How do you fill in (plug) holes in cast iron to get good results?

[HMF]

Can you buy (or make) threaded CI plugs to fill in voids in cast iron?

What is the best way to get a neat and good result?


Nelson

 

[randyjaco]

It sort of depends on where they are. If they are on a painted surface, fill with epoxy and paint over them. If they are on a platen or table, filling them with a braze rod will work, but will be noticeable. Filling them with nickle rod will be a real PITA to get flat and may ruin the surface unless you can run them through a surface grinder.

Randy

 

[george wilson]

How big are the holes? You can get cast iron threaded plugs used in plumbing. Tapered threads to sock up tight.

 

[Tony Wells]

Real automotive machine shops used to plug heads and blocks with special tapered screws that were inserted into prepped holes. They were then cut off and peened. The worked to seal the water jacket in engines where welding was not practical.

 

[HMF]

How big are the holes? You can get cast iron threaded plugs used in plumbing. Tapered threads to sock up tight.

I'm talking about holes of 1/4" or less. I wasd wondering if the holes could be tapped and the plugs glued in somehow to seal them firm (bondo or devcon?).

Then they could be sanded or filed flush?

Nelson

 

[pjf134]

Nelson,
Go to this site microweldersmicrowelding_com.htm. I have never used it and do not know anything about it but I did hear it works good. It might be worth looking into for the heck of it. It may not be cost effective for one job, but if you can use it to do more it just might be.
Paul

 

[HMF]

I'm talking about holes of 1/4" or less. I wasd wondering if the holes could be tapped and the plugs glued in somehow to seal them firm (bondo or devcon?).

Then they could be sanded or filed flush?

Nelson

Ahh, light goes on.
You are talking about your SB Drill press table.

Yes Jim- exactly- the SB DP table. I want to try to rejuvenate it. i was thinking that some plugs or screws could be used, epoxied in place and then filed smooth. The same could be done for the large center hole, which is mangled up on mine. I don't like the idea of silver braze- the color won't match, will it? And silver is softer stuff.

If I use a devcon-type steel-filled epoxy, I am thinking to add filings from a piece of cast iron to try to match the color better. There may be powdered additives that I can get from a chemical supply that will match the table color to make the holes "disappear".

Honestly, it frustrates me that people drill through their tables- there is a hole in the center. Move your work to have the drill hit the hole and that's it. Or use a block of hardwood under the work and set your depth- that is what the depth stop is for.

I was looking at another SB with a clean table, but the guy sold it for a lot more than I could spend, so I need to clean this one's table up.


Nelson

 

[HMF]

BC,

That looks great- how is it for rigidity?

My SB 10L compound has batter scars also from someone ramming it into the chuck. it doesn't look like it is anything that compromises functionality, so i am not worried. If I can get a better compound one day, I will, though this one is large dial, which is harder to get.


Nelson

 

[drawfiler]

I have done this before, firstly drill and tap the hole then counterbore oversize for a 1/8" deep or so, turn a piece of CI bar to counterbore size then thread the end to suit thread in table. Machine an undercut behind the 'head' to ease cutting off. Screw into table using locktite but ensure that the shoulder on the pin is against bottom of counterbore, allow to set and saw through undercut and clean up.If the table is ground the repair will be invisible.I did a mill this way and you could not see the studs 20 years later.
I also use this method to replsace broken out T slots.
The epoxy + iron filinngs does work but the hole must be clean.
Peter

 

[HMF]

Those are some very good methods- thanks for sharing them. The table is ground, so, if I do it right, the repairs should disappear.

Nelson