Greasless compounds vs sandpaper

[68commando]

Hi,

I'm new to this polishing and am trying to get the aluminum parts on my Norton Commando in shape. I have polished a few things with some success, but it is not quite mirror finish despite there being pits in the castings. I am having trouble getting the little scratches from the sandpaper out and I have read the "Motorcycle polishing 101". I was wondering if I can use the greasless compounds on a sisal or spiral sewn wheel instead of the orbital sander to do the majority of the sanding? Will I still have to go to the 600 and 1000 wet and dry before I go to the black, brown and white polishing compounds? It seems that sanding down to 600 wet and dry does not get the scratches fine enough for that mirror finish, although it is almost acceptable to me. From about 4 feet, it does have a polish and you can see reflections in it, although the closer you get, the less fine are the reflections. I have included a sample picture of the scratches.

Thanks

[mpierich]

Depending on access, the sander might be easier actually. And, I often sand, then use the same grit of greaseless to go over it since it leaves a more consistent surface.

What grit paper are you using? - the piece in the picture looks mighty rough. If you have gouges and scratches or a sandcast surface, start with 120, then go to 220, 320. I often stop there and go to the emery compound, but for a better result it may help to also throw a 500 or 600-grit step in there.

If it's effort you're concerned about, the greaseless is easier. If it's the time involved, the greaseless can be slow to use since you need to stop and re-apply it, then wait for it to set up before you can use it. Of course you can use two wheels, using one fresh one while the other is setting up.

Whatever you use, you need to look very critically to really see whether you're finished with any given step. Go in one direction and then see if there are scratches running other directions. Use a strong light and look from different angles.

I've been doing thisa a while and I still have phantom scratches when I'm done, but they are negligible.

BTW, Commandos rock! Ride safe.

[68commando]

The case in the picture was pretty rough to start with. I used a round or flat file to get the huge gouges and holes out, then went to maybe 150 paper or so. It was some sandpaper I have around that is used to clean copper pipe before soldering and comes in a roll. It is pretty rough, but it seems to get the file marks out to a point. Then I would go to a 220 and then 320 sandpaper and finally a 600 wet and dry. I do not have any 1000 yet, but will get some. I guess maybe I am going on to the finer grades of paper before I get the file scratches out or I am not looking criticaly enough, but then I am doing it by hand until the polishing and the cases are a lot to do by hand, especially after filing. I guess I will have to get a sander with the appropriate paper and see if I can do a better job of getting the file scratches out, I'm sure that is what it is about. I have enhanced the photo to some degree and it really does not look that rough in real life. The photo is like looking at the case from maybe 3 inches. Attached is a new picture of the same area before any work on it, so the scratches are definitely from the filing. I had to file because there were big pits in the case. I'll get a sander and see if I can do a better job getting the file marks out.

It is a blue 69 Commando S and I hope to have it back together to ride next summer; I have a lot of work to do on it.

thanks,
Dave

[jrow]

68commando,

Just some additional suggestions to what mpierich stated. Try using a die grinder with cartridge rolls. You can get just about any grit, and diameter, you will need in cartridge rolls. It looks like you have a lot of round area to do which may make it easier. You can also load 1" and larger diameter buff with greaseless and go at it that way. I have used a 3/8" drill motor with up to a 4" buff on it for greaseless and it works fine.

John

[mpierich]

I think your first mistake was using a file at all. It left more work than it helped. The lowest you should ever have to go on aluminum is 80 grit, and that's just for the worst chewed-up pieces.

If you're sanding by hand you're in for a lot of heartache. Cart rolls are good for tight areas as jrow suggests, and a palm sander is good for wide flat areas.

[68commando]

You are probably right, the file was the wrong thing to start with, now I know. I'll get a palm sander and papers and go back at it from the start. I thought I would never get the pits and gouges out with sandpaper especially by hand, so I'll go to the power tools. The die grinder sounds like a good idea, but is a bit expensive for what little I have to do, but it may come to that with the curves. I am a bit fearful of gouging the cases with the small round cartriges, but I may try a few, I do have a lot of inside curves. Maybe I can get some cartriges I can use with a hand drill.

The only aluminum polishing I have to do is the timing cover(s), gearbox cover, Z plates, primary case cover, lower fork sliders, rear wheel cover, and front wheel housing. The rest is painted or chrome.

Below is what the timing cover looked like to start with and now, at least now it has a shine to it.

Much thanks guys,
Dave

[Rasper]

Dave,

You got some first class advice from these guys. All I have to add is to reiterate what they said about one important thing: You absolutely must get all of the scratches out put in by the previous sandpaper, before you move on to a finer grit. In other words, with the 80 grit you have to sand it until all that is left in the aluminum are 80 grit scratches, no file marks, no dents, no gouges. If you move up a grit before you do this, you will never get them out. At the next level, let's say 150 grit, you must sand out every single 80 grit scratch, every last one, before you move up to say 240. The other thing about this process is: it takes a whole lot more sanding than you think it will: two or three times as much, or more. You will think you got those 80 grit scratches out with the 150, but you haven't. I have learned this the hard way. I can't tell you how many times I have gone all the way through 240, 400, 600, 800, and gone to the polishing wheel, only to realize I still had 80 grit scratches in the piece, and had to go back and start with the 150 again. The result is worth it. Don't settle for second rate. Good luck.

Richard

[mpierich]

Originally Posted by 68commando

The die grinder sounds like a good idea, but is a bit expensive for what little I have to do, but it may come to that with the curves. I am a bit fearful of gouging the cases with the small round cartriges, but I may try a few, I do have a lot of inside curves. Maybe I can get some cartriges I can use with a hand drill.

Sure, get the right mandrel and use it with a drill - might be a little slower but it'll work. Find a piece of scrap metal to practice on. The trick is to concentrate on keeping it moving across the piece or you will have hundreds of tiny gouges. Think before you touch any given area...where will you start the stroke and where will you end it? Always try to begin and end in the inside corners - then, when you have the wide area done you can clean up the corners and take out all the "stoppies". But that said, do the wide areas with the sander wherever you can. BTW, you'll likely find a lot of pores in the metal - the more you sand the more you'll see so don't get too carried away.

Originally Posted by 68commando

The only aluminum polishing I have to do is the timing cover(s), gearbox cover, Z plates, primary case cover, lower fork sliders, rear wheel cover, and front wheel housing. The rest is painted or chrome.
Below is what the timing cover looked like to start with and now, at least now it has a shine to it.
Much thanks guys,
Dave

What, not doing the engine cases, LOL? MY brother in law has a '72 w/Combat enigine setting in pieces in his basment for the last 20 years. I polished some of it but there it sits - he's a slug. I keep threatening to build a chopper out of it but he's content to let it set there. Oh well. Have fun.

[68commando]

Guys,

Much thanks for all the good info. As soon as I get some power tools and get back to this, I'll post another picture again. Re: the engine cases, they were originally painted, so I think I will leave them like that, I would like to put it back into pretty much original shape but am going to replace what hardware I can afford with stainless. I can do most of it less the special acorn nuts and the special engine hardware for around $60, so I can handle that. Below is a picture of the bike and me in '72 in Greenbelt, MD.

Dave

[bkp08817]

These guys are right on the money.
I'm in the process of polishing a set of Triumph 650 Bonneville crankcases.
I'm using several grades of greaseless with a cheap air die grinder on assorted felt bobs and even with that if can be a slow and somewhat boring process. After the greaseless I am wet sanding 400, 600, 1000, 1200 then polish with white liquid rouge. My casting were pretty good and was able to get out probably 95% or more of the pit marks. The best advise I can offer is "Patience, Patience, Patience and more Patience" Seriously if you if you have patience and don't rush through steps you will be astounded at the results. I have at least 20 hours into my cases and have a bit to go. At first you will wonder if the sore finger tips and everything is all worth it but once you finally start to see the fruit of your labor your find it was.

British Rules!