# hi help me out guys

• posted

Hi folks, I need a help. As I am basically an electrical engineer I have succeeded in micro-stepping a stepper motor by 128 micro steps of step angle 1.8degrees which mean it can at one instance move by as small as

0.014degrees. Well the problem now is that I need to convert this angular motion into its equivalent linear motion(i micron) so that I get a micron level motion. As not many were able to help me out in this regard, I started browsing the net for some way of achieving this conversion. I hit upon something on which I need your help. In a compact disk there is a rack and pinion arrangement which is capable of moving by 0.5micron (maybe, 0.05 micron...me not pretty sure). There is an optical arrangement of infra red beam which runs on this rack and pinion and which is reflect on to the ridges of a cd so as to store data in cd's. as the distance between adjacent ridges of cd is in the order of 0.5 micron(or maybe 0.05 micron) so this rack and pinion must support such minute movement of 1 micron that is required in my project,I feel. Cant this apparatus satisfy my need? Respond as soon as possible friends suchi
• posted

Since you have not stated your needs, how can we tell you if the CD rack and pinion will satisfy them?

You want to move *what* 1 micron? An ocean liner? An amoeba? A surgical instrument?

*Must* you use a stepper motor? If so, why?

How will you determine that 1 micron of motion has occurred? What is the feedback loop?

And on and on. 90 percent of your answer will be found in asking the right question.

Ed

• posted

hi, thanks for replying.. We need to move the tip of a laser beam thro a micron. something similar to a cd drive optical lens mechanism. the angular motion is converted into linear motion by a rack n pinion and this laser tip/diode moves on the rack n pinion.

we planned to use a stepper as we could microstep it to a small degree and there are no big probs like overshoot in a stepper..

feedback loop is gonna be an optical grating arrangement and a pulse counter. or an encoder.

hope i have given the reqd details.

• posted

On 14 Mar 2006 01:22:49 -0800, suchi snipped-for-privacy@yahoo.com Gave us:

The pitch of the screw for rack and pinion setup will play into this and is needed information. The pitch of the screw determines the traverse the rack makes per screw revolution.

With that known, you should be able to determine how much of one revolution is required to make a given amount of linear motion.

• posted

On Tue, 14 Mar 2006 11:32:17 GMT, Roy L. Fuchs Gave us:

An added note. The rack and pinion setup must have very little backlash in it, or said backlash must be 100% known or your system will not behave as you might expect, ie a reversal of direction will have a gap in shaft rotation before the laser head reverses direction.

• posted

No disrespect - but I'm not going to play this game. You don't seem to know enough about what you are trying to do. Go here as a starting point: