Damaged Steam Cylinder

[ianmac]

Howdy All,

I am building a C36 Class gauge 1 loco as my first loco. Everything i know is self taught.

This is where the problems begin i guess ;D

I had bored the loco cylinder and polished the steam port surfaces etc etc etc. Mounted the cylinder block into the mill and took off a few thou and everything looked fine.

Took the job out of the mill and machined up a piston to suite.

Piston didnt fit and when it did there was slop??

Then i realised i had crushed the cylinder by about 10th of a millimeter.

I felt like throwing the thing into the dirt tin but then though hang on i might be able to salvage the job if i machine up a sleve for the cylinder ??

Can anyone think of a better way......and no I cant bore any more meat out of the cylinder

[Tel]

Yow, a C36 is pretty ambitious for a first try. Good luck with it.

Now, a sleeve will most probably work but you will have to try and get that damaged bore more or less round again to seat it in, might be a good idea then to sleeve the other side as well just to even things up.

Wot's the design bore? 1/2" or so? Any sleeve you fit will be pretty thin in the wall if you want to retain any useful bore size - could always go cap in hand to Ernie for a replacement casting I guess, or fabricate one.

[ilvaporista]

Not having seen the job it is difficult to say. But is there any chance of setting up the still round part of the bore and running the boring tool through again? If you then take a very light cut over the whole bore you might come back to a parallel bore.

I have used the above on a dented hydraulic cylinder to keep a machine running. First operation was to drive through a drift made to bore size to take out the worst of the dent.

Edit
OK so after I read that there is no meat to re-bore... But is no meat really no meat?? If you can set up well could you get away with 0.1mm?

[circlip]

Ultimately the cylinder is scrap so whatever you try if you can reclaim it is to your advantage.
1. I don't suppose it will be but is it a "standard" bore? Will a standard ball bearing fit into it, if so you could SQUEEZE a ball through the bore to recicularise it.
2. Non standard size, turn a bar to the correct Dia with a tapered leading edge, and again SQUEEZE it through the bore.
Note on both the examples I have emphasized the squeeze rather than DRIVE.
If neither of the above are possible what about an adjustable reamer? Might sound expensive but if you're going to be making any more gauge 1's it will come in useful. regards Ian.

[Noddy]

Here goes;

I don,t know what variety of brass you used, but at 0.1mm hopefully it will swage back.

Turn and polish up a steel bar to the exact size bore you wanted,

round the corner of the leading edge so it will enter the cylinder

The bar doesnt want to be much over the length of the cylinder, so that it doesnt bow

If the cylinder is blind, Mark off the length of the cylinder on the bar so you're not pushing the end out. Also if its blind, form some sort of collar on the tail end of the bar so that you can pull it out again if its a through hole you only need a length of rod at full cylinder diameter which is slightly longer than bore diam for it to run straight, then turn down behind that and round off the sharp edge.

You will need to gently lube the bar and cylinder, the merest coating or you might bulge it.

Suitable lubes are: soap, lanolin, moly sulphide or graphite.
there should be lots of good background reading refs about case forming and case neck expanding on the net.

Use a press of some sort to push the rod in, and if it is a through hole, out the other side. for choice I'd use a bench vice with a block of wood with a hole in ahead of the cylinder and carefully push the rod through.

If you can't get to a vice or press, you could improvise with a car jack.

If you want to be really posh, you could bore a hole in a piece of metal to act as a guide bushing for the rod so you don't bell the mouth of the cylinder.

Good luck and Let us know how you get on

Keith

[Tel]

Good advice Ian and Keith - should get him out of trouble

[ianmac]

Thanks everyone.

I think the 36 was ambitious but you need to start somewhere and no matter which way you look at it if I started on an 0-4-0 than i would still need peform all the same sort of work on that loco.

Granted there is a bit more work in the 36 but i have learnt so much. I had never used a mill before in my life so that was interesting and im having a ball.

My advise to anyone consdering getting into this hobby is stop worrying if you can do it and have a go.

Along the way you will make some mistakes but dont throw anything away as you can always use the damaged bits for something else.

Above all I am really enjoying this hobby so much......i will be building another loco for sure. AD60 mabey.......mabey a C38 .....

getting back to the cylinders

Tel, The Cylinders are 7/16 on the plans but i think thats a little on the small side. little 5/8th is what i settled for in the end.

The next obvious questions was what about steam supply so yes I redesigned the boiler quite extensivly. Stacks more heating surface area ;D. I already asked about new cylinders and he hasnt anymore


Keith,

Thanks for the advice . I think a push bar is the way to go so I guess thats what i will be doing .

I will get back and let everyone know how i got on

Ta Everyone

[ilvaporista]

The reply from Keith sets it out the best. Use an already round solid object and squeeze it through. By 'drive' I did not intend to lump it through with a sledgehammer....

[circlip]

As a newbie to milling Ian, the one thing you've found out pretty early is how tight (or not) your bits need to be clamped to machine them, and how NOT to clamp them. It's all a learning curve and it NEVER ends, that is unless you're an expert.

[ianmac]

OK,

Thanks for the advice, i machined up a MS bar with a taper and pushed the bar through the cylinder fixing the slight oval. This had to be done twice each time the bar was made slightly larger so that it dit this in graduations rather than one big movment

In the process i have found my lathe is out by a stack.
The 3 jaw is out by .4mm WOW.

It is also cutting at a slight taper, Lets say over a 4inch peice of work you will have a slight taper of .10mm WOW.

I rang HAFCO and they are going to come out and fix it up monday morning.

I found this out because the cylinder is 16.15 at one end and 16.21 at the other so this led me to investigate further.

Anyway i purchased a reamer to day so i can fix up the problem.

Once again thanks for the advice

[ianmac]

Thanks keith

Ian

[Tel]

My experience mate, is the Hare & Forbes are really on the ball when it comes to that sort of thing

[ianmac]

Cylinder now has the covers fitted and all looks to be good.

Hafco came out this mornign and fixed the head stock.

It is now out by less half a thou ;D