12v Drill hacked to powerfeed for Mini Mill

[ZipSnipe]

Here are the results of testing the pot. Powered on and pot running motor at about half speed.

I set my meter to dc 20 v, I had the com lead from the meter to the power in ground, the red meter lead went to the right side of the 3 terminal pot and I got a 10.2 reading, then I touched to the far left lead and got a 5 reading, heres where it went weird, I touched the center pot and the motor speeds up and I got a reading of about 2

The good thing is I know I can now run my momentary switch to this center wire to the ground so that I can have rapid traverse on the powerfeed. But I still don't know which is ground. I am assuming it might be the center wire but still not sure.

The reason for finding the pots ground is so I can try different resistors to slow it down like Troyo mentioned earlier in the thread.

 

[phansen39]

If you follow the board layout it looks like power is on pin 1 on the potentiometer header. So pin 2 shoud be the wiper. The other "ground" But is not really ground.
A NO switch between 2 and 3 should give full speed when turned on.


Does your meter have say a 200k ohm range? The picture shows a 100k ohm pot. If you can meter that range. You can test exactly where the switch needs to go. If you look at the pot knob toward you and wires facing upward. The switch would go between the middle and right wires. This based a a couple of assumptions. Like turning the pot clockwise increases speed . It could very well need a dpdt switch and an external 100 k resistor.

 

[ZipSnipe]

I think the main problem I am having now is the motor is weak, I can grab it and stop it. So I am wondering if the controller is too small and that I may definitely need a 10 amp?

 

[phansen39]

Hook it up straight to its battery pack?

 

[ZipSnipe]

Ok my buddy came over he spotted that the hi lo shifter wasn't fully engaged and was making the motor weak. So now the motor is fine and strong.

So the only issue left is the slow speed is fluctuating a lil bit. I am hoping that a resistor on the pot would maybe fix it.

 

[ZipSnipe]

Well tried resistors on the pot with no good effect. So it has the power it needs , its just at its slowest setting its very jumpy, wants to either go super slow or super fast. :-(

 

[ZipSnipe]

Just wanted to point what a friend told me, that if my pot is 100k and I am trying to induce resistance that I would need resistors that are under 100k , all the ones I tried were over 100 k except 1 and it was like 47ohm or something like that.

SO I am hunting for some lower value resistors and will report results

 

[ZipSnipe]

Decided and ordered a new controller last nite from a hopefully different Ebay seller, still out of China.

http://www.amazon.com/gp/product/B00CW82ZPG/?tag=skimlinks_replacement-20

I really wanted to get this other one I found,
http://www.electronickits.com/kit/complete/motor/CKMX033.htm
I see they don't use that 555 timer and was wondering if it would have been better, but again economics came into play and I went for the cheapie, I will probably get what I paid for. Well see how it goes when it comes in.

 

[ZipSnipe]

If an electrics supply house was close by , yes. But since stuff is being shipped, the shipping charges are ridiculous. And thank you for putting that diagram up, that looks like an easy build.

 

[ZipSnipe]

Well new controller came in yesterday and hooked it up, runs perfect !!! Runs slower speeds with out any erratic behavior like the previous controller
However it is larger so today I will be re drilling the mounting holes , I will also try the momentary switch out and see if I can get it to do the rapid traverse.

 

[rodw]

Well new controller came in yesterday and hooked it up, runs perfect !!! Runs slower speeds with out any erratic behavior like the previous controller
However it is larger so today I will be re drilling the mounting holes , I will also try the momentary switch out and see if I can get it to do the rapid traverse.

Awesome you finally got it sorted. Don't you hate it when you are let down by others?

Be sure to document how you wire in the go fast switch. I got the Z axis scale of my DRO mounted last night and just have to mount the sensor to the saddle and I can come back to this project. I now know how much room I have left for the motor to mount up, so I will be revisiting this project. Accommodating the DRO was the main reason I had not made a start on this project. It is annoying sometimes that you have to do things in a specific order.

Also there is a build on madmodder that has incorporated limit switches which stop travel and knock it into go fast mode back the other way to restart the next pass. I will have to find the link for you.

 

[ZipSnipe]

Bummer, no rapid by shorting the wiper and ground together. But upon further reading of Troyo's original post he said he used a NC switch on just the ground alone, so I will try that next. Fortunately this controller is marked in English as to where the ground and wiper are.

 

[rodw]

I think you need to look at the circuit. I doubt shorting the wiper to ground is correct but I don't know much about electronics.

I would have thought the circuit would apply power to the wiper and the pot applies a resistance to reduce the voltage and thus change the speed. I think that the wiper should be shorted to one of the other wires on the pot. The purpose would be to short out the pot so there is no resistance to the applied voltage.

Here is a link for more ideas I spoke about earlier.

http://mikesworkshop.weebly.com/mill-power-feed.html

I finished the X axis on my mill DRO last night at about 9:30 last night. I still have a bit of tidying up to do but once this is done (and I have some spare time) I will finally get to this.

 

[ZipSnipe]

Yeah I tried the wiper to the power, it speeds up for a split second and then cuts off. I also tried disconnecting the ground. On the other smaller controller I shorted the ground to the wiper and it sped the motor up but looks like this larger one isn't going to do it.

I think I seen somewhere they added a relay to create the rapid traverse. So I might look into that some more, thanx for the link!!!

 

[ZipSnipe]

So I then jumper the GND to the negative lead of the motor and sure enough WHIIIIRRR!

Man, I have re read this post several times and I still missed this part where he tried jumping the gnd to motor negative. Seems like an easy test to try.

 

[ZipSnipe]

Luc, can I do the same thing with a multi tester( I don't have a test light)? wouldn't the numbers jump around be the same thing as flashing?

I should also point out the power supply I have is one that only has the two prong plug, so should I wire up a three prong and run a ground in from the plug to maybe the body of the enclosure?

 

[ZipSnipe]

you can skip this test and go directly to this
Disconnect one wire "make sure you know it's polarity" and replace it to a full ground or full live and try it,, you will have the same result
cheers

I think I will buy a test light tomorrow, your first prescription sound easier and safer

 

[John Rudd]

Zipsnipe,

The output stage is either open collector transistor or open drain if its a mosfet...either way, the motor will be connected:

Motor positive to the main supply rail positive and the motor neg to the collector/drain...

Easiset way to make the motor spin faster on return to start is to temporarily short the mosfet so that the motor is now connected across the full supply rail....or connect the motor negative to the negative of the power input to your module........


I'd stay tuned more often to this forum if I didnt keep losing my password............I spend more time trying to login than replying to posts...

 

[ZipSnipe]

Well Luc , tried using my digital multi tester to see if I would get a bouncing reading on the wires you mentioned and all read 12 volt.

But I did a lil experiment, by touching one of the 555 timer leads to the wiper, it sped up like a charm. I have to look at a 555 timer schematic again, I don't know if I am harming anything if I hook it up that way. I did it several times and no smoke or sparks and it seemed to work fine.

 

[John Rudd]

Maybe I ought to butt out of this conversation........?