different power feed

[miner49r]

Some people will tell you that I tend to overthink everything. Here is a prime example of this.

I have seen everything from cordless drills, wiper motors, to steppers. All of which have perfomed the task of driving the table admirably.

My goal is not to drive the lead screw at nose bleed speeds but to make a snail appear to be traveling at warp speed comparably. Somewhere about one revolution in four seconds. Or slower. After several weeks of banging my head against the bench and more hours in the dungeon than I care to admit, the contraption has come to life. Moderately successful, at 3000rpm the lead screw attains approximately one revolution per second but will stall with a moderately heavy finger pressure on the hand wheel.

Back to banging my head on the bench. The most difficult part is coming up with a gearing solution that does not clash. Initial thinking could result in changing the gear ratio from 48-1 to 108-1.

The motor runs at 20,000 rpm on 12 volts.
Question: Would a 24 volt motor have more torque at a given rpm than the 12 volt motor i am using?

http://www.flickr.com/photos/60496996@N02/12782533914/
"You got pretty teeth"

 

[goldstar31]

Apologies but I am sitting in what was once the stately English home of Arkwright who- many years ago started the Industrial Revolution with something a crude- and simple as the Spinning Jenny.

So I'm trying to write on an earliy perpendicular computer and getting a bit into the mood of things past.

So why on earth do you have something to run the thing at breakneck speed of 20,000 rpm when you want an output of a few turns-per week- or when there is an R in the month. Is your whatever it is, tied up to a gas turbine or something?

Regards

Norman

 

[geoff p]

You're asking the wrong questions!
Stop banging your head on the bench and THINK. As Norman points out, running an electric motor at faster than gas-turbine speeds and wanting your slower-than-a-snail output is not the most sensible way to go about this small problem.

Use a small synchronous motor (1440 RPM UK, 1660RPM (?) US) and a wee bit of reduction gearing:
e.g.
1/ a 144:1 worm would give you just 10 RPM (UK), which is 6 seconds per rev.
2/ compounded belt-drives - 3:1 x 3:1 x 3:1 x 3:1 will give you about 17 RPM (a bit faster than your required 15 RPM)
and 3:1 x 3:1 x 3:1 x 4:1 will yield a tad over 13 RPM.
Or Buy a motor+reduction-gear of the web with an output somewhere near to 15RPM.
Geoff,
Thailand

 

[kvom]

A harmonic drive can give speed reductions of 200x if that works for you. Hard to fabricate in a home shop.

 

[goldstar31]

I assume that you know about these what we call Fractional AC motors which run- UK wise at either 1440 or 2880 rpm are about 1/6th HP and have either one or two integral gear boxes dropping the speeds down to -as mentioned- useable speeds on the ends of small lathe shafts. One name comes to mind and that is Fracmo( but I'm a long way from home)
I've also got -I think 1/10th stuff which is DC and controllable.

Now this is going off topic- quite the reverse, in fact- but I have gutted the gears from the AC ones so that I can run both the Quorn and the little Kennet tool and cutter grinders which need gearing up to go at 6000rpm. Again, I have a little Stent - a fabricated one with a 2880rpm 1/6th motor but I'm a crafty old bird and have a spare set which can drive things like Potts spindles( you may never have heard of them) but they drive overhead stuff on the saddle or vertical slide. It's not new- far from it- it is what old Sparey had on his lathe to make his petrol and 'diesel' engines way back in the 40's.

So stick with your ideas as there is a valuable development- although you haven't quite grasped what can be done.

Meantime, I hope that this helps

Norman

 

[crueby]

For mine, I had found a cheap ($5 - $10) DC gearmotor that has an output shaft speed of 10 rpm - came with the gearbox, has plenty of torque to drive the shaft. Just had to make a little cross coupler fitting to hook it up to the end of the spindle on the cross slide and a little mount bracket to hold the motor - ran it from a spare 12v supply. You can find lots of variations (speeds, power) on ebay or amazon - two items I looked for were specs on output speed and torque. I just use it for final finish cuts on long pieces, not for mass material removal.

 

[RichD]

This may sound corny, but on my X3 mill I use an old 12v wiper motor powered by a cheap 12/6v battery charger connected to an old (dead) motorcycle battery. To get slow speed I use the 6v setting and speed up by selecting the other 12v settings. I have two toggle switches; one that holds it's position for constant machining, and one that is spring loaded towards "off" for jogging. Plenty of torque. Worst thing is the motor has no cooling (sealed housing). So far it has survived some tedious work for several years now. I made a mount for the motor that uses extra long studs that allow the motor to slide "away" from the coupling to disengage for manual operation.
Rich

 

[miner49r]

I'm back from a business trip. The parental controls for the wifi at my hotel would not let me log on here.

Thanks for the replies and advice. Even though we speak the same language, some of you Islanders lost me with your jargon. The head banging is over. I needed to stop confusing things by trying to convert to number of rotations per second.

The reason I was using a 20,000rpm motor is because it was sitting in a junk box. To keep from having to completely rebuilding this drive, I ordered a similar type motor which runs at 5000rpm @ 12v, has five poles, and more torque.

Until then, I have been working on the cotrol unit. Still no sure where to mount it or where the pot and switching will be located.

 

[miner49r]

The new motor arrived and dropped right in. Regearing increased the reduction from 48-1 to 108-1. All I can say is the it is a completely different machine. Table travel rates from 0.50" to 1.75" per minute with voltages from 2-10 volts.

The motor controller is indeed receiveing 13vdc but will only put out 10v. Power hungry biotch. I may install a higher voltage power supply to make up the for the loss in voltage and give me some traverse speed.

The DPDT switch will mount on the units cover. The remainder of the controls will be on the lid of the electrical enclosure which will be mounted to the wall away from chips.

Regards,
Alan


Video here
http://www.flickr.com/photos/60496996@N02/12782263503/

 

[RichD]

That's really nice Alan! Professional quality work. Overkill...yes. But I like it.
Rich

 

[BaronJ]

That's really nice Alan! Professional quality work. Overkill...yes. But I like it.
Rich

I agree ! It really is a piece of quality work.

 

[purpleknif]

I just used a gutted 2 speed 12 volt drill, a $25 speed control from E-Bay and a couple of switches from Radio Shack. Gobs of torque, an alreadt installed clutch and a socket to drive the screw.

It will really creep when you need it to !

 

[Niels Abildgaard]

I just used a gutted 2 speed 12 volt drill, a $25 speed control from E-Bay and a couple of switches from Radio Shack. Gobs of torque, an alreadt installed clutch and a socket to drive the screw.

It will really creep when you need it to !

Picture of before and after Gutting? please?

 

[miner49r]

Thanks for the kind words. Professional? Probably not. You can't see the flaws in the photograghs. My Olde Dad would say, "It works fine son, but it's not done until it looks good enough to sell."

I actually planned on using a HF 18v drill. I bought the drill, stripped it for parts, and then decided the cordless drill mod has been done too many times. Now I have a bunch of drill parts in the junk box.

And now for something completely different!"

Regards, Alan