5" Gauge L&Y Aspinall Class 27

[kipford]

The pins used in all the photos are standard aircraft skin assembly pins. The sliver pins are cleco skin pins, which are a rapid, insertion/removal pin for rivet holes. The red pins with screw tops used to be known as Avdel pins, they take longer to install/remove but pull the skins tighter together. The clamps used on the water filer are cleco side clamps. The cleco pins all need special pliers to install/remove them although it is possible to make your own. All these items are available on eBay at modest cost. The cleco and Avdel pins are available to suit 3/32, 1/8, 5/32 and 3/16 rivets. The ones in the tender photos are all for 3/32 rivets or equivalent size fasteners. I have most sizes and have accumulated them over the years from various sources, work , car boot sales and buying from Ebay.

Edited June 19, 2018 by kipford

[N15class]

We used to have them laying around all over the place at home when I was a kid. Father was an airframe fitter in the FAA, then with Vickers.

[kipford]

This is also a frustrating business. Drilling the frame holes on the last pair of tender horns and the speed controller on the mill went you what up. Now have to sort out if it is repairable or have to buy and new one at £120. Not so much concerned about the money more the hassle it causes.

[kipford]

Hurrah fixed the mill, found a wire had detached itself deep inside the control box. Horns finished and statred to be riveted to the frames. Will post some photos over the weekend, SHMRC AGM tonight, beach tomorrow.

[kipford]

Screwed up a set of 6 axle boxes yesterday, that locate in the horns where between 0.1 and 0.3 mm out of alignment side to side. The guys in the machine shop at the Mid Hant Railway identified the problem. Seems this is due to me not holding an important datum against the fixed side of the machine when flipping it over. So new piece of 32 mm square bar ordered and I will start again. 1 step forward 3 back!!!!!!! 

 

Anyway something a bit more interesting I have had a couple of parts lost wax cast in brass by Shapeways  recently. The dummy tender water scoop operating cock and the tender water cock body. Simple this same process as for any other Shapeways part. Upload model, select material, check it passes the model check, pay around 16 euros and ten days later the bits arrive. The water scoop part in particular is quite complex as an assembly. The part were printed using different values tessellation to create the stl files used for 3D prints. The first pictures shows the 3D solid model for the operating cock and water cock respectively. When you create an stl file, the software takes the solid model and creates 3 dimensional mesh formed from polygons normally triangles, this is called tessallation. The size and density of the polygons used in the mesh will effect the print quality of final parts particularly if elements of the mesh created are larger then the printer layer thickness. Pictures 1 and 2 show the 3D models of the parts. Picture 3 shows the cast parts. Picture 4 show the tessallated part of the operating cock using the standard default setting of CATIA. Comparing pictures 3 and 4 shows that the large amount of faceting on the cast part is in line with coarse mesh from the default settings. Picture 5 show the water cock tessellation after changing the settings to produce a much finer mesh. Refering back to photo 3 shows within the limits of the casting technique the water cock to have a much finer finish.

[brianCAD]

Dave,

 

What's the physical size of your components ex Shapeways?  Unless the parts are very small, I'd venture your STL files were a bit light on number of polygons. I'm a bit disturbed by the very coarse finish evident.

 

Shapeways services my part of the world from New York, so possibly results from there are different to European production?  I crank up the polygon count so that STL file size approaches Shapeways maximum of 64mb - and leave it to their software to crunch them down to whatever is needed for printing waxes at 16 micron layer thickness.  Sometimes I wonder if they have used a coarser machine setting to speed production. . . .  

 

Whoever converts the waxes into brass castings (contracted out apparently), insists on rumbling the castings - so any desired sharp edges can be lost - and certainly so if the option of 'Polished Brass' is chosen.  Adding a small machining or filing allowance to any flat face that can be accessed readily later, is one way of preserving crispness.

 

-Brian     

[kipford]

Brian

Thanks for the response. The parts are about 12 mm long so in casting terms not very big. The water scoop certainly has too few polygons, the watercock is at least an order of magnitude better and the casting is better. I did this comparison to show that the fineness of the tessellation can have a significant influence on the finishe'd part. I did not go any finer, because in my opinion the Shapeways process is not capable of giving any further benefit because of it. The photos are very cruel and by the time they are fished and mounted on the tender you will not be able to tell the difference. I have some more parts to make but these are much larger and will go to a more specialist model engineering casting supplier.

[brianCAD]

Thanks Dave.  Your parts are indeed small at sub fingernail size.  I sometimes find myself defending Shapeways when parts have been produced from elementary CAD or minimally sized STL files.  No chance of that from you, using CATIA.  Can't be many modellers so skilled or equipped with that package. The blends in your file of the three-legged component are very nicely executed.

 

A model engineer local to me, uses the same machine as Shapeways for waxes.  Most are made at the 25 micron setting (for 5inch gauge) and the castings are sold globally.  Being a fussy bu99er, I prefer the finer layer thickness setting of 16 micron, albeit it being more expensive.  I'm not sure Shapeways can always be relied upon to use the finer setting.  For a time (when it was available), I'd just buy the waxes and get another party to do the casting - for a better result.

 

Output from in-expensive DLP type printers is now proving superior to the processes described above - and is worth checking out for that 'special little bit'.

 

ATB - Brian

[Spitfire2865]

Something to be aware of if using Shapeways for brass castings, they have a minimum cost of $14 US, so regardless of how small the part is itll always be at that minimum. You are however able to sprue parts together to try to get a better cost savings.

[kipford]

A while since my last post and lots of things happening like going back to work for 4 weeks because they were in the sh1t and offered me a load of gold and silver!

Anyway here are we, still on the tender of course:

Axles Boxes:  These were supposed to be made from bronze castings, but the castings were crap, being too small and not cleaning up when machined. So I cut my losses, binned them and redesigned them in steel using needle roller bearings. I then wrote off the first steel set due to me assuming a slot drill will cut to the size it is supposed to be! The machine shop at the Mid Hants Railway where I volunteer put me right on this one and advised a suitable machining technique and sequence. The photos below show the squared off blocks and the finished items. I must admit I am quite pleased with the result and learnt a hell of a lot about using a mill.

Stages of manufacture

Finshed

 Tender Horns: These were rough machined from the castings then riveted to the tender frames. The frames were then bolted back to back and machined a couple of thou under size relative to the axle box width to allow a bit of wriggle room when I finally assemble the tender chassis.

Castings

Machining stages

 The wheels and axles were then machined from castings and loctited to the machined axles. A fairly simple job for now having made the driving trolley.

Casting and faced wheel

 

Facing in the four jaw

Various bits!

Complete axle assembly

Next start of the tender brake gear. The brake shoes I had laser cut in a ring, which allows them to be easily machined on the lathe then cut up with a hacksaw. The brake hangers bushes were laser cut items with machined bushes silver soldered to them, same for the brake shoe hangers, the sides were laser cut with machined top and bottom bushes.

Things have slowed up a bit at the moment as I am building the test etches for my LNWR kits, building the points for my sons new layout (ready for his birthday) and have just started a run of three exhibitions in four weeks!

[kipford]

A while since my last post and lots of things were going on like, going to New Zealand on holiday for 5 weeks!

Anyway here are we, still on the tender of course:

I have made about 90% of the tender now, with only the last parts of the brake system, tender springs and the water valves to go. Then it needs undercoating and assembly. I will top coat the tender body when the loco is finished.

 

On axles for first time

First stages of brake rigging.

Hope they are of interest
 

Edited April 11, 2019 by kipford

[mswjr]

Nice work Dave, Have a look at the bottom of rm web, There is a model engineering page with 5 inch gauge in it, might get more views there, Garry

[kipford]

Tender is now finished bar painting, this will be done later, it is now under wraps. Work has now started on the loco, photos of progress soon.

 

 

 

[kipford]

OK so have started on the loco itself. The frames already laser cut have temporary spacers holding them in their correct position. The centre stretcher was then machined froma casting, followed by the drag box. The drag box was a large lump of expensive bronze casting so it was essential to take it easy and get it correct, which luckily it is. I am now squaring up the cylinder casting, which is even more expensive. At this point I will not machine the cylinder bore, steam ports etc until a bit later.

First couple of photos of the partially erected frames, the next of the cylinder block on the mill. 

 

 

 

[sej]

Brilliant stuff!

 

[Coal Tank]

Very nice 

[kipford]

A stop and start time on the Aspinall since my last post. Other distractions have been haemorrhaging the time available to work on it. First after an offer I could not refuse, I went back to work for 7 weeks which involved living away during the week (very lucarative as I got paid travelling time as well) so I lost nearly two months there. Since Xmas I have had 6 weekends away at model railway exhibitions with my own Brighton East and the SHMRC's Hope-under-Dinmore. I was also finishing the production standard of an LNWR shunting engine and building the first prototype of the LNWR crane tank kits which I have been working on for the last couple of years. Finally I have been re-engineering the centre cylinder casting of unrebuilt Bulleid Swanage for the Mid Hants Railway, so the Aspinall has taken a bit of a back seat. Oh and like  I am also finishing a major piece of DIY. But am now starting to get going again and with social distancing I am going to have a bit more time to spare!

The first photo shows the two LNWR girls on Hope at the Leamington exhibition, then the bits I have finished on the loco since completing the tender. Loco frames with horns fitted but not final machined. Drag box, boiler stay, motion plate, the complete cylinder assembly including the blast pipe, front foot steps, rear foot steps/valence and the ashpan/grate.

The ashan/grate was finished last week. Don Youngs design has a fixed gate with the only access either via the smoke box and the damper flap. I was not happy with this and wanted to try and get access to empty the ashpan from underneath the loco. However the centre pull brakes prevent the ashpan being a simple drop down affair. I did not want to change or delete the brakes so came up with a compromise design which has two dropdown doors and a moving grate. By drop the doors and the grate there should be sufficient room to remove any detritus from the ashpan and grate.  The next couple of photos show the result although It is not fully cleaned up yet.

Today I started work on the axle boxes and the photos show progress so far. Being a split box design , I was very nervous about getting the fit between the two parts correct. It seems myself and my mill can work to the required

accuracy.

 

Dave

Edited March 25, 2020 by kipford

[AndrewB7585]

Hello. I’m looking at building a Don Young Aspinall so this thread has been interesting to read. A pity the photos don’t show anymore as I’m sure they could have been very useful. How are you getting on with your loco?