What sort of problem would cause this and where should I look? I've built High Level gearboxes before and they're been fine from the start, so I'm a little confused.
Here's what we're dealing with.

Tim V wrote:It is a little late to be investigating this with a fully assembled chassis but hey ho.
First off, you say it binds when the grub screw is undone. OK , having done that take the motor off. Does it still bind? Have you looked very carefully using a high powered jewellers glass at the gear wheels for muck?
Le Corbusier wrote:How is the worm gear fixed .... grub screw or lock tight?
garethashenden wrote:Le Corbusier wrote:How is the worm gear fixed .... grub screw or lock tight?
The worm is held on by loctite.
garethashenden wrote:I tested it before installation and it was good. However, I used a 9v battery so I didn't encounter the low speed problem. I'll try it with the motor off when I get home from work.
Tim V wrote:Can you measure the axle diameter? Is it exactly 1/8", some axles I have are not that dimension.
Philip Hall wrote:Sometimes on a High Level 'box the gears run close to each other, brushing each other almost. I try to avoid this by arranging washers, very thin, to keep the edges of the teeth from contact. It may be that there is some roughness on the sides of the gears that touch once every revolution.
Enigma wrote:...Where the gearwheel does not have a grub screw and to offer an alternative to Loctite fixing so that a disassembly of the box can be made later if required, I mark, drill and tap as above but then fit a 10BA cheesehead bolt with the head filed square into the tapped hole. A square keyway is then filed into the axle hole of the gearwheel to fit the square bolt head and the gearwheel slid over the bolt to locate it. This works with the narrower HL gearboxes where the gears themselves and the box sides hold the gears in mesh...
Will L wrote:This is a picture of a RoadRunner+ and the arrow shows were I think the problem will be.
roadrunner.jpgEnigma wrote:...Where the gearwheel does not have a grub screw and to offer an alternative to Loctite fixing so that a disassembly of the box can be made later if required, I mark, drill and tap as above but then fit a 10BA cheesehead bolt with the head filed square into the tapped hole. A square keyway is then filed into the axle hole of the gearwheel to fit the square bolt head and the gearwheel slid over the bolt to locate it. This works with the narrower HL gearboxes where the gears themselves and the box sides hold the gears in mesh...
Interesting idea, just ensure that where the final gear runs against the side of the previous gear as in the RoadRunner+ that the bolt head can't catch the teeth of the adjacent gear giving you a rather worse varsity of the problem he already has.
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