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Making a Geared Starter. Any ideas??


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Hi to All,

I am very new to a Metal Lathe which now occupies a place in the shed.

 

As a project, I would like to have a go at building a geared starter.  I have a Sullivan Dynatron which I no longer use as it has been displaced by the Just Engines Geared Starter.  The Dynatron turns too fast for my liking.

 

I have a spare Large Starter Cup and Rubber Insert, also from J/E and I have wondered about using something like this:-

 

DWireless Electric Skateboard Accessories Belt Motor Pulley For 72MM Wheel Sale - Banggood UK

 

Stir briskly and combine to produce a geared starter all fixed to something like a 6mm Alloy plate.   Sullivan also do a Megatron starter which illustrates the layout that I would like to follow

 

 

I can see how to mount the Dynatron but on the other side I will need some form of handle incorporating a Thrust Bearing and shaft to take the Starter Cup.  I'm flat out of ideas about what to adapt for this handle / shaft.

 

I realise that the simple option is to flog the Dynatron and buy another J/E Starter but I would like to do this as a project in metalwork.  I also realise that in some ways, The Model Engineer forum could be a place to start but then its less likely that they will understand what I'm aiming for.

 

Anyone any (repeatable) suggestions on how best to take this forward??

Thanks.  

Stu K

starter.jpg

Edited by stu knowles
spilling mistooks
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Thanks Gents.  Is it worth it?  Clearly not, I have a JE starter and where possible I hand start where possible, but its something that I would like to do.  I have the original starter and the large cup so marrying it all together seems an interesting exercise.  

Ron, Making the gears is way beyond me and at the moment, I wouldn't know where to go for an off the shelf set.  The toothed belt set is for an electric scooter so it should be sufficiently heavy duty for my purpose and seem a pretty simple set up.

I'm still stuck for suggestions on a source for the handle at the cup end

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Hi Stu

I may be wrong, but my gut feeling is that although your Dynatron starter feels too fast at the moment, it will be too slow once you gear it down. I suspect that the Megatron motor and all other geared motors will be designed with the reduction ratio in mind, to have a higher kv (rotational speed per volt) than your direct drive Dynatron.

Edited by Gary Manuel
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My first thought was that an epicyclic gear would be neat for this project and that it might come from some old item such as a bike 3 speed gear hub.  (Sturmey Archer )   Maybe old power tools like electric drills could be another source for gears and I think old Black & Decker drills had a 2 to 1 gear in pre electronic speed control era.

My second thought was to suggest you practice first by making some workshop tools - have you got the books by Sparey, Bradley, Bray or G Thomas for inspiration?

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Turning wood in a metal cutting lathe is very hazardous due to the chuck jaws extending out to catch fingers, knuckles or clothing!   So the idea of turning a wooden handle is not to be recommended on a metal lathe without extreme care.   Wood turning is more of an art and uses lathes with smooth chucks and they often run faster.   A wood turner could turn you a simple handle in a minute or two if you asked him or her.   But it's easy to buy all sorts of handles ready made for files etc or to shape an octagonal handle with simple woodwork tools.

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25mm aluminium tube (a.k.a. 'aerial mast' from B&Q).  Cut to length, mount in the lathe and put a heavy knurl on it.  One handle.

6mm mounting plates at both ends of the motor, drilled/bored to take the handle.  Fix a bearing in each end of the handle, run a layshaft through, mount the large pulley to the layshaft.  You'll need to machine collars to support/retain the bearings, retain the layshaft, etc., but that's all plain turning and a bit of cross-drilling and tapping to take grub screws, etc.

As to why you would want to climb this particular mountain - well, its because its there!!

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Thanks Gents.  I'm on the hunt for tube and bearings and will do some sketches before cutting metal.

 

Thanks for the safety advice.  My last time on a lathe was in the school Metalwork Shop.  I made a set of darts -  The Metalwork Teacher was very laid back - and probably too busy making a clock which seemed to take up a lot of his time in lessons.  Happy Days!

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I would have thought that having the motor offset would result in it trying to wrap itself around your wrist with the starting torque.  This is probably the reason that most are epicyclic.  The idea of using cordless drill gearbox parts sounds a good one.  Plenty of high quality drills are now obsolete and can be picked up for pennies with the change from Nicad/NIMH to Li-Ion batteries.

Could a bicycle headset be adapted to produce the thrust bearing and handle?  If you cut the rest of the frame away, you would be left with a tube with two thrust bearings.

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Could a bicycle headset be adapted to produce the thrust bearing and handle?  If you cut the rest of the frame away, you would be left with a tube with two thrust bearings.

 

Thats a good thought and a nice bit of recycling - cycling.  I will also look at the drill gearbox although I feel that the engineering challenges in taking this route could be more complex than the toothed belt drive option

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Robin's point about the whole thing rotating seems valid.   Maybe having the heavy battery fixed underneath would help stop that rotation.

Some starters already have a V belt pulley behind the cup which might be handy.     The boat and model car people seem to use belts for starting so it could be worth finding what they do.

Old washing machines or dishwashers seem to have lots of useful bits like pulleys &  V belts on the water pump for a free source of parts to experiment with.   If you need to buy pulleys then Picador is, or was, a source for different sizes.

Standing in front of  a large prop can be dangerous, so the idea of standing behind holding the model and pushing the model against a starter contained in a flight box or on a stand has some appeal and might be a worthwhile alternative design.  

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The layout that I am working toward will have two 'handles' in a side by side configuation. One being the original Dynatron and the second being the handle behind the new starter cup. That will negate and twisting issues.  The person holding the starter will have two hands on and a second helper will hold the model.  Its a fairly standard and accepted means of using a starter on a large model.

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On 06/01/2022 at 17:24, Robin Colbourne said:

Could a bicycle headset be adapted to produce the thrust bearing and handle?  If you cut the rest of the frame away, you would be left with a tube with two thrust bearings.

Now that sounds like a plan!  You could keep the stubs of the crossbar and down tube to act as mounts for the motor.  If you cut along the mid-line of each stub, then heat them up and beat them mercilessly to 'un-tube' them, then you might end up with plates wide enough to span the front and rear of the motor.  More easily done with those frames having larger diameter tubes.  Time to start dragging the local ponds...

 

PS - if you leave the stubs long, then you increase the distance between motor and handle, improving torque resistance for 2-handed operation.

Edited by Mike T
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