Last week I asked about getting a casting from my power hacksaw repaired (welded). Several people asked me to post some pictures of the piece.
So here they are:
I'm encouraged by the people who said that brazing is a very acceptable method for repairing castings.
Anyway, have a look and let me know if you think this piece can be successfully brazed.
Gary
Looks like the original wall thickness was to small. It appears that in use there is some kind of offset force on the part wanting to cause it to twist. The designers were aware of this and provided the little boss extending off at right angles. Nontheless the tube cracked but on the side away from the boss.
If it were mine I would consider milling off the tube and brazing on a new thicker walled tube but then again I always overbuild. You could just braze it up and see if it holds.
If you braze it needs to be done right. File the joint to a 90 degree included angle. Don't grind. Prep to full depth. The braze needs to penetrate all the way to the inside of the tube. Over build the bead for re-enforcement. The braze is going to coat the inside of the tube and the heat is going to close up the tube so you are going to need to ream the bore. I would braze a bead around the end of the tube to make a collar since that is where the craking apears to originate.
For option three I think the old-timers would have cut of all the cracked metal, made a mold around the part and poured in bronze. Then using the remaining good end of the tube as a guide, drilled and reamed.
Bud
wrote: (clip) Anyway, have a look and let me know if you think this piece can be successfully brazed. ^^^^^^^^^^^^^^^^^^^ In the photos, the color looks like brass. I assume that is due to the lighting. The piece looks like it can be brazed--vee out the cracks first, clamp them shut and go for it. For extra strength, you might also braze on a steel collar around the outside.
Too true. I fussed for about an hour trying to get the color more accurate. Digital photography is quite an art.
Anyway, the piece is actually a typical cast iron dull gray with a bit of dark blue paint in the tight spots.
Gary
V out the cracks, preheat to 600 (or more) degrees (a self cleaning oven works great!), braze away using a OA torch. I'd add some sort of reinforcing ring around the cracked area. The reinforcement could be just a 1" wide strip of 1/8" steel strap bent in a 270 degree loop. The brazing will tie the ends to the base plate area.
I would not arc weld this, secti> Last week I asked about getting a casting from my power hacksaw
I had a small casting on my big horizontal band saw break. I spent half an hour with my mill and made a new one out of steel (admittedly, yours is larger and more complex, so it will take a little longer...). And it works just fine.
In any case, before you try welding, take a few minutes and make some accurate measurements and a sketch, so, if you have a total disaster, you'll be in a position to start making chips...
Jerry
Ist of all congrats on some excellent photos. also the yellow colour is caused I think by the use of an incandecent lamp bulb. If you used say a dead white led torch to illuminate the casting you would find that it would come out white. assuming that the casting is cast iron. Now as to a repair, Brazing is the way to go but you will need to close up the sprung open cracks with some sort of clamp arrangement. As another poster has suggested, if you makeup a 1/8th in by 1in piece of steel strapping to close it all up hold this in place with say apair of mole frips you can afford to over heat, then go a head and braze it all up. Its most important that you use the right flux specially for brazing cast iron. dont use anything else.
Finally, if your not to happy to braze it up then a cold mechanical repair with strapping with the ends drilled and bolted right through would work well. you will need to hot forge the strapping in place to get a good fit and champ it in place before you drill the bolt hole. I did a similar repair last week on the planer fence. Worked fine. Keep us all posted as to results. If I had it here it would take me say a couple of hours to cold mend it. Well worth the effort id say.
Im going to have to make a pretty good sized replacement of the (repaired and rebroken) casting that holds the vari-drive components in the 18" Do-all vertical bandsaw I picked up a couple weeks ago.
Ill make it out of 1" aluminum plate
Gunner
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