Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: Freff on September 11, 2008, 04:36:47 PM

Title: Wizard Inaccuracies
Post by: Freff on September 11, 2008, 04:36:47 PM
I have just started using Mach3 R2.63 (licensed) with the come with wizards. To get some experience I have started using the wizards, the Circle Cut to be a good starting element. All the settings I entered came out on the work piece Ok except the diameter.

No matter how many times I tried the diameter always come out different to the setting I entered. Not only that they are randomly different. I have tried the circular pocket and the results are the same, always the diameter.

I'm sure that I'm entering all the settings correctly, but I'm possibly missing something. Could someone please point me in the right direction, it's getting very frustrating.

Many thanks
Tony
Title: Re: Wizard Inaccuracies
Post by: Hood on September 11, 2008, 04:49:55 PM
Have you checked to see that your steps per unit are set correctly and are giving you accurate distances, ie if you cmmand a G0X2 does it move the axis exactly 2 inch (remembering to zero the axis first ;)  )
Hood
Title: Re: Wizard Inaccuracies
Post by: Freff on September 11, 2008, 05:20:50 PM
Hi Hood and thanks for your quick reply. I commanded G0X2 and the axis moved about 1mm. not 2".
If I run any other Gcodes for example ones I have created myself in Lcam eg. then they come out fine.
Title: Re: Wizard Inaccuracies
Post by: Hood on September 11, 2008, 05:23:18 PM
ok so are you set up in metric units?
 Did you remember to zero the X axis before you  commanded the G0X2?

Hood
Title: Re: Wizard Inaccuracies
Post by: Freff on September 11, 2008, 05:27:34 PM
Yes zero'd all axis.
Title: Re: Wizard Inaccuracies
Post by: Hood on September 11, 2008, 05:32:43 PM
OK if it doesnt move the distance you have commanded then it seems you dont have your steps per unit set correctly.

 What type of motors do you have? If steppers are they 1.8 degree or 0.9 degree (200 or 400 steps per rev) If Servos what is the resolution of the encoders

What type of drives do you have and is there any microstepping set in them?

What is the pitch of your ballscrews?

Any gearing between motor and screw? if so what is the ratio?

Hood
Title: Re: Wizard Inaccuracies
Post by: Freff on September 11, 2008, 06:02:44 PM
The motors are 200 step 1.8 degree steppers. FL60STH86STH (3Nm 23 frame stepper motor) (FL60STH86)

MSD542 microstepping driver set at 8 microstep, 1800 ustep/rev.

Lead screw is 6mm 24tpi no gearing.

Thanks for staying with this Hood.

Tony
Title: Re: Wizard Inaccuracies
Post by: Hood on September 11, 2008, 06:13:42 PM
Not sure what you are meaning by 1800 u step per rev but anyway heres what your steps per unit should be
200 steps x 8 for micro steppingĀ  = 1,600 steps per rev of the motor, your leadscrew is 24 tpi so that is 24 turns to move 1 inch.
multiply the 24 turns by 1,600 steps per rev of motor and it gives you 38,400 steps per inch.
As you are set up in metric divide that number by 25.4 to get the steps per mm and it is 151.18110236220472440944881889764 steps per mm :)

Hood
Title: Re: Wizard Inaccuracies
Post by: Freff on September 11, 2008, 06:32:34 PM
Sorry that 1800 was a typo it should have been 1600 as you state.
Do I now enter the 151, etc in the motor tuning at the steps per box, leavibf the acc & rev as they are.
Title: Re: Wizard Inaccuracies
Post by: Hood on September 11, 2008, 06:36:47 PM
Yes enter that in the steps per box for each axis (presuming they are the same) and whether you will need to alter the Velocity and Acceleration will depend on what you had previously. If it was close then no you probably wont, if it was off by a bit then you may find you need to re-tune as you will maybe miss steps.
Hood
Title: Re: Wizard Inaccuracies
Post by: Overloaded on September 11, 2008, 06:37:39 PM
The screw looks like it may be 1mm pitch instead of 24tpi.....if it IS 6mm dia.
.04166666666666666666 (1 / 24) is pretty close to 1mm.
Title: Re: Wizard Inaccuracies
Post by: Hood on September 11, 2008, 06:41:03 PM
oops I had a typo in the last post also, it should be 1511.8........ steps per unit
Hood
Title: Re: Wizard Inaccuracies
Post by: Hood on September 11, 2008, 06:42:13 PM
Ah and RC could also be correct, if that was the case it would be 1600 steps per mm
LOL
 Hood
Title: Re: Wizard Inaccuracies
Post by: Freff on September 11, 2008, 06:47:35 PM
Many thanks Hood, I'll input these settings tomorrow and let you know how it worked out. I got to get to bed, 5am start for me tomorrow.

Tony
Title: Re: Wizard Inaccuracies
Post by: Hood on September 11, 2008, 06:48:31 PM
ha ha just stay up, no point in sleeping now :D
Hood
Title: Re: Wizard Inaccuracies
Post by: Freff on September 11, 2008, 07:31:47 PM
I suppose your'e right.  I had to try it. Unfortunately I coudn't start the spindle (noise). It appears to be more accurate ie it moves 25mm at G0X2.

Arrhh I didn't see those last few posts. I was going to say that I had to add an extra 0 (200) to the wizards input to get a 20mm circle. Has that anything to do with your typo.
Title: Re: Wizard Inaccuracies
Post by: Hood on September 11, 2008, 07:38:32 PM
Yes my typo had it set 10 times too small, had the decimal point wrong LOL
 I am a bit confused however, a G0X2 should move 2mm not 25mm.
Do you definitely have your units set to mm? Look under the Config menu then at Select Native Units and see what it is, should be mm if you are going to use mm as your default. Also as RC said are you sure its a 24TPI screw as it would seem more logical for it to be metric if the OD is indeed 6mm.
Hood
Title: Re: Wizard Inaccuracies
Post by: Freff on September 11, 2008, 08:22:58 PM
When I entered your first number 151. and  I would get a 2mm move with G0x2 and the decimal point was one out in the wizard inputs to get the correct cut ie 200 to get 20mm cut.

The leadscrew is 6mm so I have entered 1600 in the steps per. Now I get an accurate result in the wizard and the G0X2 moves 2mm still.

Does all appear to be correct now. 8)
Title: Re: Wizard Inaccuracies
Post by: Hood on September 12, 2008, 02:45:21 AM
Sounds like its good to go now :)
Sorry for the late reply, had to get some sleep ;D
Hood
Title: Re: Wizard Inaccuracies
Post by: Freff on September 12, 2008, 08:43:48 AM
I made a few test cuts today and all appear to be working fine. Dimensions are more accurate with steps per,  set at 1511 rater than 1600.  :)
Title: Re: Wizard Inaccuracies
Post by: Hood on September 12, 2008, 09:10:09 AM
:)

Hood