Project 65033 - a 3D printed LNER J21

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Paul_sterling
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Re: Project 65033 - a 3D printed LNER J21

Post by Paul_sterling »

Hatfield Shed wrote: Wed May 12, 2021 11:57 am
Paul_sterling wrote: Tue May 04, 2021 3:52 pm ... this project gets you 95% of the way to a J21 ...

I recall the Midland 1F effect I think I caused with LH&JC No.29, at one point they were £40-£50, now, they aren't...
That's way better than 95%.

Now, further potential for the loco mechanism from RTR. I am a happy 'basher' and since this is a Derby wheelbase, I would want to look at the mechanism from the 3F tank loco; (rewheeled with some 20mm Bach wheelsets I just happen to have) because this drives on the rear axle, has a sprung centre axle, and I suspect the motor will be better concealed.

You never know, you might manage a run on Bach's Jinty...
I did think about a Bachmann 3F tank, though I couldn't find one on eBay at the time I bought the C-class. it was uncanny, there was literally nothing available outside of buy it now, and those were just silly to say the least. it would depend on how the motor is positioned in the 3F, as the rear axle is well into the cab on the J21 and J25. Even with the C-class I had to extend the back head 3mm further into the cab than it should be.

The situation of buying 3F Jinty's has improved now, but I still kick myself for selling the 3F that I had a few years ago, as it was mint, but seldom used.

Paul.
Paul_sterling
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Re: Project 65033 - a 3D printed LNER J21

Post by Paul_sterling »

The second print gave me some area swhere I wanted to make changes to the shell, particularly where the boiler meets the front of the motor-gearbox. the pocked has been increased by 0.25mm, and I've put a number of ribs inside as well to improve the stiffness of the boiler. If this displays any substantial amount of curing warpage, I'll probably do what I did on meteor and No.5, and put some horizontal struts in that will stay in place until curing is complete, then be cut out carefully.

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The tender has seen a significant amount of work as well. Its initial print and fit trial worked well, very little required in terms of clearance, other than moving one of the internal pockets back an additional 0.5mm so that the tender has some fore and aft movement for assembly, controlled after that by the fixing screws, which use the original holes in the tender base.

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There has been a few compromises on the tender in terms of the coal space, a large boxing has been kept in order to retain the tenders capacity for DCC and DCC sound. A good load of coal and this shouldn't be an issue, something like a Margate manufacturer used to do to hide its massive tender motors.

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I still intend to detail the backhead, but that won't have a major impact on the engineering of the rest of the loco.

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Thanks, Paul.
Paul_sterling
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Re: Project 65033 - a 3D printed LNER J21

Post by Paul_sterling »

Here is a couple of structure shots for those interested in how the prints are formed.

Image20210514-11 

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It can be seen that the sacrificial framework has a direct, and very strong support structure below it, I only use ligter, ball ended support structure where the supports touch the model directly. It speeds up the clean up time, and also gives me a wider handling window. 

Thanks, Paul. 
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Dave
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Re: Project 65033 - a 3D printed LNER J21

Post by Dave »

I'm watching this with interest.
Paul_sterling
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Re: Project 65033 - a 3D printed LNER J21

Post by Paul_sterling »

T'was a very exciting weekend!

I changed the printer over to grey resin, and sliced the latest version of the files (well, almost latest, I'd made some changes afterwards, but still wanted to see the outcome).

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I did records a short video too, and will link it once uploaded.

Overall, there was a couple of minor areas to change, the middle splashers need a little extra inboard clearance, and the tender a couple of internal mods. I've also decided to remove the steps from the tender, as they were fitted straight to the frames on the original J21's, so I can't really offer that in this case, and the step frames just don't blend in.

Another print tonight, and I reckon that (unless some disaster happens in the print) should be somewhere near.

Thanks, Paul.
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nzpaul
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Re: Project 65033 - a 3D printed LNER J21

Post by nzpaul »

That appears to be a much smoother print compared to previous work, is that just the result of the change in printing material, or have I missed the bit where you've upgraded your printer as well?
Amazing outcome again, I'd love to have a go but I fear there's a great deal more work involved than meets the eye.

Paul
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Atlantic 3279
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Re: Project 65033 - a 3D printed LNER J21

Post by Atlantic 3279 »

I'm continuing to like it!
As an alternative to the now scrapped idea of printing the steps as part of the tank and bunker unit, it occurs to me that IF the shapes and sizes of the frame cut-outs, plus the axlebox spring units are sufficiently correct, then it wouldn't be a massive job to add steps manually to the frames, from metal strip or even from plastic, reshaping the frame ends first if necessary, and perhaps slotting those ends so that the treads for the steps can sit secure in the slots, rather than just being glued on their inner edges.
If the frame shapes and surface details are a poor match to the NE type, how hard a job would it be to print the frames too?
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Dave
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Re: Project 65033 - a 3D printed LNER J21

Post by Dave »

Now that is looking very good.
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manna
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Re: Project 65033 - a 3D printed LNER J21

Post by manna »

G'Day Gents

Nice :D :D :D

manna
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Paul_sterling
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Re: Project 65033 - a 3D printed LNER J21

Post by Paul_sterling »

Atlantic 3279 wrote: Mon May 17, 2021 8:40 pm I'm continuing to like it!
As an alternative to the now scrapped idea of printing the steps as part of the tank and bunker unit, it occurs to me that IF the shapes and sizes of the frame cut-outs, plus the axlebox spring units are sufficiently correct, then it wouldn't be a massive job to add steps manually to the frames, from metal strip or even from plastic, reshaping the frame ends first if necessary, and perhaps slotting those ends so that the treads for the steps can sit secure in the slots, rather than just being glued on their inner edges.
If the frame shapes and surface details are a poor match to the NE type, how hard a job would it be to print the frames too?
Hi Graeme,
Thank you! :D

Okay so frames, dimensionally, they're a good match to the originals, in length, and the D shape cut outs are close, to some variants, the NE tenders used did change from time to time, the D sometimes having less of a homogenous curve, and more of a square with two radiuses. So its not ideal for the latter, unless someone wishes to file the shapes out.

I agree re the steps, There is enough land at each of the bufferbeams to create notches to slot steps into, and I'll keep that in mind. Once the latest print comes off, I'm looking for stability of the beams, and then i'll see if slots/notches can be introduced, even if for people just to use brass strip, which would give a more dimensionally correct step (bearing in mind 1" is 0.33mm, and steps are typically 1/2 plate or less, so printing features that thin and long is a real challenge, on any print technology at present).

Printing frames is perfectly practical, Mike Trice on RMweb does it for coach bogies, however, from my own experience, I've been happier to use RTR components, as long slender frame parts are a notch harder to tune on a printer than complex boxing type parts which are naturally stronger by virtue of their shape. Moreover I just really like to avoid making printed parts that interact with mechanical components! I did do so for the S1 and LH&JC No.29, in respect of their rear truck/bogies, but I'd prefer to avoid it if I can.

For some, the frames would be a must if I'm honest, however, my view is, I'm using an RTR arrangement for the loco, accepting a compromise in terms of behind-wheel frame detail and shape, in order to gain a very simple conversion to achieve a J21, and if I do that on the loco, I'm happy to do that on the tender, on the proviso that whatever is used, provides an externally accurate tender body. Had I used a J15 donor, knowing its tender is significantly shorter than required, I'd have definitely been doing a full tender, or looking for a suitable donor elsewhere, as it is, the C-class provides a good all round donor.

Thanks, Paul.
Last edited by Paul_sterling on Tue May 18, 2021 8:50 am, edited 1 time in total.
Paul_sterling
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Re: Project 65033 - a 3D printed LNER J21

Post by Paul_sterling »

Dave wrote: Mon May 17, 2021 8:56 pm Now that is looking very good.
manna wrote: Mon May 17, 2021 9:46 pm G'Day Gents

Nice :D :D :D

manna
Thanks Guys, glad you like it.

nzpaul wrote: Mon May 17, 2021 8:37 pm That appears to be a much smoother print compared to previous work, is that just the result of the change in printing material, or have I missed the bit where you've upgraded your printer as well?
Amazing outcome again, I'd love to have a go but I fear there's a great deal more work involved than meets the eye.

Paul
Hi Paul,

In reality its both, its a different material, Photopolymer resin, and a different technology, so DLP/SLA rather than FDM which is what was used on the Q1. Its been a continual learning process to getting to this point, the CAD methods has evolved, as has the approach to printing, so whereas your Q1 was printed in parts to optimise the finish as much as possible on FDM, the prints I do now, tend to be homogenous prints in order to maximise size and bulk for print stability. I have transferred the Q1 into DLP/SLA now as well, and print it off in one piece, plus tank top surfaces, so that the ballast can still be added in there. With the Q1, its detail isn't optimised towards DLP, I could add a lot more in now, and make the ribs around the tanks, cab windows, doors etc, much sharper and smaller.

I'm revisiting the S1 at present, to see what can be done with that to bring it into DLP printing, but given its long frames (and no boiler), its likely to be a challenge, that being said, because DLP eliminates the woodgrain issue (with care) of FDM, which was the reason for using the Bachmann boiler on that loco, its perfectly possible to now modify the S1 to be a whole-body print instead.

Thanks, Paul.
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Re: Project 65033 - a 3D printed LNER J21

Post by mick b »

Very useful etch (therefore much stronger) for steps and other parts ,for many NER Locos.

https://www.52fmodels.org/accessories
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Atlantic 3279
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Re: Project 65033 - a 3D printed LNER J21

Post by Atlantic 3279 »

Those look handy to know about - just after I've made eight sets of steps that look remarkably like some of those...
Most subjects, models and techniques covered in this thread are now listed in various categories on page1

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nzpaul
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Re: Project 65033 - a 3D printed LNER J21

Post by nzpaul »

Thanks for you explanation Paul. Now that I've researched what all of the 3 letter initialisms mean, I think I've grasped a vague understanding of what your up to.

Paul
Paul_sterling
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Re: Project 65033 - a 3D printed LNER J21

Post by Paul_sterling »

nzpaul wrote: Wed May 19, 2021 8:46 pm Thanks for you explanation Paul. Now that I've researched what all of the 3 letter initialisms mean, I think I've grasped a vague understanding of what your up to.

Paul
Well that makes one of us Paul, I just lurch from one idea to another without any real understanding of anything :D :lol:

Paul.
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