Castiron Welding

Toolles · Aug 19, 2009

I bought a very old radial arm drillpress and the box table (detachable) has been abused. It has several holes drilled into it & one 1-1/4" through hole in the T slot table. Has anyone got any suggestions on how to weld up the holes? I suppose I should find some sacrificial iron to plug the holes & weld it up? I have a Lincoln AC cracker box that I've used to weld other castiron objects. More like mud dob. But it holds pretty well. I would be greatful for any suggestions or comments.
Les
See the pic: http://www.practicalmachinist.com/vb/album.php?albumid=38&pictureid=239

aametalmaster · Aug 26, 2009

If i was you i would use Crown Alloys 255 and weld it up. I would cut some copper for a backer bar to put in the tee slot and weld down to it then grind out to match. That rod needs very little preheat then wrap in insulation to cool. If you were closer to Ohio i would fix it for you...Bob

http://www.crownalloys.com/products.htm

macona · Aug 26, 2009

I would fill in the holes with epoxy, maybe a steel filled one. No since heating that table up. A lot of risk for no benefit. Its just holes.

Toolles · Aug 27, 2009

More Questions

Thanks for your comments Macona & aametalmaster. I have welded a couple of broken pot belly stoves and a few other castiron items and have never pre-heated the piece. Excuse my inexperiance but what is the pre-heating for? Is there a chance of warping or cracking the castiron? One more thing, do you think that trying to repair this table would devalue the piece as an antique? I'm not viewing this drill as an investment but sometimes a repaired object is undesirable. What are your thoughts?
PS Macona back in the late 50s through 1963 I lived in Salem, Staten, Port Orford, & Ashland Oregon. My dad was a preacher & we moved alot.
Les

Mulva · Aug 27, 2009

yes, the preheat and slow cool are all intended to eliminate cracking.

Cast iron can be quite brittle and the shrinkage associated with a weld cooling can often crack the peice. Its the same reason why nickel is a good filler metal to use for cast repairs, because it does not shrink much while cooling.

As for me, unless the holes are causeing you some sort of problem, i would not bother to weld them.

Toolles · Aug 28, 2009

Decisions Decisions

As I clean up the machine I can assess if the state of the table will affect it's functionality... whether the damage will hamper mounting vise or a work piece. I guess it doesn't have to look purdy.
Les

BIGGUNDOCTOR · Aug 30, 2009

The problem with cast iron is that it shrinks at a different rate than the filler rod. The rod usually pullls away from the cast iron.

Preheating expands the part.

I peen the weld with a pneumatic needle scaler as it is cooling to spread the weld and keep it in contact with the cast iron. Use short stringer beads, don't try to do it all in one shot-patience is the key. Weld, peen, grind, weld, peen , grind till done. Some rods are machinable, some are not. I would stay away from the old E99, as there are better rods out there. More expensive, yes, but worth the extra cost.

I then post heat to get it all warmed back up before tossing it into the ash container. I have the lower half of a 55 gallon drum that is filled with the gray wood ashes out of the wood stove. Stir them up and put the part in to allow it to cool very slowly. The wood ashes are free, and work the best for me.

starbolin · Aug 30, 2009

Toolles said:
... Excuse my inexperiance but what is the pre-heating for? Is there a chance of warping or cracking the castiron? ...

Preheating does three things. It keeps the material next to the weld ( the HAZ ) from immediatly quenching and becoming too hard. It controls shrinking. And, removes excess carbon from the joint face.

The Joint face of a cast iron weld should be heated to dark red before welding. A step most often omitted.

One more thing, do you think that trying to repair this table would devalue the piece as an antique? ....

Tools should be kept in working condition. For antique tools I would prefer a repair that used brazing or silver solder. These techniques would most likely have been used during the time the tool was new.

starbolin · Aug 30, 2009

I just re-read your original post in regards to appropriate repair. An old-timer would have tapped the excess holes and inserted a metal plug that was then peened and filed flush.

gtermini · Aug 30, 2009

starbolin said:
I just re-read your original post in regards to appropriate repair. An old-timer would have tapped the excess holes and inserted a metal plug that was then peened and filed flush.

Of the choices presented, this seems the best. The biggest problem I would see is that the table would be oil soaked, which could make epoxy or welding more complicated than one would like. It would take baking the whole unit for a long period of time to cook the oil and grease out to a point where a welding alloy or an epoxy would bond properly without porosity. With a metal plug, this isn't even an issue, if anything oil in the metal would be beneficial to the fitting of a plug. I feel that the old methods are sometimes the best. I had many problems of this sort when working on an old lathe a couple years back. Hope one of the choices works in your situation.

Greyson

machine1medic · Aug 30, 2009

Nothing gained ........

by doing what you ask to the table.
none of the fixes recover any lost strenght or soundness.

Large work will not be affected by the holes.
for small work have a plate to put under your work.

Tables in far worse condition are in use every-day.
Drill away........ and focus restoration on something more deserving.

Cheers
M1M

Toolles · Aug 31, 2009

machine1medic said:
Large work will not be affected by the holes.
for small work have a plate to put under your work.

Tables in far worse condition are in use every-day.
Drill away........ and focus restoration on something more deserving.

Cheers
M1M

I'm not to a point where I can try a fix yet but I might try to weld up a small hole make a decision on weather to continue based on the results. I do have a couple of Burgmaster 1Ds and a Rockwell drill for smaller work so I only plan on larger work on the radial arm drill.
Thanks, Les

Ries · Aug 31, 2009

I have had real good luck with cast iron TIG welding with a nickel rod.
No preheat, no post heat, no cracking. Quick, very small Heat Affected Zone, and pretty decent color match too.

The negatives are, of course, cost- you need a good Tig machine, and Nickel rod runs about as much a pound as Kobe Beef. $30 to $50 a pound is not unheard of.

But it works.

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