Problems with polishing a watch case

[Marc]

@bojan1990 I was thinking about your original post and someting occurred to me. You said you moved from P220 to P800 in 1 step. This may be part of your problem as this is a big jump and you will have to keep going with 800 for a long time to remove the marks from 220. Try at least 1 intermediate stage at 400 grit. Alternatively you could do 320 and then 600 before you get to 800. I think this may help.

[SSTEEL]

Agree with Marc, I go from P220, then move onto the following in this sequence, P240, P380, P600, P800, P1000, then P1500, P2000, then P3000 with water.

[bojan1990]

On 11/5/2017 at 11:27 AM, Marc said:

@bojan1990 I was thinking about your original post and someting occurred to me. You said you moved from P220 to P800 in 1 step. This may be part of your problem as this is a big jump and you will have to keep going with 800 for a long time to remove the marks from 220. Try at least 1 intermediate stage at 400 grit. Alternatively you could do 320 and then 600 before you get to 800. I think this may help.

Thanks. I did the sanding with water and I saw the difference immediately. Next time I will try to go slower up the grades (I have 220, 320, 550, 800, 1000, 1500 and these Silicon Carbide grades which still nobody knows what they exactly are). However, after polishing with 1500, I moved to polishing paste, but I am still not happy with results. The surface is quite smooth, but under bright like, I can see very very thin scratches. My camera is bad, and my photo skills are bad as well, but I hope you could see what problem I have:

 

[jdm]

On 11/6/2017 at 8:50 PM, bojan1990 said:

The surface is quite smooth, but under bright like, I can see very very thin scratches.

And if you were to measure it, you could be saddened  by finding the entire case now half a mm smaller, after all that wild grinding and sandpaper parading.

Both issues would have been easily avoided by, let me say it loudly, buffing, and a $10 rotary tool and felt wheels. 

Edited November 8, 2017 by jdm

[bojan1990]

58 minutes ago, jdm said:

Both issues would have been easily avoided by, let me say it loudly, buffing, and a $10 rotary tool and felt wheels. 

Any recommendation for a $10 rotary tool? Thanks.

[bojan1990]

Another two (hopefully better) photos of the problem I still cannot solve:

 

[hir3na5hra]

Another two (hopefully better) photos of the problem I still cannot solve:
 

Are you using a polishing/buffing wheel or are you just rubbing a cloth onto metal?

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[bojan1990]

5 minutes ago, hir3na5hra said:

Are you using a polishing/buffing wheel or are you just rubbing a cloth onto metal?

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No, I have only a little stick with fine cloth with a little bit of polishing paste.

[hir3na5hra]

No, I have only a little stick with fine cloth with a little bit of polishing paste.

Yeah, it's not enough I'm afraid. You really need a pendant drill/rotary tool/polishing mop to really attack that surface. If you could get hold of a dremel drill of some type, that would be a step in the right direction. Then get yourself a firm buffing/polishing wheel. Then you need a hard metal polishing compound like Hyfin or the blue colour Luxi bar. Use the compound on the wheel and go over the surface until the scratches are gone.

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[hir3na5hra]

Something like this to go on the dremel.

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[bojan1990]

On 11.11.2017 at 11:30 AM, hir3na5hra said:

Something like this to go on the dremel.

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Is is possible to use a regular electric hand drill and put the buffing wheel on it? I just do not have place where to put the fixed machine. The main problem is of course fixation - with hand drill I would (probably) need to put the drill in my right hand, and watch case in the other. What kind of pressure I need when doing this?

[hir3na5hra]

Is is possible to use a regular electric hand drill and put the buffing wheel on it? I just do not have place where to put the fixed machine. The main problem is of course fixation - with hand drill I would (probably) need to put the drill in my right hand, and watch case in the other. What kind of pressure I need when doing this?

Although technically it's possible, it sounds a little awkward. Your control might not be that great especially if you're trying to support a big hand drill. You need something small yet powerful to control the movement. Control is hugely important.

A dremel type device might not be all that powerful, but it's ideal for precision work... Which you need.

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[jdm]

On 11/15/2017 at 9:41 AM, bojan1990 said:

Is is possible to use a regular electric hand drill and put the buffing wheel on it? I just do not have place where to put the fixed machine. The main problem is of course fixation - with hand drill I would (probably) need to put the drill in my right hand, and watch case in the other. What kind of pressure I need when doing this?

Yes. You can, for example, use something like that
https://www.aliexpress.com/item/Universal-Clamp-on-holder-hanger-stand-Electric-Drill-Stand-Dremel-Rack-Multifunctional-bracket-stand-clamp/32683793943.html

However, that works better with a 5cm or bigger wheel, when doing aggressive buffing for deep scratches and dings. For anything else it's better to use a smaller tool and wheel, but I would recommend a vice mount anyway. Pressure applied depends on the job, and you learn with practice, but in general must be so the rotation doesn't slow down noticeably.