Dremel tool 1.01 - Case refinishing tutorial reqd

[gmchris 68]

Having picked up a couple of used watches this year and looking to refurbish them cosmetically now the long dark evenings are coming, I'm looking at buying a dremel-type (read 'cheap') tool. 

I've seen some complete with polishing discs, sanding discs, wire wheels etc but I'm wondering what exactly will I need? 

Mainly I need to get some scratches out of mineral glass and swatch plexi crystals, and refinish the brushed stainless sides of the cases and polish the mirrored parts/casebacks. 

So am I better with wire wheel, sander etc and do I need any compound or t-cut etc? 

Cheers 

[GenTLe 1,496]

For plexyglass you'll do MUCH better using elbow grease. The dremel is too fast and produces too heat and will mess up with the plexy.

Similar for the mineral glass: you'll risk to crack it. Mineral glass can be done with slower rotating machines and glass polish (containing cerium dioxide).

Dremel is good to polish steel, and for that use you'll need a good steel polishing paste and pressed cotton tools only.

[Glaude 1,615]

41 minutes ago, GenTLe said:

For plexyglass you'll do MUCH better using elbow grease. The dremel is too fast and produces too heat and will mess up with the plexy.

Similar for the mineral glass: you'll risk to crack it. Mineral glass can be done with slower rotating machines and glass polish (containing cerium dioxide).

Dremel is good to polish steel, and for that use you'll need a good steel polishing paste and pressed cotton tools only.

+1 on everything !

I've recently refurbished an Armani watch for my father, big deep scratch in the mineral crystal, I've tried every possible way of gaining time but in the end nothing gives you the control and result of a good ol' hand work.
Do not go too low on sand papers grit, the lower you go the harder the scratch are to remove afterwards, even if at start you make quick progress on the scratches you want to remove.
I've started with 40 grit sandpaper and that was a big mistake.
I've worked my way up from that 40 to 3200. Each grit was done in one direction (from top to bottom, bottom to top) and then the next grit in another direction to see the progress (from left to right, right to left).
Do not waste your time doing circle with sandpaper, you'll not see your progress clearly and will end up wasting sandpaper as you will miss some previous grit scratches when going on finer grits.

I've built little wooden tools to press on the sandpaper rather than using my fingers.

Last step was using some cerium oxide powder at 0.25µ you can go even lower but progress is very slow then.
For the cerium oxide I did use a high-speed rotary tool with a hard-polishing wheel conically shaped only because I haven't invested in a lower speed rotary tool. You have to constantly check the crystal temperature, if you can't touch it with your finger, it's too hot and you have to let it cool down on its own. The fact that cerium oxide is in water suspension help to dissipate a bit of heat though.
One tip for using cerium oxide : do not make a paste out of it, the more liquid it is, the better the end results (but the longer it takes), picture the same consistence of watery sand from the beach.

[10:10 Watch Repair 1]

On 06/10/2018 at 10:53, GenTLe said:

For plexyglass you'll do MUCH better using elbow grease. The dremel is too fast and produces too heat and will mess up with the plexy.

Similar for the mineral glass: you'll risk to crack it. Mineral glass can be done with slower rotating machines and glass polish (containing cerium dioxide).

Dremel is good to polish steel, and for that use you'll need a good steel polishing paste and pressed cotton tools only.

FWIW:

 Most of the manufacturers use felt rather than cotton for SS polishing, or silicone for fine detail. Check out RioGrande.com for all the tools. 

It's a good idea to take out scratches in metal with sandpaper first, you can use wet dry in very fine grits 400-2000 or 3m jeweler's paper if you really want to go pro

Polishing with a Dremel is OK, but the larger the polishing wheel, the better the result. That's why a bench polisher with 3" or larger wheels is preferred.  There's a lot of torque and speed with a bench polisher which can be dangerous.

Totally agree that it's easy to screw up plexi. For best results: for deep scratches, sand the plexi first (1000 grit or more) and then finish on a bench polisher with rouge for plastic, or red rouge for soft metals. It's not that tough to polish with polywatch and elbow grease as an alternative. Use a Dremel and a cotton wheel at your own peril, although it can be done. 

Then there's the whole keeping the original shape and edges thing... don't over polish, but that's a whole different discussion.

[Glaude 1,615]

42 minutes ago, 10:10 Watch Repair said:

Most of the manufacturers use felt rather than cotton for SS polishing, or silicone for fine detail.

Do you happen to know why ?
My bet would be durability rather than results, cotton disk goes black and heat up very fast and wear out way faster than felt, but there may be another reason for it, since your post was full of valuable insight maybe you have an idea on that too  

[10:10 Watch Repair 1]

1 hour ago, Glaude said:

Do you happen to know why ?
My bet would be durability rather than results, cotton disk goes black and heat up very fast and wear out way faster than felt, but there may be another reason for it, since your post was full of valuable insight maybe you have an idea on that too  

Felt can cut faster, which is both good and bad in the wrong hands. It also retains it's shape so if you angle your workpiece correctly you can preserve the original shape. Felt also can be flat, rounded, or knife edged. 

[GenTLe 1,496]

Thanks! Always good to have knowledgeable people like yourself around!

[Not Quite Dead 9]

Useful thread as polishing season approaches, that or roasting my nuts on an open fire.

 

 

[Nikosaldente 630]

So many watches to polish, 

So little time to do it......

Nice thread guys !

Thanks for sharing!

[Glaude 1,615]

9 hours ago, 10:10 Watch Repair said:

Felt can cut faster, which is both good and bad in the wrong hands. It also retains it's shape so if you angle your workpiece correctly you can preserve the original shape. Felt also can be flat, rounded, or knife edged. 

Thank you very much !

[gmchris 68]

Thanks for all the answers - lots of useful stuff to think about. If i am comparing rotary tools, what sort of speed range is considered useful (as opposed to too bloody fast)? 

 

[onionbag 1]

I'll refer you back to 10:10's answer.

Method  and media are the most important, Speed is a shorttcut and can prove disastrous when applied to the wrong material with the wrong media.

Take your time and learn a bit with regard to finishing materials.You must understand the finish you desire and how it is achieved.

You can always take material off..........you can't put it back on.

 

[Viking95 3]

I would spend the money on quality polishing pads, cape cod clothes, etc.

Polywatch is cheap and excellent for plastic crystals. Mineral and Sapphire can be polished but it takes time and patience.

[Glaude 1,615]

4 minutes ago, Viking95 said:

I would spend the money on quality polishing pads, cape cod clothes, etc.

Polywatch is cheap and excellent for plastic crystals. Mineral and Sapphire can be polished but it takes time and patience.

Cape cod clothes and other stuff like that (like Polywatch) are just a waste of money if you are serious about it. Thanks to GenTLe for making me notice that about polywatch : it's just car body polish sold in a tiny expensive format.
Sure it works well on plastic (doesn't work on minerals and certainly no chance on sapphire, you have to get a special polywatch product for that) but you can get a better use of your money by purchasing some auto polishing stuff. @GenTLe can give the reference of the product he uses I'm sure (remember to be something made by 3M but not sure).

If you plan to use them only on rare occasion, ready to go solution works well, but if plan on doing a lot of watch or doing it regularly, it's not worth going with those options.