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Author Topic: Homing & Offsets Advice Request  (Read 1854 times)

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Homing & Offsets Advice Request
« on: March 24, 2014, 07:59:11 AM »
Having reached the point where I have a firm enough grasp of CAD/CAM to model and process through to 3 and 4 axis G code the things I'd like to machine I found the setup and workflow habits I'd aquired with one-off parts to be less than optimal for batches of parts with several tool changes - I've been zeroing the DROs for each setup and for each machining session and tool but kept getting a sneaky suspicion there must be a better way.

Searching the forum provided several hints but without all the components in one place so the following is what I've ended up piecing together - can anyone who uses Home, Home Offsets, Work Offsets and Tool Offsets sense check this for me please?  

I'm trying to get to the point where homing gets me back on Zero for the current part/fixture/tool, is the following the best/easiest/quickest process?


 
Given that I have accurate, repeatable home switches on X, Y & Z which all home in a +ve direction I've added Offsets (Home Off) under Config - Homing/Limits to give me a zero position where I want it - currently in the table centre with plenty of Z clearance for vices, fixtures, 4th Axis etc. and some allowance for tool clearance.

I suspect that I now need to add work offsets to give the correct DRO readings for edge detected or probed part & fixture edges & faces then add other Tool Z offsets to correct for each tool I want to use.

I'm nearly there but do I first add a height offset including tool holding for my probe/edge detector then add work offsets relative to that and then add cutting tool offsets?
TIA,
Nick
« Last Edit: March 24, 2014, 08:01:14 AM by magicniner »
Re: Homing & Offsets Advice Request
« Reply #1 on: March 24, 2014, 08:15:46 PM »
I've worked out through a process of trial & error that what I've done can result in -ve Z at the top of travel so I'm starting from scratch :-)
Re: Homing & Offsets Advice Request
« Reply #2 on: March 24, 2014, 10:11:58 PM »
Hey Nick,

Here is some info that might help you along.

http://www.cnccookbook.com/CCCNCToolManagement.html

Pros and cons of different reference points/gauge lines.

Russ
 :)
Re: Homing & Offsets Advice Request
« Reply #3 on: March 25, 2014, 03:25:19 AM »
Thanks Russ.
That does help, I've put a spacer collar on my edge finder to increase it's length close to the max for normal tooling, in addition to edge finding I will use it as my gauge tool for Z touch off with it's length defined from a fixed point on the quick change toolholder taper.
My table surface is now my default Z zero with work offsets for vice and fixture heights, the maths is now simple and logical rather than confusing and mind-bending ;-) 
Regards & Thanks,
Nick