Go Down

Topic: 28BYJ-48 strong enough? (Read 3429 times) previous topic - next topic

sbright33

I'm making a DIY Timelapse Slider for Canon 500D DSLR, which weighs under 2 lbs.  It involves PVC pipes with felt between them to minimize friction.  I was planning to use a small diameter pulley with a string or fishing line to pull the camera: Like a pen attached to the stepper motor shaft.  It has 64:1 reduction.  I'd like it to travel 2m.  The friction torque is 1500 gf*cm. 

Will the 28BYJ-48 be strong enough to overcome friction and pull it slowly when it's level?

Any advice on how to make the pulley?  What problems will I need to overcome?

Why does the ULN2003 have 7 drivers?  When we only need 4?  8 would make more sense then it could drive 2 motors?

If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

jackrae

I'll answer the obvious one

A ULN2003 is a 16pin device.  2 pins supply VCC and ground, that leaves 14 pins for the driver amplifiers.  Each requires 1 input and 1 output pin, ie 2 pins per amplifier.  14 / 2 = 7  QED.

As to sliding pipes, felt on felt will surely increase friction.  Better to use a dry spray-on lubricant such as a PTFE spray which will dry and leave behind a non-sticky slippy surface.  However 2 metres is a long pull and friction will be non-linear due to bending and increased surface contact as the tubes collapse into each other.   You might be better to look at making a small carriage on which is mounted the camera and this carriage then rolls along a runway.

sbright33

It is very low friction.  The felt is small and only glued to one side.  Like this:
http://www.youtube.com/watch?v=4ILlNjfqc3E

My friend has built it.  I have "felt" how easy it is to pull.  But I do not yet have the stepper motor to try it.  That's why I'm asking.  Before I purchase any hardware.  What do you think?
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

sbright33

#3
Dec 09, 2011, 04:26 pm Last Edit: Dec 12, 2011, 04:09 pm by sbright33 Reason: 1
They seem to be the most popular on Ebay.  What is it strong enough to move?
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

sbright33

Does anyone have this motor?
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

Erni

#5
Dec 13, 2011, 11:12 am Last Edit: Dec 13, 2011, 11:14 am by Erni Reason: 1
Hi sbright33
I have a couple of these motors, they spin very smoothe and i would think they are strong enough for your needs due to the gearing. I think I could make a test somehow to see how much they can pull.
But because of the gearing they are very slow, maybe too slow for your pulley
Btw the ULN2803 has 8 drivers instead of the 7 on a ULN2003

sbright33

I understand the gearing.  I did not expect it to be fast.  But maybe speed is the issue I should be concerned about after all.  Using a pen as a pulley, how long would it take at full speed without a load?  1m/minute?
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

Erni


It is spinning about 10 RPM , at 7,4 Volt (2 cell LiPo)

sbright33

Which might be roughly about 3 sec / cm with a pen as a pulley?
Perfect for timelapse!
If you fall... I'll be there for you!
-Floor

Skype Brighteyes3333
(262) 696-9619

Go Up
 


Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

Arduino
via Egeo 16
Torino, 10131
Italy