Finishing Acrylics Complex Shapes

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gwlundgren

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I'm relatively new to turning acrylics/plastics.

I've kept my acrylics shapes fairly simple due to the difficulty of getting them smooth and shiny.

Working with the little square wet sanding pads can leave grooves, lines, and ruts in the shapes.

Is there a way to get these smoother?

Thanks! Gary
 
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sanding

gwlundgren said:
I'm relatively new to turning acrylics/plastics.

I've kept my acrylics shapes fairly simple due to the difficulty of getting them smooth and shiny.

Working with the little square wet sanding pads can leave grooves, lines, and ruts in the shapes.

Is there a way to get these smoother?

Thanks! Gary
Click to expand...
after sanding with the lathe on, turn it off and sand lenthways then repete with a finer grit same way. do that with all grits I turn coran and sant to 12,000 grit. ps; lite though through all grits.
 
Those who are expert at using a sharp skew seldom need to start lower than 400 grit , so some practice may be in order . Also best , as you have apparently done , to keep to simple curves . Forget the beads and coves , unless you like to punish yourself . Wood or plastics , I think the same rules apply .
 
Gary, I do not especially like to sand and polish, but find in my turning that I can often spend as much or more time getting to the final finish after finishing with the cutting tools. Sometimes with long detailed finials it takes special care and a long time to get the sanding and polishing done.

A very sharp edge applied with precision and skill (read practice and experience) lets the abrasives start with higher numbers, with fewer bumps and ridges to remove.

Slow down the lathe (counter intuitive right) and apply the abrasive with light pressure. Let the abrasive do the work. Clean after each grit, and never skip a grit. Learning, use the factor of about 1.5 and not more than 2.0. That is, starting at 120, next would be 180, then 320, I go with 400, 600, 1000, 2000, 4000 and then polishes

As the numbers get larger it takes less time to get through the scratches left by the prior grit.

Work thoughtfully and it will get easier to get superior finishes.
 
I am another who uses a sharp tool to get a smooth finish before the need for sandpaper. I use scrapers and am not proficient with a skew. But either way very sharp tools with light touches will leave you with a finish starting at the equivalent of 600 or better.

I made a pen some years ago with segments of brass and silver. ANY sanding caused the silver to smear. It didn't take me long to learn to turn to an extremely smooth finish that eliminated the need for sanding before adding the CA.
 
These are the most complex shapes I've turned. On these, I used 320 and 400 wet; all 9 grades of MicroMesh wet; Novus 3 then 2; and finally PlastX.
 

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I've had a challenge getting into the coves on my random colored (from my excess PR Dixie cups) PR bottle stoppers. It also seems to depend a bit on the color of the PR. The darker colors, such as deep blue, for instance. The problem is that one can't do the normal lateral sanding so the high spots look good, but the deep spots less so.
 
My own current preferred sequence:
Skew and/or round carbide; dry sand grits 400, 600; wet sand meshes 1500, 1800, 2400; Novus 3, then Novus 2; Hut Ultra Gloss Plastic Polish; ending with Novus 1.

- Bob
 
Have you tried micro magic? It's a set of three abrasive waxes. I sand to 800 then use the micro magic. I haven't needed micromesh since and I am still on my first order after at least 100 pens. It's in all the catalogs.


Sent from my iPhone using Penturners.org mobile app
 
I've been using Dr. Kirk's Micro Magic in place of MicroMesh for my last couple dozen pens. So far I'm impressed with the results. These photos show the difference between wet sanding and Dr. Kirk's. The last photo is after the three plastic polishes. You can barely see that the plastic polish did remove some scratches.
 

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qquake said:
I've been using Dr. Kirk's Micro Magic in place of MicroMesh for my last couple dozen pens. So far I'm impressed with the results. These photos show the difference between wet sanding and Dr. Kirk's. The last photo is after the three plastic polishes. You can barely see that the plastic polish did remove some scratches.
Click to expand...

That looks pretty good. How do apply it--paper towel or something? Are you still sanding laterally as well as radially? Are you buffing afterwards?

I'd love to be able to cut down on the time it takes to wet sand if the results are similar.

Regards,
Michael
 
I apply both the Dr. Kirk's and the plastic polishes with the blue paper towels. I don't sand laterally, which I probably should. I don't buff. Just wet sand with 240, 320, 400 and 600; Dr. Kirk's; Novus 3 then 2; and finally PlastX. I'm pretty happy with the results. Oh, and I dry sand with 120 and 240 before wet sanding, but that's for final shaping.
 

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Just ordered some, will see how it goes. I usually have a pretty smooth finish off the lathe. If I could get by with just a sanding with 600 then the Kirk's, that would be a huge time saver. I'd still hit it with the Tripoli and White Diamond on the buffer.
 
Michael send me your address and I will send you some Dr. Kirk's. I have not not been able to achieve the advertised results with it.
 
Rather than the square MM pads, you might try MM sheets like these:

https://www.amazon.com/SANDING-SHEE...s=micro+mesh+sheets&psc=1&smid=A2NWLOWWF5G7JX

They are more flexible than the pads and should work better on complex curves. I cut them into 1" x 3" strips and they last a long time. After going through one set of the square pads, I tried the sheets and have never looked back. You can also get them in larger-sized sheets.
 
TonyL said:
Michael send me your address and I will send you some Dr. Kirk's. I have not not been able to achieve the advertised results with it.
Click to expand...

Hey Tony,

How are you applying it? And what results are you getting?

My polish method goes like this. 320 grit, 400 grit, 600 grit, with lateral sanding between each grit, then Scratch free polish at 3000 rpm, then Micro magic 1, 2, 3, at 3k rpm with lateral sanding between each polish. Then lastly, I'll use a plastic polish. It cuts down a huge amount of time for me polishing acrylics as opposed to wet sanding with Micro Mesh.

I like to use small flannel squares to apply the polish because most pape r towels are too rough.

This watch pen I did using that method.
 

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TonyL said:
Michael send me your address and I will send you some Dr. Kirk's. I have not not been able to achieve the advertised results with it.
Click to expand...

Tony, thank you very much for the offer. I've already ordered a set from CSUSA. Perhaps someone else would like to take you up on your generous offer.

Regards,
Michael
 
Mike@CSUSA said:
TonyL said:
Michael send me your address and I will send you some Dr. Kirk's. I have not not been able to achieve the advertised results with it.
Click to expand...

Hey Tony,

How are you applying it? And what results are you getting?

My polish method goes like this. 320 grit, 400 grit, 600 grit, with lateral sanding between each grit, then Scratch free polish at 3000 rpm, then Micro magic 1, 2, 3, at 3k rpm with lateral sanding between each polish. Then lastly, I'll use a plastic polish. It cuts down a huge amount of time for me polishing acrylics as opposed to wet sanding with Micro Mesh.

I like to use small flannel squares to apply the polish because most pape r towels are too rough.

This watch pen I did using that method.
Click to expand...

Hi Mike.

Thanks for the advice. You and I spoke over a year ago about it when I called CSUSA. I was using it just as you advised me. Didn't you say you were part of the test group?

Anyway, it does reduce the size of scratches, just not as much as I would like it to - I am not blaming the product... I am sure it is me and the magnification under which I inspect my work.

Best to you and thanks again.
 
gwlundgren said:
I'm relatively new to turning acrylics/plastics.

I've kept my acrylics shapes fairly simple due to the difficulty of getting them smooth and shiny.

Working with the little square wet sanding pads can leave grooves, lines, and ruts in the shapes.

Is there a way to get these smoother?

Thanks! Gary
Click to expand...
When I started I did all the wet sanding jazz, but once you start getting good at buffing that's where the magic really happens ;)

There's a great thread here called kicked up a notch that helped steer many users here.
 
Look into flame polishing. More than a few of the duck call guys are doing it, and flame polishing has a long history of use in the wider world of plastics fabrication. It does, btw, need to be flame. A heat gun doesn't put out enough concentrated heat.
 
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