PDA

View Full Version : How would you fix this ?



JDarvall
10th Feb 2006, 07:15 AM
Hello,

I've finally got a auxilary skate for my Stanley 55 to try out, uno, to give a little extra support for wide cuts.

Anyway, its damaged. 2 opposite corners of a guiding rail have fractured off, I'm guessing from a heavy blow to the skate sometime, which encouraged it to swivel in its rail.

It probably will still work ok, since the skate doesn't really want to swivel under a bit of finger pressure, but nontheless its not desireable is it....a little bit more pressure and.....not good.

It be nice to patch it up, somehow. Its cast alright. I'm thinking maybe striking in a few weld blobs into the cracked areas, and just filing it back neatly.....but, I'm not sure.

Any ideas on how to fix that rail. Appreciate any thoughts.

Thanks

JDarvall
10th Feb 2006, 07:22 AM
Try again...the manage attachment thing seems to be working this time......

Grahame Collins
10th Feb 2006, 08:32 AM
Hi Apricotripper

No weld blobbing Ok.Weld blobbing is extremely intricate and thusly reserved for ultra experts. Seriously I would not touch it with a stick electrode- remember it IS cast iron. A better repair is to braze it.The brazing will allow you to file the repair back to shape This is an oxy acetylene pocess and the filler rod is bronze based - not silver solder.I think the correct rod is Tobin Bronze but it has been twenty plus years since I have used them.A quick check in an online welding supplies catalogue will give you the correct bronze filler rod.You will need to have brazing flux as well.

Time for school now, to face my cherubs
I will check the thread this arvo.
Grahame

bennylaird
10th Feb 2006, 08:37 AM
There is a metalic epoxy called JB Weld, not sure how much strength though as I have not tried it but have seen people use it to repair engine mounts and exhaust fittings on model aircraft engines.

JDarvall
10th Feb 2006, 09:27 AM
Hi Apricotripper

No weld blobbing Ok.Weld blobbing is extremely intricate and thusly reserved for ultra experts. Seriously I would not touch it with a stick electrode- remember it IS cast iron. A better repair is to braze it.The brazing will allow you to file the repair back to shape This is an oxy acetylene pocess and the filler rod is bronze based - not silver solder.I think the correct rod is Tobin Bronze but it has been twenty plus years since I have used them.A quick check in an online welding supplies catalogue will give you the correct bronze filler rod.You will need to have brazing flux as well.

Time for school now, to face my cherubs
I will check the thread this arvo.
Grahame

Thanks Grahame. I like the no nonsence advice.

I've just got a cheap stick welder. I've in the past managed to blob (is that the word to describe that ?) in weld ontop of steel before. It was quite messy, but it worked. But I didn't hand file it back. The file found the weld too hard. Instead I had to work the weld back to dimension using powered grinders......all a bit messy in the looks department, but it fixed the functional problem completely.....

But never blobbed on cast. I have welded up cast before with lollypops successfully. And welded up what looked like cast with normal rods as well (learn't from this forum that something that looks like cast, may not be, and can be welded with normal rods)

So, I'd better take your advice on not attempting it. Which is going to be hard to resist. (I like to experiment, and I'm stuburn:o ). Also, these auxilary skate parts are hard to buy cheap. I wouldn't want to stuff it up, and have to toss it.

The problem is, I don't have an oxy torch. I don't really have anybody locally who I know is skilled enough to do it for me for free .........But, I do have a MAPP gas torch I use for general plumbing though, and lately for hardening small blades. They get pretty hot. Hotter than the propane ones. But I'm guessing not hot enough, yes ?

Maybe I should go with Bennys epoxy idea(thanks Benny). I have got some 'steel epoxy' from super cheap that seems to work well in some applications. But, I doubt it would work any where near as well as brazing.

I just now thought of another idea that may be better. Well, to suit my level of metalworking skills... ..Instead of welding, maybe I could attach to the sides of the frame 2 pieces of say 3mm steel plate. Could tap each plate on with a couple of 1/8" bolts...First, I'd grind away the rails on each side, and flattern, then attach the little bits of plate to both sides to work as the new rails. Might look a bit patchy, but it should work (I hope :D )

Anycase. Thanks fellas. :)

Shedhand
11th Feb 2006, 02:40 PM
G'day Tripper
There's a 2 pot goo that plumbers use to bog up leaking G.I. pipe joints. It sets steel hard in 24 hours (workable after a few hours). When its cured it looks just like cast iron. I don't know how good it is to shape etc. You mix the two parts in a bucket under water (so it washes off your hands). It is water based. I'll see if I can dig up the name for you.
Cheers

PS: I was wondering if you posted the blades yet?

Shedhand
11th Feb 2006, 02:57 PM
Found some bog in the odds and sods cupboard.:) Pics self explanatory. Hope it helps. If not its excellent for mending GI Pipes.;)
Cheers

JDarvall
11th Feb 2006, 03:23 PM
Hey ! my threads back. Dissappeared for some reason.

Thanks Shedhand. I did know about that bog stuff. Sounds like thats the go. Thanks for the photos

I sent the blades off,...ummm....I don't really remember. It was the day I said I would send them off...When I said,' I'll post them after work'. So, I'm a bit worried they haven't reached you by now. Sent some other stuff that day to QLD, and if I recall correctly, he got them last monday.

Bit odd. Give it another a few days. If they don't arrive, I'll send you some more. :)

Grahame Collins
11th Feb 2006, 09:08 PM
Once the goop goes on the cast iron you hope to repair the chances of any sucessful fusion weld, stick or oxy is greatly diminished. because of the porous nature of the cast iron the residue will make subsequent attempts at a welded repair really difficult.(and add aluminium to that as well )

Hope your repair works for you.
Grahame

Studley 2436
11th Feb 2006, 09:37 PM
Ripper there are welding rods you can buy specifically for cast iron cold which are largely nickel. I think you should run a proper weld along the join rather than blobbing it on, will give you a much better weld.

It is OK to weld Cast Iron but you have to be careful how you do it. The crack has to ground out in a Vee for the weld to get in, then the job must be heated up so it is hot when you weld it. If it is not hot the cast will crack as the weld cools. If it is hot the whole lot cools together and you have a welded piece of cast.

Sometimes usually on really big jobs you can't heat the whole lot up so then you use the special rods.

The biggest problem I can see with this job is that you need to clamp it precisely so the machined Vee is still in line after you finish welding it.

Studley

Captain Chaos
11th Feb 2006, 10:27 PM
G'day Michael,
I'd definitely build the skate up by brazing with an oxy - acetyline torch. I reckon that the best rod for what you want to do would be a nickel bronze rod which was used for brazing Reynolds 351 steel tubing. C.I.G. ( now BOC - except in one African country where boc means s**t in the native tongue ) listed a rod called "Comcoat N" for this purpose. Their flux coated version of this rod was known as Comcoat Pink - the colour of the flux. This is a very good, strong brazing rod & can be filed / machined fairly easily. I've seen it used to build up broken gear teeth on various types of gears & to build up cam lobes on on a couple of speedway sliders & some Pommie make road bikes. The cams were then ground ( or filed! ) to the new profile & in one instance the lobes were hard chromed. in the other cases the nickel bronze work hardened with no ill effects.
It would be the best bet for what you want to achieve I think.
Regards,
Barry.

Shedhand
12th Feb 2006, 01:41 AM
Try again...the manage attachment thing seems to be working this time......Tripper, the broken area don't look as though they are pressure points. If thats the case and you were not going to on-sell the item I'd just sculpt a repair with bog. Seems a lotm of trouble to weld something that is not going be stressed. IMHO;)