Timber

This is by far the most complex piece of Fusion 360 work I have attempted and I have learnt a massive amount in the process.  I have tried to keep the build structured into components, have constrained everything that I can constrain and added comments so that I can remember how the drawing is created.

That said I have still struggled with the stability of the design.   This is not a failing in Fusion 360, it is simply my design evolving, sometimes not in the most ellegate way.  Where possible I have gone back and simplified sections but at some point I will go through the whole design end to end and reorder some of the construction.

This is the latest design that I plan to print over the weekend,

This thread will document the building of the above engine.   This is still work in progress but hopefully by starting this thread it will motivate me to finish the build.

I am trying to achieve a few things here:

Add to my collection of S Scale Brecon and Merthyr locomotives, the B&M had three of these locomotives

Make a locomotive that can be taken straight off the 3D printer and built in a few hours

Make a more sophisticated engine that has an integrated etched frame.

So this is where I am up to, I have a working prototype that has a few defects:

Cab dimensions are wrong so have now been corrected

The connecting rods are binding in forward, the engine runs nicely in reverse but binding (slightly) when going forward, 

Having shared my pain on the "whats on your printer" section of RMWeb, I am back here now with a finished print.  I have the MW printed body with an integrated chassis plus a seperate etched chassis.   I want to pursue trying to make a printed chassis work but if this proves to be a non starter, I can revert to etch.  

The saddle will be printed seperately and sit between the two "wings" on the bolier, being held in place with a micro magnet.   I will print this seperately along with some new wheels.

The print is of modest standard compared to some that have been shared in this section of RMWeb - but it is more than I would have wished for this time last week when I was struggling with the basics.

The notch at the back of the smokebox is for the bracket that connects the saddle to the body, this is part of the saddle print.

Seems to be heading in a better direction.....I reprinted the chassis ...now I have this in better shape I will apply the same techniques to the integrated chassis and body.

Thanks will try the attached tonight.  The good news is that it is not warping.  I set the exposure time on the slicer to 6 seconds.   It was 2.7 on the earlier model - but the rivet detail was lost.   Maybe I will recalibrate to 3.5.   The Elegroo data sheet says 6 but other blogs on the web have suggested lower.

I think that I over exposed and there are now too many supports.....i wrecked the print removing them all.   Do you remove the supports before you cure?

Try again with somewhere in the middle.

Given that I have 13 hours to kill, I put my wobbly print together.  It is as light as a feather but it has a bit of puff in it.

Thanks for all the support (pardon the pun :-)) - this is what is on the printer at the moment.   It is going to take 13 hours to print but a first peep as it moves above the resin is that it looks better.

thanks - will try this tomorrow....

These are the settings I am using on the slicer....

Thanks in advance.

Last night I had a go at reprinting the MW I class.   Looks OK from the top but the footplate and saddle are warped at the side.

Any clues.   The only "lever" I can think to pull is the exposure time.  But will this increase or decrease the risk of warping?  There are plenty of supports so not sure that is the issue?

I agree with Rob, the finish looks superb.   

Last night I reprinted the chassis.   I did not clean the resin so the detail suffered.  But the adjustments I made worked.  

If possible I would like to create a model that anyone new  joining the society who just needed a basic loco could use these prints.   Nothing fancy but something that can be built in a weekend rather than several months.

Front wheel wobbles as I dropped the model just before the video was made.

Yes - i have an etch and the 3D parts.   With every model my Fusion skills are getting better so rather than improve old artwork I have taken the time to completely redraw.   More work to do on the cab,  bunker and chassis but this is the integrated artwork.  Once complete I will put the STLs in this area of RMWeb.

6 hours ago, Regularity said:

Will it still be possible to buy/order this with an etched chassis kit?

5 minutes ago, Rob R said:

I'm glad you sorted the printing in the end.

It really is a bit of a 'Black Art' but very satisfying when you wake up to a perfect print dripping from the build plate.

Have the frames shrunk very much lengthwise?

Being the (not very) longest part they should give you some idea of the shrinkage allowance required to fit your existing rods.

A bit of experimentation will soon get you there.

Onwards and upwards

Rob

Rob and thank you for your help.   The frames are very square.  No warping that I can make out.  I am printing again tonight with medium supports.  

24 minutes ago, ScottW said:

Would fitting some brass top-hat bushes not make for a better, free running, chassis?

Possibly but I am keen to explore using plastic.   It goes like a rocket - but at the moment a wobbly rocket.  

The connecting rods are etches and this is where I encountered a small challenge.  Resin shrinks and I compensated with 3% shrinkage.   But I am not sure that this was required.   The axles fit really snug but the connecting rods are a little long.  I have some spares so simply cut and soldered pairs together to fit.

I put it on the track and it works pretty well.   The challenge is that it is so light that there is very little garvitational effect.  The consequence is that this model rocks a little.  But the chassis is very true and given how easy this construction method it feels that it deserves a bit of extra effort before I give up.

So I have redesigned the chassis limiting the vertical axle movement - will see if this improves operation.

To keep this model really simple I decided to run the axles in the 3D printed resin.  The resin is pretty tough and very smooth.  I elongated the holes slightly to alow a little vertical movement.  

Pickups are pogo plungers that simply push in.   The motor and gear box are high level.

The gearbox I had pre built - but the whole construction took less then one hour this evening.

Past 12 months or so I have been working on making a kit for a manning wardle old class I.   Varing degrees of success using a mix of 3D and etched components. 

However, on such a small loco I keep comming back to the challenge as to whether it would be possible to make a complete 3D printed loco, included a 3D printed chassis.   Others have achieved this but i am interested to see if I have the skills to do this for myself.

I have drawn most of the loco in Fusion 360 but before I go too far I want to experiment with a chassis.

So I logged onto Amazon and purchased a resin printer.  

First couple of prints were a disaster.   But following email and telephone coaching from some other members I woke up this morning and found a perfectly formed chassis with integrated boiler on my build plate.

A quick wash and cure then this evening I started to see if the chassis can be made to run.

I have started to reapply my pictures.   Not got to this thread yet but will do very soon.

these look really nice.

Amazing!

That has come out OK.  Attaching an STL.  Anyone interested can mesh this together to make a larger roof section.  I will work on the other sides first and then come back to the roof when I have the overall dimensions worked out.

STL location....

https://drive.google.com/file/d/1eTtI8_sYVauoKuayOH8M8VgYV4SpXJzO/view?usp=sharing

This is a Tinkercad slate roof I have drawn up- I will see what this prints up like before drawing the complete roof..