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| I’m hoping it’ll arrive tomorrow. I’ll update accordingly. |
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So, the new stepper motor turned up today. There was basically one thing I was concerned with and that was did it come with the electrics unconnected to a coupler or were the wires coupled in to the connector that slots on to the pins on the mount. I was disappointed. It doesn't come with a connector but also there were 6 wires instead of the 4 that I have on my original motor. After 20 minutes of fretting and googling I figured why not dismantle the new motor, remove the equivalent shaft/pin that had snapped on mine and simply replace the broken one with the new one. Which is what I did. It's a bit fiddly, a bit worrying but it got done. There's a few alterations/adjustments to be made inside the mount when you remove the old housing the motor sits on, this has to be done to be able to re-insert the new pin, but its simple and straight forward enough. Ive briefly connected the mount up to my astro laptop, plugged it in and there's no smoke yet ;) It does slew anyway. So, we'll see. I think I'll probably order a correct build from the French site listed above but I did see there's also a website called astrosyn.com based in Kent in the UK that look like they supply stepper motors for astro purposes and they're even cheaper. Hope this helps. Matt |
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Thanks, Matt! I'm glad it slews for now. Does it sound the same, or clunkier? I've noticed on my other projects that even using different controllers with the same motors changes their rhythm and sound depending on acceleration and step adjustments. I noticed the French site as well and saw that they are 119 pounds each-sheesh, when we can get 3 Nema 17's for like, 25 bucks on Amazon, that seems high. But sometimes windings are different for astro motors, so who knows? Good engineering feat you did-I probably would have done the same. I really hope you can get it to work. Now, the question becomes, "If we burn our controller boards, where do we go?"-hope that never happens. Tom |
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Just an update here. FLO have a 4 month turn around on these parts, which is quite horrendous really. £240 for a pair. |
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Tom Marsala: The Nema 17 you mention, Ive never seen them before are they a cheapo chinky version of the SW motor? |
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Nema 17 is kind of a standard and describes the size of the motor. Steppers usually have 1.8 degree per step and if you have 4 wires, they may all work with the controllers as long as they do not need too much current. I assume Skywatcher uses motors with a medium quality in their mounts to keep costs down. The gears may not need a special high torque model and from my experience, you could use a standard Nema17 motor. The only problem may be to change/put on the wheel for the belt. They may be pressed on and are possibly a bit harder to remove/put on. Compare the size of the motor housings and you are on the safe side. Motors with higher/lower torque values usually have shorter or longer housings. The measure hasn't to be precise. You can guess by eye. A stepper usually has two coil windings. So take an ohmmeter and measure between two of the 4 wires. If you measure some lower resistance, you found the wires that belong to 1 coil. Measure this on the old and the new motor and use the same pinout. If you exchange the coils, the motor will work, too. If you don't have an ohm meter, you could simply short two of the four wires and turn the motor. If it turns kind of easily, the wires belong to different coils. If the motor is harder to turn, the wires belong to the same coil. If you have a stepper with 6 wires, you can measure the resistance between the wires. Two of the six wires are connected to the middle of the coils. So use the 4 wires with the HIGHER resistance (some ohms) between them (2 pairs of course) and leave the other ones unconnected/isolated. If the two measured wires belong to different coils, you will measure a really high resistance (+100kOhms to MOhms). I know it's a bit confusing, but there are a lot of websites explaining steppers. If you find the original spare parts, it may be easier for you to repair the mount. But if you can't get them, I am really sure a usual Nema 17 would do. I am confident, that your mount can be repaired quite easily. It is a really great mount and I hope you are able to fix it. CS Christian |
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Tom Marsala: doesn't European/UK consumer rights have a minimum of 6 years? Also, manufacturing defects are covered explicitly, though more costly to prove. |
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TiffsAndAstro:Tom Marsala: We usually have two years. The problem with the manufacturing defects is, that it is hard to proove that the defect was already there. The damage can for example happen, if the belt is too tight. So I guess there is no chance in this direction. But maybe it's worth to contact the seller. I once had a damaged screw (one of the large ones that you use for polar alignment). SkyWatcher sent a replacement without any problems. I can imagine, they are willing to help in some way or another. But the original post came from january. Maybe the problem is already solved... Who knows Christian |
