Re: EDM wire tensioning

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Paul Kelly" <tech@...> wrote:

>
> A micro generating a PWM signal for your winder motor based on some

input

> would be easy (if you're a micro kind of electronics guy) it'd save

you half

> a bridge. Philips make some good power op amps, up to about 25W I think.
> As for sensors. The homebrew options that spring to mind are:
>
> A wedge shaped paddle that moves in front of an LDR, angle of wedge
> determines rate of change of the value of the LDR.
>
> Hall effect, something like a UGN3503 and a weak magnet on the

tensioning

> arm.
>
> I'm told that there are some proxes that have a linear output..
>
> All this is being on the assumption that you cant use a

potentiometer as the

> pivot for the tensioning arm?
>
>
> Hope that helps
>
> PK
>

I would consider using a uP especially if I wanted to put a speed
control on the feed roller as well. As it happens I'll probably not
go down that route as it just isn't needed.

I would use only half a bridge anyway, I don't want the spool to take
up the slack only pay out the wire, otherwise I'll have problems with
backlash causing tension variation.

Thanks for the ideas, a pot could be used for sure but I tend to find
that I come up with a solution and then tell people about it only to
be told a much better way.

I quite like none contact solutions anyway.

Graham