Festiniog Railway Cleminson 6 wheel coal wagon

A place where discussions are about 3D printing.
Trevor Thompson
Trainee Driver
Trainee Driver
Posts: 964
Joined: Fri Oct 05, 2018 6:30 pm
Location: South West Wales

Re: Festiniog Railway Cleminson 6 wheel coal wagon

Post by Trevor Thompson » Sat Jan 28, 2023 8:31 pm

Both parts of the under frame is now printed and fitted. The three "bogies" are also printed and roughly in place on the under frame:
IMG_2718.JPG
IMG_2718.JPG (1.85 MiB) Viewed 3268 times
The central one had ball bearings under it and it slides sideways nicely. The end bogies await their pivot blocks, but basically these parts all fit as intended. You can see that the central bogie is as far away from you as it will go, and the other bogies have rotated roughly where you would expect them to get to even though nothing is fixed down yet. Some filing was required to get proper fits - and you can see the dust from that. The wheels are printed, and the axle boxes are in the printer at the moment.

Things went a bit wrong then I added the black pigment to the resin bath - I added too much and the prints failed. Having watered it down with more clear resin we are printing again - hence the black bogies. The idea is to print the black components black and avoid having to paint them.

More to report shortly.

Trevor

User avatar
philipy
Moderator
Moderator
Posts: 5033
Joined: Sun Jan 30, 2011 3:00 pm
Location: South Northants

Re: Festiniog Railway Cleminson 6 wheel coal wagon

Post by philipy » Sun Jan 29, 2023 7:11 am

I've found problems with black resin, even when bought as black. Sometimes its fine and sometimes it just fails. I think it may be to do with not shaking it up enough in the bottle, and also leaving resin in the vat allows the pigment to settle out, which it does quite noticeably over time.
Philip

Trevor Thompson
Trainee Driver
Trainee Driver
Posts: 964
Joined: Fri Oct 05, 2018 6:30 pm
Location: South West Wales

Re: Festiniog Railway Cleminson 6 wheel coal wagon

Post by Trevor Thompson » Sun Jan 29, 2023 11:00 pm

philipy wrote: Sun Jan 29, 2023 7:11 am I've found problems with black resin, even when bought as black. Sometimes its fine and sometimes it just fails. I think it may be to do with not shaking it up enough in the bottle, and also leaving resin in the vat allows the pigment to settle out, which it does quite noticeably over time.
Yes I am also having problems with it. Lots of failures of things I have printed out successfully in the past with different resin.

Trevor

User avatar
philipy
Moderator
Moderator
Posts: 5033
Joined: Sun Jan 30, 2011 3:00 pm
Location: South Northants

Re: Festiniog Railway Cleminson 6 wheel coal wagon

Post by philipy » Mon Jan 30, 2023 8:08 am

Trevor Thompson wrote: Sun Jan 29, 2023 11:00 pm Lots of failures of things I have printed out successfully in the past with different resin.
Yes, that as well.
Philip

Phil.P
Fireman
Fireman
Posts: 430
Joined: Thu Jan 31, 2019 3:28 pm
Location: Staffs. UK

Re: Festiniog Railway Cleminson 6 wheel coal wagon

Post by Phil.P » Tue Jan 31, 2023 10:34 am

I would think that you would have to increase exposure-times / power, and curing would also take longer, for 'black' items? - I assume 'black' resin is more opaque, than others?

Or am I being naive?
Phil.P

Trevor Thompson
Trainee Driver
Trainee Driver
Posts: 964
Joined: Fri Oct 05, 2018 6:30 pm
Location: South West Wales

Re: Festiniog Railway Cleminson 6 wheel coal wagon

Post by Trevor Thompson » Wed Feb 01, 2023 10:07 am

Yes I suspect that you may have a point in as much as when I have added too much pigment then the resin is too light resistant for it to work. However I did an exposure test on the black pigmented resin when it had been diluted and found that it hadn't affected the exposure time at all. So I think the answer is actually no - it didn't need longer exposure times.

Philip had an interesting point about the pigment settling in the tank, and I have been raising and lowering the plate to mix it quite a few times before setting it off to make sure that this isn't a factor.

I think part of the issues is to do with the type of resins in use. I am not saying anything negative about the clear resin (with or without pigment added) it is working properly for me. However the "tough" resin which costs twice as much certainly performs better. Whether its is twice as good is something I haven't worked out! The supports SEEM to part during printing more with the standard resin - but that is just a gut feeling and may be more to do with using black pigment.

Trevor

User avatar
philipy
Moderator
Moderator
Posts: 5033
Joined: Sun Jan 30, 2011 3:00 pm
Location: South Northants

Re: Festiniog Railway Cleminson 6 wheel coal wagon

Post by philipy » Wed Feb 01, 2023 11:13 am

Trevor Thompson wrote: Wed Feb 01, 2023 10:07 am The supports SEEM to part during printing more with the standard resin - but that is just a gut feeling and may be more to do with using black pigment.
Hmmm... my gut feeling has been that supports part more easily using the tough resins although I'm not using the same supplier as you, which is of course another factor to take into consideration when doing comparisons. I've had a feeling that the tough resins are more viscous than standard types, irrespective of colour, and create more drag which allows the supports to give way. It may be that that could be overcome by playing with exposure times, speed, etc, not to mention the support parameters, but that would all take a lot of work and would only be worth it, IMO, if I was wanting to standardise on one specific resin for everything.

Going back to my point about the black pigment settling out, I only noticed it when I inadvertantly left a few mm of resin in the machine for a several weeks over the Christmas period. When I realised and went to clean it out, I noticed a whole load of tiny black specs sitting in the bottom of the vat and the 'black' liquid above it was much more translucent than opaque as it should be.

I think when I've worked through ( and chucked failures) the various coloured resins I've got in stock, I'm going to standardise on translucent green which seems to be much more reliebale that denser, coloured, resins.
Philip

Trevor Thompson
Trainee Driver
Trainee Driver
Posts: 964
Joined: Fri Oct 05, 2018 6:30 pm
Location: South West Wales

Re: Festiniog Railway Cleminson 6 wheel coal wagon

Post by Trevor Thompson » Thu Feb 02, 2023 7:53 pm

I now have the "bogies" printed. The pivots for the outer bogies are also bonded in place. I used 2mm diameter balls on the outer bogies and 2.5mm balls on the central bogie. The pivot bolts for the outer bogies are 8BA, bought bolts worked, but I made up some special ones on the lathe. A short length of 3mm diameter rod formed the connection pin mounted on each end the centre bogie. The bottom of the wagon with the balls in place:
IMG_2727.JPG
IMG_2727.JPG (1.72 MiB) Viewed 3014 times


The 2mm balls are very easy to loose!

I found the correct position for gluing the pivot blocks by assembling the bogie to the pivot, with bearings in place and gluing them into place on full lock, ensuring that the angle ends were even on both sides.

The bogies secured in position:
IMG_2729.JPG
IMG_2729.JPG (1.56 MiB) Viewed 3014 times
I have started to make the axles up. I don't think that the resin printed wheels are going to work. The axle is 3mm diameter. I mounted a wheel in the lathe and bored the hole 3mm. When I pressed the wheel on to the axle the hub of the wheel split. That also happened with a second wheel. There has to be some interference fit - or the wheels have to be glued on - and I was expecting to have to glue these. So I will print the wheels on the filament printer tomorrow - I know they will work.

The bogies seem to fit neatly, and the outer ones seem to hold the middle one down sufficiently to prevent balls from escaping when the wagon is turned over. They all move freely as I intended. I am making the axles so that there is little sideplay in the axleboxes. Any sideplay, particularly in the centre axle will prevent the centre bogie moving sideways as intended.

Trevor

Trevor Thompson
Trainee Driver
Trainee Driver
Posts: 964
Joined: Fri Oct 05, 2018 6:30 pm
Location: South West Wales

Re: Festiniog Railway Cleminson 6 wheel coal wagon

Post by Trevor Thompson » Wed Feb 15, 2023 2:11 pm

A bit of a change of direction on the wheels. I found some stainless rod which was 2.98mm diameter, and which I could make fit into 3mm reamed holes in the resin printed wheels. So back to resin printed wheels. The axles were turned down for the bearings:
IMG_2769.JPG
IMG_2769.JPG (1.35 MiB) Viewed 2903 times
That is the 3mm OD, 1mm ID bearings which I have been using on my slate wagons, fitted onto the end of the axle. Of course I had to fix the wheels onto the axle using superglue.

Some gentle easing with a file was required to get the axle boxes to move freely in the W irons. The axle fitted and held in place by these "keepers" which are superglued to the ends of the w irons:
IMG_2771.JPG
IMG_2771.JPG (1.74 MiB) Viewed 2903 times
The paper is there to keep the superglue away from the axle boxes. It has a strong tendency to glue the axle boxes into place - and of course I want them to move freely under the influence of that spring which you might just be able to make out in the next photo.The holes in the end of the "keepers" are for 1mm diameter rod which supports the bottom of the w irons - as per the prototype.

The finished wagon on its wheels, and with magnetic couplings fitted. It seems to run on the test track OK - but I think it will need the weight of a load of coal to keep it on the track:
IMG_2773.JPG
IMG_2773.JPG (1.77 MiB) Viewed 2903 times
It just needs some final painting and it's ready to add to the goods wagon fleet.

I will sort out the STL files and add them to the 3D files section shortly.

Trevor

User avatar
Peter Butler
Driver
Driver
Posts: 5219
Joined: Sun Sep 09, 2012 10:33 pm
Location: West Wales

Re: Festiniog Railway Cleminson 6 wheel coal wagon

Post by Peter Butler » Wed Feb 15, 2023 4:46 pm

Looks superb Trevor. As long as a little additional weight keeps it on the track you have winner!
The best things in life are free.... so why am I doing this?

User avatar
philipy
Moderator
Moderator
Posts: 5033
Joined: Sun Jan 30, 2011 3:00 pm
Location: South Northants

Re: Festiniog Railway Cleminson 6 wheel coal wagon

Post by philipy » Wed Feb 15, 2023 6:19 pm

Very nice Trevor.
Philip

Post Reply

Who is online

Users browsing this forum: No registered users and 3 guests