Mossys 3D Models

Paul

Rob has told me he knows someone how gets working motion starting with cast resin and you will be aware how inaccurate that is compared to 3d printed so it has to be possible. Do I have the skills to get it working that remains to be seen, it's just a walk in the dark at the moment and as almost everything else relating to the loco is done why not try. Even if it doesn't end up as working motion it's extremely good dummy motion. Brave no, daft definitely and a good excersie in

 

Some more progress towards a working gear. A few bits needed reprinting and I had a feeling the connecting link was the cause of the motion not rotating so ever onwards.
I have replaced the piston and valve rods with brass rod (they are a bit long but that's fine for now), lengthen the slide bars again a bit long but easily fixed and finally sorted the connecting link out. I wasn't sure how much longer to make it so opted for +1mm, +2mm, +3mm and +4mm. First test was with +4mm links and hey ho motion, whoop whoop.

My pc doesn't like my Iphone so I have set Rob two short videos of it in action, the boss was the camera man I just turned the axle, so any complaints should be addressed to her not me and I'm not responsible for any feedback she provide.

Next step is to figure out the slide block and tidy a few bits up. Then on to the motion bracket which gives me a real problem. As it stands the connecting rods attach to the frames with .9mm wire, the cylinder back plate is an interference fit in the frames and the con rod/big end I think may well be 16ba cheese heads, if/when I can get 16ba nuts, there are plenty of cheese heads for sale, but nuts are like rocking horse dropping. All of which means the whole thing can be lifted out of the chassis, but what to do with the motion bracket that's the problem. But all up I'm feeling a bit smug and more positive about the whole silly project.

 

A couple of hours after grinning like a Cheshire cat I returned to look at the slide block and it fit, well it didn't and less than 2 mins thought was need to figure out why.
The width of the slide bock is drawn to GA dimensions, based on a standard 26mm chassis I have 2 frames 2mm think leaving 22 mm to play with, the block is 23.5 mm wide.
Fortunately only roughly 1/3 of the block sits below the frame so a new test rig is now printing with the very small area needed to fit the block reduced to .5mm. all up strip down the working model wait 2 hours for the print and say another hour for its wash, blowjob and cured perm. Basically playtime stopped for today let the puzzle recommence tomorrow.

 

Before looking at the slide block and the new test rig, I spent an hour or so this morning fiddling about with the motion as it stands. Two things stood out, the con rod wasn't smoothly rotating about the eccentrics barrel, there are at least 2 spots where it sticks slightly and there is also a lot of free play latterly across the motion either or both could be the cause. One probable problem was the way I had printed the eccentric barrel parallel to the build plate, so to test it I have create two new prints with the barrel vertical to the print plate and at 45/45 degrees. The lateral movement could be caused by any of 3 places where the inner portion of a joint isn't flush with the outer All three the piston rod carrier, the radius link - pendulum link union and the connecting link - correcting link union have been modified to close up the gaps, yet another run of the printer is required to create new test bodies.

 

Paul,

So far I haven't gone for any cream abrasives etc, just patience and gentle filing. The main problem is the conrod/big end rotating smoothly about the eccentrics drum, even after numerous dimension checks, tolerance changes and multiple reprints it always seems that one rotates freely the other not, fiddling, filing etc helps a little but doesn't resolve it satisfactorily and if that isn't right forget the rest, it's starting to get frustrating so say the least but I will soldier on. Despite all the above I have actually achieved what I wants, which was realistic dummy motion, what's going on now is a vanity project which may or may not get used.

Will the gearbox/motor fit, with dummy motion yes definitely, with implied motion who knows in theory yes, pretty much all of the motion sits below the gearbox but hey ho just another bridge to overcome!

 

Sounds good, yes please

 

Smooth Running at last.

I deliberately took a couple of days break from the Joy's motion just to relieve the annoyance and frustrations and came back to the job yesterday. More fiddling and filing same result, so I finally took the step of trying Mr Dundee's idea. An investment of £1.25 to buy 500ml of Cif Cream and an hour this morning of twiddling the conrod around the eccentrics barrel plus a bit more time on the "smooth" running conrod and both are close to silky smooth. Thanks Dundee, time for tea and toast before reassembling the test rig, happy days. Having used 5ml of CIF anyone want to buy 495ml of CIF cream, mind you the postage would be 3 times the cost of buying a bottle.

 

Since the success of the CIF this morning I have slowly rebuilt all of the Joy's gear this time including the slide block and it's fully working, sadly no photo as my Iphone and pc aren't friends again! All being well photo or video (assuming a compliant female video assistant) to follow tomorrow.

A few observations from brief testing so far, The slide block is rocking back and forward as it's meant to but minimally. The Joys motion moves nicely. As with the slide block piston and valve rods move back and forward but again little movement. I'm also not sure the slide bock is correctly positioned. So the next plan is to move the slide block forward incrementally and see what affects that has, but I suspect the main problem is being as Rob described it illusionary movement rather than actual the throw of the eccentric (4mm) isn't sufficient to drive any further movement. So lots more testing to do but I'm finally a happy bunny!

 

A very basic photo, hopefully a video later when it brightens up a bit.

 

Paul,

The video will be delayed I have spent the morning on domestic duties and she seems to have more lined up this afternoon, grrrrrrrrrrrr.

 

Andy

I spent my entire working life in IT, designing and implementing software worldwide, 40 years+, yes I predate PC's!, but I'm a social media leper. I can sort of use whatsapp that's what the Moss tribe use to communicate with each other and can manage simple photography and texting on the Iphone the rest is just somewhere up in the stratosphere as far as I am concerned. The last video Rob kindly loaded on to here for me, I'm hoping he will do the same this time around.

Anyway I have decided to make a couple of tweeks to the rig so I might as well get those done first before taking the video. I'm now excused domestic duties for the evening so I can get those changes done today. The videos takes 2 to do one to hold and operate the test rig the other to take the video that's swmbo, so I must have earned enough credits to day for her to help out.

 

I never did get the new version of the inside motion assembled some how family matters and other bits and pieces got in the way they are sitting in a takeaway curry carton. Instead I started working on a G4 road van, but that has been put aside and I went back to reviewing the loco chassis and body work. The chassis is fine but I appear to have lost the most up to date version of the body as a number things I know had been model have 'gone missing'. Anyway those have been sorted plus a couple of things I knew needed addressing and for now the body is done except for the backhead but that was always going to be a separate assembly. Everything that is brass will be bought in castings except for the boiler ring which will need to be painted brass. The beastie looks like this now:





Out of curiosity I imported the body into Chitu ran the auto support routine and sliced it up, just over 100ml of resin and a Chitu suggested print run of 10 1/4 hours, they are always over estimates. A similar test on the chassis ran up 35ml of resin and an 8 1/4 hour print run. Lets just hope for some nice warm weather soon so I can test print them.