Cast iron work surface pitted.... Filler????

[beezapilot]

Yeah, not really gunsmith stuff, but you guys are the metal masters.

I'm a sucker for old & orphaned tools, so picked up a mid-1950's Craftsman bandsaw- there is quite a lot of charm in cast iron and steel cover panels. Cleaned it up, oiled the bearings (still look good), repainting the panels...

The problem is the work table- there is some pretty ugly pitting. A small bandsaw is not going to have a lot of weight, but would like a smooth table anyway.

Read up on various fillers, brazing rod & silver solder and the like- but all came with the warning that uneven heating of CI would result in warping.

My thought was some quality marine epoxy infused with aluminum filings as filler.

Am I way off base with that?

[shortlegs]

JB weld with metal or without will work.

[NyFirefighter357]

I'm a member of http://www.vintagemachinery.org/home.aspx this is the direct link to the forum http://www.owwm.org/ they all use JB Weld to fill rough cast iron work surfaces and such. Fill and sand it flat. You might want to check that sight out for restoration advice as well.

[MyFlatline]

Bondo might work and + 1 on the JB Weld. Coat it with a 2 part paint when you are done and it should last. My table saw has a cast iron top. It needs sanding down ( I used spray paint) and will use a good 2 part durable paint next time.

[john.k]

You can buy metal filled epoxies,incl CI filled ,but they tend to be expensive.One that I have used to fill up internal pitting cavitation in cylinder blocks is Devcon......good,but expensive.

[OldBearHair]

JB Weld times two.

[LAGS]

Bondo, JB Weld or any of the Simpson Construction Epoxies available at Home Depot or Lowes.
With Epoxy, use a trowel wet with Denatured Alcohol.
Saves a lot of finish sanding.

[country gent]

Several of the epoxies will work here. I have used plasti steel compound on drill press and mill tables with good results. JB weld works good also. Another Ive had good results with is bisonite steel bedding compound. The issue with filling rust pitting is it may not be deep enough to give good solid coat and enough thickness for strength of the fill to hold up and not chip out. You may need to cut it a little deeper and roughen the surface for a good solid bond. Thin layers of epoxy don't normally hold up real well being brittle they tend to chip out easily. On a saw like yours the best fix for a truly smooth table might be a piece of plate the size of the table held on with 4 screws 1 in each corner. Make it up as the table is with the cut and guide in it and bolt it down. A piece of 3/16" or 1/4" plate ( could be aluminum or steel ) bolted down with flat head allen screws and sanded polished up will hardly show and make for a nice working surface. Otherwise you might end up deepening the areas some to get a good area thick enough to hold up. I have milled areas out and fit in 3/16" thick plates gluing them in and then finishing back down to surface, usually milling and grinding close the hand scraping and stoning in to finish.

[Bazoo]

Slather on the JB weld, then use your random orbit sander to grind it down with the table surface, progress through finer grits to whatever you like.

[leebuilder]

Yup JB weld or similar like Devcon liquid metal. It's all in the prep, so it sticks and won't crumble. Use to restore mill vice bases with those products, mill flat and you know its perpendicular to the quill.
Good luck

[Jeff Michel]

Find someone with a vertical mill and have them fly cut it. It's probably what what they did originally at the factory. It will likely only take of a couple thousandths to remove the pitting and won't affect the integrity of the table. I have seldom used fillers on surfaces that won't be painted. If you go the fill route, you might consider Devcon Plastic Steel, performance wise it's the best out there and a decent match with cast iron but not perfect but better than JB Weld Just my opinion, others will differ. Couple of pictures as you progress would be nice. Good luck with your project

[KCSO]

Liquid Steel and finish by sanding smooth. Has lasted 40 years so far.

[oldred]

Welding or brazing would not only warp a table like that but would likely crack it in the process, welding would almost certainly lead to cracking. If you are talking about rust pitting then products like JB weld and the other thick putty epoxies are probably not the best choice here. I agree that those products, JB weld and similar, would be the cat's meow for deep gouges or holes like what is often found on drill press or milling tables but as others have pointed out it just don't work very well for shallow holes or rust pitting. Use the thinnest Epoxy you can get, the thinner the better, and wire brush that table with a grinder fitted with a wire cup brush to remove all contamination in those pits. After it has set up hard take a flat sanding board and sand the ENTIRE table until flat, don't dwell on any of the filled spots or you will leave shallow dips in the surface.

I rebuild old machinery as a hobby and have for years, mostly farm equipment and tractors but old tools also, and I have tackled this very problem many times in the past. Honestly JB weld and thicker putty like epoxies have not worked well for me at all for simple shallow pitting such as commonly encountered with rusted iron and one of my favorite fillers is not epoxy at all. I use iron fillings (iron/steel grindings work well) mixed in polyester resin filler such as used in fiberglass lay-ups, this stuff is as hard as the epoxy and adheres to even shallow surfaces much better than putty type epoxy. Several types of products can be used successfully and while JB weld and the putty type epoxies certainly would be hard enough I think in this case due to the thin amounts needed adhesion is going to be a problem with them.

[oldred]

Liquid Steel and finish by sanding smooth. Has lasted 40 years so far.

Yep that works really good, I have used this with very good results, the stuff is unbelievably hard and sticks to cast iron like ugly sticks to an ape!

http://www.permatex.com/products/adh...-metal-filler/

[Walter Laich]

ran across this and got some great ideas

thanks

[beezapilot]

Well, thank you for all the input. There were some things put forth that I'd not thought about. As an experiment I took a piece of aluminum, drilled some random depth small holes in it, attacked it with a center punch and hammer, then a ball pein hammer for good measure - it was properly ugly when I was done. I mixed up some JB Weld and worked it in with a razor blade & alcohol. After it had kicked off I sliced it up on my bandsaw, the JB hadn't made it to the bottom of some of the holes and punches. I don't think that would effect performance of the finished surface, but I thought that was interesting.

I use WestSystems epoxy when I build boats, so tried another piece of aluminum, with 207 hardener the epoxy has a long working time before it kicks off. Apparently as it is more liquid for longer, as I worked it again with a razor blade for a spatula I could see air bubbles coming out of the holes. The bandsaw slices showed that the epoxy made it all the way to the bottom of the holes and there were no voids.

I called tech support for WestSytems, he explained that they actually sell an aluminum powder to mix with resin, but for a small job like that I could use bandsaw chips.

He did offer a little more advice with the prep- that as soon as I got it clean enough that I felt I should proceed that I use one of the rust converters, spray it on, let it cure and they sand / wire / blast again. He indicated that cast iron is porous, and a bit of rust under the epoxy might haunt me later on. Neutralizing the rust may be a good idea.

Photos to follow.....

[country gent]

Another way to go might be one of the "restorer bar top type epoxies. Build edges up with several layers of masking tape 1/16"- 1/8", tall set up as level as possible. Mix epoxy and pour in working around in a thin coat over entire top. (spread as evenly as possible). Warm with a heat gun or blow drier to smooth level and remove air bubbles then let cure. this would make a hard smooth even surface that should hold up well. Another plus it would also cover the entire top reducing the chances of future rusting.

[beezapilot]

***** Sorry for the delay***** An epilog and lessons learned. I went with West Systems epoxy and fine steel filings. I tried the easy route and visited my buddies shop for swarf from his brake lathe- that would do for BIG pits and large surfaces, but a little coarse for this application. I found an old ax head at a yardsale with an interesting pattern, but had some rust pits so de-rusted that and took a file to it to smooth out the craters. With the resulting filings mixed up a nice slurry with the epoxy.. I went with 207 hardener as it has a long work time and thought that would give it time to be self leveling.. to a point it was. Sanding fully cured epoxy is tough at times, full of steel.. took a while. Had to hand sand as the power sanders paper didn't last for beans. The result is a "glittery" surface, like sintered metal. The cold cast process made a very tough surface! I think that it will last my lifetime.

[oldred]

Pitchers! We need pitchers or it didn't happen!!!!!

[country gent]

With some epoxies heat from a heat gun will soften the mix and help it flow out, It also helps to remove air bubbles. A good fine chip comes from the cut off saws pan. those are fine chips also. But remember to clean and dry these chips before mixing into the epoxy to remove oils and cutting fluid residues. Chips from a band saw or power hacksaw, filings from a file, dust from a belt sander or surface grinder all can be use full. Another was the chips I made when scraping in machine members these were very fine and thread like, but it took a lot of scrapping to accumulate any amount. A weeks scraping might yield 1/2 cup of chips LOL.