I mentioned earlier that there were a couple of "gotchas" with the gearbox assembly. Or at least with my construction of it. This is the first of them. It's a rather picture heavy post, as I want to illustrate the snags that I had, and how I got around them.
The first one is due entirely to my own stupidity! But it might be educational as a way to get out of a hole.
Having reamed out all the holes and soldered up the gearbox, I followed the instructions, and attached it to the front of the motor (having double checked twice which end was the shaft I was going to grind off!). Having started to tighten the tiny screws (I must buy some more from Chris when his business returns from furlough), I could only get one of them part way in, and the second one not at all. This is where the obstruction was, from a couple of different angles:
48xx gearbox mount (1).JPG
48xx gearbox mount (2).JPG
Taking the gearbox away again, it seemed that there wasn't enough clearance at the edge of the open area for the screw to sit down squarely. The problem is in the area marked with the red circle:
48xx gearbox mount (3).JPG
So faced with such a problem, I did the only thing possible, and attacked it with a file. Not a gurt big one in this case, but a fine needle file as I needed to get into quite a small space:
48xx gearbox mount (4).JPG
The result was a notch that meant that I could have room to get the screw head to sit down properly. Of course, I had to do this on both sides:
48xx gearbox mount (5).JPG
Finally, I was able to get the gearbox properly mounted to the front of the motor, and sitting down squarely:
48xx gearbox mount (6).JPG
48xx gearbox mount (8).JPG
The final proof was in making sure that the motor shaft with the worm in place on it was exactly central in the hole in the front of the gearbox:
48xx gearbox mount (7).JPG
And all was good with the world. So why did I have this problem in what is normally such a well designed kit?
The answer is that I used the wrong gearbox faceplate. The kit provides for two - one for the 1224/1424 motors and one for the larger 1624 motor.
I had mis-remembered (and forgotten to remeasure) which motor I had. I even crossed through the section of the instructions referring to the 1624 and giving the correct part number. I'd inadvertently selected the smaller faceplate, which of course didn't fit until I made it so.
The moral of the story: of course, measure twice, cut once. Or measure twice, and choose the correct bit of the instructions! The good thing is that once the next "gotcha" was out of the way, everything is running beautifully with the motor and gearbox. More of that next time.
Cheers
Paul
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