Wiper motor differences

@hapiel Go to a scrap yard and get your cake and eat it to. Pick a common car that has strong enough motors and save a lot of money.

@hapiel

I had 24 volt windscreen motors on the robot base shown below.  They were very powerful.  I could push a couch around and the wheels would do burnout if the robot base hit a wall.  It could carry a man. However, when used in a differential drive they need to be of equal quality. Also, the wheels had their own bearings, the motors carried none of the weight and they were attached to a heavy metal frame.

 Very quiet due to the simple gearing.  No metal on metal. Just one threaded rod driving a single "plastic" gear. Unlike having lots of gear cogs in a gear box there was little or no real slack.

Thank you both for your replies!

I had a look at the local scrapyard, but they cost about as much as new ones here even if I remove them myself, and that way I'll have even less information beforehand about what I'm getting...

Great to know they have almost no slack! Thanks also for the inside picture, I didn't realize there would be a pcb behind the cogs. What are those even for? I was hoping I could put a potentiometer on the back of the cog to be able to read its position like a servo...

Also very nice that you were able to find a similar mirror pair, that might be useful for me too if I manage to find that!

Thanks for your help 🙂

Edit:

Another question, any suggestions on how to couple a shaft to it? I need a shaft of about 70mm on the end. I was thinking of drilling a hole in a shaft, tapping it, and screwing it on, but come to think of it I worry that it might not be perfectly straight, and therefor I can't get the far end to spin through a bearing?

@hapiel 

Thanks also for the inside picture, I didn't realize there would be a pcb behind the cogs. What are those even for? I was hoping I could put a potentiometer on the back of the cog to be able to read its position like a servo...

Also very nice that you were able to find a similar mirror pair, that might be useful for me too if I manage to find that!

The window wipers were not a mirror pair!  Power door window motors however do come in complementary pairs.

Another question, any suggestions on how to couple a shaft to it?

I need a shaft of about 70mm on the end. I was thinking of drilling a hole in a shaft, tapping it, and screwing it on, but come to think of it I worry that it might not be perfectly straight, and therefor I can't get the far end to spin through a bearing?

@hapiel I think you need to think more of a coupling sleeve, that way the centering issue isn't a problem. 

Yes, I'm considering that too. I've never worked with axis couplings, but without adding a key to them (as I don't have the tools to create a slot for that), would a clamp coupling be able to resist a 30Nm torque? Also, most of these motors come with a thread on the axis, so I'd have to look extra carefully to find one without...

@hapiel A couple thoughts. Is the shaft rotation one way, is it against the threads (i.e does it tighten or loosen) if that is one way against (tightening) then filing a flat spot on both to allow a grub screw.

Yeah, it will definitely rotate both ways, but I've calculated that some high strength loctite may support the connection just about good enough.

@hapiel That's an interesting use of Loctite. Let us know how it goes.

I did a reply to the DB workshop.  I guess it doesn't post stuff like that. Here's my reply:

I use 2  W/W motors on my Rose engine.  One drives the main spindle which runs on a 1" shaft and is quite heavy; I further reduce the rpm by about 1/2.  The other drives a cross-slide carrying fairly heavy cutter assembly; also rpm reduced further.  The only thing that might concern you is that these motors are not meant to run continuously so they tend to heat up.  Mine do run continuously for  quite some time thus I run a small fan over them while in use.  I hope this is helpful.

Correction: they are actually power window motors not WW motors.  The shafts are driven via home-made pulleys using large, heavy o-rings for belts.  The drive pulleys are sized differently from the driven shaft pulleys thus the speed reduction.

Coot

Further to my response,  I use a potentiometer to vary the speed on one of the motors and switches to control direction of rotation on both of the motors.  I have used this arrangement for several years without problems. 

Coot

By now I have  summarized all that I ever wanted to know about wiper motors in this video, perhaps it's usefull to someone some time:

@hapiel 

Thanks for posting. Another use is to make a motorized cart (or wheel barrow) for moving bricks, dirt and other things in your gardening requirements as they are very strong.