Frustration

[steamlaser]

I have spent the last few years slowly building my 2 inch Clayton.
I have just reached the stage where I can finally assemble the cylinders, Crankcase and Crankshaft. I found that everything is stiff and locked up solid despite, great care being taken to "get things right". On this site people seem to be able to churn out a stream of "good" bits everyday. Where am I going wrong . After all this time struggling to make all the bits, one almost feels like giving up!
So tonight in frustration I abandoned the workshop, but tomorrow, after I have taken someone to the Rememberance Parade , I will go back and make a fresh start. I just hope all that is required is the use of a file and emerypaper !

[Jim]

Hi,
Is it possible to give a bit more detail as to exactly what has locked up and under what circumstances?
You can be assured that you are not the first to encounter problems. All my free running bearings on the Burrell locked solid as started to fix the horn plates.
Jim

[albert]

Hello,
When I built my first loco it ran first time out---I was working along side a Metal work teacher who was also building his first loco--he built his to absolutly dead to size it did not run--he had to strip the chassis and add some freedom to a lot of parts.
As a total beginner mine ran due to my inability to get every thing spot on.
Could this be your problem??
Remember a drawing in this game is only a guide--no tolerances for one thing are not given--you have to add them.
Albert.

[Deleted]

Nov 13, 2011 9:12:12 GMT albert said:

Hello,
--he built his to absolutly dead to size it did not run--he had to strip the chassis and add some freedom to a lot of parts.

Albert.

Steamlaser.
As a precision engineer I was in exactly the same boat as Albert describes: spot on dimensions and interpreting 'Bare' as a close running fit. Not so!
After some 'adjustments', the front and rear coupling rod bearings are now oversize and the axleboxes float a bit more than I thought they should!
Keep at it, it's easier to take metal off a part you've spent hours and days making than to put it on again!
JB

[pault]

Hi All
Legend has it that when Armstrong Whitworth built a batch of Black 5’s during the war they could barely pull a train and ran hot almost all the time. The reason, they were built in an aircraft factory and aircraft clearances were used. They were taken into railway works, given railway clearances problem solved. When you look at full size specifications and drawings you will find the clearances given, and may be surprised at how large some of them are.
One important thing to note is that larger clearances do not have to mean less accurate. The tolerance can be the same regardless of the clearance, therefore requiring the same degree of accuracy.
You also have to remember that a loco is not a ridged machine, and things like wheels do not move up and down totally square all the time, so somehow this has to be allowed for
Personally on a 7 ¼” gauge loco I would leave 0.003/4” clearance on coupling rod bushes and big ends, 0.001 ish on small ends, pistons and piston valves 0.002/3” with cast Iron I might go a touch more if the bores were large. The reason, corrosion, make the valves and pistons with a couple of tenths clearance and they will be solid in the bores after the first couple of steaming. Axle box bores I would have 0.001/2” clearance, but I would have 0.003/4 clearance in the horns. When it comes to valve gear I make the pins a snug fit. All this is just a personal thing and the loco will very quickly create the clearances it wants.
Regards
Paul

[jasonb]

I would suggest stripping the assembly back down, have a quick check of each part to make sure it is to drawing (assumeing thats correct) and then start building it up again one piece at a time carefully checking each piece moves freely. Hopefully that way you will spot whats causing the tightness, it may be something not to size, a tight fit, two parts not lining up or a nut or bolt pulling things off as its tightened up.

J

[Jo]

You seem to be describing exactly the same problem I have with my Clayton engine. When I stripped mine down I found that the spindles for the valves were not perfectly in line and ended up having to cut off the valve guides from the steam chest and silver soldering replacements to get them correctly aligned.

She is still too stiff to run and needs another strip down......

[steamlaser]

Nov 13, 2011 7:09:20 GMT Jim said:

Hi,
Is it possible to give a bit more detail as to exactly what has locked up and under what circumstances?
You can be assured that you are not the first to encounter problems. All my free running bearings on the Burrell locked solid as started to fix the horn plates.
Jim
The pistons move freely in the cylinders.However when I connect the trunk guides that contain the castings which holds the small end of the connecting rod, things tighten up.I have eased the bronze castings, but things are still very tight.
When I then fit the trunk guides to the front steel plate of the crankcase, I have to use a hammer and drift to get the guides to sit flush with the plate.(But all my screw holes line up!)
The cranks shaft bearings, dispite being reamed in line are still out. I am having to fiddle around with shiming to try and get some sort of alignment.(The crankcase is prone to flex even though I have brazed on the flange for the sump.) Because the cylinder block casting was short on metal I have had to change the distance between the bores. I can only find the correct centre distance of the crankshaft assembly when everything is aligned and running freely. I am concerned that I will end up with so much extra metal being removed that the whole thing shake itself to bits. I was hoping that I had picked a simple first model to build ,but fear that I was wrong.

[Jim]

I think it fair to say we have all been along the path you're on now so don't worry too much.
As Jason suggests I'd start by reassembling the trunk guides checking along the way to see exactly what's binding where and and why. Then with pistons, piston rods and cross heads moving freely I'd move to fitting them to the crank case, repeating the checking process each step as you go. That way you can identify the exact cause of any problem and correct it. Unfortunately it does take time but you'll get there. You're now at the "fitting" stage of Fitting and Turning, something we all have to do.
I had problems with the cross heads on Boadicea binding. It took a lot of easing of nuts and checking with feeler gauges before I found the problem could be solved with 5 thou shims under the brackets holding the slide bars.


Jim

[jasonb]

I'd have a look at how concentric the trunk guide bore is to the cylinder cover and any location spigot that goes into the cylinder for starters. Sounds like the trunk guide is out of line with the cyl bore.

J

[steamlaser]

Thanks for all your advice and input.
I will be starting at the cylinder head end and working backwards until everythng is running freely. As I am not trying to produce a "show winner", if it is a bit clanky it will not matter. I concider the Clayton as a training exercise before I possibly attempt anything more complex.
I am going to take a break on the Clayton and finish the four plates on my cubical sundial.Hopefully I will return in due time ,refreshed to tackle the problems with the stiff motion works.

[Rex Hanman]

When I built my Rob Roy it was so tight it would only turn over with the regulator fully open and if you pushed it along the track it was more like it was on skis than wheels. ;D

Must be a metalwork teacher thing!

Don't give up, the satisfaction you will feel when you eventually get it right makes all the headaches worth while!

[sentalike]

An old railway loco driver told me many years ago that the time to panic is when everything goes QUIET!