Member postings for Luker

Any late 50's twin cylinder. Parts are interchangeable for the most part, kick start easy and have that lovely sound that only a twin can produce.

My Ariel 650 has BSA heads and rockers…

Hi Robin, I normally don't get involved with online prognosis because there could be any number of reasons for what you getting there, but in this case I feel your pain! I had something similar when I bought my lathe and it was actually a design issue on the machine itself, and very specific to the machine, so may not be applicable to you. Most of the modern Eastern import gear head lathes sold with CQ numbers suffer from this. If you drop us a picture of your lathe and makers code, and its the same as mine I'll take some pictures with a short write-up and post...

I also thought the letters were a little harsh, with the author doing a good job in keeping the article and topic simple for most people to grasp the underlying principles. Seems people are very quick to complain about errors in drawings or poorly designed models but modern design methods like parameterization and linked 3D geometries don't find favour (at least if these letters are to be taken as the norm). If a designer uses all these CAD methods then models can be virtually assembled, the linkages tested and dynamically checked and drawings produced to a much better (building) standard than in the good old days of drawing boards. I for one enjoyed that article and found it informative, and make extensive use of parameterization, linked geometries, dynamic simulations, FEA and all other manners of jargon that you hear politicians say on a daily basis. (for Howard )

I had to replace a lost probe point a few years back. Normal inner ball from a std bearing was annealed similar to how Jason suggested; the only difference, it was heated on some dry sand (with a little dishwashing liq) and pushed in with a wooden dowel. Was drilled and tapped using HSS. Any concentricity issues are inherently solved by the small centre drill breaking, but even with a wobbler type probe if you centre it with your finger on the ball all will be good...

Press stick; used for center finding and assembly aid. Also good to stick charts to workshop walls..

Looking forward to this thread!

Here's mine: Its a V-block set that can be used as an angle as well...

I would push a bar of the correct diameter in some sand and cast as normal. Copper tends to react with oxides so casting into any pipe needs to be done with the pipe very clean, and don't stand over the pipe when casting. Once poured, cover the top of the copper with coal dust, otherwise it "boils". Sand mix:

3% water

10% bentonite (from beauty shop-face mask)

5%coal dust

5%starch (cake flour)

rem sand

With such a simple mould you'll probably get away with 3% water and 10% starch (rem sand)

I'm surprised copper isn't cast more often, a number of the older models had copper chimney stacks...

Yep this little loco is loads of fun on the track, and easy to drive (no pesky roof or cut-outs to take skin off). She takes two large adults without slipping or complaining (haven’t connected another drive cart to see how many people she could carry). She has a constant lead valve gear so you just slip the reverser in full forward and you can forget about it until you parked in the station again. I haven’t found the valve gear to be lumpy (suppose that’s the benefits of dynamic simulations) and I can get my fingers between the cylinders for maintenance etc. I actually blew out one of the valve chest gaskets when I was (abusively) testing the loco and it was no issue to take the cover off and replace the gasket (just baking paper, no sealant) on the loco. I had forgotten to tighten two nuts and she still steamed for the rest of the day. Incidentally when I test a loco I do a proper job to make sure the design is sound.

I like the analysis of the gents in the manufacturing yard picture! Seems like, even in those days the person that’ll do most of the work is furthest from the loco.

Na, I just liked the look of that low pitched boiler and the odd valve gear. I actually didn’t know of the connection to Pretoria…

I call this my COVID loco; it was designed and built in the first 9 months of 2020 when we had a very restrictive lockdown.

Hi everyone. Here’s a little sneak peak of my next construction series… hopefully not much longer before it gets published.

An exceptional video of the Ballaarat by Anthony Dawson (thanks to him for permission to embed it here)…

Thanks Nigel. Everybody at our club likes the wooden cab, it's a little sad that the roof and back panels are removed for driving. But she looks good on the display stand.

The water valve handles look like that because the builders used a valve that lifted instead of the normal turn-taper valve. I kept the valve simple in the model but tried to capture some of this detail.

One highlight of the American type loco is the stability on the track with the compensated suspension over the trucks(bogies) and driving wheels. She really does glide; even on our rough track.

The final installment of the Wahya series is in the current ME; finishing off the tender fittings. I hope the readers enjoyed the write-up as much as I enjoyed sharing the design and build. To close off the build I thought I would post some pictures of the ride-on seat (sporting fittings for the shovel etc. and hand break) and the full loco at our track. Thanks to everyone who sent comments both through ME and this forum, much appreciated!

Thanks Keith.

Yep I agree, and it should be a decent hauler. Its going to be an interesting build, I'm looking forward to see the loco take form.

Hi Bill,

I had a look at this loco today, its a 3.5g 4-6-2 with Facilitas on the side of the engine on the GA. As Peter said the drawings are old with no sheet descriptions etc. It looks very similar to the picture you posted.

The frame, motion work, wheels and cylinders etc. have been completed for the most part and the boiler looks like it’s complete but not fitted. A couple of interesting points that had me stumped...

1. There is no wetheader in the smokebox(according to the boiler drawing), it looks like the steam line to the cylinders is from the steam dome?
2. There are 4 flues for superheaters, the boiler is rather large with a long barrel and wide firebox. Seems a little excessive.
3. Both the petycoat and chimney are internally parallel.
4. For a typical loco like this, are all the steam lines from a turret or should they be on the backhead?

I’m curious to know if anyone has seen this loco in steam. Looking very quickly at the proportions and drawings it looks like it will be one hell of a steamer…

Ps, Peter I hope you don’t mind me adding this in…

Hi Chas,

I honestly don’t know if acetone works on other printer filaments, never tried. In my humble opinion and from my personal experiments fume polishing has less effect on the vertical edges of a print which is where it’s needed most.

The spray is not for porosity it’s to seal the print. If you have hundreds of lines thermally joined there might be places where they don’t join properly. When dipping the pattern the slurry fills these areas causing poor surface quality. If you’re using printed patters for investment moulding the foundry should do a vacuum test. An easy way for you to check is to submerge the pattern in some warm water and check for any bubbles as the air inside the pattern expands.

I think you misunderstand Jason and I RE the flexible (silicone) moulds. The end result is a wax pattern you give to the foundry. A positive is printed using 3D printing (or a sample), the silicone is poured around this (a negative mould), and finally you can pour wax into this mould. I unfortunately don’t have pictures of this exactly but I have used this process to make badges for one of my vintages, the underlining concept should be clear from the pics… Incidentally you don’t need to buy potting silicone, calking silicone with corn starch mixed in and a little terps as thinning agent will also work if you want to experiment a little. Tricks for mixing and releasing agents are in the article…

I agree, the bulking agents for these automotive fillers is talc. It absorbs water during the investment dipping process and creates ash when the shell is fired...

Hi Chas

The commercial prints for investment casting are typically done using a 0.6 nozzle, I would check with the printers what size nozzle they’re using. As you say the layer height and to a lesser degree the nozzle size will improve print quality at a cost. Acetone works on ABS prints but this is not suitable for investment casting as the ABS expands and cracks the shells. You need to check with the printers they are using the correct printing media.

Prints can be smoothed with steel wool, and you get a special silicon spray used in the investment foundry industry that seals the prints, but it is unlikely you’ll find this anywhere other than a specialised foundry supplier. I have used this on a large investment pattern we had sealing issues with.

I’m sorry to say that with once-offs there is no substitute for meticulous checks and repairs of the patterns. For multiple parts, as Jason mentioned, you can’t go wrong with silicon moulds. I wrote a short article on 3D printing for pattern making (including flexible moulds) in ME that might be of interest to you.

Hope this helps…

A-frame + transport frame maybe?

All my loco's have different couplings so it varies, but a simple clamping system to the tracks is used for all of them. The engine has a more substantial support than the tenders but essentially the same.

Talking picture...

I'm way to lazy to pick up a loco! Hopefully these pics of my transport 'system' will give you some ideas...

The stand with hoist...

The common transport frame for all locos...

Loading for a track day, all points interlock to prevent mishaps...

There's always something better but I've used that mix for cylinders and it works well. This of course depends on the piston width, rings etc. etc. I've also used that mix for eccentric straps and axel boxes so it has good bearing characteristics. It melts easily and it doesn't slag too much, but it does skin a little. Generally the skin sticks to the crucible so it doesn't end up going down the sprue. BTW you melt the scrap brass and tin first then add the copper, the other way round the brass freezes the copper and melts on the top. This will start fuming long before the copper has re-melted. To improve the surface quality you can add cake flour to the facing sand.

I've submitted an article on riser and ingate design with a smaller version of my program. The idea was to upload the program to this site as a guide for the backyard guys.

I was hoping Noel would join in on this one, Noels castings are exceptional!

You only prop the pattern on the sand when ramming the bottom part of the pattern. This is to keep the draft angles correct relative to the split lines. When you flip the box and fit the top part of the pattern it all works out.

I can't comment on casting brass cylinders as I've never done that, but I expect they won't last as long as the bearing alloys or cast iron. I have mixed Gunmetal from brass but the amount of brass used is relatively small to get the required amount of Zink, you still need to add Tin and copper. I have made Alumina bronze, tin bronze, gunmetal and cast iron cylinders and all have worked really well. The cheapest is the cast iron and alumina bronze but you need to add silicone to the alumina bronze to improve machinability. Incidentally all my alloys are mixed from scrap, and when I had a few tested they were surprisingly within spec. As Noel says the shrinkage and radii depend on the material and size of casting. If that's a ¬2kg (5 gauge cylinder more or less) I would use 3mm in that pocket and 1.5-2mm radius everywhere else. 5Deg draft in the pocket will help with removing the pattern without knocking the sides, as Noels says 3Deg everywhere else (from your pic it looks like you're using green sand). As for the risers and ingates I wrote a program to work this out, if you send me the surface area, volume, alloy you intend to use and weight of the end casting I'll plug it into my solver and post a screen grab. If you give me an indication of what alloy you intend using I can give some guidance on dusting and what to add to the facing sand to improve finish.

Other than the health issues with fuming zink the actual mass loss is very small unless you really cooking the melt for long periods. I did post a capping inoculant on one of the forums that will help with this.

The cost of this hobby gets me down a little, its not what its about. All my articles are geared to help the guy with limited recourses, using commonly available items.

The smokebox ring looks really good! Cylinders will be a breeze!