you read and digested the method I outlined in the link I posted? In particular you need to thouougly
understand both why and the implications of that method:

Quote
Should it transpire that your machine axes can or have been moved between sessions this method would fail.

The other alternative which I think you must consider is a non-volatile multiturn absolute encoder. I recommend
you look closely at the Delta A3 series servos. They have a 24 bit absolute encoder that apportions its bits into 'so many
revolutions + so many encoder counts within that revolution'. It has a battery backup so when you turn your machine on
you don't have to home it because the machine can 'remember where it is from the last session'. They are the latest and
greatest and aren't cheap.....but you get what you pay for.

Craig
'I enjoy sex at 73.....I live at 71 so its not too far to walk.'