Garden Railway Forum

Very nice job Rik.

I'm going to have to do something similar but starting from scratch, for my Wickham trolley. I just hope I can do as well.

Peter Butler wrote: ↑Mon Mar 15, 2021 4:10 pm Now that's what 3D printing is for!

My thinking exactly. It would be difficult to construct such a convoluted shape in any other way, methinks.

Rik

philipy wrote: ↑Mon Mar 15, 2021 4:30 pm I'm going to have to do something similar but starting from scratch, for my Wickham trolley. I just hope I can do as well.

At least I had the original on which to base it. Starting from scratch would have made it twice (if not more) as difficult.
Something I found useful (eventually), was to draw the motor, worms and bearings as a unit and use it to check how well it fitted. With TinkerCAD, I could actually turn it into a "hole' which I then used to carve a motor shaped compartment inside the closed block. It means the real motor is a perfect fit - uncannily so ......

Rik

And so the saga continues ......

After reassembling the loco, I gave her a test run. Still very disappointing in terms of pulling power. Even with a standard load of eight goods wagons the loco really struggled up my 1:40 gradients which my other locos gallop up. It also slowed appreciably on curves; the curve on the gradient brought it to a snail's pace on full power. I discovered the gauge on the drivers was slightly wide, but pushing the wheels tighter on to the gears to bring them to gauge made minimal difference. I stripped the motor block down to see if my clamshell was rubbing on anything. Nothing evident but I filed possible pinch points just in case. I reassembled and found there was very little improvement.

In desperation, I assembled a duplicate Lyn motor block which JimmyB has kindly sent me - which looks almost new.

Another test run and exactly the same outcome! Too little power to cope with a standard train!!

I can only assume that, for whatever reason, the large worms seriously impede the motor's ability to transmit power.

My next resort is to see if I can replace the worms with smaller diameter versions. I've ordered a gear puller and have found out how to calculate the mod value of the worm wheels. I just hope I can find a couple of replacements somewhere......

I will not be defeated!!

Rik

According to this online calculator, it looks like it's a 0.5 mod gear on a 2.5mm shaft which is reassuring that it's not something obscure.

https://www.technobotsonline.com/gear-s ... lator.html

Rik

Rik, I believe that the smaller worm is the solution, but I do not believe anybody has mentioned what the issue (apologies if you have and I have missed it), I think this is all to with "moments around a point".

The centre of the motor spindle is the fulcrum, and the motor provides the power which is a constant (assuming constant voltage input) the the further you move from the fulcrum, less load is required to equal the power output, ergo the larger the worm the less power drive you have.

Jimmyb wrote: ↑Sat Mar 20, 2021 8:41 am Rik, I believe that the smaller worm is the solution, but I do not believe anybody has mentioned what the issue (apologies if you have and I have missed it), I think this is all to with "moments around a point".

The centre of the motor spindle is the fulcrum, and the motor provides the power which is a constant (assuming constant voltage input) the the further you move from the fulcrum, less load is required to equal the power output, ergo the larger the worm the less power drive you have.

Thanks Jim
That's exactly my thinking though as a former primary school teacher my explanations are far less eloquent. I was out on a walk with a mate (a former physics teacher) yesterday and I found the easiest way to explain it was to use my walking pole like a propeller. Much more effort was required to rotate it when my other hand was stopping it further away from the handle and much less effort when the resistance was closer to the handle.

My mate agreed with my practical demonstration and then explained it all with moments.....

Rik

ge_rik wrote: ↑Sat Mar 20, 2021 8:54 am
then explained it all with moments.....

Blond ones?

philipy wrote: ↑Sat Mar 20, 2021 1:44 pm

ge_rik wrote: ↑Sat Mar 20, 2021 8:54 am
then explained it all with moments.....

Blond ones?

Melting ....

Rik

That is a blooming brilliant build Rik. You have mastered the art of this 3d printing stuff. Yes it is easy enough and the more you work on it, the easier it gets I have found, but I am still a marathon away from doing anything as brilliant as yours.


SUPBERB.....


PS I was looking for another emoji to say how brilliant it is, but it seems to have disappeared....

philipy wrote: ↑Sat Mar 20, 2021 1:44 pm

ge_rik wrote: ↑Sat Mar 20, 2021 8:54 am
then explained it all with moments.....

Blond ones?

Edit - apologies, this post adds nothing to the thread, but Philip's comment made me laugh out loud!

I think I've cracked it!!


Only took me three months!

Rik

Fantastic Rik..Well done, she doe's indeed run very smoothly now. I didn't notice any slipping at all, what a fantastic feeling you must have had when you saw her running and pulling all those wagons.

I agree also about having to redesign stuff with 3d builds, I am always doing it.....

Looks fine to me, Rik.
Very satisfying when you get to this stage.

Thanks chaps. She still needs to be tidied up a bit and some of the detailing installed ( eg the outside frames) but I'm pleased with how she now performs. You'll also notice the chuff synch now needs re-adjustment but she's now much more controllable at slow speeds.

Rik

An A+ for perseverance Rik. You must be very happy to see it dragging all those wagons.
And a most interesting video too.

I really enjoyed watching the video, your railway is beautiful.

It's fun for me to see Skibbereen mentioned as that is where I live.

mikki wrote: ↑Fri Jun 18, 2021 4:00 pm I really enjoyed watching the video, your railway is beautiful.

It's fun for me to see Skibbereen mentioned as that is where I live.

A lovely part of the world and definitely on my list of go to locations once this Covid business is over

Rik