Binding Gearbox

garethashenden
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Re: Binding Gearbox

Postby garethashenden » Fri Jan 27, 2017 3:46 pm

Will L wrote:This is a picture of a RoadRunner+ and the arrow shows were I think the problem will be.
roadrunner.jpg


I see what you mean about there being the potential for something to catch in there. However, on my gearbox that is just an idler gear not a second reduction. Isn't that a Loadhauler compact? Not that it really matters. I don't think that's the problem here.

I'm going to put the axle back in the chassis and see how it does there. It did smooth out yesterday, even if it wasn't supposed to need breaking in. Fingers crossed.

garethashenden
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Re: Binding Gearbox

Postby garethashenden » Fri Jan 27, 2017 4:17 pm

garethashenden wrote:
Will L wrote:This is a picture of a RoadRunner+ and the arrow shows were I think the problem will be.
roadrunner.jpg


I see what you mean about there being the potential for something to catch in there. However, on my gearbox that is just an idler gear not a second reduction. Isn't that a Loadhauler compact? Not that it really matters. I don't think that's the problem here.

I'm going to put the axle back in the chassis and see how it does there. It did smooth out yesterday, even if it wasn't supposed to need breaking in. Fingers crossed.


Update !
It runs like a pig. Bellow about speed step 20 it will hardly move. The motor growls but nothing much happens. At about speed step 30 it runs and it runs relatively smoothly, but the motor/gearbox kicks up about once every wheel revolution. I'm going to take it apart and see if I can find the problem. I think I will also order a new gearbox. This is too fast for a shunter. Even watching the wheels go around yesterday on speed step 1 it seemed too fast.

Oh, one other thing. I had snugged the grub screw yesterday and it turned the axle without any problems. Now it slipped with the rods on, so maybe tightening it caused the problem.

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Tim V
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Re: Binding Gearbox

Postby Tim V » Fri Jan 27, 2017 5:22 pm

Sounds like it's seized.

Wash gearbox and all bearings in IPA/your favourite de-greasant. A High Level gearbox should run smoothly with no lubricant - though not long-term. with luck you may wash out someswarf that has got stuck in there.

Once clean with the motor off try moving it with your fingers - and report back.
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Russ Elliott
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Re: Binding Gearbox

Postby Russ Elliott » Sun Jan 29, 2017 12:00 pm

The advice to rub the gears on some wet and dry before assembling seems very sound, but, referring to Will's diagram, how can some space be ensured at the arrow point, apart from sleeving the final gear on the left-hand side?

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Will L
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Re: Binding Gearbox

Postby Will L » Sun Jan 29, 2017 1:41 pm

Russ Elliott wrote:The advice to rub the gears on some wet and dry before assembling seems very sound, but, referring to Will's diagram, how can some space be ensured at the arrow point, apart from sleeving the final gear on the left-hand side?


Assuming both gears are resomably smooth, it doesn't seem to be necessary on the gearboxes I've got running. The are no forces trying to press them together.

Which thinkin about it...
garethashenden wrote:... There are a number of fibre washers on the axle taking up most of the slack inside the gearbox but there was a little bit still there. I cut a gap in a new washer and stuck it in the space. Then I oiled everything and tried it again. I couldn't see any reason why the axle was moving over, but with the new washer it no longer did this. The gearbox was quite unhappy about this, almost stopping completely at slow speeds. It ran better at high speeds but with a slight bogging at that spot...


...may not be true in Gareth' box. The high level boxes are all designed with sufficient spacers to keep anything in the right place, so he should not need all those fiber washer, I'd take them all out, and give the sides of that final gear a good polish.

dal-t
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Re: Binding Gearbox

Postby dal-t » Sun Jan 29, 2017 2:49 pm

At the risk of diverting into a totally unproductive siding (for which mucho apologicoes and lashings of humble pie with double doses of grovelling cream if it proves to be so), can I just ask how much endfloat there is on the motor shaft? I enquire because I notice the addition of a substantial flywheel (which I personally applaud, although it generally attracts the opprobrium of the experts on here), and in my youthful and indisciplined days I encountered a very similar problem to yours with an EM 0-6-0 chassis fitted with flywheel. It turned out that following over-enthusiastic application of force to persuade the reluctant lump of brass to assume its designated position, I had disturbed the motor bearings so much that the worm was able to wind itself forwards and back into a 'binding' position when it came under load. This only revealed itself when there was the full resistance of wheels, quartering and coupling rods reacting through the drive chain, somewhat negating the catch-all protection of test at every stage (which I'm pretty sure I had done anyway, since to me it falls in that magic smudge-bucket of 'common sense'). I'm sure your other, far more experienced, commentators have already considered this, and dismissed it with erudite and soundly based reasoning, but sometimes, just sometimes, the problems revealed by us rough and ready types can take even those of encyclopedic knowledge and opinion down the blind side ...
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Tim V
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Re: Binding Gearbox

Postby Tim V » Sun Jan 29, 2017 4:46 pm

Good point.

I hadn't remembered that problem, as I scrapped all fly-wheels many years ago - DCC doesn't need them.

It's a very good idea to do minimal work on the motor - don't cut off shafts, and don't bash them with hammers.

As an aside I saw a large layout maintenance table where flywheels were being bashed on and off with large hammers. I don't think they got it - that their actions were destroying the motors, so they needed to replace them again.
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garethashenden
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Re: Binding Gearbox

Postby garethashenden » Sun Jan 29, 2017 9:37 pm

Both the flywheel and the worm are just sliding fits and held in place by loctite. The washers are mainly to keep the axle from moving side to side in the chassis. I probably could have put them outside the hornblocks with the same effect, but this was easier. It does move too much without any washers, so they have to go somewhere.

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Jol Wilkinson
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Re: Binding Gearbox

Postby Jol Wilkinson » Mon Jan 30, 2017 11:55 am

While flywheels can give some benefit, their impact is proportional to the square of their rotational speed. So, when you probably most need their effect at low speeds they give the least benefit.

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Allan Goodwillie
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Re: Binding Gearbox

Postby Allan Goodwillie » Mon Jan 30, 2017 5:01 pm

Hi Gareth,
I may have missed it but are you fitting the coupling rods each time you test?

The reason I am asking is that it is possible to have the same problem and symptoms, but due to something entirely different. I had the same problem the other day with one of the Barclay locomotives I have been building. Two of the chassis have been built for some time and were both running sweetly. One had a Portescape motor and gearbox and I decided to use it on a mainline loco that I am building for my Grayrigg layout and decided to replace motor and gearbox with a Mashima and a multibox. I assembled the combination and ran it in as I normally do before fitting into the chassis. I took off the coupling rods and replaced the motor and gearbox taking great care to get the quartering of the wheels right. It ran OK one way however going the other there was a stutter every revolution! Consternation! My first thought was that I had managed to get the quartering wrong, but before trying to alter it I had a look under the magnifier.

Here are the photographs before and after - see if you can spot the difference.

DSC01499.JPG


DSC01500.JPG


Normally I keep my coupling rods tied together as pairs, however here I had simply taken the two rear ones off and because they were painted red on both sides, when I assembled them again I, by mistake, had swapped sides. :o

Now, I build my locos by first making up the coupling rod pairs on a jig - so there is no difference in length so it was not a case of binding. However if you look at the top illustration centre driver you can see that the overlap is incorrect and what was happening was the coupling rod in one direction only was catching on the centre boss each revolution.

I took them off and fitted them correctly as the second illustration shows and - perfect! Serves me right for loosing track. :!:

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Re: Binding Gearbox

Postby martin goodall » Tue Jan 31, 2017 5:38 pm

Re flywheels: Mike Sharman always recommended that they be 'de-coupled' from the motor, by the use of a universal coupling or neoprene tube to avoid putting an unnecessary load on the motor bearings.

I also recall Mike's advice to fit bearings on both ends of a worm-fitted gearbox, again to avoid unwanted loads on the motor bearings. Mike never liked the widespread practice of hanging a worm or a flywheel off the end of the motor shaft with no additional support.

(Sorry for the digression.)

billbedford
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Re: Binding Gearbox

Postby billbedford » Wed Feb 01, 2017 10:53 am

Mike Sharman was never a engineer....
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Jol Wilkinson
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Re: Binding Gearbox

Postby Jol Wilkinson » Wed Feb 01, 2017 11:51 am

Did he claim to be?

Philip Hall
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Re: Binding Gearbox

Postby Philip Hall » Wed Feb 01, 2017 4:35 pm

Actually Mike Sharman was (and is, come to that) a very fine engineer. If he hadn't been, he wouldn't have given us all those wheels and gearboxes. His background in the RAF helped I guess, as did the same background that Steve Hodgson had which helped him in taking over the business. I'm not sure that he claimed to be anything, being the kind of chap he is, but in my book he was an engineer in the truest sense of the word.

Philip

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Jol Wilkinson
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Re: Binding Gearbox

Postby Jol Wilkinson » Wed Feb 01, 2017 4:53 pm

Hi Philip,

many of us know of Mike's background and the work he did that was of great service to many of us when we embarked upon finescale model making, but it seems he doesn't measure up to Bill's standard.

Sadly his range of wheels have disappeared off the market, as have Bill's.

Jol

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Tim V
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Re: Binding Gearbox

Postby Tim V » Wed Feb 01, 2017 5:40 pm

You can look at Alex Jackson's article on his coal tank to see decoupled flywheels, and worms supported at both ends - from 1952!
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Allan Goodwillie
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Re: Binding Gearbox

Postby Allan Goodwillie » Wed Feb 01, 2017 9:27 pm

Without going into too much detail quite a number of motors actually came with these features, showing my age here :cry: , and Mike was only repeating what was the common thinking of the time. If you come across John H Ahern's "Miniature Locomotive Construction" (published 1947 - the year before I was born :!: ) you may be able to pick one up as I did last summer for holiday reading, for a couple of pounds second-hand. He shows quite a number of techniques and motor/gears sets as used in is locomotives and includes flexible drives and tender drive units using all the features described. :x

Many of us have much to thank Mike for as he was only too happy to produce wheels for less known prototypes, he did quite a number for Scottish engines and simply added them to his range. Anyone having met Mike and his wife, who was just as happy to run trains and chat at exhibitions, will know what a nice couple they are and appreciate what a great modeller he is. His models are quirky and interesting and inspired any number of modellers.

There is film of his layout on the internet, if you want to go looking. :)

Technology continues to impress and is changing the face of modelling, making it easier to gain perfection and building from scratch becoming rarer. Mike was an excellent scratch builder and it all worked which must say something for his ability in a different era.

This, of course should not be seen as any criticism of Bill as we all know with pleasure just how much Bill has enabled many fine models to be built by means of his own skills and is truly appreciated by all those who have used them - two great enablers using their individual skills. How lucky we have been to have both men. :)

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Re: Binding Gearbox

Postby Knuckles » Thu Feb 02, 2017 7:22 am

I have contracted the Worm Bind disease a few times now. For me it seems the culprit is sometimes the motor even straight out of the packet because some have more play than others and as the shaft jiggles in and out every time you change direction it disturbs the mesh. I have only used Mashima's but one of my Hornby RTRs suffers from the same issue. Other than motor replacement I'm unsure what to do, might try to pack the space so it can't jiggle and see if it improves.

No idea if this helps anyone, hopefully...
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billbedford
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Re: Binding Gearbox

Postby billbedford » Thu Feb 02, 2017 9:53 am

Philip Hall wrote:Actually Mike Sharman was (and is, come to that) a very fine engineer. If he hadn't been, he wouldn't have given us all those wheels and gearboxes.


If he was the engineer you suggest the wheels would still be in production.

...and I would suggest that trying to get his flexichas to work well has put more people off finescale than just about anything else.

His background in the RAF helped I guess, as did the same background that Steve Hodgson had which helped him in taking over the business.


Yep, but he was an engine fitter, so never responsible for any design work.
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Jol Wilkinson
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Re: Binding Gearbox

Postby Jol Wilkinson » Thu Feb 02, 2017 10:19 am

Bill,

does that mean a designer is an engineer? Somehow I don't think so. Mike worked within the technology of the time and the demands of the market. Both of those have changed and it is easy to be critical from a distance. The products of some of the "keyboard" designers who are creating the products which apparently represent the way forward for our hobby could do with a bit of an "engineering" input.

The disappearance of his range of wheels from the market under present ownership (I probably know a little more about the details of that than most on here, including you) left a hole that nobody has filled. While they weren't perfect, they were available in sizes that enabled many of us to produce models that are no longer readily possible. You introduced a range of wheels based upon "modern" technology, what happened to them? I would be happy to buy an accurate wheel that runs true and is easily and accurately fitted.

Exactoscale wheels promised that, but like Ultrascale don't have a range that provides what I want. AGW get's nearer with some and Markits - so beloved of 00 modellers and which fit the easy to use requirement - don't do the sizes I want, never mind the wheel profile.

So before you knock Mike, his ideas and his products, remember he did a lot to move the hobby forward for many of us, in the "model making" sector where your business now flourishes.

Jol

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Will L
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Re: Binding Gearbox

Postby Will L » Thu Feb 02, 2017 4:52 pm

billbedford wrote: ...and I would suggest that trying to get his flexichas to work well has put more people off finescale than just about anything else.


Producing a reliable running chassis by what ever method you use has always been a bit of a challenge, but trying to suggest that Mike Shaman flexi chassis is notably more off putting than any other method is distinctly questionable. For me flexi chassi was the first method which enabled a kitchen table modellers to produce a chassis that would work reliably. In those days, producing a good rigid chassis needs tools and techniques which I didn't, (still don't) have. Remember at the time the accurately etched fold up chassis which can be assembled rigid was in the future.

It is true that compensated chassis as a breed do have problems and disadvantages, but given the pick up issues to which rigid chassis are given, they still represented the best way forward until really workable sprung chassis stated to appear, and these built on the techniques developed to implement flexi chassis.

No one single person is ever solely responsible for the pushing our methods forward, but I can't help feeling that Mike Sharman gave as big a push to the wheel as anybody.

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Re: Binding Gearbox

Postby Philip Hall » Thu Feb 02, 2017 5:44 pm

Jol and Will sum up my feelings about Bill's views so succinctly that I am glad to have no need of further comment.

However, I would also like to emphasise that I have built many 'Flexichas' and never had any difficulty in getting an impeccable performance out of them, both now with the benefit of donkeys' years worth of experience, and in my early efforts as a complete beginner. It is still my method of choice for a chassis simply because for me, it's simple and it works.

Philip

billbedford
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Re: Binding Gearbox

Postby billbedford » Thu Feb 02, 2017 8:23 pm

Jol Wilkinson wrote:Bill,

does that mean a designer is an engineer? Somehow I don't think so.


An engineer is by definition a designer, since they will be creating something which did not exist before. It its only the laxness of the English language which lumps mechanics and fitters in which engineers

Mike worked within the technology of the time and the demands of the market. Both of those have changed and it is easy to be critical from a distance.

The disappearance of his range of wheels from the market under present ownership (I probably know a little more about the details of that than most on here, including you) left a hole that nobody has filled. While they weren't perfect, they were available in sizes that enabled many of us to produce models that are no longer readily possible.


Mike approached wheel making as a modeller would, with each type of wheel an individual project. This was fine as long as he or any of the subsequent owners were willing to spend long hours almost hand making the wheels for relatively little reward. But it was not something that lent itself to the business outgrowing the one-man-in-a-shed approach or being transferred to more modern production machines.

You introduced a range of wheels based upon "modern" technology, what happened to them? I would be happy to buy an accurate wheel that runs true and is easily and accurately fitted.


The wheels are more or less ready to go, but are held up while I do do some, shall we say, less speculative work. But if you know what you want and I can find drawings then I may be able to help.


So before you knock Mike, his ideas and his products, remember he did a lot to move the hobby forward for many of us, in the "model making" sector where your business now flourishes.


On the other hand there were so many dubious ideas around in the early days of finescale which have ossified into 'the way we do things" that I some time think it might have be better not to have started from there.
Bill Bedford
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dal-t
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Re: Binding Gearbox

Postby dal-t » Thu Feb 02, 2017 9:19 pm

Should we maybe get back to the original issue? At this point I'm really not sure whether we have helped Gareth or not. Allan's pictures of inverted coupling rods reminded me that I've also encountered such a problem, on a 7mm loco where I misread the marking of the rods, and it did indeed produce some very 'lumpy' running (which I actually cured by accident when I took the rods off again for another reason). But if I've read the posts correctly Gareth is now (unless there's further progress?) encountering even more binding than before, so far from curing the disease we've made it worse (clearly not directly/deliberately)! At the risk of starting another wild hare, I don't suppose any of the problem could be due to applying oil in the vicinity of fibre washers? I know the better ones are fire, flood, oil and solvent resistant, but I had one batch (from a certain well-known Devon-based manufacturer, I believe) which turned to a soggy mess in such circumstances.
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billbedford
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Re: Binding Gearbox

Postby billbedford » Thu Feb 02, 2017 10:24 pm

Will L wrote:Producing a reliable running chassis by what ever method you use has always been a bit of a challenge, but trying to suggest that Mike Shaman flexi chassis is notably more off putting than any other method is distinctly questionable. For me flexi chassi was the first method which enabled a kitchen table modellers to produce a chassis that would work reliably. In those days, producing a good rigid chassis needs tools and techniques which I didn't, (still don't) have.


The original Flexichas idea had square bearing blocks with a turned groove in them running in slots (hand) cut into thin frames. So not only had you to cut square and parallel slots in the frames, you had to assemble the frames square and then find a way of stopping the bearings turning with the axles. Then once the loco was built and running it was realised that the horn guide bearing surfaces were totally inadequate and the loco stopped running due the general sloppiness around the bearing. Of course various manufacturers made improvements to the system such as separate hornguides with proper bearing surfaces etc, but it wasn't until recently with the advent of commercial assembly jigs that building Flexichas frames became a simple operation for the majority of modellers.

While there are many here who would contend that Flexichas is well within the capacity of most modellers I would suggest the it's complexity and fragility compared with the simple mechanical, if not aesthetic, robustness of 1/32" plate frames drilled for axles and frame spaces lost the finescale end of the hobby many potential adherents.
Remember at the time the accurately etched fold up chassis which can be assembled rigid was in the future.


It has always surprised me that fold-up frames came so late and have been taken up by so few designers.
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