Casting defect in cylinder wall

Hi Guys,

I am after a bit of advice please.

I've been given an old Stuart No.4 steam engine which wasn't working, amongst a few other problems I found a small hole/defect about half way down the cylinder bore. The defect, which I presume was an occlusion in the casting, is approx. 1/8" dia. across and 1/8" deep.

Is there anything I can do to fill the hole?

Many thanks,

Sarah

Hi Sarah,

I have not long ago finished a No4 (have a look at photos) and had some casting defects in my castings, albeit on the outside.

I was made aware of a product called 'JB Weld' by this forum and found it very good for this purpose.

I would make sure the casting cavity is super clean and pour the mixed product into the hole after heating the casting to encourage the resin to flow into all parts of the hole, allow to cure and machine as though it was all casting,

It will be fine!

Alan

You could alternatively make a liner from thin walled ....0.015".....K & S brass tubing and after boring out the cylinder fix the liner in place with a Loctite type product. K & S tubing is readily available in model shops and is said to have a true bore.

Mick

Fill the hole with braze and then hone/re-bore.

Paul

Give us an idea of the size of the casting, type of piston ring and is it IC, Steam or just going to run on air?

If just air then JB Weld will be OK and possibly with steam but may not tak ethe temp of an IC.

You may get away with leaving it but depending on the rings, if there are any fitted there is a risk of them catching on the edge of the hole.

Is the bore already to finished size or have you still got some machining to do?

J

Hi Guys,

The cylinder is 1 1/2" bore , with a cast iron piston ring. I do want to run it on steam and the bore is already machined to size.

I had a look at 'JB Weld' and apparently it is okay upto 550 degrees F, but I'm not sure how it would last as I presume the surrounding cast iron would expand around it each time it is run on steam.

Thanks for your comments so far.

Regards,

Sarah

Didn't realise the bore was 11/2" so forget what I said about K & S tubing which can be used as a fix in smaller cylinders with "O" rings. The idea of relining , using hollow phos. bronze might still apply though, if you have worries about JB Weld (powerful stuff).

Mick

Well unless you are going to be running at several hundread psi then the JBWeld will be fine temperature wise and any expansion of the Iron will be negligable.It will stop any tendancy for the ring to catch.

As the JBWeld is a bit thinner than some fillers lay the cylinder on its side with the hole at the bottom while it sets, allow a good 24hrs.

J

The no., 9 that I'm working on (same size, horizontal), is going to get the JB Weld treatment in one or two places. Seems like there could be quite a lot of these engines that need reascuing.

Sarah, I think you'll be OK with JB Weld, when you warm it prior to applying The JB Weld, only heat enough that you can still hold it in your hand, sit it on a radiator, or some sort of heater will do.

You say your engine has iron rings, mine at the moment has none, but the groove is about 1/4"/6 mm wide, and I wounder whether I should fit one ring, or two narrow ones in the one groove.  Ian S C 

Edited By Ian S C on 15/10/2012 12:34:23

Hi Ian

The drawing for the No.9 shows two rings each 1/8" wide.

Regards

Norman

I've always found JB Weld flows enough by itself, infact its a bit too runny when using it to form fillets and can slump if you are not careful.

Just one thing about the JB Weld make sure you get the one with the red and black tubes, not the KwiK set (blue & yellow) or the stick.

Norman, thanks, I imagine they are normally in two separate ring grooves, but I'm not making a new piston. Ian S C

Ian

No just one groove. No width given but marked to be a "close sliding fit to rings" The depth of the groove is marked as bore dia less 1/8 " It doesn't actually show a thickness for the piston either but dimensions 3/32 in. each side of the groove.

Any other "little snags" I may be able to throw light on please ask!

I think this engine is worth some effort - it should be a handsome project when restored.

Regards

Norman

Thanks for that Norman, I'll keep most of my questions etc to the post I started "what Stuart is this". Ian S C

Hi Ian,

It is common Stuart practice to have two rings in one groove. The Stuart Beam I'm refurbishing at the moment has this arrangement,

Regards

Terry

Thanks for that Terry, with this thing anything could be right/wrong. Did a bit on the govenor today, made the balls, well I annealed two 1/2" ball bearings, and drilled them, I'll rivit them on the arms. Ian S C

HI Sarah,

In practice a blowhole that size, if a blind hole, will have no huge effect on performance aside from damaging piston packing . If you use a single o-ring, which is very narrow, there is also the chance of momentary blow-by wasting a little steam.

I assume your piston is already a decent fit. If so, you don't wnat to change the bore and have to make a new piston. there is no great stress or mechanical function to this repair - just plugging a potential leak and making teh wall smooth so it doesn't damage cylinder packing.

I would not use a liquid product, but fill the hole with a small blob of Isopon P38 body filler, slightl;y proud (mix a larger amount to ensure you get a good even mixture of resin and hardener). Allow it to partially cure, but before it is rock hard use a straight, sharp edge (the corner of the shank of an HSS tool would do) to scrape the filler level with the cylinder wall without removing any metal. The ease of working P38 is why I suggest thios 'cosmetic' material rather than the more structural JB Weld.

Once hard you can, if you like, ligthly go over the patch with a light abrasive, but beware of damaging the cylinder wall.

Joey

Hi Guys,

Thanks for all your replies. I don't know if the engine has ever run so I might fix all of the other faults and initially try running it on compressed air. If it does cause a problem  and I can clean the hole out well enough then I will then try the JB weld solution. I have never tried making and fitting a sleeve so if it comes to that I will probably ask for more help then. I will have to read up on interference fits, does anyone know of a good site to visit?

Thanks again,

Sarah

Edited By Sarah Frazer 1 on 18/10/2012 16:13:49

Hello Sarah,

Get a copy of "Machinery's Handbook " it will tell you all you need to know about proper engineering , loads of copies on ebay , it's a 3" thick reference book that covers most things you'll ever need to know.

Personally, I think I would make a cast iron liner for your engine and loctite it in place,

I've got a Stuart compound marine engine that I bought part built, with a similar problem to yours, whoever started my engine made a nice job of it , but then left it in a damp shed for some considerable time, this has resulted in the larger cylinder going rusty in one place, there is not enough metal to re-bore it , so I had planned to fit a loctited cast iron liner.

The pistons have still to be made, so I can make them to suit the new bore diameters.

Richard.

Hi Richard,

Does your compound engine have cast iron piston rings?

Mine does, and if I sleeved it then would I have to make my own piston rings to suit the sleeve?

Regards,

Sarah