A mechanism for your scratchbuilt project

Re: A mechanism for your scratchbuilt project

Postby ConducTTor » Thu Mar 06, 2014 11:19 pm

Actually motor size is not an issue. There are multiple motors that will fit within a TT scaled hood.

The main hurdle is a proper truck/gearbox.
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Re: A mechanism for your scratchbuilt project

Postby krokodil » Sun Mar 09, 2014 4:58 pm

As I see the Hollywood Foundry makes the same mistake in the design as was made by Zeuke and later BTTB. The highest reduction should be on the first transmission stage - ie from the motor axle. In other words the worm should be on the motor axle - like the new models are mostly made. It is not a good practice to have the worm gear on the wheel axles. This solution is usually noisier and the reliability is sometimes lower.
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Re: A mechanism for your scratchbuilt project

Postby ConducTTor » Sun Mar 09, 2014 6:25 pm

Very interesting drive (friction). Have you tried putting small flywheels on each side of the large friction wheel?
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Re: A mechanism for your scratchbuilt project

Postby ctxmf74 » Mon Mar 10, 2014 12:49 am

"It is not a good practice to have the worm gear on the wheel axles."

I guess it depends on how they are arranged? Many of the best running O scale locos use worm gears on the axles with preliminary gear, belt, or chain reduction between the motor shaft and the axle gears. I haven't looked into the Sazmodel drive to see how it gets it's fine low speed performance but it would be a good model to copy from preliminary operational results....DaveB
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Re: A mechanism for your scratchbuilt project

Postby Rob M » Mon Mar 10, 2014 10:39 am

* ConducTTor the first two videos don't show up ?

You need to remove the "&feature" from the link.



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Re: A mechanism for your scratchbuilt project

Postby ctxmf74 » Mon Mar 10, 2014 1:04 pm

"but I see there are no B TT scale shells out there. I'll have to scratchbuild something to get a general size."

Lionel makes some 120 scale A units that are cheap and might make a good test loco. They come with decent truck sideframes that could be applied to powered trucks...DaveB
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Re: A mechanism for your scratchbuilt project

Postby j p » Mon Mar 10, 2014 4:04 pm

Bernd wrote:
ctxmf74 wrote:"but I see there are no B TT scale shells out there. I'll have to scratchbuild something to get a general size."

Lionel makes some 120 scale A units that are cheap and might make a good test loco. They come with decent truck sideframes that could be applied to powered trucks...DaveB


Lionel makes TT scale products???????? :shock: :o

Bernd


Used to make - and they are listed here on this board
http://www.ttnut.com/lionel-1-120-scale-model-locomotives-t793.html

to ctxmf74: B unit for Lionel's A was a resin kit, no need to do any double work.
(I have not painted my B unit because of lack of decals. Now I can make decals, so the B unit has a chance to get completed..)
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Re: A mechanism for your scratchbuilt project

Postby areibel » Mon Mar 10, 2014 4:56 pm

They're not too bad to find, unless you're looking for a particular road name.
They made a GP9 and an F3, they're a little funky in that they're not true models of the prototype, they're models of the Lionel O scale ones. The GP has a funky cab (like the tinplate one had to clear the motor) but the F unit is actually pretty nice except for the headlight it a little too small.
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Re: A mechanism for your scratchbuilt project

Postby j p » Mon Mar 10, 2014 5:13 pm

Bernd wrote:
j p wrote:Used to make - and they are listed here on this board
http://www.ttnut.com/lionel-1-120-scale-model-locomotives-t793.html

to ctxmf74: B unit for Lionel's A was a resin kit, no need to do any double work.
(I have not painted my B unit because of lack of decals. Now I can make decals, so the B unit has a chance to get completed..)


Ah, USED TO MAKE, I see. So one has to reinvent the wheel then? Have to say those are some nice looking engines. Let me guess, you'd be hard pressed to find one for sale unless it was an estate sale?

Bernd


Have you tried ebay? It is very easy to get most of them and they are cheap.
http://www.ebay.com/itm/Santa-Fe-Super-Chief-F3A-Diesel-1-120-Scale-Die-Cast-by-Lionel-Classic-Series-/171264708464?pt=Model_RR_Trains&hash=item27e02c0f70
http://www.ebay.com/itm/LIONEL-TRAINS-1-120-SCALE-Southern-Pacific-F3-SERIES-1-/271418398129?pt=Model_RR_Trains&hash=item3f31cc15b1
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Re: A mechanism for your scratchbuilt project

Postby krokodil » Tue Mar 11, 2014 4:02 am

Bernd wrote:Hi krokodil,

I believe the biggest mistake in all model engine drives is the use of worm gearing. The models should have 90° helical gearing like this. Hobbytown of Boston drive had these. Their problem was the use of spur gears on one of the gear towers, plus the motor solidly mounted to the chassis making for a noisy drive.
Bernd



Hi Bernd

that is correct, however with this gear you cannot achieve the targeted reduction ratio (in the given space) that is why almost all models in smaller scales have to use worm gears. In such gear you can easily achieve 1:10 or even higher reduction, the same reduction with helical gears (I use them in my Scale 1 models) or standard gears requires several times bigger space and more moving parts. (noise sources)
That is why the good practice is (Athearn, Roco etc.) to use the worm gearing on the highest speed axle, and the secondary reduction later with cheaper and simpler mechanical parts, rotating already on lower RPM and generating less mechanical noise.
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