Mossys 3D Models

Hi Paul.

I don't think it's a problem of tolerances, if what appeared to be the problem viewed in Fusion we are talks mills on both the long and short axis's. The problem is the thing was drawn 6 months ago and I haven't a clue where I got the measurements from. When this test bed is printed I will get a good idea what's needed.

 

Work on the chassis has begun, just a basic test with the bearings and wheels fitted it's all nice and level which is a relief, but I have a question probably best answered by Rob P who suggested correct radial mountings front and back.



The outside dimension of the frames is 26mm, with bearings fitted to the radial truck and the wheels fitted there is only 1-2mm of lateral movement, how the &*(^ is it meant to go around curves? A supplementary question is if I fit the bearings internally in the radial truck, that would provide an extra 4mm of lateral movement to the wheels, but, what causes the radial truck to rotate as opposed to the wheels moving at right angles to the chassis?



Later.

The next job was to make up the coupling rods, 2 of my nemesis's all rolled into 1. I hate trying to laminate coupling rods and I hate soldering nickel silver (I have never got the hang of it). Four hours later, untold loops of solder-unsolder, scorched fingers, a substantial amount of finest Yorkshire bile and far to many smoke breaks they are done. I even broke open tonight's Burgundy for a small snifter. For me they look good but given what the experts on here can do they would rate between poor to down right shoddy, I just hope they fit. If anyone feels the need they can happily unsolder and rebuild them for me. Happy days, Grrrrrrrr.


Mossy

 

Guess what, having survived making the coupling rods they didn't fit! After a lot of fiddling about I found the answer. The wheel base is 8' 1 1/2", that's 56mm + 1.5" convert which is 0.875mm. Someone NOT ME spaced the wheels at 56.125mm, hardly surprising the rods didn't fit. Does .7mm matter in the great scheme of things, well it does for me so a major redrawing of the chassis is in order. Fortunately I have almost all the components needs for the chassis as separate bodies so it's just the frames and spring assemblies that need rebuilding, I hope. In the mean time I have drafted up and am currently printing coupling rods spaced at the wrong dimensions. it's a silly experiment but has anyone else tried using 3d printed rods?

Mossy

 

What a frustrating week.

Chassis print 1 was excellent but there were dumb errors so the design was amended and a second print kicked off, again printed perfectly but that's when the 2nd dumb error (see post 883 above) popped out of the woodwork.

More changes and a 3rd print but this time just the middle third as all it was for was to check things had been fixed, yep fixed, but then the fun really kicked off.

Then were a few print lines on all 3 previous prints so I set the print up 45 degrees x 15 degrees and did my usual, medium auto support, then modify where I want light supports and finally stich the print down with a series of heavy support. Many hours later an inspection of the print, arghhh it had more curved bits than a bent banana as was despatched to the bin. Back to a simple 45 degree angle for Print 5 which failed dramatically after about a 3rd of the chassis had printed for no reason I could figure out.

Go 6 and finally a recognisable chassis, a couple of blemishes but both out of sight so I decided lets build this one. Wheeled up and with the motor fitted and my not very good coupling rods, here we go. Every run I tried after a minute or so the same retaining nut popped off, obviously something wrong with the rods, so I decide to use the 3d printed rods I had done for the 3rd print test. It runs, forward and back no sign of anything binding, I have emailed a short video of it running to Rob P as I haven't a clue how to load videos up.

More work and testing needed but after the week that was I'm just glad to make some progress, 40 hours of printing to get this far, I still need to resolve the radial truck problems (see post 882 above) and final print. And after that I have the body, boiler and interior parts to work through.

Mossy

 

In amongst all the chaos with chassis prints I had another go at the loco no plate as I didn't like the main font. Using a scan of page 211 of Ken Hooles book I drew each of the numbers 3.2mm high using a combination of straight lines and control points, each of which can now be copied and combined onto a number plate blank. Giving the below, I'm much happier with the plate now and the process can be replicated for any given number plate.

 

Thanks for doing that Rob, bit naff but just the basic first test. I'm not sure on the viability of resin coupling rods so may well stirp down the nickel-silver rods and go for a rebuild.

 

Hi Paul

The chassis felt fantastically smooth from the first print but not happy when the nickel steel rods were added after discovering and fixing my mathematical blooper which is why I decided to try 3d printed rods. My 3 brass locos with brass rods are as rough as a butcher dog in comparison, so I am considering creating rods (and perhaps classis's) for those as well.

The rods in the video were uncured, it was just a 'will this work' experiment. Since then I have drawn a proper set angle at 45 degrees, not tried 45-45 yet, and after curing them I have run it slow, medium and fast in both forward and reverse with no problems. They are of Craftsman resin as that's what was in the vat, I really need to create a set using ABS. I really need to figure out to make the radial trucks work so I am going to consult sensi Pulham after the Chris's Art Exhibition this week end then it's on to the brake gear..

Number plates. I don't know why I didn't think of creating models of the numbers, but it was relatively easy using control point splines, Mr P put me onto this function which I am now using more and more.

As for the naughty bit, I found the recommendation to use KY Jelly as a lubricant on your Drummond thread, so bought a small tube, which SWMBO spotted within 15 minutes, I'm not sure she believes me that it's for a loco. Such is life!

 

Not had much time for the Class A chassis as a whole pile of family bits have been getting in the way but finally got a couple of sessions. The radial truck problemss have been fixed although I'm not sure what kind of radius it would go around, but as Rob pointed out real rail tracks are straight with very gentle curves.

Finally I could start playing with the brake gear which has been printed for a while. The brake shoes are printed separately so they can rotate about the brake hangers, and similarly the hanger can rotate about the brake mountings. They are also drafted front to back by 5% so they can sit nice and close to the wheel and being resin there is no chance of shorting, all tricks I have copied from Rob Pulham. For the test everything was held together with .5mm pins First problem basically the hangers, pull rods and actuating gear is all to fragile, it needed beefing up especially around the various holes so new prints are required, I printed beefed up pull rods to continue the test. As can be seen in the picture there is something wrong with the actuator that needs investigating, I think the pull rod is 1 or 2 mm to short, the lefthand rod runs up to the Westie gear which was stored in a cabinet in the cab behind the left splasher, the righthand rod to the brake standard located on the front of the left rear sand box in the cab, but as a first test and with a few adjustments I am a happy bunny.



The plan is that when all positioned correctly the tiny triangular mounting, brake hangers and pull rods will be a separate body, located in to the chassis using the .5mm pins and the link between all this and the actuator is just a push fit and should be therefore easily dismounted for maintenance etc, famous last words! Next to fit and sort out the sprung pickups and wiring to the motor, sadly more family faffing about first.

 

Thanks for that Paul, to be honest I haven't looked at the problem yet, I have spent the day in pageplus trying to draw something which even approximates to the white/green/red quadrant's that are needed for Andy's block instrument, all that has happened is I have cabbaged my brains trying to understand the utterly incomprehensible help text provided with the software. I would love to know who writes the stuff because they have sure never tried to use it. Just to increase my frustrations I then switched to the enormously complex word again an total failure, the highlight being another dose of brilliantly written hinder text. Not the most productive of days and it's Wednesday so later on my two left feet will be trying to dance. Tango, Fox Trot, Rhumba and the Cha Cha darling to look forward to. A sort of self inflicted event, swmbo was desperate to learn and I foolishly offered to accompany her.

 

Andy I don't think I'm my wife's cha cha cha , and definitely not her 'Daaarrling' if we are ballroom dancing her toes seem to somehow always be where my foot lands, if it's Latin dancing with arms whirling about the back of her head is exactly where my arm is. I'm not sure why she persists on dragging me along.

 

Hi Paul

On the test chassis mine are held in place with .5mm pins with the heads reduced in size, they currently catch the coupling rods as it rotates, but if I put them in from behind that should solve the problem. At the moment everything is a push fit so it's an easy change to make and test.

 

While waiting for long print runs of parts of the class A loco, I started a new drawing only project a dgm 116 autocar, and kind of got obsessed with it to the detriment of the class A. It's pretty much done the only thing I am struggling with is the queen posts, on the diagram I was using they weren't shown but I have a diagram of a dgm 5 coach, which uses the same under frame, it's queen posts are shown but still to fuzzy to use. Does anyone have a clearer drawing of NER Queen posts? Also still to be drawn are the drivers controls.



The coach is far to big to print unless chopped in half which would then need some very clever joints to ensure everything is in line and parallel and 4 10-12 hour print runs. I have even gone the full hog and drawn a full chassis and all it's cross members (they would get in the way of any jointing and would need revising). After all that it looks like this

Drivers End


Emergency Stop End


Chassis


Seating

Left to right, end wall third, third-third, third-first and end wall first



The chuckle brothers, aka Rob P and Paul L have know about this project for a while and were/are convinced it would be printed and enjoyed gently winding me up about it, now publicly, I have no intention of printing this coach, now or any time in the future!