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b.r.b.
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Joined: 03/10/2008
Location: United States
Posts: 8

Posted: 02:59am 07 Oct 2008

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Hi everyone:

I'm building the mini mill, using a 24V stepper motor from an old laser printer.

I'm having a lot of trouble making blades that actually turn. At first, I used schedule 40 PVC pipe which in retrospect was WAY too heavy to work well as a blade.

I got something much lighter weight - but it still won't turn. To test my blade out, I'm putting it in front of a box fan. Even at high speed, nothing seems to happen.

Is there some method I can employ to determine what my trouble is? I should mention that my blades are 21" long - which is more than the 14" blades in the directions.

ANY help or suggestions would be greatly appreciated.

Thanks,

John

Gizmo

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Joined: 05/06/2004
Location: Australia
Posts: 5118

Posted: 11:33am 07 Oct 2008

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Any chance of a photo?
If you hold the little turbine in front of your box fan, and give it a flick, will it continue to run?

Glenn

The best time to plant a tree was twenty years ago, the second best time is right now.
JAQ

b.r.b.
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Joined: 03/10/2008
Location: United States
Posts: 8

Posted: 08:10pm 07 Oct 2008

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I'll post a pic later on tonight. When I flick the blade - or start it - it just stops.

How much torque does it take to turn a stepper motor on average? If I spin it should it go for a little while - or immediately stop?

MadRat

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Joined: 30/09/2008
Location: United States
Posts: 21

Posted: 05:20am 09 Oct 2008

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Take away the load until it gets into the rpm range where it is useful to you. Your blade is getting stopped before it starts.

Go Huskers!

b.r.b.
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Joined: 03/10/2008
Location: United States
Posts: 8

Posted: 02:44am 10 Oct 2008

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I'm not sure what you mean by load. It's not hooked up to anything at all.

I think my problem is that my stepper is high torque. I tried my blades on another motor I pulled out of a different printer - and it spins crazy fast! This motor though only has two wires so it can't be a stepper right? I think it's some kind of really tiny dc motor.

Funny thing was that even though it was spinning like crazy - when I attached the leads to an led - nothing happened.

When I attach the same led to the high torque stepper - it doesn't take much to light it up.

Does anyone think it's worth pursuing some sort of gearing mechanism to reduce the torque required to turn the motor? I will make some really big blades and see if that helps in the meantime.

Thanks!Edited by b.r.b. 2008-10-11

GWatPE

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Joined: 01/09/2006
Location: Australia
Posts: 2127

Posted: 06:28am 10 Oct 2008

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The stepper would be producing AC, so the LED will indicate, connected either way. The other motor would produce DC. Does the LED lite if connected either way?

Gordon.

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b.r.b.
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Joined: 03/10/2008
Location: United States
Posts: 8

Posted: 06:54pm 10 Oct 2008

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GWatPE:

I tried connecting the two wires to the led, nothing happened then switched them and still nothing even though it was spinning pretty fast. I'm wondering if the little DC motor isn't worth it (maybe RPMs will have to be too high?)

I made a much bigger blade for the 24V stepper and now it's spinning but it's hard to get started. My blades are over 2 ft long now (total diameter). I guess I could go to 3 ft...but that just seems way too big.

I think I'm going to try a 3 or 4 blade setup to see if that solves the starting problem.

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