cars
Active Member
Posts: 27 
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Post by cars on Oct 8, 2014 17:58:27 GMT
I am new to model engineering, but am progressing at a reasonable rate on my first project, LBSC'S Tich. I have cylinders attached with pistons, and valves, all coupling rods are in place and walschearts on one side. My question is, How tight, or loose, should it all be ?? I can turn everything by hand by turning the driving wheels, it all feels quite tight, but does move smoothly through a complete cycle. As ever all comments will be much appreciated.
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Post by albert on Oct 8, 2014 18:12:59 GMT
Hello Cars,
If it turns with undue force and the axcel boxes move up against the springs ok then I would hope it will bed in well when running.
Albert
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cars
Active Member
Posts: 27
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Post by cars on Oct 8, 2014 19:01:28 GMT
Thanks, I'll let you know when we can put compressed air on it !!
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Post by Deleted on Oct 8, 2014 19:06:35 GMT
Have you packed your pistons yet? Mine was very tight due to this but running on air (lubricator filled with air tool oil and of course copious lubrication to all other parts) soon got it bedded in.
Regards from another current Tich builder,
James.
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Post by sncf141r on Oct 9, 2014 0:31:44 GMT
And another one - mine "bedded in" after my first successful run. It was hard to get the wheels to turn round beforehand!
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Post by standardsteam on Oct 9, 2014 17:58:23 GMT
..me too, the motion was fairly stiff to start with, under compressed air I flicked the wheels and it nearly chopped my finger off - after running for a bit it eased up considerably with generous oiling. Incidentally when I tried to run it first I left the ball out of the oil clack and I was initially despondent all my hard work didn't seem to function!
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shooter
Part of the e-furniture
If it 'aint broke....don't fix it!
Posts: 252
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Post by shooter on Oct 9, 2014 18:11:23 GMT
another tight Tich here, again, after running on air with copious oil she soon loosened up a bit. She was still more stiff than I would have liked and this remained until the first steaming.She then loosened up a treat and I can now push her along and everything turnes smoothly. She runs a treat I might add. I'm just a rubbish driver/fireman !!
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cars
Active Member
Posts: 27
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Post by cars on Oct 10, 2014 8:17:06 GMT
It is very re-assuring that I appear to be progressing in the correct direction with this ! I certainly recognise that there is going to be another steep learning curve when it comes to firing/driving.
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steam4ian
Elder Statesman
One good turn deserves another
Posts: 2,069
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Post by steam4ian on Oct 11, 2014 11:54:00 GMT
Tich Tightness. Does that lead to Jock itch?
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dscott
Elder Statesman
Posts: 2,437
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Post by dscott on Oct 11, 2014 20:10:18 GMT
Now a lovely tip given to me by an old Model Engineer was to do a first run on air when the wife is out and borrow the hair drier. All locomotives are tight until she has warmed up to operating temperature...the same for older car engines! My dear departed MGBGT had a horrible first mile most mornings then she was fine!
David.
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cars
Active Member
Posts: 27
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Post by cars on Nov 27, 2014 12:53:34 GMT
I have now progressed to a position where I have connected it to the compressor to see if it works. Well the high level is that it doesn't !!!! When I apply about 60 psi to the steam tee, I just get a continuos flow from the exhaust. I have checked that the valve slides a free to sit on the ports, but am not sure where to go from here. As ever, any comments and guidance would be much appreciated.
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Post by cplmickey on Nov 27, 2014 13:07:39 GMT
I've got a similar problem with one of mine so I'm just making up a way of driving the wheels to try to bed things in a bit as I can turn it by hand but with some resistance. I suspect I can do this with or without compressed air so eventually the air takes over. Mines a 9F so there's a lot of bushes which can give resistance to movement (I've reduced it to an 0-6-0 for starters).
I've bought a low rpm motor and am belt driving a printing roller with it (soft rubber but with a steel core made to give it some rigidity. I've no idea if it will work but seemed worth a try.
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Post by sncf141r on Nov 27, 2014 15:08:25 GMT
I have now progressed to a position where I have connected it to the compressor to see if it works. Well the high level is that it doesn't !!!! When I apply about 60 psi to the steam tee, I just get a continuos flow from the exhaust. I have checked that the valve slides a free to sit on the ports, but am not sure where to go from here. As ever, any comments and guidance would be much appreciated. Hmmm - if you have revolved the wheels by hand with the valve chest cover off, and only ever saw one valve port open, the issue may be that the valves are maybe held off at an angle. What happens if you CAREFULLY apply air, and turn the back wheels? (watch your fingers, if it takes off, you do NOT want a finger caught by a side rod...) The valves must float very slightly to ensure that they seal properly. More thoughts: 1) Put some heavier oil into the valve chests - might help with sealing. 2) you do have piston packing, correct? When you figure it out, it'll be one of these "that was obvious" moments! JohnS. |
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cars
Active Member
Posts: 27
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Post by cars on Nov 27, 2014 15:53:39 GMT
Thanks for the comments, I haven't been brave enough yet to try turning it with the air on ! I have tried it with some very thick oil additive. Time to get cleaned up now as its parent evening at school. Try again later
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Post by Roger on Nov 27, 2014 20:10:45 GMT
I'm sure we all would like to see a 'running on air' video, I certainly would.
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cars
Active Member
Posts: 27
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Post by cars on Nov 28, 2014 10:57:27 GMT
You would like to see a video, not as much as I would !!! Rest assured that when it runs, I will do my best to make a video go viral.
In the meantime, I think that the return cranks are in the wrong place, and I think the crank pins have moved. So far I have drilled the back of one wheel and welded the pin in and ground it smooth, just about to start the other.
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Post by Deleted on Nov 28, 2014 11:19:08 GMT
Oh dear !!--------A locking grub screw fitted half-and-half at the rear would have allowed you the option of repairing/changing the crank pin at a later date, should the need arise !!
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cars
Active Member
Posts: 27
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Post by cars on Dec 7, 2014 18:09:15 GMT
I am very pleased to update that Tich is now working on compressed air. The problem was a difference between the drawings I am working to and to LBSC's book, the resultant error meant I had the valve timing on one side 180 degrees out. Anyway, now sorted and running on 80 psi. I shall run in and get the operating pressure down.
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cars
Active Member
Posts: 27
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Post by cars on Dec 7, 2014 18:09:21 GMT
I am very pleased to update that Tich is now working on compressed air. The problem was a difference between the drawings I am working to and to LBSC's book, the resultant error meant I had the valve timing on one side 180 degrees out. Anyway, now sorted and running on 80 psi. I shall run in and get the operating pressure down.
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Post by Deleted on Dec 8, 2014 0:30:15 GMT
I bet you tried to set both sides from looking at the one picture ??.......anyway it's good news at last and a major milestone achieved towards that first run on the track !!
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