One for the NER conniseurs

The boss was over in Manchester yesterday on an extra granny day care day, left Monday afternoon, so ignoring the list of jobs she had written I started playing drawing a very obscure NER wagon a C3 designed to carry bulky light weight loads. Only 101 were produced so in NER terms as rare as rocking horse droppings.

It's based on the C2 open, very much a bog standard Victorian open and the most common wagon on the NER, just under 25,000 in service in 1903, so that was the starting point. Floor and brake gear still to do, but that's a simple job.



Then on to the cage fixed on top of the C2, It comprises a lightweight frame supporting a wire mesh cage. Creating the wire mesh was pretty mind numbing but you just grit teeth and get on with it.



I'm not sure how well it will print, the wire mesh is .25mm pipework, but that's for later as and when I get to print it. All up a simple job but a real rarity.

Mossy

 

Paul

Given what's happened in the Ukraine overnight (all rather sad and worrying) I'm sure resin prices will rocket after all any reason to hike prices when there's a perfect excuse, just like fuel, fast up, slow down. Or perhaps I am jus being a sceptic.

As for waiting for the summer, I have solved my Baltic printer problem, crude but effective. I have built a printer tea cosy out of an old closed cell camping mat held together with gaffer tape. It's just 4 sides and a roof taped together. It's also sat on a closed cell foam mat. Before each print ruin I warm the resin using your recipe ex another thread and also warm the built plate in hot water. All a bit tedious and messy but it works with no failures to date.

Mossy

 

Rob,

Drawing it was mind bogglingly boring, but needed a vast amount of care and concentration, plus it was the third go before I was happy with it.

As for printing, well we shall see sometime in the future, there are a lot of things lined up for print, but I'm back in decorating mode again.

The biggest problem I can see is that because I have modelled all the washer plates and bolt heads on the inside faces of the wagon, how the ^%$^ am I going to get a floor in there unless I print it integral with the body, which I'm not happy about. Anyone got a suggestion?

Mossy

 

I hate it when clever people point out the bleedin obvious!

 

Paul,

Having the floor in place works for you as you favour printing 45-45, I have been printing parallel to the build plate (as favoured by Andy S) so having the floor in place creates enclosed boxes and the hazards they create. The wagon currently has a full chassis which creates 13 boxes, though to some extend 6 of those vent to the outside reducing the number to 9.

The other wagons I have printed don't have full chassis's just 2 simple cross members and I'm still think about using 3 point compensation as I don't trust the resin w irons to be strong enough to handle either rigid or sprung wheels. Overall I am favouring Rob's sprung styrene solution. It's a knotty problem that needs thinking about.

 

A Curates Egg

Having successfully finished the sketches of the C3 I simply couldn’t resist; would the mesh cage print. Probably? The initial plan was to print one of the panels, but as always things moved on, why not print the body/chassis and cage after all they are pretty standard but it would test the join between the body and cage. Then, $%^&^ it, add in a floor and lets just see what happens after all it’s a test print isn’t it.

Chitu reckoned 1 ½ hours, but I know it lies, the Mono reckoned 4 hours, ok that’s not bad – a similar length of time to a van body. What were the results? The Curates egg.

One of the cage sides printed without any problems.



Both side cages failed, the body-mesh joint didn’t form properly, and the top horizontal supports are a mess.



The other side had a support failure which ensured everything above it failed, but everything either side of the failure worked perfectly.



Finally the floor, good and bad, but not acceptable, so it’s probably going to be Robs sprung styrene solution.

The plan for a second test print is:

I have reviewed the build logic for the end screens and spotted a difference to that for the sides screens, so those have been recreated.

Check out the support failure – was it a lack of supports or is there some print residue on the FEP.

I have also beefed up the vertical central supports in all panels from .25mm to .5mm just to provide more support.

Leave out the floor.

Isn't life fun.

 

Hi Paul

It is certainly different to the run of the mill wagon, that's why I decided model it and see how it would print.

Mossy

 

One step forward and two backwards

After being tide up with family duties I finally managed a second test print today not totally successful.

The wagon printed far better without a floor - an easy tick.

The print failure failed again but I found out what was wrong. A shaggy dog story but hey ho. The FEP had a minute hole in it and some resin leaked out onto the screen protector and got cured creating a "blind spot" which was causing the failure. How I didn't see it who know, but anyway it's been removed and a new FEP installed.

Again the side screens printed perfectly but the work to correct the end screen (this time they were created identically) failed with the same problem. So I have beefed up the end screen and redrawn the side screens to maintain the symmetry. I will do another test print tomorrow, with fingers, toes, legs and gentleman's bits crossed I have fixed the problem.

Mossy

 

A Temporary Halt

Another test print and the same failure despite beefing the cage up. I still can't understand why the side cages print perfectly, while the end screens fail. When the design is identical and both are printed in the same orientation.

The only thing left to try is a 45-45 print, but, my build plate is to small, printing the body and cage as a single body the best I can mange is 45-15 or 30-30. The other solution is to print the two as separate bodies, but the cage is so fragile handling it after printing would be extremely difficult. I know it fits easily on the larger build plate of a mono X, so for now it's being parked and will be picked up when I have bought a Mono X.

Mossy

 

Paul,

Thanks for the suggestions, they make a lot of sense. After posting the I quit for now, I spent quite a bit of time thinking through the problem,

As I see it the transition from .25mm mesh to a 1mm square top support is where the failure occurs, but there isn't enough room to get supports in position to relived the strain.
What I have done is a redesign of the top of the frames to make room for supports (the scruffy attached diagram shows the old and new design). I can just about get some medium supports in place to help the transition. Your child supports on the mesh would also help, when you suggest minimal penetration what would you suggest.

What I still can't my head around is why both plan 1 and 2 work perfectly on the sides, but fail on the ends?

As for the mono x, sadly money I had saved for it has had to be used elsewhere so back to saving up for it.

Mossy

 

So close BUT

The problematic ends printed perfectly. As for the sides, well,
Problem 1 Each cage section has a central support, well they would have done had I extruded them dohhhhh.
Problem 2 The new supports on one side worked without a problem other that the difficulty of removing them. Sadly on the failed side a number of supports attached themselves to the internal bolt details and proved to be a serious &^%$% sod to remove which resulted in damage to the internal details.

What next? Well the side screens need a rebuild, tedious but not a problem. But then onto to new supports.
The problem is the gap the supports have to fit through is between 2 and 1.5mm, I can see a number of solutions. Print the cage as a separate body - already rejected it would be to fragile. Take more care positioned the supports on the side so they don't line up with the bolt detail, print the chassis as a separate body i.e. remove the gap problem completely. Find a way of getting Chitu to extend the diagonal section of the supports so they are positioned on the other side of the chassis legs. Paul - any ideas on the last of these?

I currently favour printing the chassis as a separate body as its the safe option.

As a solace I printed a C2 body and chassis without any problems.

Mossy

 

After a couple of hours I have cracked the problem I hope. By fiddling about with the Chitu support settings, they now run horizontally from the cage frame for 6mm and then drop down vertically to the skate. This makes sure the supports run inboard of the chassis and not between the chassis and side. Now all I need to do to do a test print.



I also dug out this photo of a loaded C3:

 

Major steps forward

I finally figured out why the supports were catching one side and not the other - the chassis was misaligned by .5mm. What a ^%$&^% idiot. That was easily fixed but still decided to go with the extended supports for the cage top.

I finally got a chance to do another test print yesterday after multiple family days. Success it looked good and cured it this morning. Also knocked out and cured a C2 body. Another lesson salted away but wasted a chunk of resin before figuring it out. All part of life's rich pageant I guess.