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Chester Conquest mill power feed
John Rudd:
My motor for my power feed came today...
It's an ex Ford Fiesta wiper motor and should do admirably...
There was no scientific process involved in the selection guest a wild stab in the dark...
After all experimentation is what it's all about...
Here's a picture
John Rudd:
Having got the motor, I'm going to fit it to the left hand end of the mill table...No particular reason, just feels more comfortable for me.
I've tried ot remove the handwheel, but it's a bit stubborn..I may need to warm it with my hot air gun..or maybe resort to something a bit more brutish..
attaching the motor necessitates a plate mount to pick up on the two holes that hold the end plate to the mill table...2 hex steel pillars with an M6 thread should see to that...
Another picture...
John Rudd:
How to power the motor...I cobbled together a pwm speed controller using a 556 timer chip and a mosfet.
The 556 is a dual 555 timer, the pwm frequency is around 300Hz, annoyingly it makes the motor buzz at 0%...A little tweaking is needed to prevent this as it causes the mosfet to become all hot and bothered...Suffice to say when built it will have a heatsink attached...
An issue I identified with the circuit is the high component count, also there are no safety features...if the motor should become stalled, something is likely to fry...
So, current limited output or limit switches on the table?
So many choices and so little time....decisions.. decisions....Time for a lie down!
Darren:
Looking good so far, how many leads does your motor have, mine had 3.
I knew there was another reason I shied away from a timer circuit. I have mentioned it before but forgot to say when we last exchanged posts on this subject.
Some motors don't like timer/freq circuits cos it makes their windings "bounce". That's what you can hear buzzing. Not only can it heat the windings it can also damage the insulation.
Coils and transformers/chokes can have the same problems unless designed for PWM circuits.
Not trying to teach you to suck eggs, I just knew there was something I was forgetting to mention before.
John Rudd:
My motor has two wires...single speed...flat out!...
I think to over come the buzz at 0% pwm, I'll use a switched pot to kill the power to the electronics...
Still mulling over( not milling... :clap: ) what to use for speed control, 556 or pic micro...Pic version will use less components and mean an easier pcb to design... :coffee:
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