MikeTrice

Attached is an early attempt at printing a V2 body. Note the deformation around the front of the smokebox.

The way the normal printing process works is a section of the model is exposed against the FEP and then gets pulled up ready for repositioning  for the next layer. The print is stuck to the FEP and peels away. This takes a certain amount of force and as the FEP is flexible it will effectively bow. The force and amount of bowing is dependent on the area of the current layer against the FEP.

If the print encounters a sudden change in cross section when printing the additional required force and bowing of the FEP can cause surface blemished to appear. In the case of the V2 the hollow smokebox suddenly encounters the additional area of the smokebox door and results in the distortion shown. To resolve I had to modify the model to radius the inside transition from smokebox to smokebox door effectively smoothing out the sudden change.

Changing the angle of the print might work, it all depends on what you are trying to print. As @Durley states distortion could occur when encountering a wagon floor and removing the floor might solve the issue:

If you have not already done so it is worth joining a Facebook group catering for the Photon Mono.

This very poor quality image shows the inner end of the set complete with short buffers and lack of couplings:

The screw that raises and lowers the build plate. I use a white Lithium grease. The lines you are experiencing could be jerking of the lead screw which the grease will help avoid.

It is also worth grabbing the build plate arm and seeing if there is any play when moving it up and down. If there is it could suggest fitting an anti backlash nut, or if one is already fitted, a better one.

Can I suggest you check the tension of the FEP and lubricate any lead screws?

The point is if left in the sun unpainted they will continue to cure.

8 minutes ago, Tony Wright said:

However, the rigid chassis performed dismally on Mike's 'obstacle course' of a test track; it consisting of dodgy joints, twisted alignment and irregular curves.

Reminds me of the train scene in Our Hospitality with Buster Keaton:

2 hours ago, gr.king said:

Another visible anomaly in Mike's comparison of Kirk with original roof and Kirk with better roof is the height of the side itself, The re-roofed example has presumably had material added at cantrail level to increase the height of the side. I'm not sure that gives the right appearance, if hairs are being split. I did a detailed comparison of side-heights and beading positions on various LNER and GNR carriage models versus official figures on drawings about three years ago.

 

You are correct, I overdid the increase. If you also remove the moulding draft from the top of the Kirk sides they need extending the compensate.

3 hours ago, Willie Whizz said:

The thing that has always left me a bit uncomfortable about Kirk Gresley carriage kits, having built several, is the roofs - and especially the 'domed ends', which seem to me not at all the right shape, compared both to photographs and to the otherwise much-maligned current Hornby models, for which the roofs at least don't seem to attract the same degree of criticism even though the roofs are far more 'visible' from most angles  of viewing (as opposed to photography) than the sides.

 

Which is correct (or at least, less incorrect)?  If it's the Kirks, is it simply a case of sanding the roof ends down somewhat (and adding a small square of plastic card to those that don't have that characteristic little thingumajig already moulded-on)?

There has been discussions previously here:

I have posted the following image before. With Kirk kits a simple improvement is to remove the moulding draft from the window openings:

The model on the left is as supplied. The one on the right has had the openings squared up. The roof has also been replaced as the Kirk ones are a bit top heavy.

On the open the sacrificial skirts are only needed for the parts facing the build plate. The rest are just wasting resin. Otherwise looking good.

To help illustrate the problem of vacuum I have taken the liberty of annotating your image:

Note also how @stevel image shows the wagon is orientated open side towards the build plate. This avoids the vacuum issue.

Edit: Regarding the vacuum issue consider a cup placed on the surface of water rim side down. When you try and lift it you can feel the suction effect. Placing the open side of the wagon towards the build plate there is no longer an unvented void to cause this.

I generally try and print at 45 degrees. This would help ypur cattle wagon a lot but you could probably do with some support to the horizontal planks that are open. It should be possible to add some feeds to the inside of the wagon to help support them.

On the open wagon I suspect the issue is caused by suction as the body prints. Try turning it through 180 degrees so the supports feed into the top edge. Another option is to include some holes in the floor of the vehicle or leave the floor out altogether.

Apologies if this has been mentioned before but there are photos of GNR wagons with white rims and the LNER certainly adopted this for both wagons and carriages. In the dim distant past I think I heard it was to make detection of cracks in the tyres easier presumably on passing out of the respective works. As stated previously the white eventually became dirty.

With clothes pegs it is worth reversing some in their springs:

Most resin 3D prints use UV light to cure. If left under UV light (daylight) they will continue to cure long after printing and will get brittle. You need to keep them under cover initially until a coat of paint can be applied which should protect them.

I don't believe so.

14 hours ago, Bucoops said:

I always wondered why Gresley A1/A3s had spindly looking ones at the front with beefy ones at the back mind.

 

For some reason they are double sprung at the front as seen here on Green Arrow:

Might also be worth looking into Toner Transfer Paper: https://www.ebay.co.uk/itm/111793870005

or https://www.amazon.co.uk/10PCS-Toner-Transfer-Electronic-Prototype/dp/B09X4JXJNM/ref=sr_1_5?crid=93SDZ5MRVG24&keywords=toner+transfer+paper&qid=1679149861&sprefix=toner+transfer+paper%2Caps%2C78&sr=8-5

Is it worth trying a PCB Marker Pen to touch in the toner imperfections?

1 hour ago, Chas Levin said:

Is the NRM store open to the public at the moment? Any idea who made it, or when, or from what drawings? Is the label legible in your original photo?

The model is in a glass cabinet near the floor so not easy to photograph. The label is not readable on my photos but this one at least shows the museum's reference number:

https://www.deviantart.com/rlkitterman/art/1-16-LNER-Sentinel-Cammell-Steam-Railmotor-at-NRM-790380223

As far as I am aware the stoe in unaffected by the rebuilding works so should still be accessible to the public. Note the model does not appear to be lined.

This may not help but lurking in a cabinet in the NRM store is this large scale model of a railcar:

3 hours ago, Chas Levin said:

Isn't the extruded aluminium quite thick to do this with though? Have you ever done it with aluminium Mike?

Yes, I have done it. The aluminium bends quite easily.

Regarding sawing a series of slots you form the roof like the Kemilway products illustrated here by @Rob Pulham in his Flickr collection:

The diagrams show the roof as being 9'0" over the cornices so any variation from that dimension would be down to the fusion of parts or quality of the kit. As you say one of the existing metal roofs might actually work out ok. LNER roofs are slightly smaller over cornices than the quoted 9'0" so it might work if additional strips were added to the cornice to make them thicker.

To curve the ends saw a series of slots along the length of the roof to match the length over which to roof curves down and bend the aluminium to suit. Back fill with car filler.

To do a 3D printed roof I would suggest the body is built then placed top down on a scanner to allow an accurate profile to be matched to both length and width and end curves.