Turning Acrylics

[jondavidj]

I am asking for help on the acrylic blanks. I can turn them down fine and they look alright. The problem I am having is little scratch marks when they are completed.

After turning them, i wet sand to 12000 and the use high gloss finish, but it does not take the scratches out.

Any help would be greatly appreciated.

 

[wdcav1952]

Jon,

I'm not acrylic expert, but maybe Ed4copies will chime in when he gets back from whatever show he is at this weekend.

I turn my acrylic blanks with a sharp skew. At the very last part of the turning, I resharpen the skew, and lay it flat like a scraper. I just barely contact the blank with my skew/scraper, so it is removing almost no acrylic. I am not a fan of wet sanding, but many are. I sand through 600, and then switch to automobile polishing compound. After that, I move on to scratch and haze remover (Kit, yellow bottle, about $2 at Wally World). Then I finish with plastic polish. However you choose to finish acrylic, it is imperative to remove the scratches left from each preceeding grit of the abrasive of your choice.

I hope this helps in some small way.

 

[skiprat]

Jon, I'm certainly no expert on finishes, but I once had a problem of putting scratches on the acrylic during the polishing stage, lathe on. I now do my final wet sanding and polishing by hand.
Which direction are your scratches?

 

[LEAP]

Jon are you sanding lengthwise on the blanks after each grit?

 

[ashaw]

Iam had the same problem when I first started using acrylics. This is what I do now.
1. When sanding slow the speed down. I started at 120 - 400. Sand length wise in between grits.
2. I use the acrylics simular to mm. Still slow sand through the first three grits. Make sure you are using water.
3. Speed up the lathe to 3750 and sand though the grits using the last three remaing pads. Lat one (12000).
4. Auto Compound. Take it off with micro fiber pads (One from auto stores) Paper towels will put scratched back into the blank.
5. Auto Wax made for power buffers again using micro fiber to take it off.
Hope this helps

 

[Rudy Vey]

Like William said, use a sharp skew and use it scraping, barely touching the acrylic blank. Then I sand dry through 2000 grit and finish up with a swirl remover, automotive polish or else. If you get too deep scratches or ridges, you have maybe some nicks, re-sharpen and hone.
If I see some scratches after I went through all the grits, I re-sand.
I have found that the Abranet sanding sheets do a great job, and I like them better for the first grits (like 240, 320 and 400). Some acrylics, or resins, not sure what one would call them, need to be wet sanded. Just two nights ago I finished one of these blanks and could not get them done without small black marks. Did it four times always around 1000 -1500 grit I got it - switched to wet MM pads and it worked out fine.

 

[jondavidj]

Thank you for your advice. I will print this when i get ready to do the next acrylic tomorrow. I will try and post the picture today so you can see.

The scratches are left to right if you are holding the pen upright and when it is on the lathe, i sand from left to right. I hoipe this answers the questions.

 

[Tom McMillan]

I've tried a number of items supposed to take out scratches from acrylics, but nothing works better for me than EEE UltraShine--I normally only wet sand to 1200.

 

[redbulldog]

I have been using Ed Davidson's article and have not had any problem with scratches on the acrylics.
His articles are in the IAP library.

 

[low_48]

You may be doing everything right except not staying on the blank long enough with each grit, especially the courser ones. You may not be fully cutting out the previous scratches when you change to a finer grit.

 

[gmcnut]

Hi all,

I will be turning my first plastic very soon and all of this information is very good.

 

[PenPal]

Finishing Corian I do some of the above but aways finish with Brasso,if you can find it in tube form it is less messy and thicker. It works a treat,I always use stainless steel spacers as brasso in polishing near brass goes staining black which is adisaster with white Corian,one tube lasts for a long time.In my army life it was standard practice for Brasso on our uniform brass.I have used toothpaste as well,it works too. Peter.

 

[Blind_Squirrel]

Get this: http://www.woodcraft.com/family.aspx?familyid=2036

 

[jahlg]

I use a white scotch brite to put on the scratch remover, its very fine and takes out thelast scratches, even did a jet black acrylic Navigator and the finish came out great.

 

[txbob]

Try a little toothpaste on a paper towel. Gel toothpaste is finer grit than regular toothpaste.
Happy turning,
txbob

 

[mdburn_em]

Wow, a lot of answers here.
I only wish I could get my wood finish as good as my acrylics, that's another post I guess.
I bought the little pack of colored squares that are advertised for plastics by anybody. http://arizonasilhouette.com/ProductCart/pc/viewPrd.asp?idproduct=490 is just one example.
I will turn and finish with the skew. I then lightly sand with 280, 320 and 400 grit sandpaper. I have the non-vs jet so I do all my turning and finishing at the same speed.
I'm in the mid-range.
I then wet sand with the six grits that come in the pack. As has been mentioned, it's crucial to shut the lathe off after every grit and sand the whole blank side to side. L<=>R I do this for the sandpaper and the wet sanding.
I then apply Hut Ultra Gloss plastic polish and I've got a wet-look finish.
The whole procedure is really fast and effortless.
Light touch, let the sanding product do the work.

 

[Russb]

After sanding a final polish with Brasso.

 

[woodmarc]

Another solution to mull over.

I use the Plastic finishing kit from penn state
http://www.pennstateind.com/store/pkfinkit.html

Then hit it with some Craftics 20/20 polish. I have had some great success with this.
If I find imperfections, then I beal buff. (only done once so far.)

The secret to wet sanding is the slurry created, Keep your speed fairly slow, <1000 rpm, and remove the slurry between grits. Don't let the abrasive dry out. Heat is not your freind with any of the synthetic blanks.

I always finish with a couple of coats of Caranuba. It's not necessary, I just think it gives the pen a usable grip.

My 2 Cents.

 

[alamocdc]

Starting with too coarse a grit will leave scratches that nothing will remove but a longer time with each subsequent grit. This is true regardless of what you are sanding. With acrylics I always wet sand... notice I didn't say "damp" sand... If I don't get water slinging, it ain't wet enough. I know, and I hear you... "Wow, I bet you have a problem keeping the rust down on your lathe!" Not at all. I cover the metal parts with plastic before I start sanding, and immediately dry those that are not coverable using a blow dryer for the final step of drying. Yes, it may add time to the process, but it keeps my lathe safe from rust and I don't have scratches in my synthetics. As already mentioned, I use my skew to turn acrylics. This means that I can usually start sanding with MM 4000. Once in a while, I might need to start at 320 grit wet/dry sand paper, but that is unusual. I use MM (wet) all the way through 12000 and finish with Novus fine scratch remover (or equivalent). The result... no scratches, and the true test are the black resins I make. Some synthetics are harder to see fine scratches in, but black will show you where your weaknesses are.

 

[ed4copies]

The moral of the story:

LOTSof ways work.

My add-on advice: Stop the lathe at about 1000 grit (or when you start to see a shine) and look for visible scratches THEN. If you inspect carefully and there are none, then the exist in your end product, look to change the rag or paper towel you are using in the finishing process. IF you are using a buffing wheel, shave it-you have a "rogue thread" beating up your blank.

Otherwise, all the above suggestions WILL work - apparently - for someone!!!

My experience last year in "field demos" drove home the problem with applicators. All paper towels are NOT created equal.

Test and retest - success will follow.