Guy Rixon

"Racking" usually means distortion of a structure under uneven load. I suggest that the racking plate doesn't protect against the spring punching out the floor, but it does stiffen the headstock and the other cross-member behind the spring (which is taking the pull from the drawhook?) against being pulled and pushed out of shape by the buffing and traction forces. 0.25" of steel end-on might be quite useful for that. But I don't work on full-sized coaches so it's only a guess.

This is based on only one photo, mind. It's possible that one particular painter mis-read the livery sheet and got laughed at. If the point of an unpainted interior is to avoid contaminating the load with paint flakes, there must have been some very specific logic to say that a load above the side sheeting isn't vulnerable to this. I speculate that loose loads had to be protected from contaminated and crated loads, or stacks of sacks, were considered immune.

After a summer and early autumn away from model-making, I've acquired a wagon during a brief return to the workshop. This is a mid-period D1327, built by Ashford works in 1883. It's rated at 10 tons load and has the ordinary, low-speed running-gear instead of the "express" type that became typical between 1885 and 1895. The model is based on a one-piece print from the design of skinnylinny, realised in PU resin by DLS process. I got this, and its three siblings, by an indirect route and can't arrange supplies for anybody else. However, if you should be offered something equivalent I suggest grabbing it as the quality from this process is very good. The original design includes axleguards and axleboxes, plus a pre-planted brake hanger, but not buffer guides. Mine got modified from that form because I lack the tools to finish the printed running gear. The printed bearings weren't a running fit on 26mm axles as received, and reboring to take brass bearings needs a special tool. It was quicker for me to remove the axleguards and fit Bedford ones than to acquire the bearing-boring thingy. Changing the axleguards to sprung parts forced me to change the axleboxes, as it's hard to hollow out the printed ones to clear a moving bearing; PU resin is harder than polystyrene, but just as brittle. The printed originals were fine cosmetically, but the easiest way was to sacrifice them and replace with RFM prints. The buffer guides were home prints and the buffer heads (unsprung) by Slaters. The brakes are the original parts, but I had to move the brake hanger firstly to clear the axleguard bridge and secondly to align with P4 wheels. It's quite hard to glue a resin brake hanger accurately into place, so I ended up making it into a free-standing assembly with plastic outriggers, placing that and CA'ing when it was aligned; seems to have worked.

I didn't put the Laycock vents on the print as I wasn't able to get to a GER one to measure it; no chance to get on the roof of the preserved coaches. Also, lots are available as castings and they don't vary all that much between railways. If you think large vents are needed, and particularly if you want larger diameter relative to the point-to-point length, then I recommend the SE(C)R castings sold by Branchlines. PS: or the prints sold on Shapeways by Bluebell Model Railway Shop, which are a model of the same thing, but neater than the castings.

Personally, I'd be OK with receiving designer's commission a few months later. It's what happens at SW anyway. To avoid a flock of micro-transactions, they accumulate the designer's cut and pay it once per month, and only when it exceeds $30. For me, that meant I got paid two or three times a year.

Yes ... but (for me at least), the big problems with Shapeways are not their print costs, but their vast shipping fees and their refusal to accept things as printable that are known to print well. If their charges per print could be matched, then I think a British version might have a market.

I'm interested, and could upload some STL files for tests. My stuff is only appropriate for the resin printers. To make this a viable replacement for Shapeways, we'd some agreements on how printability is worked out. Who does the support generation? How many iterations of test prints (with support variations) are needed to prove printability, and what cost to whom? What's the consistency of prints after printability is proven? If a third-party customer is unhappy with the results, how is this resolved and who pays? There's also the question of spruing parts. At Shapeways one has to sprue repeats of the same part. On my home printer, it's usually better not to. Would the resin parts be supplied trimmed or on their supports? How fully cured would they be? Shapeways FUD prints seem to be a little more robust that resin prints on my home machine. There are things that I can print at home but they break too easily in service so I don't bother. We'd need to know the minimum feature-sizes for the resin. If it's "no wires or walls thinner than 1 mm", then none of my range is viable. Also, if a print does happen to break during washing, who pays for the replacement? Sorry if this seems a bit picky, but to make 3rd-party sales work well we have to sort all this out. I'm sure that there are workable solutions if we don't have a rabid pack of shareholders making things difficult. If some prints are commercially infeasible (i.e. only OK for printing at customer's risk) then that's understandable, but we'd need to know before putting them on sale.

Thanks for the link. Their material guide for high-detail resin doesn't list minimum wire and wall sizes, so it's hard to be sure, and the firm is shut down for holidays at present. I'll ask them later. AFAICS, they don't offer 3rd-party print-on-demand, so not very attractive to me. I don't want to be in the supply loop. However, if I chose to license my designs to societies, a firm that does good, batch printing with SLA might be very useful.

Yes. It's interesting to consider the desirable characteristics of such a company. Runs materials that allow very fine details. Allows customers to print down to near the true limits of those materials at customers' risk. I.e., the "print it anyway option" is more widely available. Runs materials that allow surfaces to be properly flat without finishing processes that grind off details. Offers shipping options at a range of prices, including domestic, national mail service. Supports 3rd-party sales, so the designer doesn't have to be in the supply loop. Has at least a basic web-site for ordering, with perhaps hooks to connect from a Shopify site. Doesn't set too high a margin on the print prices. (That's desired features from the point of view of railway-gear suppliers. Investors would have other demands, of course.) It's the combination that's difficult. Shapeways have managed more of those features than any other company I know of; it's just a pity they now fail on the most important. I know that some modelling societies are investigating domestic printers that do nos. 1 to 4 and no 7, and leaving aside the feature for 3rd-party sales. Perhaps that's the way forward?

With regret, I have to announce the withdrawal of the Rixon Finescale Models range from Shapeways. Recently, Shapeways have started to reject items from orders as unprintable, even when the same models have been printed successfully before. They apply rigorously some rules on minimum part-thickness that are not enforced in the automatic tests, so that alleged problems can only be found by ordering a test-print. They apply thse rules retrospectively, so models that have already be test-printed are also likely to fail, and they don't respect the fact that a model has 100% success in printing. Finally, I'm told that any model can be rejected if a Shapeways engineer thinks it might break during processing, so nothing is safe, even if brought into line with the rules. Many of the products in this range are likely to be deemed unprintable under these rules. All the axlebox-spring combinations have to go, and all the brake assemblies. None of those are worth printing if they are made thick enough to meet the rules. Other products may be at risk too, but without doing test-prints of everything I can't be sure which will pass and which will fail. I can't afford to test-print everything again at once! Therefore, I will be taking the whole range off-sale for the foreseeable future. The shop will remain as a record, and I might put some products back on sale if I validate them with test prints; but that would only happen where I need the prints for my own work. I apologise to anybody who's been inconvenienced by this, but Shapeways have put me in an untenable position.

I suggest making the infills for the turnouts as removable units, locating on pins that go through into the baseboard. That's 1 mm brass pins that slide in rather than hammered track-pins. Then you can lift them out and fix them if they give grief. Or lift them out and bin them if they give continual grief. That's what I'm planning for my layout.

The coarser standards in 4mm scale make this harder, particularly with the over-scale throw of the points. One could cheat a little and paint the surface over which the points move the same colour as the road surface. Then the bicycle-swallowing canyons would not be so obvious.

It's nothing to do with P4 vs. EM. The problem that Dave T. describes applies to both gauges because the same chairs are used for both gauges. AFAIK, the EM tolerances aren't loose enough to overcome this. The DCCconcepts 3-point gauge for EM looks like the kind that avoids the problem by only gripping the rail head. It's harder to tell from the picture of their roller gauge, but that looks OK too. If you have either of these you can test the matter: put in a loose rail and if it can rotate in the groove a little around the axis of the head then its should be OK. If it grips the rail with the web at a fixed angle then you have problems. The gauge-narrowing problem can catch you out on curved, plain line as well as in turnouts.

Chapel tramway, Southampton; the wharves are on the River Itchen. Less well known than the tramway between Eastern and Western Docks. This was still running when I lived in Southampton as a child but closed before I was old enough to go exploring the town. IIRC, one of the wharves retained an internal railway after the connection to BR was severed. PS: if one zooms on the OS map (available free on the Library of Scotland site), there's a curiosity: the sharp curve from the exchange sidings to the tramway goes through the back yard of a house in Melbourne Street; it nearly goes through the outside loo! My guess is that the tramway was original worked by horses and connected via a turntable. The curve was presumably put in later when the industrial users got locomotives.

But if the radius of the transition curves goes to infinity at the point where they meet, does that not do the same as a straight length? How much straight would one need?