Friday, May 22, 2009

Small DC Geared Motors

So last time I mentioned that I have two small motors and they looked very much like that from JMI, so here's a shot of them taken side by side. The JMI seems higher quality, but they're essentially the same. One of them is now mounted on my C5 OTA for motorized focusing.

Today, I took the other one out to see how I shall use it. Actually, I've two projects in mind:

1. Motorize the focuser of my Orion 100ED: this one is funny, since the original owner has a gear mounted on the focuser knob, that gear is from JMI but the motor has been broken, so I will only need to provide another motor with suitable mounting hardware, then it will work again. I would say that gear should mean 30% done if I go for this project. I guess if I have to use this long 100ED with my TG-SP II, I will want to motorize the focuser since this scope is going to be marginal for this little mount and thus a motorized focuser certainly helps.

2. Motorize the Tmax of my Solarmax 40: with a NGF-CM on my Ranger now, focusing is now a snap, but Tmax tuning is still now very great right now. If I can motorize the Tmax, the field will definitely be even more uniform than I can do now.

So, after some searching with the pile of "rubbish", I found a small motor box with wheels there, it is from a toy car. I tried to use the JMI controller on the motor, but it won't move unless I move the wheel a little bit, I guess the initial current is not big enough. And that motor is too fast for Tmax tuning. Anyway, the wheel seems useful since it has some rubber on it and thus, it can turn anything by friction!

I removed it from its shaft and found the hole a little bit too small for my motor, okay, it's easy to enlarge it. So I did it.

This is a protype mounting solution, and it works. With only a single rubber band, the balance is very poor, but then the motor can turn the Tmax easily right now. So my next target is to build a better mounting for it and then my solar image should improve!


BTW, those motors are available from ebay when you search for DC geared motor or something alike, they are available at a fraction of cost than the original, of course, you need to build your own mounting/adapters and it could be the hardest part.

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