Need ideas on finishing

eac67gt

eac67gt

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H-M Supporter Gold Member
I am making these laser focus knobs for my son. I will be anodizing them and need to get them as clean as possible. The outside I polish but can not get into the slots to polish or even finish correctly without speeding mass amounts of time. Two of the focus knobs I make have 3/16" slots and the other 1/8" slots. Of course the 3/16" would be easier to finish but even that is difficult. Any ideas on how to put a nice finish/surface in these slots before I anodize?

Attached are two pictures. One is before polishing and the other after.
 
Possibly adapt or make a buff and polish with white polishing compound using a Dremel mototool? IIRC they make a cylindrical buff which might work or be adaptable to this....

The 1/8 slots would be hard, but even then one could cobble up a thin buff. Or slit an arbor and insert increasingly fine wet-or-dry (400 - 600 -800 grit) in the slot....I've polished small holes this way...
 
Great idea! I will have to try the split arbor idea. I will let you know how it works out. Thanks!
 
Acid, but careful, dont use muriatic or you might blow. Get documented on the steps of anodizing, you will find they clean the parts in certain acids, this will give back an even color.
 
If you are making a bunch, you might look at getting a small vibratory finisher. It's basically a bucket that you fill with polishing media (and your parts). When you turn it on, it the bucket shakes, causing the media to rub against the parts. It tends to give a matte finish. The trick is you have pretty fine slots, you would have to find some media smaller than that to get inside, and not get stuck...
 
DMS said:
If you are making a bunch, you might look at getting a small vibratory finisher. It's basically a bucket that you fill with polishing media (and your parts). When you turn it on, it the bucket shakes, causing the media to rub against the parts. It tends to give a matte finish. The trick is you have pretty fine slots, you would have to find some media smaller than that to get inside, and not get stuck...
Click to expand...

I was going to say that, also. You can get a vibrating polisher from a sporting good stores. They use them for polishing spent brass. You can let them tumble for days with different grit media. Takes all the hand work out of it.
 
Dremel makes felt bobs that small. You would have to coat them with abrasives. You can also get sand paper strips for a scroll saw. If you have a scroll saw you can rig up a holder for most any shape and glue sand paper or abrasives to the shapes. Usualy a vibratory sanding drum is not going to smooth out tool marks or deep scratches without really rounding over sharp edges. But a vibratory sander would be the way to go for final finish.
With care you could make small wood dowls with glued abrasives that could be chucked in a drill press and used to polish the inside of those slots. I would also suggest that when you are polishing the main body of the piece that you support the sand paper with thin, stiff plastic backing to prevent the rounding off on edges. Unless that is the effect you are looking for.
All and all i would go with a scroll saw and home made sand paper holders. (And a vibratory sander for a finish if you are going to make a lot of them.)(Or Felt bobs and polishing compound if it is a one off.)
 
If you specify "bright dip" to your anodizer, they will look nice without any polishing. It's basically an electro-polishing process with hot nitric acid.

Tom
 
I ended up taking a piece of 1/4" aluminum rod thatwas in the scrap and turning it down to about a 1/8". Then I used theslitting saw a put a slit in it. I slipped emory cloth in it and put the rig inthe drill press and proceeded to put a finish in the holes. It was way betterthan it originally had been but not a perfect finish. When I tried fine wet-drysandpaper it would tear every time. I made sure I wasn't putting too much paperon that it was binding in the holes. This is why I went to emory cloth, itdidn't tear. I then refinished the outer surface with a nice polish and then Ianodized it. It came out really nice. My son took it immediately and wrapped itup before it got messed up so he can sell it.
The one problem I was having with not being able to finish down inside theholes correctly was the anodizing for some reason did not want to take right.There were spots that would not dye. I cleaned the part extremely well beforeanodizing but twice I had the same problem and then had to strip the anodizingback off. The first time I dyed it a dark blue and the spots stood out like asore thumb. Now the dye has taken perfectly. I am not sure what the contaminatewas down inside the holes/slots but the desmut/deoxidize did not remove it.
Here is a picture of the finished product.
Ed
 
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