encoder digital readout

[TF and the wire]

I have been given yet another project at work. We have a printing machine that has a set of rollers, whose gap can be altered using push buttons to drive a motor gearing arrangement. The operators need some sort of readout to tell them roughly the gap between the rollers.

I was thinking of putting a proxy to read a disc with say, 8 notches on one of the shafts. Taking this to a counterthat would simply count the number of pulses. The display would simply show a reading. Experience would show the operators which number corresponds to a certain gap.

The oerators now say they could do with it actually displaying the reading in millimeteres. So this would mean relating the minimum number to read say 1mm, and the highest number to display 7mm.

Apart from some clever calculation of the number of notches required on the disc, what would be the best way of doing it electrically?

It doesn't need to be too accurate. The operators normally set it to approximately the required gap, run a few boards through and tweek it to get the correct gap.

 

[netblindpaul]

This depends on the display you have and the capabilities of the items you select.
you could fit linear encoders & a DRO that would give you a resolution to the micron with an accuracy/repeatability to less then 5 mu.
It really depends upon the exact mechanical design of the equipment.
I provided such solutions before.
Paul

 

[pmac10]

Red lion make good counters. does a motor advance and retract the rollers? a bolt head being picked up on rotation by a inductive proximity switch and fed into the counter should do the trick. the red lion counters i used give a calculation and corresponding dip switches to use but i found a simplier way around it. something like how many pulses for 7mm and how many for 1mm and flip dip switches as appropriate bit more to it than that but sound like you know what your doing, iwas trying to turn something like 3 pulse per second to distance travelled in minutes, theyre definitly good controllers and easyto use
hope this helps

 

[TF and the wire]

It doesn't have to be that accurate. We use many different encoders, but a simple proxy reading a disc will do. The problem I have is how to make for example a count of 538 display 1.0 (mm) and say a count of 6757 display 7.0 (mm)

 

[netblindpaul]

Chuck it through a PIC?

 

[pmac10]

the manual for the counter will tell you, the counter chuck it through a pic

 

[TF and the wire]

Just had a look at some of the counters on the Red Lion website. I've learned a bit more. It seems that some counters have a scaling factor which is used to multiply a count value to display the value in other units, in my case millimetres.

I would also need to tell the counter when to count up and when to count down. Again, some have a seperate input which can be programmed to instruct this. I presume that the push button on the machine that drives the gap smaller would also have to put an input onto the counter when operated.

Can anyone confirm that I am correct in this?

I'll have a look on Tuesday to get an idea of the number of pulses per millimetre.