Best Way to Fix Rusty Half Center?

[SteveHGraham]

This is highly annoying. I have never used the tailstock thing I got for my rotary tables, but today while I was moving the big table off the mill and putting on a smaller one, I noticed that the half center was rusted to the point where it felt rough. I have no idea how this happened. I don't have big rust issues, and I always try to keep cast iron coated with something.

Anyway, here it is. I think it's an MT 2. What's the best way to get this crap off without ruining it? I don't have a tool post grinder to make it like new.

I could just dump it. These are probably really cheap. Yes; I see them on Ebay for $13.

Also, related issue: I don't have an ideal clamp to hold the back of the rotab down. Or, actually, I don't have an ideal stud. The shortest stud I have is so long, when I tighten it, the nut doesn't hit the clamp. I stuck two very heavy washers on top, and now it works. I also put a 1.5" under the back end of it because the clamp is so narrow, it barely spans a table slot, and I wanted to distribute the force.

Should I expect any problems with this? I don't foresee any, but I've said that before, and...

[atomarc]

I don't know how to fix it but I would run it as is. I have a dead half center like yours and have used it maybe once in 30 years. They work well when threading close to the end of a small diameter shaft where tool or tool holder interference would be an issue but a live center with a long snout works just as well.

Other than that use I can't think of when it would be used. Being a dead center, it would clunk along at very low RPM's so a pitted finish doesn't seem like it would affect anything.

Stuart

[SteveHGraham]

I'm not sure why they sell this thing with a half center. You would think a regular dead center or live center would work fine with a rotary table. Maybe it's just the cheapest option?

It's same taper as the tailstock on my small lathe, so I can always use the lathe live center.

I know it's silly but I hate to see tools get crapped up, even if they still work.

[hammermill]

Polish it up with steel wool,apply you chosen sealer and go on. We expect better from here on.. oh I doubt it is cast iron

[SteveHGraham]

While I'm whining, I don't comprehend the cast iron plugs Phase II sells with its tables. I assume they're supposed to fit in the bore to keep junk from falling through (guess who dropped a carbide cutter in there), but if you put the plug in, you can't install the adapter plate or chuck. The bore in the plate is too small. I guess I should open it up.

I'm thinking I should just machine a gadget I can shove in there, with an eye on it so I can take it out. Maybe a little aluminum bucket that will fit snugly in the chuck bore. I could take it out if I needed to run a long, thin piece down into the chuck, and unlike the plug, it would have a handle.

[SteveHGraham]

Polish it up with steel wool,apply you chosen sealer and go on. We expect better from here on.. oh I doubt it is cast iron

I wasn't really thinking. Most of the junk in here that has no paint on it is cast iron. Table saw, mill, lathe, my Chinese dental implants, the plates in my head...

[Harold_V]

I'm somewhat troubled by the color of the "rust" you speak of. Rust, as we know it, isn't black, but a deep red/brown color. The center appears to me to be black. Are you sure it's rusted? It appears to be coated with something instead, whether intentionally or by accident.

Black oxide is, of course, black, but it's highly unlikely that the piece in question is black oxide coated, as that's a hot process (285°F), which converts the surface to Fe304. There is an alternate chemical blacking, accomplished at lower temperatures, but it generally is a very thin film, much like black oxide. It would not create pitting.

If the piece is truly rusted, it will have pitting. If it has been coated, it most likely will not. Try cleaning a small area, using a razor blade.

Harold

[SteveHGraham]

It looks black because I sprayed it with something.

[arthur.marks]

Steve - not sure if you received the half center with only the rotary table or if you bought a RT with tailstock. The half center is often needed for setups using the tailstock. It allows milling cutters to clear the end of shafts. For example, if you are milling a flat on the end of a shaft, the cutter must be able to go 1/2 the cutter diameter past the end of the shaft to create a full flat. Otherwise, if face milling with the end of the cutter, you'll end up with a curved divot. If using the side of the cutter, you'll end up with a curved up section. The edge of the cutter has to go over the end of the shaft. To do that, you would run into the hardened center if not a 1/2 center.

[ctwo]

I don't have a half center, but would like one. It does not seem that one would be able to run a cutter over one for a 1/2 flat on a rod. Wouldn't the cutter still rub on the half center's flat?

[arthur.marks]

ctwo - none of them are truly 'half.' There is always some bit of fully round area on the end of the point. The amount depends on the size of the center (1MT, 2MT, 3MT, etc.); although, the 1 Morse size can get awfully small. For example, these half centers have a diminutive 3mm (~1/8") diameter cylindrical portion. A 1/4" is far more common, though, for a 1 Morse size. Remember, if the point was truly half, there would be no support in one axis at all!

[atty]

Steve,

You're in Florida. I remember my 30 years in St. Pete very well. You can watch PVC rust, if you're bored enough.