Messages

1

General Mach Discussion / Re: 4th axis

« on: July 17, 2013, 10:01:13 AM »

You are right i haven't considered that but I will have a look at Ger21 posts if I can find them. My problem stems from with one rotation of my motor I am moving the "a" axis 100mm as opposed to my "xyz" of 5mm. However I have seen many similiar 4th axis and they seem to work ok so I am definately missing something. thanks again I will stick at it.
Bill

2

General Mach Discussion / Re: 4th axis

« on: July 17, 2013, 05:52:03 AM »

You are absolutely correct of course. I have changed my stepper driver to 1/8th step. therefore have now 1600 steps per rev on my motor and 4800 steps per rev on my axis which gives me 13.33 steps per degree rotation.However I have set my a axis to linear as opposed to angular for carving in the round.

What I had failed to take into consideration is that I am using a timing belt to drive my axis which has a 5mm pitch so the result of one rotation of my axis is a linear move of 300 mm.(20 tooth pulley on my motor and 60 tooth pulley on my axis). so as I understand it I have to set my steps to 16 steps per mm i.e. 4800/300=16.

This dosen't seem very practical so i may have to rethink my gearing arrangement and use a timing belt with a smaller pitch. I have tried the 16 steps per mm but this results in lots of lost steps. I have not much experience in what might be the best velocity and accelleration settings should be, so it is trial and error for me.

Do you have any suggestions? By the number of posts I see youv'e made you must have lots of experience. again thanks for your interest in my post and putting me on the right track.

I'm getting a bit long in the tooth now, not as quick as i used to be. However will get there in the end.
Bill Cameron

3

General Mach Discussion / Re: 4th axis

« on: July 13, 2013, 07:31:20 PM »

Thanks for replying to my post. My drives are set to half step so 400 half steps per rev. my linear axis are set to 80 half steps which with 5mm pitch ballscrew gives me 1mm movement With the same setting on my a axis this equates to 1200 half steps per rev or as you say 1200/360 = 3.333 steps per degree. it appears i may have made an error gearing my drive 1:3 may have been better 3:1. my motor is never going to get up to speed. I do have the option of going to 1/8 step could this help? not sure I have a complete grasp of this yet

4

General Mach Discussion / 4th axis

« on: July 13, 2013, 04:40:01 PM »

Hi newbie to forum. have just built a 4th axis for my router and now need to calibrate same. It is geared 1:3 i.e. the motor turns 1 rev and the axis turns 1/3rd rev.having a bit of brain fade, can anyone help me with this. many thanks