GWR57xx

As far as I can tell from internet searches no N6s made it into preservation. Does anyone know differently?

I've been doing a few changes to the design. The solebar flanges have been made thinner, as have the W irons and V hanger. Supports have been added to the brake handle and ratchet and these both now print ok. The door hinges have been moved down onto the solebars - I was originally working from a good quality photo of a P4 wagon, which nominally uses the same chassis as the N6 but on looking at fuzzy & grainy images of N6s (I can find any clear ones) they clearly have a totally different hinge system. I am a little bit concerned that the details (straps, brackets, rivets etc) are not prominent enough. I've only been looking at the prints so far as plain grey resin, so I took some recent test prints and gave them the Halfords grey acrylic primer treatment: The details show up much better with a bit of primer, compared to the plain resin on the right. I've also been working on the main chassis. This is the first test version - still needs a few tweeks, such as profiling the back side of the buffer beam to give the drawhook and spring full movement. It also rolls quite nicely. I took a video, but unfortunately I don't seem to be able to login to my Youtube account in order to add it here - YT says it's sending me an email to verify my identity (to the correct email address), but the email doesn't arrive...

You're most welcome! The one I downloaded from WhamBam's website is 2.6mm deep. If you apply the flexiplate to the magnetic base and measure the depth of the combination then this is the depth of spacer you need (allowing for the minimal thickness of the protective paper covering the glued surface of the magnetic part!). Yes, you'll need to print and fit the spacer before you apply the magnetic base, otherwise the platform will try to move through the screen with expensive results! Also, I seem to remember having to recalibrate the home position ("Set Z=zero" in the Tools menu) after adding the plate. I first ran the setting procedure without the platform fitted and measured the distance between the screen and the platform bracket to make sure it was the same as before.

Thanks. I also want to slim down the V hanger and W irons once I’ve got the basics sorted. Then it will be a case of experimenting with different thicknesses to get the best compromise between thinness, stiffness and brittleness for the resin.

Having been encouraged by the solebar success I wondered if 8s might allow the body to be printed in one piece. So another test - nothing ventured, nothing gained ... Sadly, NOT. It is certainly much better than the results at 5s with none of the big blowouts seen before, but there are still very bad layer lines for the lower third of the body (A). There are also (B) some small pinholes. Not easy to tell from the photo, but they are tiny holes all the way through the side. The opposite side wasn't quite so bad, just one pinhole: So it looks like I'll be printing the body as two pieces to be glued together later. No big problem! Also, I'll stick with the 8s exposure time for now as it seems to work well for strength and I can adjust the diameter of holes to cater for the expansion so that they end up being the correct size in the finished print. Thanks for suggesting that @beejack, I would never have tried it otherwise.

Exposure tests are all well and good, but they don't really tell me how well my wagon will print, so I ran a test print of the solebar at 8s: This was printed flat to the build plate with no supports, similar to the photo above. I am super happy that the brake handle and ratchet came out so well - I was really expecting them to fail. This means I won't have to make them as separate parts and glue them on. They weren't quite perfect though: Totally unsurprisingly they both have a bit of delamination at the ends. I have now added supports at these points, so hopefully they'll be perfect next time.

I've done a bit more experimentation. I looked again at the 8s results from the flat exposure tests and decided it was worth trying the more demanding vertically oriented tests to see how they turn out. I'd previously settled for 5s as the results seemed pretty good. Here's a comparison of the 5s and 8s test results: First of all I have to say how impressed I am that this little entry-level printer can achieve anything like this level of detail at all. Here's the Phrozen test piece: A) the holes on the 5s piece are quite a bit more open than those on the 8s. B) not easy to tell from the photo but the very finest hair-like columns on the 8s piece are much firmer. More significant is the row of hex columns on the far right, where the 0.3mm to 0.6mm didn't print at all on the 5s but are perfect on the 8s. C) the patterns on the 5s piece are more defined. D) the hole in the "nut" is slightly narrower on the 8s. The 5s hex measures 3.06mm across the flats compared to 3.09mm for the 8s, so it's grown a bit. Here's the Starship test: A) the biggest difference is the strength of the finest hair-like columns on the wings. B) the trenches on the 8s are very slightly less well defined. c) the gaps between the walls are equally slightly less wide. All in all though, both exposure settings have produced good results, it's just a trade-off between different features.

Ah, yes, I'd forgotten about that. There's a video guide here: https://whambamsystems.com/fbs-for-resin-support and also a free download of the stl file for the little spacer that needs to be fitted to the Z axis stop bracket (note that this is the correct depth for the Wham Bam system but may not be the correct depth if you are buying someone else's which may be a different thickness). I just sliced the stl and printed the spacer. I remember thinking at the time "How much trouble would it be for Wham Bam to print these off and include one in the package", since it is bespoke to the Mars 3. It's very easy to fit, just unscrew the bracket and re-fit it with the spacer in between. I found that the original screws were just long enough to cope with the extra depth.

The best add-ons I got were UVTools (free download software) and a Wham Bam magnetic base plate. UVTools lets you optimise various settings in the slicer output file - I guess you’ll be using the basic Chitubox? The main ones I use are the base layer exposure delays to eliminate “elephants foot”, and also the “Raise platform on print finish”. I ran my first print before I knew about UVTools, and at the end of the print the platform raises to the top of the Z column. There is a lot of resin still dripping off the base plate and this falls from a great height into the vat, splashing resin up the sides of the cover and all over the inside of the printer. This nifty option allows you to set an extra step at the end of the print to hold the platform at a lower height for long enough for the worst of the drips to finish, saving a lot of cleaning up. UVTools will also identify errors in your design, such as suction cups, overhangs, islands, resin traps etc, which can save you a lot of failed prints. I find the magnetic base plate makes removing prints from the plate an absolute doddle. I see lots of videos on line where folk are trying to chisel their prints off, scratching the base plate and often breaking their print that they’ve just waited several hours for! It consists of the magnetic plate which you stick to your Elegoo one plus a thin flexible steel plate that is held on by the magnet. At the end of your print just unclip the steel plate, flex it and your print will pop off effortlessly. Hope you enjoy your 3d journey.

Have you wired some of them is series and the brighter one in parallel by any chance? It also might be the case that they contain different luminance leds - they can range from about 3mCds to over 3000mCds.

Nice bits of kit. You may find it becomes a bit addictive!

I printed the calibration matrices (XP2 & Phrozen's XP Finder) at 8s normal exposure. The prints have been washed but not yet cured (I'm letting them dry), so it remains to be seen if these prints are less resilient than those with lower exposure times. They don't look as bad as I expected, but there is obvious "bloat" - i.e. small holes and gaps are filled in, raised objects are wider than designed. I'd previously stopped at 5s on the calibration tests after running 2.5s, 3.0s, 3.5s, 4.0s, 4.5s & 5.0s as this seemed quite a jump up from Elegoo's recommended 3.0s. I'm now curious as to how much higher than 5s I can go, so I might experiment further.

What printer and resin are you using? Those settings seem high - Elegoo recommend 3s for their ABS-like grey v2 resin on a Mars 3. When I changed over to the ABS-like I ran all the various exposure calibration prints I could find with different exposure times to find the optimum for the kind of printing I’m doing (i.e. not the miniature figures that most of the tests seem to be aimed at). I got up to 5s normal exposure before details started to blur, so I’ve stuck with that. I’ll try at test at 8s just to see what happens though, thanks for the suggestion. I hope I’m not tempting fate saying this, but I’ve had no trouble with base plate adhesion using 10s base layer exposures, and don’t get any “elephants foot” either (I use UVTools to optimise base layers).

For very small delicate bits of thin ply I sometimes use CA, which soaks into the ply and gives it a lot more strength. For areas where a fine bead of glue is needed I use: I use the fine applicator nozzle to lay down a thin line. For slightly larger areas where accuracy isn't so important I use: I usually put down a few blobs in the middle of the piece then use a paintbrush to spread it out thinly over the required area (brush washes off with water, providing you don't let it set on the brush). For larger areas I just use plain old PVA applied thinly with a paintbrush to both surfaces and left for a couple of minutes to become slightly tacky before joining the surfaces together (brush washes off with water). I have also tried: but found that (as it says on the bottle) it is instant, so you have to get the alignment spot on first time because there is no second chance.

I can’t envisage how to do that successfully, as there is always going to be a large suction cup in at least one corner? The way I’m doing it now is a bit long-winded but does seem to produce good results and also avoids having to remove any supports and the pimples they leave behind.

On the other bits I've printed off I've used CA which seems to work fine, but I haven't tried glueing the wagon bits as yet.

Yes, Slaters nominally do an N13 as mentioned in the other topic, and I have one in my kit stash. It has a few issues though, as superbly described here: Netherport Given the issues magmouse found it would probably be easier to print my own!

I need a brake ... Simple lever brakes, single side only for the N6, ta very much. Fortunately Miss P's earlier message reminded me (not that I should have needed reminding) of the fantastic resource that is gwr.org.uk, which provided ample information to (hopefully) prevent me getting it wrong while making it easy to draw up: I didn't include the flange-way arm as it's on the back so would never be seen.

I've now made a few improvements to the suspension unit thanks to @Miss Prism's helpful diagram. The changes include: shortening and widening the W-iron moving the spring hangers in slightly re-profiling the springs shortening the axlebox body slightly adding the missing oil filler pot The superimposed image now looks like this: All in all, very worthwhile. Thanks for alerting me to the issues Miss P. Now that I've got a bit more competent in using DesignSpark I'm really starting to enjoy it.

Apologies for the radio silence on this thread - I got a little bit distracted. I was working in the lab late one night ... printing off some simple bits for the next step of the coal stage build when I started thinking about designing the wagon that was the original inspiration for getting the printer in the first place. Since then virtually all my modelling time has been spent working on this: I got totally engrossed with this side project, but hopefully the brunt of the work is now done so normal service will resume when the first N6 rolls on its own wheels!

Thanks - so is that a single print? I have a Mars 3 so a 7mm wagon just barely fits when flat on the build plate. I think trying to angle it would only work with a shallow depth of model, otherwise it will overflow the useable area? If I can get my "kit" of parts to print successfully separately then I'll call that a win!

Thanks - I'm aiming for a buffer height of about 24.2mm (7mm scale), which isn't as easy to get right as I naively assumed when I began this journey. In the interests of science (and getting it right) I had a go at superimposing your very helpful diagram (wish I'd started from there) on my design: I'm surprised it's as close as it is to be honest, given how I arrived at it (measuring things off photos on my PC screen mostly!). It is a tad low, as you say ...

Maybe I need two versions - one empty, one loaded? The coal stage ramp would have some of each... But then, apart from me and you, who is ever going to notice? Besides, there will be so many other "approximations" and compromises on the layout that this would probably fade into insignificance. But if it's wrong it's wrong, and I may as well try to get it right at the outset ...

I know I'm missing a nipple (oo-er missus) above the "W" - on the to-do list. I just wanted to see how it prints so far. Hot off the printer: First impressions, it looks pretty good so far. After washing: After my problems with the body I am very pleasantly surprised and encouraged. The box on the left of the photo has a lot more rear support than the one on the right - just experimenting. The springs are extended at the back up to the front of the W-iron, and the axlebox is extended at the back up to the rear face of the W-iron. The one on the right has a gap between the springs and W-iron and the axlebox had space behind it. Both seem to have come out as designed, and at "normal viewing distance" I don't think the differences would really be noticed?

Does it look any better with a bit of context? This shows it with a 3'1" wheel. The axle is aligned exactly with the centre of the circular part of the front face. PS: I meant the centre of the circle of which only a semicircle is visible, not the centre of the face, but I'm not sure that's made it any clearer! The axle is centred on the horizontal line that cuts across the bottom of the semicircle? I know what I mean!!!