Re: Rolling Stock for Banavie Road

Dog Star

Western Thunderer
Your solution to joining the parts for each side - two outers and three inners - so that the joints between inner and outers do not co-incide is an excellent idea.

From the information given so far, I think that the time taken to produce the body in the previous photo is around twelve to fifteen hours... which seems a really good investment for the result. I shall be interested to see how long the repeat body takes to get to the same stage.

regards, Graham
 

JimG

Western Thunderer
I shall be interested to see how long the repeat body takes to get to the same stage.

I'm working on the Full Third now. :)

Another time user is heat forming the sides, which takes about half an hour per part. I allow twenty minutes in the over at 100F to mould the tumblehome, but I've found that I have to let the Plastikard cool on the mould for about ten minutes otherwise the thinner edges tend to "frill" if taken off while still hot.

Jim.
 

Dog Star

Western Thunderer
Another time user is heat forming the sides, which takes about half an hour per part. I allow twenty minutes in the over at 100F to mould the tumblehome, but I've found that I have to let the Plastikard cool on the mould for about ten minutes otherwise the thinner edges tend to "frill" if taken off while still hot.
Your post suggests that you are allowing the plastic to "form" under gravity whilst soft. If that is correct then why are you not cold forming the plastic to shape and then warming to release tension in the sheet?

regards, Graham
 

JimG

Western Thunderer
Your post suggests that you are allowing the plastic to "form" under gravity whilst soft. If that is correct then why are you not cold forming the plastic to shape and then warming to release tension in the sheet?

Graham,

The parts are lightly clamped on a former to shape the tumblehome then put in the oven for about twenty minutes at 100F. I was finding that if I released them from the clamps immediately after removing them from the oven, that the thinner sections of the parts - especially around the edges - would distort. I find that if I leave them clamped in the former and allow everything to cool for about ten mintes, that the parts retain their moulded shape with no unwanted distortion.

However, I've still got problems with dimensions. The inner parts of the third sides were too short this time and on measuring them, I found that the three outer sections were too long and the inner parts were the correct length. I'm now just going through all my numbers and checking that they are correct. So far all the numbers look right, so it looks as though I will have to review the actual cutting of the parts.

Jim.
 

Dog Star

Western Thunderer
Jim,

Thank you for describing the heat forming process - very much as I expected. As I generally let "hot" plastic cool naturally and in the forming jig then I have not spotted what you describe as "frilling" - I understand what you mean and I shall try to avoid that featurette in the future.

Regards, Graham
 

ScottW

Western Thunderer
Hi Jim,

Looking great, despite the small hicup between the length of the inner and outer sides.

I'm also considering what to do about the joins. I was worried that the sides might not curve similarly and give quite noticeable ridges, but in fact the joins are pretty good and would only require very slight sanding to get them absolutely flat. But they don't look anything like the light grooving done by the Olfa cutter to represent the other door joins.

Could the answer to your door joint problem be simply to run an Olfa cutter very carefully down the existing join?

Regards,

Scott
 

JimG

Western Thunderer
Looking great, despite the small hicup between the length of the inner and outer sides.

I'm trying to get to the bottom of these dimensional problems. In the first, the inners were too long and in the third the inners were too short - or rather the outers were too long and the inners were the length they should be. I've audited all the CNC code and it is correct to the original CAD drawings. So once I get the AGM over tomorrow, I'll start producing parts again and measuring every one as it comes off the machine and see if I can suss out what's causing the problem.

Could the answer to your door joint problem be simply to run an Olfa cutter very carefully down the existing join?

I was afraid that the joins would be too good to locate a cutter in. :) However it would be an obvious thing to try. I'll wait till the joints have set hard so that the Olfa doesn't plough into the join.

Another problem is that I can't really see how good, bad or indifferent the door edge scores are until I paint them - the problem of working in white Plastikard. :)

Jim.
 

JimG

Western Thunderer
It looks fantastic Jim you must be really chuffed:thumbs::bowdown:

I'll be really chuffed when I've solved the size problems. :):):) But I do like the bolections and they have worked well and were easier to do that I had originally thought. My main problem now is that I have to paint the these bodies sometime and the picture of your van a day or two ago reminded me of the task ahead. The Caledonian had gold lines round all the panelling and round the outside of the bolections, so I'm hoping I can get the painting somewhere near as good as yours. I'm even thinking of using single hair brushes.:):)

Jim.
 

Dog Star

Western Thunderer
... I'm hoping I can get the painting somewhere near as good as yours. I'm even thinking of using single hair brushes...
Somewhere within an article on the Norris layouts, might have been Modellers Backtrack or might have been MRJ, there was a bit about how Miller had lined one of the engines. Miller is reputed to have said that he used a brush made of two whiskers from a tiger. Apart from the idea of Sid James hunting a Tiger up the Khyber, supported by a train of tea and tiffin, there might be some truth in using two stiff whiskers from "Tiger-the-puddy-cat" in the manner of a drafting pen.

regards, Graham
 

Rob Pulham

Western Thunderer
I'll be really chuffed when I've solved the size problems. :):):) But I do like the bolections and they have worked well and were easier to do that I had originally thought. My main problem now is that I have to paint the these bodies sometime and the picture of your van a day or two ago reminded me of the task ahead. The Caledonian had gold lines round all the panelling and round the outside of the bolections, so I'm hoping I can get the painting somewhere near as good as yours. I'm even thinking of using single hair brushes.:):)

Jim.

The best tip that I can offer which improved my lining no end is to open your can of enamel and let it thicken for a week or two giving it a stir now and then to stop a skin forming. As it comes it is too runny and drops out of the bow pen rather than flowing out.
 

JimG

Western Thunderer
Somewhere within an article on the Norris layouts, might have been Modellers Backtrack or might have been MRJ, there was a bit about how Miller had lined one of the engines. Miller is reputed to have said that he used a brush made of two whiskers from a tiger. Apart from the idea of Sid James hunting a Tiger up the Khyber, supported by a train of tea and tiffin, there might be some truth in using two stiff whiskers from "Tiger-the-puddy-cat" in the manner of a drafting pen.

That might be where I got the idea. Somewhere in the back of my memory is something about lining with a single bristle brush that I've read somewhere. I've done a bit of Googling but can't come up with anything.

Jim.
 

JimG

Western Thunderer
The best tip that I can offer which improved my lining no end is to open your can of enamel and let it thicken for a week or two giving it a stir now and then to stop a skin forming. As it comes it is too runny and drops out of the bow pen rather than flowing out.

Thanks for that. I'm keeping all the rejected pieces of panelling to use as practice pieces. :)

Jim.
 

JimG

Western Thunderer
It's been a while since I've done anything about the rolling stock for the layout. Most of my modelling has been concentrated on loco building, but I knew I would need some stock to go behind a loco so my attention has turned back to rolling stock. One of the first things needed is axleguards for wagons. There are some etched brass ones available from the S scale parts store, but I would be looking for ones which would be more suitable for Caledonian and other Scottish pre-Group companies, and I wanted sprung axleguards as well.

I had already drawn up artwork for sprung axleguards to go under the Drummond four-wheelers which had worked fairly well but needed a bit of fine tuning. So I opted to adjust the original artwork to (hopefully) improve operation and got PPD to re-etch them. And last week, a nice shiny sheet arrived back from Lochgilphead.

axleguards-01.jpg

Ten sets are laid out as individual sets so that if there is a possibility of the axleguards being wanted by others, individual sets can be broken off quite easily.

axleguards-02.jpg

An individual set in close-up.

axleguards-03.jpg

...and the individual parts broken out of the etch with the tabs folded up, along with an Exactoscale 1.5mm OD parallel journal bearing and a spring from (in this case) 0.0085" guitar wire. Just below the spring wire you can see the holes for the spring in the base, when it is folded up.

axleguards-04.jpg

A dry run with the parts. the spring acts on the tab at the top of the bearing carrier and it also holds the carrier in place, as does the axle when it is in place. The bend in the spring wire, as seen in the previous picture, prevents the spring moving right and the lug at the left prevents it going too far in that direction. The spring is inserted from the left, bending it gently over the lug to get it in the hole.

The intended method of assembly is to insert the bearing carrier until it sits on the lugs at the top of the "W" iron, then flex the spring wire to get it to sit on the lug on the carrier. The spring wire can be flexed by gripping the projecting end and wiggling it around. The operation has to assume that there is no easy access to the spring and bearing carrier from the inside since a 3' 7" coach wheel does a good job of covering everything up.

axleguards-05.jpg

The first adjustment to make to the etch was to bevel the tops - left - to allow the spring to be flexed over easily. Also, the lugs at the top of the "W" irons were reduced from 1mm long to 0.5mm to make slipping the bearing carrier up over them a lot easier.

axleguards-06.jpg

I also need some parallel journal axles. The S scale Parts Development department had investigated getting them produced but the minimum order quantity was something like 10,000. :) We reckoned that might have supplied the next two generations of S scale modellers. :) So I worked out a way of producing my own. I've finished up turning the points off the Society's pin-point axles (plenty of them :) ), drilling them 1mm and inserting short lengths of 1mm silver steel rod held by small dabs of cyanoacrylate. This works well and takes only a few minutes per axle in the lathe

axleguards-07.jpg

This is the assembly complete with the axle to check that everything fits and works.

axleguards-08.jpg

...then the assembly with the wheels on the axles. I'm still fiddling around to find out the best way of getting the spring in the right position. Sometimes I get it in position in a couple of seconds and at other times, I have to fiddle around for quite a while before I get it right. I'm also going to fit it in an underframe in case anything gets in the way and fouls the flexing of the spring. I'll also have a try out with wagon wheels since I suspect that the smaller diameter wheels will allow easier access to the spring from the inside and the external flexing of the wire won't be required.

The total movement of the springing is 1mm with the correct height of the vehicle being when the spring is at mid travel.

The original etch was designed to use the Exactoscale 2mm diameter bearings and I opted to use the smaller 1.5mm diameter bearings for the redo, but I think I will revert to the 2mm diameter bearings for any future etches. The bearing projects through the carrier and locates in the slot in the "W" iron. What I didn't realise is that the smaller diameter bearing is also 0.25mm shorter, so doesn't project as much through the carrier. This means that the positioning of the "W" irons needs to be quite precise. The longer 2mm diameter bearings will give an extra 0.25mm of projection which will give a good bit more leeway in the positioning of the "W" irons.

Jim.
 

SimonT

Western Thunderer
Jim,
this is really interesting but what is the function of the two tabs on the W-iron? Presumably the keep plate stops everything dropping out. The complicated Exactoscale spring units need a guide on the base to stop the slider splaying out but you don't have one. Is the fit of everything tight enough to stop this happening?

SimonT
 

JimG

Western Thunderer
Jim,
this is really interesting but what is the function of the two tabs on the W-iron? Presumably the keep plate stops everything dropping out. The complicated Exactoscale spring units need a guide on the base to stop the slider splaying out but you don't have one. Is the fit of everything tight enough to stop this happening?

Simon,

The tabs on the upper part of the "W" iron provide a sort of shelf for the bearing carrier to rest on and prevent it dropping out of the assembly as shown in the picture below.

axleguards-09.jpg

When the spring is in place, it holds the bearing carrier on these tabs.

I have had experience of Exactoscale and Bill Bedford sprung axleguards and this is my attempt to get round some of the features I didn't like. For instance, one of the benefits of using guitar wire springs is that you have the facility to fine tune the springing by altering the gauge of the wire. But on the Exactoscale units, the wire is clamped in the bearing carrier so altering that wire becomes a bit of a job to do. With my system, changing the gauge of wire will be relatively easy.

The one problem I might have is accommodating the spring retaining lug in some wagon underframes, especially if the framing under the floor is being modelled. I can see this as a a possible reason why Exactoscale clamped the wire on the bearing carrier to limit the length of spring extending outside the "W" irons to avoid clashes with other underframe items.

The lower end of the carriers is prevented from splaying inwards by the shoulders on the axle. I machine the axles to give 0.2mm clearance which gives an easy - almost mini-agricultural :) - fit to allow the bearing carriers to move easily, but still retain the of the bearings in the slots of the "W" irons. You can fine tune this fit by tweaking the "W" irons in or out, but I'm trying to set the units up with the "W" irons perfectly vertical if I can.

As for the alignment, it does depend on the "W" irons staying where they are put. I've etched them in 15 thou nickel silver so they are reasonably firm and don't wave about in the breeze too much. I do put a solder fillet in the internal corners which does stiffen them up, but I do have to be careful that the fillet doesn't foul the upward movement of the bearing carrier and I'm going to have a look at some alterations I can make to avoid this problem. It's also the reason I am reverting back to the 2mm OD bearings which will give an additional 0.5mm play allowance.

Jim.
 

JimG

Western Thunderer
Jim - what is your cream coloured work slab? I'm guessing a natural stone floor tile?

Tony,

I am trying to work out what the cream coloured work slab might be. :) I'm guessing that it's what's under the blue handled pliers in the last shot in the original post, and that is cork floor tiles. It was an experiment many years ago and it has worked out quite well, providing a resilient surface which is reasonably flat. But it does get dirty over the years and I assume that cleaning it would mean going over it with a sander, which I don't really want to do in the workshop. So I tend to cover it up with an A3 green work mat. :) The bit in the picture is a clean(er) bit. :) I have to confess that these tiles have been down for almost forty years, so maybe not too bad an exercise. The workbench under it was a base for a full length Victorian mahogany veneered dressing mirror which was left in my last house in Scotland when we moved in. I junked the mirror and took a saw to the central beams to narrow the base, then put a piece of chipboard across the top as a work space, and covered it with the aforementioned cork tiles. I've often wondered what the original mirror might have been valued at on Antiques Road Show. :)

workshop-01.jpg

Jim.
 
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