Post by choochooenthusiast on Jan 16, 2022 10:09:29 GMT
Greetings, its been a while.
Well here I am with another project, the B1 has ground to a halt for the moment. But, I'm really liking these Don Young drawings so I've been getting stuck into them.
Here's some images of the Pony Truck and the axle boxes for it.
The axle boxes are split and held together with some countersunk M3 screws. They slide very smoothly and the leaf springs work. It was just a matter of bending the individual leaves into a curve as they came off the print bed still warm.
Post by choochooenthusiast on Jan 22, 2022 2:00:52 GMT
Afternoon, where I am anyway. I've been very busy modeling while I have the week off work. The laser cut Acetal frames arrived. I've finished the horns, axle boxes and springs (one of each). Found some spare bolts lying around to make sure it all works before printing the remaining five of each.
I followed the same process for the leaves as the pony truck. Bent them to shape by hand as they came off the build plate.
Thinking about how I'm going to paint the springs now. Any suggestions?
As for the horns, definitely more bolts than necessary, but if it was full size she would have that many. I've noticed on Prince of Wales they are using machine screws? Maybe rivets are no longer sufficient.
I've noticed on Prince of Wales they are using machine screws? Maybe rivets are no longer sufficient.
The bolts for the horns on Prince of Wales are all fitted bolts. I believe this was the norm for many years on the LNER. To ensure the horns are a good snug fit in the frames, the front face of the horn cut-outs and horns are tapered by 1/8".
I used to be a regular volunteer in Darlington Locomotive Works doing work on Tornado and Prince of Wales though I haven't been in for some time now. The problem with just going in one day a week is that you rarely get to start and finish a whole job which can be a bit demoralising. On the other hand you can have days which are very rewarding.
Post by choochooenthusiast on Apr 13, 2022 0:37:11 GMT
Hello again, I've found some free time and a bit of motivation! This is all the progress that has gone on since the last post. Some of it you've probably seen but here we go anyway!
The chassis, loosely bolted together with a few 7BA bolts. Most of the frame stays are done. It now just needs the drag box, smokebox saddle and the pony truck stays.
About 10 hours printing per driver.
All axle boxes printed. Just require cleaning up and and some araldite to attach the mount for the spring buckle.
Currently the shed is in disarray and I can't get to the lathe to make some proper axles so to keep the build moving along I printed some.
Here is the front coupling rod. This is the only rod I've made so far but plenty more on the way. The bushes are made from Prusa's 'Viva La Bronze' filament. Its a very convincing colour. Lots more on the way. I'm currently making up some crankpins and the remaining pieces for the chassis.
If anyone has suggestions for how to paint Acetal plastic I'd be very grateful, I've heard its very difficult but you never know what someone might know on this forum.
It looks as if it is not an easy material to paint. We used a lot of Delrin (acetal) at the company I did my draughtsman apprenticeship at, but it was never painted. However, I didf find this on the 'net. It is a nasty mixture, due to the concentrated sulphuric acid. I've copy and pasted the web address, rather than just copying the text, because there is a video included :-
Post by choochooenthusiast on Jan 15, 2023 0:48:39 GMT
Hi Paul, looking at preservation photos I noticed this. I'm just wondering how long ago they might have made those parts black.
I've had a bit of a breakthrough in the motivation department. (But having a few days off work helped)
LH Cylinder complete. The Motion Plates are printed in 2 parts and Epoxyed together.
The Valve Crosshead Guide bracket is printed as one piece. The first attempt of printing this oddly shaped part left it in 6 different pieces. Adding a few filleted edges and bumping up the infill percentage has helped the strength of the part considerably. This layer adhesion issue is simply due to printing it vertically - each layer is a potential weak spot. Even though the motion plates are much longer, they are a lot stronger because they can be printed flat.
I also made a little jig to set the crankpins. I'm waiting on more silver filament, the gold return crank is just for the purpose of this job.
Post by choochooenthusiast on Jan 29, 2023 12:49:18 GMT
More progress - the valve crosshead assemblies in place. The combination levers, drop arms and union links all printed and temporarily bolted up to see if it moves as it should. Thankfully it does, there are a few tight spots on the slide bars that need some work, but otherwise it all fits nicely.
I suppose one advantage with 3d printing is that the printer is always going to produce evey single part to within a fraction of a mm of the plan with complete consistency - a taxing achievement through manual machining!
I've meant to ask, what is the workflow? Are you recreating the components in the Don Young drawings in CAD, then exporting directly from the CAD program to your printer?
Post by choochooenthusiast on Mar 18, 2023 7:38:09 GMT
Apologies for the inactivity but my printer has had some difficult layer shift issues and I've worked away at it slowly over the last couple of weeks when I got a spare moment.
Before all the issues started I did the chimney in two halves, one of the highest quality prints to come off my machine - and at a crazy 0.05mm layer height. Halves was the only way to print without supports. As well as that I made up the pony truck pivot stretcher which helped diagnose the problem.
I must get onto the lathe and make a pin for it.
The print issue was to do with belt tension. A funny thing about that, when performing the selftest feature, it gave a reading to say the belts were too tight. After loosening, recalibrating, adjusting first layer height and running a test print. It was no better, so I went the other way and tightened it more than before as the belt felt way too loose and I suspected it was jumping the teeth on the stepper gear. All this to say it gave the opposite reading and had me scratching a hole into my head. Fixed now.
I've now got it printing better than before, so after trying out some smaller prints (valance, running board bits) I dared to do my longest print yet. 35 hours later and I have a smokebox and ring.
Lots of trial fitting going on here.
Right I've been neglecting the other side of the loco, so I'd better put some time into sanding and filing valve gear bits.