Conti Prestina Espresso Machine Restoration 101 (Completed and Indexed) - Page 12

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
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drgary
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#111: Post by drgary »

It will be about a week or two before I can get to the next step of getting the bolts out of the boiler, and the painted panels and frame are now out for powder coating. Meanwhile, I thought I would float a couple of questions about polishing the stainless steel panels.

There's already a great thread on that topic here: Polishing stainless steel panels. The main things I gathered there are that it's one thing to shine up a steel panel, another to get rid of hairline scratches, and yet another level of intensity to sand out deeper scratches. The most knowledgeable guy weighing in there (no surprise) is Dave Stephens (cannonfodder), who recommends a powerful bench grinder plus an expensive array of buffing wheels, each matched to a specific grit of buffing compound and, I think, first starting with sandpaper to progressively deal with the most intense scratches and then back out to a mirror finish. The grit thrown off using a big grinder and various polishing rouges is intense enough to require a sealed respirator. That alone wouldn't stop me but certainly makes it an outdoor project.

So I'm wavering on the idea of settling for a nice polish but not removing all the tiny scratches. I've already looked into electropolishing, and the only shop that answered quoted me $350 to $400 for 6 panels (for the Prestina and my Oly Coffex), more than I want to spend. As I understand it, electropolishing is a similar process to chrome plating, so that's no big surprise.

Here's the condition of the front panel, which is like the others. Don't be fooled by the brass-like color of some of these photos. It's all stainless steel, so that's a photo anomaly. There's no brass showing through anywhere, and the rough, rectangular patch on the right bottom is old adhesive from the serial tag.

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I have a Craftsman random orbit sander that I've used successfully with furniture. It's 4 1/4 inches diameter. Previously I've used sandpaper with an adhesive backing to prep wood. But I don't know whether a buffing wheel can be attached or whether the correct type of sandpaper will adhere for polishing steel. Certainly this isn't any high-powered bench grinder. Here are a couple of photos of that tool:

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So here are my questions:

Will the random orbit sander be useful for any of this polishing task? If so, what steps and what kinds of sandpaper pads or buffing wheels should I use? And with this level of tool, should I give up on getting out the deep and fine scratches?

Also, should I consider electropolishing, and if so, has anyone worked with a shop that's affordable? I have found a good chroming resource, but they don't do electropolishing and I'm guessing without getting their quote that chrome plating would probably cost at least $200.
Gary
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kmills

#112: Post by kmills »

1200 grit wet/dry paper and some elbow grease should get you to a point where plating will take care of the rest. Ask what steps the plating service offers. A good thick nickel plate then chrome on top will leave it pretty darn smooth. You may need to do 800 grit if 1200 is too fine. You may be able to get away without much sanding too. Be careful with the random orbital sander and don't let it sit in one spot too long or you'll get clover shaped scratches. If you are just going to polish, I dont think you will have much luck with the sander, but you can check what pads are offered for your sander and give it a try if they have cotton pads and some polishing compound.

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drgary
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#113: Post by drgary »

Thanks, kmills. I hesitate about chroming because of cost and want to see what I can do myself first. If I try to stick with buffing and polishing, and my random orbital sander can't take buffing pads, I see similar tools for sale for about $35. So if I get something like a car buffer and the right polishing compounds, might I have better luck? Also, for rotary polishing wheels, is there anything that will fit into an old Black and Decker drill?

I would have to try these of course and can envision turning the drill so the polishing compound goes off into a barrier I set up instead of all over me and my garage. I also don't have a feel until I try this for how hard the steel is and what it takes to polish out scratches, which involves removing a small layer of steel. It may well be that the fastest, least expensive course for a good result is chrome plating. With a buffer or drill, am I considering tools that aren't up to the job?
Gary
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kmills

#114: Post by kmills »

Most hand drills have a half inch chuck or less, a buffing wheel with a proper spindle may work. A cordless drill will be a hassel too, you better have 3 batteries to roatate through or a plug model. You will get REALY tired, see if you can strap the drill to a bench vice and hold the part, rather than the other way around. My geuss is your going to make it shiny with scratches. Maybe thats ok though. Another option is to do a brushed look. This is generally more user friendly in the end because it hides scratches and fingerprints and general grime. Its also significantly easier to do. Here is a neat resource http://www.espresso-restorations.com/metal.html

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drgary
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#115: Post by drgary »

Fortunately it's a corded drill, and yes, locking it down and applying the part is the best approximation to a grinding wheel. I may try that first and see how it works.

Thanks also for the reminder about the espresso machine restoration site. A brushed look is a real possibility too. That may be my fall-back on the Prestina; it's a commercial machine "look." For the Coffex, maybe chrome but I'll try polishing first.
Gary
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ANeat

#116: Post by ANeat »

I wouldnt recommend a drill, they arent constant duty and after a bit it will be toast. If you want hand held look at a variable speed buffer, perhaps even something like a automotive buffer. Just be sure and fasten the piece down somehow. It wouldnt be too tough for the buffer to send the metal flying :shock:

Look at some of the vids on youtube concerning polishing
LMWDP #332

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drgary
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#117: Post by drgary »

Good points, Adam. Thanks!
Gary
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RayJohns

#118: Post by RayJohns »

Polishing anything, plastic, brass, aluminum, metal, wood, whatever... it's always about sanding down to the biggest scratch, pretty much.

It's also generally always about using progressively finer sand paper or polishing compounds. Just this weekend I had to wet sand and polish my little sister's head lights on her car. She was caught in a snow storm a while back and her head light lenses looked like someone had media blasted them (they were yellow and foggy and she could barely get any light on the road).

Anyway, I vote the "brushed look" for sure. Polishing is a pain in the back side and not only takes a good amount of elbow grease, but it's also high maintenance (in a way that makes your ex-wife and $1000/hr call girls seem overly easy going and laid back). Again, my vote --> brushed look. Use a green scouring pad and/or some Bon Ami or something (with a little oil or water tossed in). You should end up with a real nice satin finish and it's easy to maintain.

If you decide to polish, then I would try the following:

First off, do not use the orbital sander under any circumstances. Those things will leave a pattern that you'll never fully remove. I would recommend a good sanding block (the type sold at autobody shops). Start with 400 or 600 sand paper and wet sand (this means sanding with a constant flow of water across the material). If you start with anything much lower than 400 or 600, you will most likely induce more scratches that you remove.

From there, just keep going. 800 or 1000. Then 1500. Then 2000.

Once you wear yourself out with 2000 grit emery cloth, then you can switch to using something like Bon Ami (it's a soap cleaner stuff for the kitchen). Mix in a little oil. Either that or switch to a metal polish, such as Blue Magic. You can also use polishing compounds, but generally those are used with buffing wheels and using a buffing wheel on a flat plate can cause problems if you aren't careful. For one, it can induce heat, which - if you aren't careful - can warp the panel. I'm a big fan of hand sanding/polishing.

With something like blue magic, you apply it, then start polishing with a paper towel. Everything will turn black; just keep going. Then clean it off with a cleaner/degreaser. If you want to get really tricky, you can use rubbing compound, then polishing compound (automotive products for paint), then switch to a metal polish.

You can also try using stuff that is designed for polishing plastic. It's often a super fine polishing compound in liquid form. I've never used it on metal, but I would assume it would work.

Did I mention I'm a big fan of the satin "brushed look" ????

:)

Ray

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ANeat

#119: Post by ANeat »

You could always do a turned finish, I grabbed this image off the web

Image
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drgary
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#120: Post by drgary »

Great stuff, guys. Whatever I decide to do, others reading this will try all those different approaches. :) BTW, I wonder if the cartoon face on that turned finish is a decal, and if so, whether those can be used on a surface that will develop some heat?
Gary
LMWDP#308

What I WOULD do for a good cup of coffee!