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Member postings for Luker

Here is a list of all the postings Luker has made in our forums. Click on a thread name to jump to the thread.

Thread: facilitas 3.5 gauge
16/05/2021 19:01:49
Posted by br on 16/05/2021 18:50:51:

Hi Luker

Credit for the picture goes to Keith Long who provided the link. I just lifted it and posted.

Fine looking engine

As an aside, I do find mystery threads like this that get you digging, most interesting,


thumbs up 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.

16/05/2021 18:44:36

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…

15/05/2021 06:05:53

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…

ariel badge on bike.jpg

flexible silicone mould.jpg

14/05/2021 08:25:54
Posted by JasonB on 14/05/2021 08:20:38:

I'm not sure some of these spray on primer fillers will work on the wax prints Chas is talking about, OK for plastic or masters for the silicon moulds.

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...

14/05/2021 07:46:05

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…

Thread: Locomotive Transport
29/04/2021 12:54:30
Posted by Speedy Builder5 on 29/04/2021 08:11:06:

I like the idea of your hoist. I was thinking about an overhead track system, but still have the problem of workshop to field track. How do you "Tie down" your loco to the flat bed ?

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...


28/04/2021 16:59:32

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...


Thread: Loco Cylinder Casting Pattern Advice
22/04/2021 06:39:05

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.

21/04/2021 06:49:51

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!

20/04/2021 16:09:26

Picture worth 1000 words...


20/04/2021 15:40:29

HI Buffer, you need both cores if you don't want large risers to prevent draw. You can use a staggered split line. When ramming patterns with a non-uniform split line you place a little casting sand on the moulding board, dust then push the pattern into the sand and ram normally. Then with the other side of the pattern you remove the bottom sand and continue as normal (normally it just drops off when you lift the box).

You going to need casting radii to prevent corner draw on those webs as well as a decent draft to get proper (tight) ramming in those pockets, otherwise you are going to get burn-on.

Hope this helped!

Thread: Design of boilers
20/04/2021 09:17:14
Posted by Nick Clarke 3 on 04/03/2021 09:43:55:
Posted by Luker on 04/03/2021 09:34:42:

I am not a fan of any requirements for professional or welder certification for the smaller boilers.

In the UK a non-coded welder needs to submit recent weld samples to professional inspection to comply with the current boiler code in addition to the inspection by a club inspector. This applies to all welded boilers and the material (welded steel or TIG welded copper) is not specified.

See paragraph 6.2 here **LINK**

Hi Nick,

I’ve finally had a gap at work and gone through the UK 2018 boiler test code (thanks again for the link). I found it a decent code to read. I’ve read far worse! Interesting stainless boilers isn’t specifically disallowed; it just can’t be tested using this code due to “specific” requirements. This makes sense if boiler inspectors aren’t trained with certain materials and current manufacturing practices. The code allows for a 3rd party boiler inspector to certify a published design of such a boiler provided he understands working with stainless (and is commercially certified). Boilers according to the code can be welded by “non-coded” welders but test samples just need to be commercially tested (as you pointed out), here I’m not sure if this will show any more than the standard v-sample vice bend test. Incidentally I think the section with the minimum sight glass point above the crown is a little dodgy; there should be a specified min value typically 10% top of nut.

At our club the boiler construction and testing follows and exceeds the requirements of this code, other than the use of modern materials and construction techniques. With this comes the necessary calculations and testing to make sure it is safe. As modern materials and techniques become more common place hopefully clubs will be more comfortable with newer techniques.

Thread: Wahya construction series
19/04/2021 15:20:29

Some pictures and schematics of the tender, described in the last article... The breaks were interesting for me.


tender trucks.jpg




17/04/2021 13:15:15

Hi Everyone,

A few more pictures of the Wahya cab... The steam valve handles are some of the smallest castings I've done (4 gram). The pointer in the gauge was made using a cellphone charger (electro-stripping technique).





Thread: Pattern making using 3D printing
12/04/2021 18:04:41
Posted by Brian H on 12/04/2021 17:54:37:

VERY interesting article. Are there any 3D printing materials that can be used in the same way as 'lost wax' ? That is without the need for runners.

I realise that this would destroy the pattern but it would be easy enough to print another.


Yep, that's in part 2 wink

12/04/2021 17:28:32

Thanks Ady, Neil.

I do actually use Cura, but I personally prefer to scale in the modelling package, with the pattern a linked part so it gets updated if the model is changed. The biggest problem with scaling in Cura is with items with a large hole (like eccentric straps or any part with a cavity in the middle that will be rammed); when scaling, the hole gets bigger but in the mould the metal shrinks away from the sand, again making the hole bigger. So you actually need to scale the part then resize the hole smaller to remove the scaling you’ve just added, minus metal shrinkage and any machining allowance.

Sadly the story in my article of the tips I order being liberated is actually a true story. I agree though if you can get the nozzles rather buy them. Incidentally the brass nozzle I made has lasted 2Kg and is still going strong, I’m not sure how long they should last?

The picture is of some castings from 3D printed patterns (cast iron) but the cavities required the resizing (smaller)…



11/04/2021 13:04:45

I was inspired by Jason’s thread and pictures of his Thompstone engine, so I took a few pictures for the “Pattern making using 3D printing” article. It morphed into a video, which I’m going to pay dearly for next time my beautiful wife wants to make a rotisserie chicken.

The video shows the 3D printed patterns and the (green sand) cast components. All these components are used in my various live steam locomotives, with all the patterns printed using ABS and cast in my back yard using a home-made waste oil furnace. The materials shown in the video include two different grades of cast iron, brass and alumina bronze, with most of the alloys mixed from scrap or base metals. The methods and techniques for this type of pattern making and casting is explained in the articles as well as methods to use these techniques for investment casting and flexible mouldings for those of us that enjoy restoring vintage bikes and need to make badges.

Thread: Thompstone Engine
07/04/2021 07:58:15

Hi Jason,

I read part one yesterday, enjoyed the write-up and I am looking forward to the rest of the series! That is one fine looking engine thumbs up !

Thread: Loco wheel profile chatter
03/04/2021 09:54:03

Hi Nigel, all makes sense, but if you’ve machined over 50 wheels it’s more of a chore than fun. The beautiful thing about this hobby is you can never be bored, currently my interest is in developing an alternative alloy for steam cylinders as tin is becoming exorbitantly expensive; cast the first cylinders a few weeks ago. The little ‘skinny’ mandrel handles a 1.5mm roughing cut without complaining which is not bad considering I mix my cast iron to be harder on the outer profile for my non-tired wheels; this is of course with chromite sand in this area. The wheels I cast in this fashion actually outperform the tired ones.

I started restoring bikes when I was at school, I don’t recall having any problems clocking the drums and skimming. I do however recall battling with rebuilding and truing up the wheels. If you interested in vintages I’ve uploaded pics of my 58 and 25. I had to make the brake shoes for the 25 as they were missing.

This morning I did a few experiments on a spare wheel, and I found a few ways to get rid of the chatter. Buffer’s method worked also, thanks for that. I think this little exercise will make a nice write-up, thanks to everyone that pitched in and steered me in the right direction.

PS: Buffer can I mention your method? If so can you PM me your name for reference.


02/04/2021 20:21:12
Posted by Weary on 02/04/2021 19:36:45:

Hello Luker,

LBSC's mandrel for turning locomotive wheels was fitted as follows:

"Chuck an odd casting or disc of metal a little smaller than the back of the wheel ..... recessing at the middle for about 1/32 in depth and 1 in. or so diameter" (quote from 'Virginia' notes, but similar wording appears for other builds) and then fitted with a mandrel which was subsequently turned to appropriate diameter. Thus the mandrel was principally for centering the wheel which was fully supported by the 'odd casting' or 'disc of metal' held in the chuck. The nut on the end of the mandrel was used to pull the wheel back into firm contact with the ad-hoc faceplate.



Hi Phil, I stand corrected. I just checked my Martin Evans book and he followed a similar approach. Looks like I found a novel way of doing things, and as a plus my wheel flanges have additional grip for those corners laugh

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