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Gear Advice - shopping list help?


garygfletcher

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I am building a Johnson Spinner 4-2-2 tender driven loco with a custom made 15mm driving wheel it will be driven through a drive shaft from the tender.

 

I am thinking I would like to go with the H19 motor with a 30:1 worm gear. I then would like to use the recommend double reduction mechanism M0.4 from the spur gear to the driven axle. 

Wheel wise I was thinking 7mm for the bogie (from 3' 6 ½) - is there a bogie assembly kit?

And 8.5mm for the rear wheels (from 4'6" ).

The tender wheels 8mm (from 4'3" ).

And some simple straight track to try it on..

I have attached a rough drawing that may offer an illustration.

If you wouldn't mind helping - I would be immensely grateful! I am not adverse to some trial and error so if a rough outline and keeping some items in stock for myself later would not be an issue, I can certainly add and experiment later.

With thanks

Gary

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You really need 8.5mm tender wheels for 4'3", and 9mm for 4'6".

 

I'm not quite sure what you mean by M0.4 double reduction as there aren't the gear sizes to produce a 2-1 reduction, just in M0.3.

 

Izzy

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Many thanks for the input on wheel sizes.

 

Regarding M0.4 here is what I was told... 

 

 

You initially have to chose whether you want to use M0.4 (coarser) gears or M0.3 (finer) gears. 

M0.3 have a larger range of sizes but M0.4 might be easier to mesh, again your choice.

 

and

 

 

 

 page 11 of the current Yearbook ( "Example of Double reduction mechanism")
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If you want a target of 40:1, then here are a couple of choices. 14T on driver, 18T next to worm wheel. (18/14)*30 = 38.57:1. Alternately, 14T on driver 20T next to worm, (20/14)*30=42.85:1.

 

You can play around with the exact sizes if you wish, but they will affect the positioning of the worm wheel/worm/driveshaft.

 

Coreless motors are often recommended for their smooth running. If the £45 Maxon from shop 3 is too much the Nigel Lawton 8mm motor is highly regarded. http://www.nigellawton009.com/MidiMotors.html

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Yes, sorry, I just took it to mean by double reduction that you were looking at a final ratio of about 60-1, so 30-1 followed by 2-1. A single wheeler is one type I haven't built over the years, so others who have will say what reduction works best, but as a rule I favour higher reductions than most other modellers anyway and would want at least this given the size of the driver. For example with my class 15, which has one of Nigel Lawtons aformentioned 8x16mm motors, I used a reduction of 49-1 with 6.8mm wheels.

 

Izzy

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[...] For example with my class 15, which has one of Nigel Lawtons aformentioned 8x16mm motors, I used a reduction of 49-1 with 6.8mm wheels.

 

Izzy

Izzy, are you using 100DP or 64DP gears? Or, if metric, M0.3 or M0.4? If you use the 64DP (or M0.4) how many teeth the gear on the driver has, as the 6.8 mm wheels are very small? I try to figure out how could I achieve a 60:1 reduction on a tank engine with 7 mm wheels and 64DP gears.

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If you want a target of 40:1, then here are a couple of choices. 14T on driver, 18T next to worm wheel. (18/14)*30 = 38.57:1. Alternately, 14T on driver 20T next to worm, (20/14)*30=42.85:1.

 

You can play around with the exact sizes if you wish, but they will affect the positioning of the worm wheel/worm/driveshaft.

 

Coreless motors are often recommended for their smooth running. If the £45 Maxon from shop 3 is too much the Nigel Lawton 8mm motor is highly regarded. http://www.nigellawton009.com/MidiMotors.html

 

 

Thanks for the link Gareth, I bought a few of Nigel's motors.

 

Regarding your suggestion would the following give me a complete "kit"? Few questions as well...

 

Wheels 

 

2 x 3-062  7mm spoked bogie/tender wheels

1 x 3-066  8.5mm spoked tender wheels

3 x 9mm?? There doesn't appear to be a plain spoked 9mm?

 

Wheel Assembly

 

4 x 3-101  Acetal gear muff 3.2mm o/d (imperial gears)

2 x 3-103  Acetal axle muff 2.3mm o/d (bogie wheels)

1 x 3-112  Drive bush - turned brass

1 x 3-113  Frame bush - P/bronze

Is there a bogie assembly?

 

Motor

 

1 x Nigel Lawton's Midi Motor

 

Gears

 

1 x 3-385  Spur Gear Brass M0.4 14T 3.0mm bore

1 x 3-388  Spur Gear Brass M0.4 20T 3.0mm bore

I cannot find an imperial worm gear?

What gear attaches to the drive muff?

Are there bearings for the worm gear shaft, what does the shaft sit in?

I cannot find any gear rods in the catalogue are these purchased separately?

 

General

 

3-528  Etched Handrail Knobs - Fret of 20 - are these suitable for the Johnson Spinner - No pictures?

 

 

 

Anything I missed out?

 

 

With thanks

 

Gary

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The imperial worm/gear set (3-362) has been replaced by the metric one: 3-364. Because of this you will need some stepped gear muffs (3-102a). But if you use only metric gears then you need to adjust the order for the muffs: 3-102b and you don't need any of the 3-101. For the wheels with no gears you need 3-100 muffs (much cheaper as it is not essential for the bore to be concentric to the muff).

 

You don't really need any 3-112 Drive bush - turned brass, they are very big; better take two sets of P/B frame bushes (3-113)

 

The muff carrying the worm gear and the idle gear (14T) is supported to the chassis frame using two stub axles (approx. 3mm each). These ca be cut from the "Locomotive axle steel 1.5mm dia x 75mm long" (3-110).

 

In my opinion, 3-528 are suitable for any model; so small they are hardly visible.

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Izzy, are you using 100DP or 64DP gears? Or, if metric, M0.3 or M0.4? If you use the 64DP (or M0.4) how many teeth the gear on the driver has, as the 6.8 mm wheels are very small? I try to figure out how could I achieve a 60:1 reduction on a tank engine with 7 mm wheels and 64DP gears.

 

Erm, neither I'm afraid Valentin, sorry. It's a real fudge as is normal for me, and uses Bachmann (American) diesel bogies (correct wheelbase & wheel size for a 2mm class 15) with a 14-1 ratio driven by a layshaft via NL's belt drive system using 1.1mm/5mm pulleys. It's a bit crude (my design and construction - not the NL parts/motor) but works okay and was needed because of the short bogie wheelbase.

 

I think you would need to use 100dp/M0.25 gears to stand any chance of getting a 2-1 second stage gear reduction with 7mm wheels and clear a 100dp 30-1 gear set even using a small dia muff.

 

Izzy

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I put together a rough drawing to check my understanding, which is the 15mm wheel has a muff that fits a 20T spur gear, then a 14T gear to a worm gear to the drive shaft?

 

I have altered the parts to all metric - does this list look better?

 

 

Wheels 

 

2 x 3-062  7mm spoked bogie/tender wheels

1 x 3-066  8.5mm spoked tender wheels

3 x 9mm?? There doesn't appear to be a plain spoked 9mm?

 

Wheel Assembly

 

1 x 3-102a  Acetal stepped gear muff 3.2mm and 3.0mm o/d (imperial gear and metric gear) (DRIVE WHEEL)

4 x 3-100  Acetal axle muff 3.2mm o/d (driving wheels) (TENDER)

2 x 3-103  Acetal axle muff 2.3mm o/d (bogie wheels)

2 x 3-113  Frame bush - P/bronze

Is there a bogie assembly?

 

Motor

 

1 x Nigel Lawton's Midi Motor

 

Gears

 

1 x 3-385  Spur Gear Brass M0.4 14T 3.0mm bore

1 x 3-388  Spur Gear Brass M0.4 20T 3.0mm bore 

1x  3-364  Gear-set M0.25 30:1. Skew cut brass gear 3.0mm bore. Acetal worms 1.5mm and 1.0mm bore. 

Are there bearings for the worm gear shaft, what does the shaft sit in?

2 x 3-110  Locomotive axle steel 1.5mm dia x 75mm long

 

General

 

3-528  Etched Handrail Knobs - Fret of 20 

 

What size rod goes with the handrail knobs?

 

 

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post-25822-0-19498400-1429039291_thumb.png

post-25822-0-72286000-1429039315_thumb.png

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To answer two of your questions Gary:

 

There are no loco bogie kits, you have to make up your own with n/s or brass sideframes, p/b bearings and a perspex, tufnol or pcb spacer.

 

Regarding the worm wheel shaft, as someone else has said, that is made from two short lengths of axle steel fitted into the muff so that they do not touch (pushing a wee scrap of paper in before you put the second piece of shaft in helps to make sure they remain insulated from each other) that runs in a bearing in each frame.  if you study the drawings i sent you, you will see that.

 

BTW, i see you've decided not to go with the drive shaft under the footplate.  ;-(

 

Jim

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I put together a rough drawing to check my understanding, which is the 15mm wheel has a muff that fits a 20T spur gear, then a 14T gear to a worm gear to the drive shaft?

 

I have altered the parts to all metric - does this list look better?

 

 

Wheels 

 

2 x 3-062  7mm spoked bogie/tender wheels

1 x 3-066  8.5mm spoked tender wheels

3 x 9mm?? There doesn't appear to be a plain spoked 9mm?

 

Wheel Assembly

 

1 x 3-102a  Acetal stepped gear muff 3.2mm and 3.0mm o/d (imperial gear and metric gear) (DRIVE WHEEL)

4 x 3-100  Acetal axle muff 3.2mm o/d (driving wheels) (TENDER)

2 x 3-103  Acetal axle muff 2.3mm o/d (bogie wheels)

2 x 3-113  Frame bush - P/bronze

Is there a bogie assembly?

 

Motor

 

1 x Nigel Lawton's Midi Motor

 

Gears

 

1 x 3-385  Spur Gear Brass M0.4 14T 3.0mm bore

1 x 3-388  Spur Gear Brass M0.4 20T 3.0mm bore 

1x  3-364  Gear-set M0.25 30:1. Skew cut brass gear 3.0mm bore. Acetal worms 1.5mm and 1.0mm bore. 

Are there bearings for the worm gear shaft, what does the shaft sit in?

2 x 3-110  Locomotive axle steel 1.5mm dia x 75mm long

 

General

 

3-528  Etched Handrail Knobs - Fret of 20 

 

What size rod goes with the handrail knobs?

Gary,

I wouldn't want to comment on your shopping list particularly but ...

You won't drive the axle gear directly from the worm gear.  What you'll need is a smaller gear than the worm gear on the same shaft (so that this new gear doesn't interfere with the worm), this smaller gear will then engage with one on the muff of the driving wheels.  The worm gear will also be on a muff too by the way as it is bored to fit a muff.

I think that Gareth's comment on gear ratios may be wrong too, I think that he meant that the 14T spur gear will be on the worm gear shaft with the 18T one on the driving wheel axle to get the 38:1 ratio (although that's not how I read his comment - it reads that the 18T spur is on the same shaft as the worm gear - I think that will give you a less that 30:1 ratio.

 

Hope I'm right in my reply, and that my comment is useful.

 

Regards,

 

Ian

 

PS The thinner muffs (2.3mm daiameter) for bogie can be used on the tender wheels too.

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BTW, i see you've decided not to go with the drive shaft under the footplate.  ;-(

 

Thanks Jim, on my first loco I wanted to go as simplistic as possible to prove that I a) have the skill and b) patience. I do plan on making half a dozen (maybe more of the differing iterations) of these and refining the process, I think as part of that I will certainly migrate to a drive shaft under the footplate.

 

At the moment I feel like this is a bit of a pandoras box I am slowly unravelling.

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With regard to the 9mm wheel the only two options would be to use an undersized 8.5mm. Or a 9mm outside crank one and remove the extended axle portion. This would be for the rear loco carrying wheel. Three 8.5 would be for the tender.

 

Izzy

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You won't drive the axle gear directly from the worm gear.  What you'll need is a smaller gear than the worm gear on the same shaft (so that this new gear doesn't interfere with the worm), this smaller gear will then engage with one on the muff of the driving wheels.  

 

Thanks Ian, like this?

 

That leaves me with even more confusion as to what these gears should consist of :( it seems a dark art.

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Thanks Ian, like this?

 

That leaves me with even more confusion as to what these gears should consist of :( it seems a dark art.

That is the sort of arrangement you want, but the worm wheel and gear should be on a muff, the same as the driven axle, with two pieces of shaft in the muff as i described above.  Not sure what you mean by 'consist of'?   Do you mean material, which is as supplied, or sizes, which have been quoted to you by others?

 

Jim

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the worm wheel and gear should be on a muff, the same as the driven axle, with two pieces of shaft in the muff as i described above.  

 

Okay thats clearer, thanks :)

 

 

 

Not sure what you mean by 'consist of'?   Do you mean material, which is as supplied, or sizes, which have been quoted to you by others?

 

Yes sizes, I now have an additional gear, you have to remember I have never even held these gears in my hand so it makes it a little difficult to visualise. What I have done so far is thanks to yours and others input which has been nothing short of fabulous really.

 

Soo.. if I have

 

1 x 3-385  Spur Gear Brass M0.4 14T 3.0mm bore (To WORM gear)

1 x 3-388  Spur Gear Brass M0.4 20T 3.0mm bore (On Drive Wheel)

What does that leave me with for the additional smaller spur gear?

 

I think with this, once you get them through the post and look at them through the packaging... it clicks...?

 

Cheers

 

Gary

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Thanks Ian, like this?

 

That leaves me with even more confusion as to what these gears should consist of :( it seems a dark art.

Gary,

 

That looks better, but as Jim has also said, the worm gear and the small spur gear next to it will also be on a 3mm muff.  The actual shaft through the muff will need to be in two separate parts (with a small insulating gap separating them to prevent a short across the two frames - assuming that you intend to use the recommended 2mm scale method of split frame construction, i.e. the two frames being insulated from each other).

 

If you look on the 2mm Association website products pages (the Loco and coaches section (Shop 3)), and click on the little camera icon next to 3-351 and 3-358 you will get an impression of what the gears actually look like (although they won't necessarily be the ones that you are looking to use it will give an indication).  By the way, the worm itself is over long and will need to be cut to the length you require - I think you actually get 2 worms these days one 1mm bore and one 1.5mm bore.

 

Hope that helps.

 

Ian

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Given the massive size of the driving wheel on this loco, would it not simply be possible to utilise a single stage drive with a large wormwheel. The Association sell used to sell a 38:1 worm set, but I seem to recall you can buy something larger (perhaps 50:1) from Ultrascale.

 

EDIT: yes, Ultrascale do and you can see them here: https://www.ultrascale.com/eshop/products/CAT015#WWGS2

 

This one looks particularly interesting: https://www.ultrascale.com/eshop/products/view/CAT015/243 Its a bit wider than 2mm wormwheels typically are, but for a single stage reduction there is still space, or you could turn the gear down.

 

Just on an historical note, Ultrascale used to make the Association imperial gear range. They stopped supplying us  because they could not keep up with the volume we needed along with their other product lines, but they did not stop making the gears. So it's actually possible to buy all of our former imperial range from them (and it seems at cheaper prices!)

 

Similarly, if there are metric gears you are interested in that are not in the Association range, you can order them directly from our Polish supplier. 

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I would agree with Chris, the 38:1 which you can still get from Ultrascale, when combined with a descent motor in the tender, is perfectly adequate for a express loco. I also have some 39:1 gears that I got from Brian at Branchlines which have the same centres.

As for wheel sizes, I wouldn't worry about opting for the closest size down to prototype by half a mm. Firstly, it gives a bit more clearance, particularly useful on something like a spinner which has next to none behind the footplate valances and, secondly, our over scale flanges will more than make up for it visually.

Above all, particularly for your first loco, keep it simple.

 

Jerry

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Here's my Jinty with the body off. It should illustrate the arrangement of the gears in a double reduction drive. The worm wheel has 30 teeth, on the same shaft is a gear with 14 teeth. Meshing with the 14T gear is one with 18 teeth. It's hiding behind the middle driver, but you can see a few of it's teeth. The worm is supported by a bearing at either end. I can't remember if it has two shafts or just one, it doesn't matter in this case as both bearings are on the same side of the frame.

 

IMG_6151_zpsd4348113.jpg

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What does that leave me with for the additional smaller spur gear?

I think perhaps my arrangement with the worm under the worm-wheel is confusing you.  In order to prevent the worm fouling the gear on the driven axle I need to move it back and therefore require to put a small lay gear in between the small gear on the worm-wheel shaft and the gear on the driven axle.  This gear contributes nothing to the reduction, only serving to transmit the drive across the gap created by moving the worm/worm-wheel away clear of the driven axle gear.   In the arrangement in your drawing you don't need it as the gear on the worm-wheel shaft is driving directly onto the one on the driven axle.  As others have said, with such a large driving wheel, you could get away without the second stage reductin by using the biggest suitable worm-wheel directly on the driven axle.

 

Chris, thanks for the pointer that Ultrascale still make the 100DP imperial gears.

Jim

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If I was doing it, I would go with a spur reduction from the motor shaft in the tender to drop the drive shaft below the footplate and another in the loco firebox to lift the drive back up to the height needed for the worm gear on the driven axle. 

Incidentally, I realise it is probably just a representation at this stage so you are probably aware of it, but if you make your universal joints as shown in post No. 10 the shaft will fall out. They need a sleeve on the outside to keep it in place.

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