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Author Topic: What are the units of measure??  (Read 5226 times)

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Offline Hood

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Re: What are the units of measure??
« Reply #10 on: February 11, 2013, 01:57:26 PM »
Ok lets start from the start so we are talking about the same thing. If you zero the axis then command a move from MDI, say G0Z10 what does the DRO in Mach read?
If it is anything other than -10 then either your steps per unit are not correct or you have scaling n that axis.
Hood

Actually the DRO will read -10 even if steps per unit are wrong but what we need to know is does the axis move down 10mm as well.
« Last Edit: February 11, 2013, 01:59:55 PM by Hood »
Re: What are the units of measure??
« Reply #11 on: February 11, 2013, 02:00:08 PM »
I'm not at the machine now, but yes, similar to what you said.  if I zero an axis, measure by hand 1", and then manually jog to the 1" mark, my coordinate is 3.9-something instead of being 25.4.  same thing is happening for all the axis.

Offline Hood

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Re: What are the units of measure??
« Reply #12 on: February 11, 2013, 02:02:29 PM »
Ok dont jog, command the move and see if motion moved equals axis DRO reading.
Hood
Re: What are the units of measure??
« Reply #13 on: February 11, 2013, 02:49:42 PM »
it won't, I can see that when it runs my gcode.  the 31.75 it tries to go to is way off the table, when it should only be 1.25".  I can see this happening.

Offline Hood

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Re: What are the units of measure??
« Reply #14 on: February 11, 2013, 02:52:57 PM »
What do you mean it wont?

Why do you talk in mixed units? you are set up in metric yet you are always talking inch?

Set your native units to what you use most, if you use Imperial units the majority of the time your native units should be Inch and your steps per unit should be calculated for inch. If you use Metric most of the time set native units to mm and steps per unit calculated per mm.
Hood
Re: What are the units of measure??
« Reply #15 on: February 11, 2013, 03:45:46 PM »
I mean distance moved won't match the DRO, which I have been saying all along.  if I move an axis 25.4mm it will read roughly 3.9mm on the DRO.  so, when my gcode calls for 31.75 it tries to move the axis far further than the table allows.

Offline Hood

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Re: What are the units of measure??
« Reply #16 on: February 11, 2013, 04:57:20 PM »
I am not asking you to move a distance, I am asking you to command a move from MDI and see if the DRO corresponds to the command and also if the distance moved corresponds. Jogging a set distance and looking at the DRO is a totally different thing.

Ok think the best thing is for you to attach your xml and answer a few questions so I know what I am looking at.
1. What units (mm or inch) will you predominantly use?
2. What pitch ballscrews do you have?
3. Do you have gearing between motor and screw?
4. Is it steppers? If yes what is the microstepping of the drive?
5. Is it servos? If yes what is the encoder count?

Hood
Re: What are the units of measure??
« Reply #17 on: February 12, 2013, 12:30:36 PM »
got it figured out, the docs I was looking at had the wrong steps value.  thanks.