Jump to content
  • 0
Titanium

Polishing screw heads with diamond paste

Question

I've been making some screw recently out of 316 steel but my stalling point has been polishing the screw heads. After I cut the slot I have been filing them flat then rubbing them in diamond paste.

 

I apply the paste to an aluminum sheet and start with 45 micron diamond paste and rub the screw heads in it. Clean them then repeat with 8 micron and 0.25 diamond paste. However the finish is not good. I'm aware if you buy sets of diamond paste there are 7 grades to go through so it might be I'm jumping sizes to quickly but as the paste is expensive I thought I'd check here first. From start to finish how long should it take to polish a screw head.

 

This is quite frustrating because I feel like I've go the hard bit down but the part that should be easy is not working.

Share this post


Link to post
Share on other sites

17 answers to this question

Recommended Posts

  • 0

Doubt that diamond paste will be effective on a filed surface as it will be 'rough' by polished standards.  ! would start with wet&dry papers going down to 2500 grit then go onto the polishing pastes.  Thoroughly clean after every grit/paste size and do on a flat plate.  Dialux bar polishing medium (grey I think for steel) may be better than diamond paste.

Share this post


Link to post
Share on other sites
  • 0

  polishing or restoring screw heads is an art !       with a lathe (or a drill press)  cut the head and then go to "wet and dry" sand paper to 1,000 grit,   you are done.  the slots are a whole different art.     vin  

Share this post


Link to post
Share on other sites
  • 0

How are you holding the screw for polishing? Typically it would be held in a tripod tool if going for a flat polish.

I would recommend a couple of paper steps before polishing, I typically use 20 micron for serious flattening then 12 micron and go straight from there (after cleaning) to diamond paste,
Aluminum is not a good substrate for polishing, the surface oxidizes in minutes and that is as hard as ruby. If you don't want to find or make a tin or zinc plate, thick plexiglass works well. Roughen the surface with a clean file before using.

Share this post


Link to post
Share on other sites
  • 0
16 minutes ago, nickelsilver said:

How are you holding the screw for polishing? Typically it would be held in a tripod tool if going for a flat polish.

I was holding them in a modified collet. Thanks for all the advice everyone on here has given one. Once again I though the answer was simple but it will keep me busy for 6 months.

Share this post


Link to post
Share on other sites
  • 0
2 hours ago, Titanium said:

I'm aware if you buy sets of diamond paste there are 7 grades to go through so it might be I'm jumping sizes to quickly but as the paste is expensive I thought I'd check here first.

What do you use? I buy from China and it's cheap, probably not the best grade but it works fine for me to polish crystals.

Edited by jdm

Share this post


Link to post
Share on other sites
  • 0

This is how I went about polishing clock screw heads. You need a lathe or a screw head-polishing tool that fits in a vice. Start by removing the bur with a flat needle file not to course. Then use emery sticks of various grades down to the finest they have, finish off with the finest crocus paper. Clean the screws. Those screws would be ready to blue. That is how good they will be.   

Share this post


Link to post
Share on other sites
  • 0
On 8/19/2019 at 4:17 PM, jdm said:

What do you use? I buy from China and it's cheap, probably not the best grade but it works fine for me to polish crystals.

I got it from CousinsUK it is £20 to £10 per tube. I know I don't use a lot but that is still £2000 to £4000 per liter (not that I'd use that much in my life). Which is more that most champagne.

I had a second idea. First I cut the head to size -thickness wise not diameter wise- so that it is a little to thick. Then I cut the slot. The head is really untidy at this point. I could then attached a diamond grinding disk (like this one https://www.eternaltools.com/small-diamond-grinding-wheels ).

I could attach this disk into a mini lathe as supposed to a watch makers lathe. I'll clamp the screw into a vice on the cross slide and this will allow me to grind the head to size whilst keeping the head flat and level and prepare it for the first steps of polishing? What does everyone think?

Share this post


Link to post
Share on other sites
  • 0

Are you going for a flat polish or rounded polish? I'm guessing rounded (which is pretty much anything besides mirror flat/black; from slightly rounded to domed). In that case Oldhippy has you on track, chuck the screw by the threads, smooth out the head with a few grades of abrasive paper or stones, then in my case I use a micromotor tool with a felt buff and polishing paste, no need for diamond. White paste for polishing stainless that comes in a stick. Screw spinning in lathe, hit it with the felt buff at 5-10k rpm in the micromotor. You might spend 3 minutes per screw total if they're really rough to begin with.

Micromotor can be Dremel, Proxonn, or fancy pro stuff, the screw doesn't know the difference.

Share this post


Link to post
Share on other sites
  • 0
4 minutes ago, Titanium said:

I got it from CousinsUK it is £20 to £10 per tube. I know I don't use a lot but that is still £2000 to £4000 per liter (not that I'd use that much in my life). Which is more that most champagne.

I guess these are https://www.cousinsuk.com/product/diamond-paste-cousins

They say brand Cousins, which  means made in India or China. Very similar to this https://www.aliexpress.com/item/2028617063.html

12 grades for $7.52 inc. shipping,

I agree with some of the comments above, diamond past is not the best for metal that is relatively soft, other abrasives and techniques can produce better results.

PS, don't worry about Champagne, it's acidic after a while. Italian Prosecco is cheaper, tastier and mixes well to Spritz,

Share this post


Link to post
Share on other sites
  • 0
1 hour ago, nickelsilver said:

Are you going for a flat polish or rounded polish? I'm guessing rounded (which is pretty much anything besides mirror flat/black; from slightly rounded to domed).

I was going for flat. The problem really started because the "normal" polishing techniques were rounding the screw head.

Share this post


Link to post
Share on other sites
  • 0
41 minutes ago, Titanium said:

I was going for flat. The problem really started because the "normal" polishing techniques were rounding the screw head.

My method works with all types. No need to buy bloody paste. If you are going to use a dremel type  tool, you could use emery cloth instead of emery sticks.

Share this post


Link to post
Share on other sites
  • 0
On ‎8‎/‎19‎/‎2019 at 7:42 AM, Titanium said:

I was holding them in a modified collet. Thanks for all the advice everyone on here has given one. Once again I though the answer was simple but it will keep me busy for 6 months.

   if you have a tap and die set,   (and a lathe) just thread a hole in a brass rod and you have the perfect "screw holder".    doe's not work on left handed thread.    vin

Share this post


Link to post
Share on other sites
  • 0
8 hours ago, vinn3 said:

   if you have a tap and die set,   (and a lathe) just thread a hole in a brass rod and you have the perfect "screw holder".    doe's not work on left handed thread.    vin

A very good tip that is Vin.

Share this post


Link to post
Share on other sites
  • 0

There's flat and there's flat. If you're doing a screw for an old high grade (or new) watch that's mirror polished flat you need specific tools and you need to finish on tin or zinc or similar with some sort of paste. Back in the day it was usually diamantine (aluminum oxide), nowadays usually diamond. There's an order of magnitude of effort between pretty flat and shiny and dead flat and mirror finish inspected at 30x magnification.

For a case screw 'pretty flat and shiny' is almost certainly A-OK. No need to get freaky with it.

Share this post


Link to post
Share on other sites
  • 0
On 8/19/2019 at 6:18 PM, oldhippy said:

This is how I went about polishing clock screw heads. You need a lathe or a screw head-polishing tool that fits in a vice. Start by removing the bur with a flat needle file not to course. Then use emery sticks of various grades down to the finest they have, finish off with the finest crocus paper. Clean the screws. Those screws would be ready to blue. That is how good they will be.   

I got my emery sticks yesterday and this works very well. I could not find any crocus paper. It is apparently been replaced with something called micro mesh sheets.

I went down to 2500 grit emery sticks then used a felt bob in the micro motor to get a mirror finish. It worked well. I might get some Micro Mesh Sheets and see how they work. Anyone every used these?

Share this post


Link to post
Share on other sites
  • 0

While I've read this with interest and haven't been able to add anything useful to the above I can comment on micromesh.

It's incredible stuff, I use it in model kit making for flatting then buffing clear coat on my car and motorbike models after spraying and curing.

Working through the grades to the finest leaves you with an incredible shiny finish so should fit your needs admirably. I finish with Tamiya polishing compounds but in most cases these aren't really necessary but they also work excellently for polishing acrylic crystals and get regular use for that.

I bought sheets rather than pads as they're better value and would be more suitable for your needs, the pads are small squares and foam backed for modeling to avoid burning through high spots on contours but with the sheets you could attach strips to a flat surface for ease of use.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Answer this question...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...