A compact gearbox

G'day all.

I needed a tool to rotate fishing rods at about 6 rpm while the epoxy on the coatings dried (to avoid 'slump'

I settled on a defunct power screwdriver that was inherited from a mate long passed. With an adjustable DC power supply it was ok.

During the disassembly of this tool I noticed that it had a pretty remarkable gearbox, a 6 tooth drive cog on the motor driving 3 intermediate gears driving a planet which drove 3 more intermediate gears via another 6 tooth gear which drove the output shaft with enough torque that it was difficult to stop by hand.

The shaft on the electic motor (about 1.5mm dia) has a flat to locate on the tiny gear which also has a tiny 'D' shaped hole in the drive cog.

Here is a link to the patent that I found.

www.google.co.in/patents/US4003274‎

All in all it's a lovely design. I would love to know how the tiny 'D' shaped hole was made in that tiny gear

Regards from the land of the kangaroo

* Danny M *

Hi Danny,

These gearboxes are pretty amazing things. You'll find them in battery powered drills as well. I fitted one from a 18V drill into a steel case to make a toolpost mill/drill.

> how the tiny 'D' shaped hole was made in that tiny gear

Possibly spark erosion?

Neil

Hi Danny

I suspect that you will find that the pinion is a sintered part and hence the hole is made with the flat as part of the same pressing process as the teeth. Usually they are made from sintered bronze.

Peter

G'day.

Decided to fit a toothed pulley to the output shaft (ex-HP printer) and use the printer's toothed belt to drive another pulley fixed in my C3 Mini-Lathe leadscrew via an expanding mandrel. With my variable D.C. power supply it could be yet another fine feed design.

If it works out I shall take some photos.

Regards from the land of the kangaroo

* Danny M *

G'day Gray.

Thanks for that link, it will simplify designing the mounts for my leadscrew drive assembly.

The drill he used has a multi-speed gearbox, even better for my intended use.

(That Unimog would make a nice up-to-date project for M.E.).

Regards from the land of the kangaroo

* Danny M *

Danny

I dont know a bit about fishing rods why not just use an epoxy that doesnt slump?

Edited By mike mcdermid on 23/09/2013 23:34:05

G'day Mike.

The epoxy that I use is especially formulated for rod building and is slow drying. The manufacturers recommend to rotate the rod at 5-10 RPM. With a decent build of clear coating on the bindings, almost any epoxy will run to the lowest point as it dries. If you hunt around for a rod building blog you will note that one can purchase dedicated rod building lathes if one is keen enough. As I only build a few rods a year the slow RPM of the battery drill (with a variable DC power supply) driving a belt around the rod handle is ideal.

A decent rod, eg; St Croix SCV Graphite Blank, Fuji gold-plated titanium guides, reel seat, cork handles with a custom binding will set one back about $500. There are a few people here who will willingly pay $800-$1000 for such a hand made rod, but at that price the finish (and the performance) must be immaculate. Can't afford to let the epoxy slump!

Have a look at **LINK** for examples

Anyway, to get back onto the topic of powerful compact gearboxes, I intend to play around with adapting them for my minilathe leadscrew drive and then look at using one to drive my X2 mill X-axis. If successful I shall write it up.

Regards from the land of the kangaroo

* Danny M *

The one time I built up a fishing rod from a blank ( late 70s, I think it was a Cod 5, my brother would know - he is still 'looking after' it!) I used somewhat faster epoxy, but rotated the rod by hand.

It was very satisfying to fish with a rod I'd 'made' myself, although I never seemed to catch much!

I like the Unimog - the Matchbox one I had as a kid was my favourite.

Neil

Edited By Stub Mandrel on 24/09/2013 13:17:11

Some years ago model motors for 6v & possibly other voltages, were available with multi stage modular epicyclic gearboxes.

The gearbox ratio could be varied by adding or removing modules to suit the output speed required.

the picture should demonstrate things more clearly than I can explain, the example shown dates from the 1980s (I think) and is very smooth running.

I do not know if these are still available.

Nearly forgot, the output shaft was meccano size as well.

Edited By V8Eng on 24/09/2013 20:38:53

How about one of these with a variable dc supply for your power feed?

Russell.

I had a lovely yellow reversible Meccano motor with a six-speed gearbox, you selected the gears by sliding small black sliders in and out. A little work of genius as it was adaptable to alm,ost any model.

I also had a monoperm special that was a complete washout in my Vic Smeed ASRL. Replacement with a 540 'buggy motor' and 8-cell nicad pack saw it (literally) run rings around an off the shelf speedboat.

Neil

G'day Danny,

Are you using Erskine Epoxy on thie bindings ?

There are a few options for turning rods as the epoxy dries : an old rotisserie motor from a microwave , a spit roast drive motor (you can get a battery powered unit for around $30 and run it from a small power supply , the oscillating drive from a household fan can be used as it is just a worm drive off the end of the motor shaft , just strip the fan unit down so it is just the motor , power switches and run a pulley off the oscillating drive output .

I have also seen a car windscreen wiper motor used to do this and if you use a pulse width modulated speed controller you can slow the motor right down .

I picked up some industrial drive motors ( 240v) from EBay very cheaply that run around 30rpm but this is for a camshaft grinder I will start designing shortly.

I hope you get to test the rods you build !

Its been a while since I wrapped a rod , usually a beach rod with either double diamond or chevron pattern at the front grip and the guides were mostly a three coulour affair ( main under binding with bands that have a gold single turn inlay )

Ian

Posted by SLOTDRILLER on 25/09/2013 19:26:52:

G'day Danny,

Are you using Erskine Epoxy on thie bindings ?

I hope you get to test the rods you build !

G'day Ian. Erskine epoxy. As I live next to lake Hume I certainly do road test rods and lures. There is much satisfaction in using a tool that one has hand made, whether for fishing or a lathe accessory.

Regards from the land of the kangaroo

* Danny M *

Hi V8,

I think that motor you have there is a monoperm super - I see the built in red reversing lever. As well as the meccano compatible output shaft the four holes on the base should be Mecanno size and spacing as well.

Looks like the yellow motor I had was a monoperm + 'ricard' gearbox, and yours is a monoperm super pluse 'pile' gearbox. By Marx, not Meccano, but obvioudsly made to be compatible.

See LINK

Neil

Hi Stub.

Thanks, that is a useful info site.

You are right about it being a Monoperm super, I also have a couple of Decaperms, these were all really good reliable motors.

They were originally bought for use in an SLEC Tank, having decided that flying model aircraft was not working out for me, and ground level models might be less costly!

Two Decaperms drove the tracks through some modified Meccano gears, independent control / reversing was courtesy of PCB type resistance boards fitted on top of The RC servos.

The Monoperm took care of turret rotation (the pile gears were used to get the speed right), and the gun elevation was by a small servo in the turret fed via slip rings / brushes on the turret rotator shaft.

I recently dug the tank out during a major loft clearance, it is a bit battered and corroded, might have a go at restoring it, but with loads of conflicting demands on my time lately even using the workshop is proving really difficult.

Edited By V8Eng on 26/09/2013 21:03:01

Danny,

For a slow-rotating mains motor I have used a discarded electric tin opener, faster than 6 rpm, but powerful.

Phil

I've just found two beautiful little epicyclic gearboxes in an Astra wing mirror (don't ask why I have a spare one). They work with 12V motors that have short spade-ended shafts and include a simple overload clutch.

Pretty expensive at £29 the pair, but at least I gained something

Neil