West of Scotland Group's "Starters" Build a loco project

[Allan Goodwillie]

I might mention here that the third axle does not have to be fixed, it could be sprung in the same way. I think you get a slightly better ride with all axles done this way, for the simple reason that if there is a problem with any spring on the other axles the third axle will have at least one spring taking up the slack as it were. Height setting in the situation differs a little. Providing wheels are put on correctly and the motor mounted in the proper way allowing for some flexibility, then there is no problem having a fixed or sprung end axle.

Something else worth mentioning is that I also use a system for keeping horn blocks in order along with other components, it is simply a piece of MDF with double sided tape on which the horn blocks etc. are set out as they would appear from below and the top of the MDF being the front of the chassis.(See Illustration)

Allan

[Allan Goodwillie]

Making and fitting Sand boxes

This is the time to make up the sand boxes before assembling the axles and wheels. I used, in this case, a square brass section. Working from the drawing, mark where the sand boxes should go on the chassis, make sure they are set opposite one another. I would also suggest that you mark each side of each box on the chassis. That way you are less likely to solder the boxes on the wrong side of the single line. - Done it myself!

When cutting square material it is important to mark it all the way around. On Brass it is not always easy to see the marked lines.

There is a blue material ,which you can buy and which you paint on before marking, which has to be cleaned off before soldering. I have used a candle instead. The metal placed in the flame gets a coating of carbon which can be easily marked without a heavy score. I use my Vernier gauge to mark off directly from the drawing. All sizes are then constant. Each piece is cut off leaving the line showing, then put in the vice and a flat file used to bring it down to the line. The square material is squared up again before marking the next piece. I have also taken the angle off the corner at the same time, marking and filing two at a time, side by side, in the vice.

Once you are happy with them all you can go on to the next stage of soldering up.

(Solid bar of the right section can also be used, but does require more heat in soldering and also requires a hole for the sand pipe to be drilled in the base for the fitting of the pipe later. My own preference is to use square brass tubing, it can be left open at the top if covered by the footplate. I solder a wire in later then seal the top and the base with some plastic filler after filling with lead)

Allan

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covering the brass with waxy soot

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The marking using the vernier

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A clear line showing

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Cutting to near the line using a hacksaw

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cleaning up the facings before marking the next one

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[Allan Goodwillie]

Soldering the sand boxes

When soldering items like the sand boxes on to the chassis I suggest the following technique. Clean all surfaces using a glass fibre brush or fine wet and dry - I prefer the latter myself - the glass fibres get everywhere.

Once all is clean. Start by painting flux on to the rear of the boxes and then add a thin layer of solder (the green stuff suitable for brass). This is called tinning (a common soldering technique).

Then paint a small amount of flux on to the chassis where the box is about to soldered. Before adding heat, it may be useful to use a heat sink of some kind, to stop spacers or horn guides moving accidentally.

Here again the heating of different materials will come into effect. The brass will heat quicker and the heat will spread quickly over its surface allowing the solder to melt and the boxes to settle. The fact that the heat will stay more localised in the nickel silver, will stop the heat escaping too quickly to other already soldered items.

Method A

I place the boxes on the sides of the frame and solder them in place one at a time. The frames are held in place on a block of balsa using pins. In the illustration I am using the holes for the brakes temporarily, to hold things down. The brake wires can be put in after the boxes have been fitted. (If you have already fitted the wire for the brakes that's OK.)

When heating, I touch the top of the box where it meets the top of the chassis with a little solder and watch everything melt into place, holding the box with a cocktail stick in its correct place. Using the cocktail stick allows for moving things around a little, if necessary.

Do not overheat, but try to make sure all is square before releasing the heat.

Method B

An alternative to this method is to hold the chassis in the vice (you have to be careful not to tighten up too far and distort the work), or use your helping hands if you have them. Use a heat sink clamp to hold the box in place and again heat. The clamp will align and place the box in one, make sure all is square before you heat.

If you are worried about soldering your boxes don't be, simply glue them on with epoxy glue

See scratch building is not too big a deal, before you get too excited check that you have soldered each box in the right place. If you managed to place them all correctly well done!
Allan

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Boxes made, paint on some flux prior to adding a thin layer of solder this is called tinning

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Tinning the boxes (make sure you are tinning the correct sides)

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The tinned box about to be placed along with a cocktail stick used to hold it while tinning

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Photograph showing the arrangement for the frames and heat sink

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Heating the boxes on to the frames holding the boxes in place using the heat sink clamps and holding the frame carefully in the vice

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[Allan Goodwillie]

Preparing the wheels

You may assume that all these lovely packets of wheels are perfect, but you would be wrong. Again examine what you buy when you buy it. Three of the wheels in the sets I bought had loose rims - easily put right by using Locktite 601. A couple of axles still had turning pips on their ends ( these had to be taken off ) and I discovered that all were slightly too short , not really a problem using my system as it turns out. Some wheels can also have their moulding pips still on the back and these have to be removed as well. (see the Sharman example)

Gibson wheels have a shoulder moulded on the rear and it is worth reaming out a little to allow the axle to go in more readily. I also take the edge off the axle end to avoid it cutting into the plastic as it goes in.

I also take a small drill and gently cut a little into the crank pin hole from the rear, this will allow the end of the pin to rest level with the back of the wheel. It also means that when fitted the crank pins will not conflict with anything as the wheels turn around.

Ultra scale wheels are better quality, but are more expensive and have a smaller range, but check them in the same way in case there is any problem.

Look at the examples below

Allan

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The end of the axle showing a turning pip

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A Sharman wheel ( forgive the paint work ) showing plastic moulding pips

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Reaming out the axle hole, only take off a gnats whisker

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Preparing the crank pin hole

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The crank pin hole ready

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[Allan Goodwillie]

Fitting and checking the crank pins

Now screw in the crank pins. I am using Gibson crank pin sets and his wheels. Sharman wheels came with the pins already fitted ( fine as long as they all have the correct throw - difficult to deal with if not, if you are using them I hope they are OK )

I have also heard recently that the new Gibson wheels are coming out without the holes drilled - this is most unfortunate as you are relying on them having been properly drilled in a proper engineering situation. This may mean that we will need yet another jig to keep everything right when drilling. I believe my old friend Chris has designed, and uses one of these, so I will have to persuade him to tell us what it looks like.

In the meantime these wheels are OK and I have taken the crank pins and carefully screwed them in from the back of each wheel, trying to keep everything straight, and not over tightening the screw into the back of the wheel in case it sends the screw off centre.

I have set the crank pin jig to the correct throw and now test each wheel in turn. You may have to alter this ever so slightly on the first one. Once you have a clean drop on the first crank pin then do not alter the setting, make the rest the same.

To test

Here is how the jig should be used.

Place the wheel face down on to the jig with the turned down axle lined up with the axle hole and the crank pin pointing down into the crank pin hole. I do this holding the jig slightly towards one side. I turn the jig level and if the wheel does not drop then I tap it gently from one end while held in helping hands. If the wheel has not dropped properly into the lower position then check the pin and straighten until it drops down cleanly - see illustrations below.

We now have identical crank pins and throw on each wheel.

Allan

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The wheel in the upper position with axle and crank pin in alignment

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Te wheel in the dropped position indicating that the crank pins are parallel to the axles and that the throw is correct

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Alternative way to test using the helping hands and tapping lightly at one end - thus blurred image

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[Allan Goodwillie]

Fitting a wheel

First mark the centre of your vice.

Now to fit a wheel to an axle. First take a wheel with the crank pin fitted and checked. Fit the crank pin plug into the wheel jig and align it with the line marked on the washers. Place the wheel crank pin into the slot and move the wheel to a position where the wheel rim is supported equally all the way around. Place the jig with its wheel, the axle placed in the axle hole, in the centre of your vice using the guide lines.

You may wish at this stage to add some Loctite 601 glue to fix the axle more permanently to the wheel - not completely necessary unless you are intending pulling long heavy trains. The glue takes time to set really hard so there is time for fiddling about if necessary.

If not using glue (which acts as a lubricant as the axle enters the wheel) I tend to place a bit of saliva on the end of the axle to act as a lubricant.

Make sure everything is level and that the axle is set to go in straight. Use a small square to check this in each direction. It is not necessary to be 100% sure, as once the axle starts to penetrate, the hole will guide it. If you have a lathe you can use it. A lathe is not necessary however.

Tighten the vice carefully and feel for the wheel coming to a halt. We end up with a wheel rim that is at right angles to the axle and an axle parallel to the crank pin.

If the jig has done the right job then the axle should come right up to the wheel boss. If for some reason you have gone too far - a sign that your centre plug is not quite thick enough, then place the wheel on top of your vice, wheel face upward and support as much of the wheel rim as possible.

Use your centre punch and a small hammer to gently tap the protruding end of the axle until it is level with the centre boss. Go too far then reset using the jig.

If this is all OK then take the wheel and fit it to your gearbox and motor unit. You can see mine being tested for wobble. Turn over the motor at a slow rev. and with a marker tap each time the wheel turns and dips.

(One of the subjects I used to teach was ceramics. Centring a leather hard pot on a wheel used this technique- where one would tap the pot using the fingers at the greatest position.)

Once marked then use a screw driver to gently lever up the wheel at its lowest dipping position to alter the set of the wheel. Repeat until there is no wobble to be seen. The six axles on the two locomotives required only one wheel to be adjusted slightly. When you turn the speed up the wheel should spin without any sense of wobble.

Allan
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The jig showing the plug and washers making up the jig

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This is how the parts are aligned before the wheel with its crank pin is fitted Note the line on the washers is aligned with the crank pin slot in the inner plug

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The wheel , axle and jig set up in the centre of the vice ready for tightening, notice the line is still showing somewhere near the top of the jig

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Testing for wobble , the motor under power

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[Allan Goodwillie]

One email I received from John Bateson on this subject this morning is from Philip Hall who also thinks along the same lines as me on Gibson and Sharman wheels. his technique for preparing the wheels is as follows:

"a dodge I have used with Alan Gibson wheels (and Sharman, if you have them) – it’s less applicable to Ultrascale as they’re a less flexible kind of plastic – and Terry asked me to send a note to you about it for possible publication.
It’s simply that I put a very pronounced chamfer on the axle end – say about 60 degrees – round it off and smooth it with a flexible emery board (the sort sold for polishing nails that you can find in a chemist). I put the axle in the mini drill and spin it around at about half speed. This ensures that there is no possibility of the axle taking a shave off the wheel as it’s pressed in. The slight objection to this is that it leaves a slight gap around the end of the axle, but this can easily be concealed with a touch of filler if you think it shows too much. Since I started making the chamfer more pronounced I’ve found the wheels go on much more easily and true."
-Philip Hall

I would like to add further to this myself.
I have noticed over the years that there is a difference in the plastic used in various wheels. I found that Sharman when fitted using other methods, did not always go on true, but if left overnight, often trued up as the wheel matched its hole with its axle. Not entirely sure what was going on here, but I did notice this happening.
Gibson wheels do not do this unfortunately, and do require truing. Without using a lathe, the method used above has been my solution to the problem and it does work, providing you have a descent vice.

Sharman wheels have the plastic moulded into the rim in such a way that it is locked in and I have not come across any where the rim comes off. The Gibsons do not have this however, and it is worth checking to see if the rims are loose. It is no big deal, if they are loose. Simply make sure that all is flat on the back of the wheel except for the obvious spacer in the middle of the wheel. Put the wheel on the open jaws of the vice put some loctite 601 on the plastic rim, it will not dry in the open, and press the rim into place and make sure all is level and that it is properly seated down. Clean off everything. Now leave overnight to ensure the glue has dried in the vacuum and cured.

I also have used the old Studiolith Mk. 2 press which could double up as a very good wheel press as it gives a good feel to what you are doing. So if you happen to have one of these or see them in a second hand stall then consider buying, you can, of course, use them for their original purpose to punch sleepers, etc.

I would like to take the opportunity to thank both John and Philip for this contribution, I am aware that not everyone will be reading this thread and feel that Philips contribution should still go into the next Scalefour News - I like the practical bits.

Allan

[Allan Goodwillie]

Fitting wheels (continued)

Setting up and staying organised for the second wheels being fitted

First of all, lay out your chassis on the bench with your horn blocks set out in their correct guides - remember you marked them earlier and place your axles already fitted to one wheel in their correct positions with the horn blocks fitted in place. Lay out your motor and gears for the fixed axle and lay out the axle bushes for this as well.

It is worth checking to make sure that the axles go through the bushes without any friction. There can be a burr left on one edge where the drill has left a rough edge during its passage through the block during production. Simply take your large reamer and clear this rough edge away. An alternative would be to use a large drill (larger than the hole) and turn it a couple of turns by hand enough to take off this rough edge.

Make sure that all the components are fitted on the axle before easing the end of the axle in to the second wheel. Don't force the wheel on as we have been careful to set the first wheel and the fact that the wheel rim is set correctly to the axle is important to the success of the next stage. It is enough for the wheel to take a little bit as we now have to get the quartering right. I hold the axle tight in a pair of pliers without touching the set wheel I press the other wheel on using finger pressure only. It does not have to be completely true at this stage.

Double check that all the bits required are on the axle - you can tell that I have forgotten items myself, don't worry we all do, but it is best to get things right first time before quartering and pressing on.

Allan Stay cool!

[Allan Goodwillie]

Quartering wheels

The next stage is to quarter the wheels before pressing.
We have looked at various jigs and although one is not necessary, I would recommend either making one or purchasing one. Allan Ferguson's I particularly liked.

What we are looking for is consistency which the jig will ensure.

You will need to know which way your particular locomotive was quartered. The majority of the British companies used a right hand lead. In other words, If you are looking at the locomotive from the right hand side the right hand coupling rod should be at the three o'clock position when the left hand one is at 12 o'clock, this ensures the correct quartering.

There are other variations however, three cylinder locomotives had 120 degree settings for example - this would require a different jig from the one we are using here. It may surprise then to say that the majority of modellers do not bother about that and simply quarter the way we are doing here. Only by looking at the locomotive from underneath would you notice anyway.

A story against myself, in my "OO" days , as a young lad, when I first tried building a kit, I did not know about quartering. I fitted the coupling rods on (two part) and did it placing them using opposite positions - right hand at bottom when left at top - consternation the loco would not run - I read the construction notes and nothing !

This mechanical faux pas left me bewildered until a friend told me about the importance of quartering and how one set of coupling rods should be a quarter of the way round compared to the other. Its a bit like fools mate in chess.

Now you must consider which of the wheels should be leading. With everything set out before you, the underside of the chassis facing upwards,the front of the chassis away from you and the correct bushes set in the correct place.

A right hand lead would mean the crank pin on the left hand wheel as you are looking at it will be pointing away from you while the one on the right hand will be pointing down towards the bench.

I roughly quarter them and then lift the wheel set into the quartering jig. I leave one side , the side with the loose wheel, slightly loose to allow for easier fitting then when all is in place I tighten that side of the jig.

I drop the wheels into place.

(Make sure you have placed the horn blocks in the centre and that they are not getting in the way of the correct functioning of the jig.)

I set the fixed wheel crank pin against one side of the v stop and turn the loose wheel on the axle until the two crank pins are in the quartered position making sure that the axle is well set into the jig.

Hey Presto Your wheels are quartered! Joy unconfined!

Take care not to disturb this setting before you press your wheels. I now go on to press this first set into place before doing the next. I check that I have quartered with the correct lead again before pressing - just to be sure!

Allan

[Allan Goodwillie]

Completing the wheel sets

The wheel sets having been quartered, it is now time to complete the fitting of the wheels. Please take care with this stage as it is one of the key stages towards good running. Work in a good light and give yourself plenty of time - another Saturday morning project. Having said that, don't be put off by my suggestions. Your wheels will go on correctly and square.

The motorised axle

Before we move on to this, I would just like to mention that the fitting of the unsprung wheel components is just the same, except you must remember the motor and gear box also has also to be fitted!
Note Do not tighten the grub screw fully and leave the final drive gearwheel loose on the axle to make for easier fitting.

The fitting of the other wheels

A smidgeon of blue tack on the end of the grub screw, as a precaution in case it drops off, may be a good idea, saves hunting about on the carpet for half an hour with a magnet.
Make sure that the motor / gearbox unit is the correct way around before quartering - we have all been there!

Before the wheels are placed into the vice, fit a small washer on the end of the axle using a tiny amount of blue tack or glue not super glue to temporarily fix it in place. It is important that the washer/ washers have are a smaller diameter than the axle. They are there to make sure that it is the end of the axle that is going to take the force of the pressure and not the wheel boss.

The other wheel is set into the wheel press jig in a similar way to before, using a little loctite, if you wish, or personal lubrication!

When all has been placed on the centre line make sure that the crank pin of the set wheel is clear of the vice and at the top.

When you are satisfied that all is fairly square then gently close the vice a little to allow the axle to enter the wheel. Do not tighten up at this stage.

At this stage you fit the back to back gauge in from underneath.

Why underneath?

This is to avoid any possible fouling due to the back ends of the crank pins (which will be towards the top of the vice.) Hold the gauge to the fixed wheel and then tighten gently watching the second wheel pressing towards the B-to-B and finally straightening, ensuring the correct rim to axle relationship.This is one of these operations best done with a magnifier - it is so much easier to see.

[u]Please note this operation does not require a lot of pressure as you do not want to upset the fixed wheel's relationship to its axle. You can tell how far you need to go, as the point when the wheel straightens to the gauge, is it.

If you prefer, a second washer jig, same as the first, could also be made, if you feel it necessary, and fitted on instead of the small washer. I feel there may be a tendency to over tighten using two sets of jigs, however,and I stick to the one small washer.

Just in case you are worried about this stage.

The worst you can do on tightening using this method is that you move the first wheel a little, but you have reached the stage where the wheels were parallel and moved on slightly, so the axle has moved slightly in the wheel and therefore may not be not entirely flush with the boss. As long as all is square I would not try to correct this as the main relationships should be OK. The axles are often a little short anyway. There will be a limit to the travel on the newly fixed wheel anyway so it is not going to be much, if you think about it.

The gauge should be a sliding fit between the wheels.

Complete the other wheels and place the wheel sets into their correct positions in the chassis as you go along, making sure that you have everything sliding up and down and turning where it should.
If you have done this stage correctly all of your wheel sets should have their rims square to the axle, crank pins in line and ready to roll.

If you have completed this task then very very well done! Give yourself a Yabbadabbadoo !

Before going Yabbadabbadoo, oh too late! Just go and check the B-to-Bs and also place the wheels in the quartering jig and make sure all is well, if it is not, then you are going to have to take some remedial action at this stage.

Since the lubricant is still in there, you should be able to adjust the wheels in the quartering jig using your thumbs. If the B-to-B is out then gently tap out the axle supporting the most recently fitted wheel in the vice. Re-set using the gauges, and double check the quartering in case you have knocked that out during the process.

If all is fine then all together........ Yabbadabbadoo!

Well done!

Allan

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The washer( a long one )fitted on the end of the fixed wheel with a piece of blue tack

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Set up the wheel set in the vice - make sure you have the crank pin clear of the vice jaws!

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View of the set up with the B-to-B in place from below

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The drive unit made up and ready for fitting - I do hope you remembered to put the unit in the correct way around, this one is easy to test for wobble

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[David Knight]

Allan,

First off, a very interesting and useful thread, thank you. Second, what would you recommend for fitting fixed axles in the frame ie where there is no provision for removal as may be the case with some of the kits and replacement chassis available? The actual pressing of the axle is not the issue it is the quartering that gets a bit dodgy

Cheers,

David

[Allan Goodwillie]

Setting the chassis height

Before fitting the coupling rods, I like to level the chassis. This does not take long.
Before starting I make sure that the fixed axle is sitting level in the chassis and I then tape it in place.

If the back axle is not sitting correctly the chassis will sit lop sided , you can check with a square. If you have constructed your chassis well, this should not really be a problem. If anything is wrong this way then take out a gnat's whisker from the slot on the higher side and this will allow you to alter the level if necessary. Having such a problem when using this method of construction is fairly unlikely , but worth checking for, before going on.

Having checked this, I lash up the motor and the other axles temporarily with some tape, to stop them dropping out.

If you are building the compensated chassis then I hope you have made sure that the compensator is resting on the top of the axles when you put the axles in, if not then do that now. Also make sure that the compensator does not foul anything, including spacers as there has to be freedom of movement hear.

Place the chassis on a sheet of glass and using your vernier check the ride height front and back making sure that the back axle is set into its guide.

To alter the compensator is not too difficult really. The compensator, if fitted, can be taken out for bending by pushing the wire out from the side of the chassis.

If the front of the engine is sitting low then the compensator will need bending downwards towards the ends, do this gradually a bit at a time until the chassis sits properly and that its top edge is level.

If the chassis is sitting too high at the front then bend the compensator upwards at the ends.

If you are building a sprung chassis then fit the screws on the top of the horn guides and screw the front pair down until the chassis sits level front and back with all four wheels on both axles sitting level on the glass. Then screw down the two centre ones until there is no slop in any of the boxes and all wheels are sitting correctly. No springs are used at this stage.

It is also worth checking again that the chassis is sitting level when seen from the front or back,if wrong then it means another look at the rear axle. You then have to go and reset the other wheels after any alteration until you are sure all is sitting level and the chassis top edge is at the correct height.

Allan

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Temporary taping of the motor and rear wheels to keep them fully in the guide

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Temporary taping of the axles allows for movement, but stops the wheel sets dropping out Note the compensator in place on this compensated unit

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Checking the height using the vernier's end gauge

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Fitting the screws into the guides of the springing units on a sprung chassis

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The two chassis sitting level

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[Allan Goodwillie]

Fitting the crank pins

Having levelled the chassis it is now time to deal with the coupling rods.

I had paired them up earlier and now it is time to fit them. Before I do, I check the coupling rod thickness by putting a bush through each hole in the coupling rod in turn, if the coupling rod is thicker than the bush, then thin it down using a file until the bush just stands proud of the rod. Do not file the bush. This will allow the coupling rods to move without any friction due to the retaining nut and washer. Remember to do this also with the combined thickness of the middle joint.

Plenty of locomotive builders put engines together without this check and assume that it is the quartering out if they do not get good running.

When checking each hole and bush, take a smidgeon of material from the hole using a suitable broach taking a small amount from the back and then from the front in turn until you have a working clearance, which will allow the bush to just turn in the hole, keep your holes round but take only the minimum of material away. Do this with each of the coupling rod holes taking care as you go.

Before test rolling the chassis make sure that the back axle is still free to move and that the gearbox grub screw has not tightened up. Give it a roll before adding the coupling rods to check.

We now deal with the first two axles and get this part of the chassis running.

Fit the two front coupling rods on to their bushes and wheels , fit nuts and washers and try to run it down the slope. It may well go first time , but do not be disappointed if it doesn't.

If it doesn't then take a little smidgeon again from the holes that may still be a little tight,using the previous technique. Now try again. Continue the process until there is no sense of binding and the chassis runs down the slope. Now do exactly the same thing with the rear axles having disengaged the front coupling rods - again treat the chassis as an 0-4-0 and when that is working, then combine everything to form an 0-6-0 chassis. Again do a rolling check. All should be well.

If at any stage it is clear that things will not run you may need to double check the quartering on the jig, just in case you have moved something. Unlucky if you have, more likely to happen with "Sharman's" than "Gibson's" Especially if you checked after you pushed them home in the vice.

If you really have to:

Sharman wheels can be turned and quartered by hand, simply resetting them in the jig and putting a bit of pressure on one of the rims holding the other rim in place with its pin against the stop. If you are lucky then they will not go out of gauge, but I would still run a B-to-B through to check.

If you have moved the Gibson wheel out of its quartering then I am afraid you will possibly have to re-quarter and re-set the wheels by taking them apart again If you want to try the same trick as the Sharman's then I suggest you wear leather gloves as it is possible that you may cut your fingers otherwise on the flanges.
If you have to, take off the wheel you fitted last on the axle by supporting it in a vice and gently tapping the axle out. Use your centre punch and a small hammer. This is when you realise that it is not always a good thing to glue the wheels on.

Double check your other wheels two small amounts can combine to form something bigger.

Go back and re-do your quartering and setting and check the other wheels while you are at it just in case - might as well deal with it - although disappointing I know, do it now, this is a job that is best just tackled full on and dealt with, but do not hurry with it just make sure you get each stage right. Put off if you must, but tackle it the next Saturday session.

Once you have your axles set correctly then have another go with the coupling rods and I am sure you will have success this time.

Important - Do not be tempted to solder or glue your coupling rod retaining nuts on at this stage. You have done a simple rolling test, but there are more tests to come before doing this.

Go and relax for a while the most difficult parts are over you have done well.

Allan

[list=]

Connecting up the front two coupling rods rear bush being held in place using blue tack

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View of the chassis rear and the fitting of the rear coupling rods is under way

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Temporary support holding the chassis in place as the nuts are tightened before a rolling check for all wheels

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Both chassis dealt with and waiting for fitting of pick ups and under gear before power testing.

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[/list]

[Allan Goodwillie]

Hello Dave,

Simply -
I tend to treat other chassis in much the same way and make the fixed axle so that it can be dropped out as I do with the other axles. This method I am recommending allows you to deal with all the tricky bits away from the chassis and deal with any problems within a sub unit. By creating jigs that keep the basic relationships right all the bodges including the quartering are eliminated.

Although it takes a little time to alter any chassis, it saves time in the end which would be spent trying to get good quartering etc. There are some cases where you have to quarter by hand and there is no choice.

I am hoping to cover your question by showing examples of what I have done on other chassis.

The idea of showing this method here is that there should be no bodging and that things like quartering should be done using jigs to get it right every time. If the only difference in construction is the fixed rear wheel then this final quartering could be done by hand. I have been able to use my quartering tool in conjunction with many a chassis. Brake gear and sand boxes can get in the way, but not if they are left off and glued on later. The wheels are still pressed on in the vice using the same jigs having fitted one wheel first.

I do prefer not to be doing it this way however as I am sure you will understand.

I am intending to have a short break at this stage for people to catch up on the building notes and to get their own locos on a bit, I am also involved in a couple of exhibitions coming up and have a couple of locos to deal with fairly quickly as well as the construction of other items. I am hoping that some people will maybe show a couple of photos of work in progress or photos of putting some of this information into practice.

For those local to us:

The West Group have a meeting next Tuesday evening in Glasgow. I will also be with the East Group and "Burntisland " at Glasgow Model Railway Show coming up soon, so if anyone wants to meet me or wants to come along to a group meeting we would be very pleased to hear from them as we are encouraging new members.

Starters are more than welcome.

I will try to answer any questions during this short break, promise

Allan

[Russ Elliott]

I like your coloured dots on the blocks! (I tried using paint, but being fairly clean brass, it only stayed on for about two minutes, so I now scribe lines with a scriber, but they tend not to be very visible.)

Anyway, concerning the securing of crankpin nuts onto the bushes, I had a four-coupled chassis which ran reasonably with the nuts not tightened up, but as soon as I tightened the last nut up, the chassis would bind slightly. I suspect I had got a mismatch between rod centres to the hornguide/block centres, but there was a certain amount of slop between the bush and the pin (Sharman wheels). I think what was happening was that, before the nut was nipped up onto the bush, the bushes were free to take up a 'revolving' position around their pins, and hence no binding was evident, but as soon as a bush was nipped up in position to secure the bush position, inevitably the chance of it being locked in the 'optimum position' was minimal. I found, by nipping up the nuts a fraction at a time, I could get slightly less binding, but it was never a satisfactory process, because I could never be sure any single bush axis was properly on its pin axis. Any suggestions?

bush-pin-slop.png (1.19 KiB) Viewed 8793 times

[David Knight]

Allan,

Thanks for your reply.

As a possible aid to anyone who needs to remove a wheel may I suggest a look at Scalefour News 145 and the article "A Poor Man's Wheel Puller" some pics of which follow. This tool is also handy for making fine adjustments in gauge for both drivers and carrying wheels.

Cheers,

David

[Allan Goodwillie]

Hi Russ and Dave,

I will try to cover various points you have raised. First of all it is interesting how many small things can be a problem that you may never think about. It hadn't occurred to me that this could be a problem with the bushes and that may be because I tend not to tighten mine up fully, but go to the point where there is no discernible gap and then solder the nut and washer in place.

This, I suppose, means that it is still possible for the crank pin bush to revolve if it were slack on the nut. The reason I do not tighten them up fully is because I have found that in tightening up fully, sometimes you can bend the crank pin and throw it out of true, resulting in binding. Having gone to some trouble to set all the crank pins to a point where they are completely accurate it would seem a pity to loose that accuracy.

When I get around to soldering I put a cigarette paper between the washer and the coupling rod and bush. The bush, rod and crank pin having been given a coating of grease, I then apply the nut and carefully wind that up , but do not over tighten, as the paper is providing the working tolerance.

I trim back the coupling rod pin until flush with the top of the nut and file the surface clean and ready to take solder. (This operation requires a little care again - not to bend the crank pin. I use sharp side cutters and a piece of wet and dry stuck on to a lolly stick - yes we will come to that one later.)

Then I put a little amount of flux on the nut and momentarily touch it with a small soldering iron bit with solder on the tip. A quick puff of flux and the job's done. The paper also means that the whole thing does not solder up solid.

I do not dwell on it, as you do not want the heat going down to the plastic and melting it! The paper acts as a spacer and also stops flux splash back on your wheels and valve gear. I should perhaps have said this when describing the fitting of the coupling rods, but I have not reached the position where I would have soldered them, as the wheel sets will be dropped out again (probably several times) as I deal with other matters, particularly the pick ups .

I will go back and mention this in the notes, as I do not want anyone soldering up the crank pins at this stage, if they are following me and building a chassis on their own - I still have to cover running /testing where all sorts of things come into play.

As you can see Russ this method means that the bushes are given "free scouff" - a Scottish expression meaning " Complete Freedom from the domestic authorities" so I suppose they do as they please, it probably splits the wear between inner and outer surfaces I should imagine. I have to say that I have had no particular problems with this as far as I have been able to detect, but that is maybe due to my method of securing the coupling pin nuts and washers. Please let me know how you get on, you could try a temporary fixing using blue tack, if your pins are still full length, and try setting them to give a small margin and see what happens.

It strikes me that if engines haven't run for a while, that a little touch of oil would stop any tendency for the bushes to seize up and cause bother by their egocentricity when they are taken out and run.

The markers I use, as you can see in the photographs, are CD markers made by TDK and do seem to mark permanently, anyway I am happy with them. One or two kit manufacturers have numbers etched on their frames and blocks, which I think is a very good idea. One of our West group members is having a go at one just now (a Dave Bradwell N2 Kit - a beautiful kit and one worth taking time over and enjoying) This is his first project and I am looking forward to seeing how it is progressing at our next meeting. I am sure we will post on the web some photographs to show progress and the finished work eventually.

I am hoping other members having a first or second go and using this thread to give them ideas and comfort, as well as advice, may like to send photographs of their projects at various stages. I for one would look forward to seeing them - I will be a Scalefourum this year with a workbench and would love to see any locos in the metal as it were, finished or unfinished.

I would also like to thank Dave for reminding us all about the simple and cheap wheel puller - easy to adapt and make - I knew I had seen it somewhere, but had not had time to go and look it up. Excellent! I must have a go at making one which would slip along the back of the wheel rim, catching most of it and screw in to the end of the axle so that the relationship between wheel rim and axle was maintained. Very interesting Dave , yes very interesting I will go and read the article tonight.

Thank you both

Allan

[Philip Hall]

I had a four-coupled chassis which ran reasonably with the nuts not tightened up, but as soon as I tightened the last nut up, the chassis would bind slightly.

Russ,

Some of the crankpin bushes I get do not always have the hole in the middle. I keep a stock these days and weed out the faulty ones. This is usually the cause of the problem.

Philip

[Russ Elliott]

Philip - I think my Sharman bushes were concentric but of over-large bore. I'm not planning on trying it, but I guess eccentric good bore bushes might have their uses, if they could be orientated correctly:

eccentric-bush.png (3.55 KiB) Viewed 8762 times

[grovenor-2685]

Yeah but sods law says they will always be oriented wrongly.
I have come across those eccentri bushes too, they don't go on the loco.
Cheers
Keith

[Russ Elliott]

Yeah but sods law says they will always be oriented wrongly.

That's why I'm not planning on trying it!

[Allan Goodwillie]

I think this proves my point about checking everything at the point of purchase as you do travel hundreds of miles to get to a show, sometimes, and it is best to check before the journey home. I bought a gear set one time at Scalefour North , only to find that one of the gear wheels was missing when I reached home.

I bought spare bushes some time ago to replace ones which have been on locomotives I built years ago. I thought I would replace them during a rebuilding program. I do have a look at my bushes before fitting, but I have to say that I have not come across the problem up to now, maybe I have been lucky, but it has made me go and check what I have in stock, but I have not come across any rogues.

I would be wary of using any odd ones too Russ!

I remember my father bought a brand new car once and found it would not run properly, in fact the vibration coming from the engine had to be believed. He took it back to the garage and the car was sent to Fiat - it turned out that the camshaft was oval instead of round at the ends, it just had not been machined correctly! A replacement was put in and all was well in the end although it did take some of the shine off the purchase of the car.

I don't think there is any mechanical process that cannot go wrong and the fact that dodgy components do get through is more to do with the checking process, so we have to be our own checkers I guess. We can always go back to the manufacturer or supplier who, if reputable, will be happy to exchange.

Difficult if you have had the items for years, I personally would be unlikely to go back after a period of years.

Allan

[Philip Hall]

Russ,

Some of the later Sharman bushes were a bit sloppy. If they weren't too bad, my solution was to fix them with a drop of Loctite 601 - this seemed to centre them acceptably as it set. You could still get them off again with a touch of brute force if required.

Philip

[Russ Elliott]

Some of the later Sharman bushes were a bit sloppy.

Yes, thanks Philip, I think that was my only substantive point. It's worthwhile checking that the pin does come out of the front of the wheel at a proper 90 degrees as well. I think it's true to say that most people will only seek out a Sharman wheel if there isn't anything suitable from either Ultrascale or Gibson. (I understand the remaining stocks of Sharmans are still available on enquiry to the Stapletons, but it is very unlikely that any further new batches will be produced, unless for a special high quantity order from a kit manufacturer, say.)

It all adds up to Allan's point about trusting nothing and checking everything!

[David Thorpe]

Tool Listbuy a caliper gauge, you get very nice digital ones out of places like Liddle at a very reasonable price, once you have one it will surprise you how often you will use it.

For anyone who is interested in one of these, Aldi (at least here in Scotland) currently have digital calipers at £8.99. They're 4 in 1 calipers in that they'll take internal, external, step and depth measurements, they've got an LCD display, and they come with a case and a spare battery as well as a 3 year guarantee. As is the case with Aldi "specials", when they're gone, they're gone.

David