52" shear clean up

[Ed T]

Didn't get much response over on GJ so I thought I'd try this group as well.
I recently purchased a 16 ga. x 52" "stomp" shear from a government auction. It's a JET made in Taiwan. It appears that it was never commissioned since all of the some-assembly- required items were still wrapped up in their original crate and, for the most part, the ground bed and blades were still covered with petrified cosmoline. This is a good thing since the poor thing was stored outdoors long enough that a lot of the paint is coming off and there's a lot of "surface rust".
So, now the big question. The major castings are pretty rough under the paint and the entire surface is built up with a fairly heavy layer of filler/primer and the sanded to be smooth under the finish paint. After I sand blast the whole thing, some or all of the filler will be gone and the remaining surface will be rough. While this is of no functional significance, I would like to bring the surface up to a reasonable level of "goodness" before I repaint. What would be the recommendation of the group for a good way to accomplish this. I've considered just a skim coat of bondo and then sand my brains out. Spray polyester high build primer like feather-fill or whatever it's called now. It is not practical to disassemble the machine. The parts are too heavy to handle easily. Any thoughts??
Yes, there may be some pics later, but it's more work for me to post the pics than it is for me to do what the pics show.
Thanks,
EdT

 

[Tin Falcon]

Always decisions. Hard to tell without looking at it. so questions back to you. the number one question is the rust under the filler. if yes then sand blast and start with a clean casting . if the rust is just on the surface on the high spots on the casting then sand it and leave the existing filler in place and add a little if needed.
in my various jobs I have used bondo , evercoat (premium talc and polyester filler) and spay on primer filler.
Use bondo only if the areas to be filled are large or deep . evercoat for small inperfections and mix small amounts it kicks quick but sands a lot easier and sooner than bondo. use spray filler if if all or most of the part has many small shallow imperfections.
the bottom line is what is the current condition of the casting. how much time money effort do you want to spend and what do you want it to look like when finished.
It is a casting not a finished boat hull or restored antique car. so decide accordingly.
are you totally confused now???
Tin

 

[Ed T]

Thanks for the reply. Certainly, it's my intent to take the thing down to base metal in every area that it is reasonable to do so. In some poking around with a scraper the max thickness is < 1/16 " thick and the underlying filler is bondo or something similar I'd say. I think what would be ideal would be a bondo that can be brushed on, but I've not seen any that was reasonably priced, yet. Anyhow, I'll get it cleaned up tomorrow unless it's still raining, and test out a couple of approaches and see what works. BTW, you're 100% right on the scope of the project. It's not a fancy car or a piece of furniture and the finish is mostly to keep it from getting rusty and looking OK; not perfect. Easy to get carried away. The last 5% of "perfection" takes well over 50% of the time. Functionally, it's good to go like it is, but there's a certain satisfaction in working with "nice" equipment rather than something that looks like scrap.
Thanks again,
EdT

 

[Tin Falcon]

well an option is to thicken up some gel coat with airosil cabosil aka fumed silica. just mix into the gel coat until you get the consistency you desire. then mix in the catalyst and brush it on. bondo is polyester resin and ground walnut shells. but different brands ad grades use different blends of polyester and filler.
if you want to fair the surface fill in any obvious imperfections then sand down . hit with a good sanding primer mist with a spray of layout dye. sand the die will stay on the low spots spot fill sand and spot prime. when is like you want top coat. there are many ways this can be done.
Tin