Garden Railway Forum

RobRossington wrote: ↑Mon Jun 14, 2021 11:09 am Looking at it would I be right in saying that your new motor block has the motor sat lower so that the new smaller worms can reach the axle gears?

Yes, that's the long and the short of it. A bit hit and miss making sure the gears mesh correctly. As the motor block housing is closed, it's not possible to see the gears or make adjustments. I'm now on my fourth variation..... Way one takes around 18 hours to print....

Rik

ge_rik wrote: ↑Mon Jun 14, 2021 8:20 pm As the motor block housing is closed, it's not possible to see the gears or make adjustments.

At the risk of asking a stupid question, would it be possible to print a small window in one side of the housing, just large enough to see the mesh?

ge_rik wrote: ↑Mon Jun 14, 2021 8:20 pm Yes, that's the long and the short of it. A bit hit and miss making sure the gears mesh correctly. As the motor block housing is closed, it's not possible to see the gears or make adjustments. I'm now on my fourth variation..... Way one takes around 18 hours to print....

I'm fairly sure you can get transparent PLA filament. Print the test housings using that.......

- if the gear mesh is badly out you'll soon know.

- if you are lucky and the mesh is OK, then the clear gearbox won't be clear after a coat of paint.

You'll probably need to hold everything up against a bright light to see the silhouette of the gears and there'll be so much distortion it will be like trying to read a newspaper through the bottom of a beer glass. Still a lot better than printing bits 'ad nauseum' until you get a gearbox that seems to work.....

Some plastics in transparent form are brittle, polystyrene being an example, and others like ABS and HIPS just can't be made in transparent anyway. I've no experience with PLA, so it may be that once you get a working gearbox, you may need to print one more in solid colour to get the physical properties you need.

Regards,
Graeme

GTB wrote: ↑Tue Jun 15, 2021 5:38 am
I'm fairly sure you can get transparent PLA filament. Print the test housings using that.......

........You'll probably need to hold everything up against a bright light to see the silhouette of the gears and there'll be so much distortion it will be like trying to read a newspaper through the bottom of a beer glass. Still a lot better than printing bits 'ad nauseum' until you get a gearbox that seems to work.....

Yes you can get transparent PLA, and I did think about suggesting it, but in my limited experience, "translucent" is more accurate than transparent. I used it for the 'glass' in my platform lamps and its fine with a bright LED inside but not really see-through. It may be possible to improve the clarity by fiddling about with settings, but that would take longer, with uncertain end result, than the hit and miss approach anyway, I'm afraid.

Hi
Yes, I've tried putting windows into the sides but the wheels are in the in the way. The wheels and axle stubs are a single moulding and so I can't align the gears without them.

If my mk IV version doesn't work, I might try designing either a moveable cradle for the motor or moveable mounts for the wheel bearings.

Rik

ge_rik wrote: ↑Tue Jun 15, 2021 7:49 am If my mk IV version doesn't work, I might try designing either a moveable cradle for the motor or moveable mounts for the wheel bearings.

I also thought about whether a multi-piece housing might be a better proposition. Basically a two piece assembly to carry the motor,with separate gear boxes at each end that carry the axles/worm wheel and can be adjusted up and down.

In the case of the wheels getting in the way of seeing the gear mesh, replace them with a simple temporary axle the same dia. while doing the adjustment. Doesn't have to be metal, even a suitable plastic tube would do the job. You might even be able to print something suitable, as all it has to do is pass through the bearings and the bore of the worm wheel to line them up.

Graeme

philipy wrote: ↑Tue Jun 15, 2021 6:09 am Yes you can get transparent PLA, and I did think about suggesting it, but in my limited experience, "translucent" is more accurate than transparent.

I'm not particularly surprised. If I'd thought about it, that printing process is bound to have tiny voids and bubbles dispersed through the part, even if the filament is transparent.

Graeme

GTB wrote: ↑Tue Jun 15, 2021 1:17 pm In the case of the wheels getting in the way of seeing the gear mesh, replace them with a simple temporary axle the same dia. while doing the adjustment. Doesn't have to be metal, even a suitable plastic tube would do the job. You might even be able to print something suitable, as all it has to do is pass through the bearings and the bore of the worm wheel to line them up.

Graeme

That's a good idea. The stub axles have an additional socketed square section on their ends which fit into square holes in the worm wheels. Quite a complex bit of engineering.
However, not outside the realms of possibility of a 3D printer Rik