Welding drill marks in Cast Iron?

[jweaver]

Hi all..

I have just bought a old Pillar Drill (Fobco Star).. It has a number of 'drill marks' in the bed and I want to fix them.

I originally thought about welding, but I decided to use Chemical Metal.. My plan was to drill them out a bit futher to make them clean and then fill with Chemical Metal (perhaps mixed with some filings).

But now I have seen it, I can help thinking that a spot of weld might work.

What would happen if I used the MIG to fill the marks? And then ground off the excess with a flap disc?

Should I stick with "Chemical Metal" or is doing this with a MIG possible/advisable?

Jon

 

[dan.taylor.1]

You'll just make it crack if you weld it with mig, unless preheat and the right filler (silicone bronze type stuff) is used. I'd stick with chemical metal and flat it off after, I'd leave the holes rough too so it has something to bond to.

Dan

 

[jweaver]

You'll just make it crack if you weld it with mig, unless preheat and the right filler (silicone bronze type stuff) is used. I'd stick with chemical metal and flat it off after, I'd leave the holes rough too so it has something to bond to.

Dan

Cheers Dan.. Glad I asked now.

Jon

 

[rory1]

Personally I would leave it alone. A drill mark in a bed wil rarely give you any problems unless you are drilling very small components clamped to the bed which is unlikely.

you would generally use a vice in a drill such as a fobco, unless it was a large component in which case it would bridge the hole/drill mark.

Grinding or flap discing the repair would give you more of a defect than the hole you started with!

 

[rtbcomp]

I used Milliput on mine, more for aesthetics than anything else.

 

[Pete.]

You'll just make it crack if you weld it with mig, unless preheat and the right filler (silicone bronze type stuff) is used. I'd stick with chemical metal and flat it off after, I'd leave the holes rough too so it has something to bond to.

Dan

Chemical metals don't need any 'roughening', but they do need a clean surface to bond to. If there's oil or cutting fluid in the hole it would be better to over-drill it slightly to ensure it's clean.

 

[striker]

I used jb weld on mine. Flatted level with a block and emery tape.
Almost an invisible repair.
Paul.

 

[awemawson]

Many years ago when I re-built my Bridgeport Milling machine I was daft enough to get a local welding firm to weld the many holes in the bed that the previous owner had made. I was having it totally re-ground anyway. They did the 'right thing' building a fire brick box round it and pre-heated it for ages, then used nickel rods to weld it up. I wish I hadn't, as the welds still stick out like sore thumbs even after surface grinding.

If I had my time again, I'd bore out the holes to a nice finish, turn cast iron plugs, loctite them in, THEN re-grind

 

[aametalmaster]

MIG is perfect with the correct cast iron mig wire like Crown Alloys 44-30, but I don't know if you can find it in your neck of the world. I use it all the time to fix boo boos for customers...Bob

 

[TechnicAl]

http://www.mig-welding.co.uk/welding-cast-iron.htm

 

[dannyp]

id just leave it well allone TBH