Wanting to power a lead screw

Tony, that Furnass switch will be fine *as long as you don't switch under power* - it's rated for about 10A contact current (and unlike the Chinese offerings it's probably built to withstand higher than on the sticker), the issue that makes 'em drop the rating for DC use is arcing under load - AC (obviously) interrupts the current 120 times a second so an arc will quench and not erode the contacts, DC being constant will maintain the arc until the contacts separate far enough that it can no longer jump the gap - more so with an inductive load like motor windings (this is how a car's ignition coil operates, after all, producing thousands of volts and needing a condenser/capacitor on the points to absorb the voltage surge).
Big Industrial lathes with DC motors (Monach 10EE and the like) have enormous contactors with arc-blowout magnets to divert the arc and lengthen it to help quench it, often high-temperature insulating blades that cut the arc, and quite often resistor-capacitor "snubber" networks that handle the induced voltage spikes from the motor windings. It's quite normal to de-rate relays, switches and contactors by a factor of ten or more when using an AC-designed contacts to switch DC...

Just my ha'pennorth,
Dave H. (the other one)
 
Thanks Dave.
That sounds good.
Even with the little DPDT switch from Radio shack, I have been turning off my power before switching direction.
(just fooling around on the bench, I don't have the lathe hooked up yet.)
There is an "Inhibit" feature (2 terminals) on these KBIC-120's that you can hook a switch too, and short the inhibit terminals out before switching directions also.
I am pretty sure I would be safe using the inhibit feature also.
Too, I have a threaded spindle, so I would not want to hit reverse on the fly either.
Thanks again
Tony.
 
mrbreezeet1 said:
Thanks Bob, Maybe I'll try one. I am not even going to bother returning this one to R.S for exchange.
http://www.amazon.com/5k%2126-Shaft-Linear-Taper-Potentiometer/dp/B00C9NWQ8A
Boy, that does look like it's made nice.
Hopefully l can get a break on shipping if l buy more than one.
Click to expand...

FWIW... I ordered two of those, just came in today... think they'll work great. Refreshingly enough, on the bottom is stamped "Made In Canada"... kudos to our cousins up north on putting out good stuff! :)
 
l just got some NOS off e bay.
Tocos cosmos PR123 Part # RY-5976. They are 5=k ohms.
4 of them shipped for $12.50.
I have read They are a good brand.
I don't know 1st hand.
But l know l had a few now bad from radio shack.
 
British Steel said:
Jack, that sounds like it's an audio taper (logarithmic* or "A" taper) pot, where each (e.g.) 10 degrees of rotation gives the same multiplication of the signal - if you imagine a graph of rotation across the bottom, output upwards, it gives a J-shaped curve, a linear pot ("B" taper) will give a diagonal line / - so the audio taper will give next to no output for most of the rotation then jump to nearly full speed, makes it difficult to adjust it over the last few degrees as you've found...
That's how we hear things, in audio work each 3dB increase sounds the same to our ears but is in fact a doubling of power - our ears "compress" the range so we can hear changes in low levels and cope with a right bloody racket with the same instruments (our ears!). The human ear (unless old and deflicted like mine) has a dynamic range of about 140dB - that's a factor of 100,000,000,000,00 to one, from the "pin dropping" to close up to a jet engine spooling up or a 44 magnum at arm's length - impressive, not many things we've invented can manage that without fiddling and adjustment :)

I wouldn't swap the pot to a lower value, unless it was something thrown in at random by the vendor and not the original, there's a reason they specify the type and value! But so swap to a linear pot if it says "250K A" on the back, you want "250K B"

Just my ha'pennorth,
Dave H. (the other one)

*actually it's technically an "antilog" or exponential function, but the ear's logarithmic so that's what it was labelled long ago.
Click to expand...
I am sure it is leanier. Has no sharp increasing speeds. It is hidden by the board and need to de solder all of it. I did check it with multi meter as to the resistance of starting operation. I will try about 150k ohm pot. I do need to replace the transistor first. Not in a rush or home to change them. I would have been better to find a pwm for my lathe rather than this cheap fan speed control. Will still get use out of it.

Jack
 
mrbreezeet1 said:
Lead-screw drive up and running, (About Time) Video to follow.
Click to expand...
OK guys, the long awaited leadscrew cobble job is complete.
All in all not to bad.
First impressions were, before I actually took a cut, "Man, this speed is WAYYYYYYYYY too slow, guess Im gonna need a different motor, or different pulley arrangement"
Well, I said, OK, lets not condemn the job before taking a few test cuts.
And it is fine. I found I can stall it with my hand on the pulley, (with a work glove on) so torque is not out the was-Zoo.
But maybe thats a good thing, sort of a weak link, safety net type of deal.
here is a Video, It's a little slow, as in not a best seller, but you can get the idea.

Thanks to all, for all the help, and I hope between my efforts, and the efforts and comments and help of all the guys in this thread, may inspire and help someone else in a similar project.
All I can say is, "Tony, why didn't you do this 5 years ago"?...........LOL
 
mrbreezeet1 said:
OK guys, the long awaited leadscrew cobble job is complete.
All in all not to bad.
First impressions were, before I actually took a cut, "Man, this speed is WAYYYYYYYYY too slow, guess Im gonna need a different motor, or different pulley arrangement"
Well, I said, OK, lets not condemn the job before taking a few test cuts.
And it is fine. I found I can stall it with my hand on the pulley, (with a work glove on) so torque is not out the was-Zoo.
But maybe thats a good thing, sort of a weak link, safety net type of deal.
here is a Video, It's a little slow, as in not a best seller, but you can get the idea.

Thanks to all, for all the help, and I hope between my efforts, and the efforts and comments and help of all the guys in this thread, may inspire and help someone else in a similar project.
All I can say is, "Tony, why didn't you do this 5 years ago"?...........LOL
Click to expand...

Congrats! Got er done... you can experiment/swap out pulleys later to get the range you want, but for now, you got it working! Enjoy the success of the project...
 
Thanks Bob, I just saw this alert. I was putting motor bearings in a Delta 1HP motor tonight, for a belt sander I am probably going to end up selling, as I have a powermatic 6" belt sander now too.
That thing was a bear, wrestling out of the cabinet, esp with my bad Knee I got now. LOL
Looks like I need a new knee installed they said.

Darn armature wouldn't fit under my arbor press, had to hammer on with a sleeve, I don't really like to do that.
They went on pretty easy though. I might have been better off getting a regular hyd. press, but this #2 greenard is Cool!
No, actually, it is working quite well as it is. I have it on the higher of the 2 speeds right now, and as reference, about 9:00 is a pretty fast cut, and about 6:00 is nice and slow. I have it with connectors so I can change the spade terminals from High to low.
I might try the low range again, to see if I can control it better, more crisp or anything.
Post office delivered My 4 pots I ordered from e bay today, and the punks stole them off the porch again.
Probably thought it was meds.
Told the post office to just start holding my packages again.
Did I ever tell you guys I hate this town?
 
Porch thieves... argh, they're everywhere... ya, even for the little stuff it's usually best to require a signature or pickup at the local PO because the little rats will just take them if they have a chance. Had a printer (from Amazon Prime) delivered last year, it was set to email me upon delivery which it did. I was back at the house in 30 minutes to put the box away but the thief beat me to it and nabbed the printer. To Amazon's awesome credit, they actually had a new replacement printer delivered to my door in 2 days, no hassle, no extra charge, just a signature...

EDIT - just happened to think... send me a PM on where to send it, I ordered an extra POT when I got mine, don't really have a use for it atm so it's yours if ya want it...
 
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