Plastic Newbie

[kludge77]

As admitted in an earlier thread, I'm a newbie with acrylic blanks.

I'm fine with the turning process, but having a heck of a time getting all the scratches out. Seriously, I feel like I'm wet sanding FOREVER.

With a wood pen. I have my lathe @ full crank. I sand to about 320, lather on the CA then MM to 1200 Done. A beautiful pen.

With acrylic (last one was a cool PVC pipe) Wet sand to 600, then wet through MM AND plastic polish and I STILL can see scratches on the blank. What is the method and the speed for this material.

I hate scratches!

Thanks.

 

[hasha2000]

I'm a newbie to the whole process of pen turning, but I did do one acrylic. I was told that if you sand length ways between grits it takes the scratches away, and it did!!!

 

[Displaced Canadian]

I would guess that you maybe changing to a finer grit before you have removed all of the deep scratches.

 

[lazyguy]

I havent done any PR myself but I would think that 320 is not fine enough to go to MM. Some have said that 1500 MM = 400 I am not sure on that but I always take my wood to 600 before CA. Just a thought Newbie to newbie

 

[alphageek]

A couple of questions (so we can try and help):
What grit do you start at?
Do you try lengthwise sanding between grits at all (especially when course)?

One thing I would suggest is to look into buffing... it has helped me greatly.

A second thing is I attempt to sand lengthwise at the courser grits to make the "round the blank" scratches go away. (note for me that is 320 and 400 grit)... I never use anything more course than 320 these days).

 

[Dave Turner]

I find a 8 to 10 X magnification hand lens and good lighting to be invaluable. I frequently assess the status of the surface to make sure it is uniform and there are no larger/deeper scratches before moving onto the next grit. I'm surprised at the number of times I think everything is going along well, only to find a residual scratch or two. By checking frequently, it helps keep me from having to go back several steps to fix it.

 

[nativewooder]

IMHO, you should go to www.woodturnerruss.com to learn about the proper methods for sanding.

 

[kludge77]

A couple of questions (so we can try and help):
What grit do you start at? Do you try lengthwise sanding between grits at all (especially when course)?

I start at 150 and go through 600. As far as sanding lengthwise, I rarely do that on wood so I'm not in the habit. I can totally try that.

One thing I would suggest is to look into buffing... it has helped me greatly.

Not quite there yet. But if nothing else works, I'll totally try it.

A second thing is I attempt to sand lengthwise at the courser grits to make the "round the blank" scratches go away. (note for me that is 320 and 400 grit)... I never use anything more course than 320 these days).

You start at 320? I can do that. I'm not using the sandpaper for shaping or anything. Just always started at 150 or 240...

Thanks!

 

[alphageek]

IMHO, you should go to www.woodturnerruss.com to learn about the proper methods for sanding.

I agree there is alot of good tips there, but I don't think it will help too much in this thread unless I'm missing something.. He really focuses on wood. Acrylics really do have a different set of rules sometimes. If there is a section on acrylics there, please point it out as I can't find it. I would be interested in it as I do like alot of his tips.

 

[jttheclockman]

Throw the sandpaper away,----- far away from acrylics. You need to learn to use your tools better and in particular a skew. I go from skew to MM and never toch with sandpaper. If you can not or are not getting a blank that is baby bottom smooth and ready for poishing then tools need to be sharpened and learned to use better. When you use sandpaper and especially starting at 150 grit you are introducing such huge scratch marks it will take forever to get them out. Stop doing that!!!!

You are using the wood mentality on acrylic and that is no good. I would not even start with 150 grit on wood. I start with 400 grit and if it is abit corser I might go as low as 220grit.

Now when sanding do not hold in one place always keep the paper, mm or whatever moving side to side. No need to go lengthwise with acrylics. There is no grain to fight. One other thing and is very very important wipe the blank down after each grit. I use white viva towels on acrylics because I found the blue shop towels to add scratches especially when polishing. As some said you can also turn to the polishing wheel and there are tricks there too. Remember heat is your enemy at all times on all type blanks. Good luck.

 

[gt64155]

For me, I use a skew to turn the pen, and to sand I start with wet 600 grit, then (both the 1000 and 1500 are from the local auto parts store) 1000 and then 1500. I then go to 3600 with MM and use plastic polish. If you are not using a skew to turn the pen, then you need to learn how. If I can do it, I'd think anyone could learn. Try and get a copy of Alan Lacers skew video. It's great. You can learn to use a skew with this video and practice. Your pens will look better.

Bill

 

[kludge77]

Thanks everyone for the advice!

I'll try a planning cut on the last pass and start with the MM. We'll see how I do...


Cheers!

 

[jttheclockman]

Thanks everyone for the advice!

I'll try a planning cut on the last pass and start with the MM. We'll see how I do...


Cheers!

That is a start and you will see a difference. Remeber though sharp tools!!! Report back with your findings please.

 

[J.L.DAVIS]

Throw the sandpaper away,----- far away from acrylics. You need to learn to use your tools better and in particular a skew. I go from skew to MM and never toch with sandpaper. If you can not or are not getting a blank that is baby bottom smooth and ready for poishing then tools need to be sharpened and learned to use better. When you use sandpaper and especially starting at 150 grit you are introducing such huge scratch marks it will take forever to get them out. Stop doing that!!!!

You are using the wood mentality on acrylic and that is no good. I would not even start with 150 grit on wood. I start with 400 grit and if it is abit corser I might go as low as 220grit.

Now when sanding do not hold in one place always keep the paper, mm or whatever moving side to side. No need to go lengthwise with acrylics. There is no grain to fight. One other thing and is very very important wipe the blank down after each grit. I use white viva towels on acrylics because I found the blue shop towels to add scratches especially when polishing. As some said you can also turn to the polishing wheel and there are tricks there too. Remember heat is your enemy at all times on all type blanks. Good luck.

Question....how fast from side to side should you be moving the MM or sandpaper? Would the heat from the sanding cause scratches to be more evident or cause other problems?

 

[ed4copies]

Question....how fast from side to side should you be moving the MM or sandpaper? Would the heat from the sanding cause scratches to be more evident or cause other problems?

Heat can always be a problem with resins, plastics, acrylics, celluloids, etc.

My suggestion is do NOT use padded sanding pads, use instead the sheets of MM that have thin backing. I sand dry-but you may use water, if you want.

Heat will affect some plastics (celluloid) a GREAT deal--as in ruin the blank if it gets hot, it develops a "warp" that won't come out. Other plastics just get radial "build up" that is also very difficult to remove---so don't PUT IT THERE!!! If your fingers get hot, so is the BLANK getting hot.

Don't sand for more than 30 seconds, then as you change from one grit to the next, don't hurry. Give the blank a chance to get cool again.

LOTS more thoughts, maybe I'll write an article and publish it on a website:biggrin::biggrin::biggrin:

 

[maxwell_smart007]

I wet sand with 600 sandpaper before switching to the first micromesh grit..I know that that's a backtrack, but it's my method, and it works for me...

Andrew

 

[jttheclockman]

Throw the sandpaper away,----- far away from acrylics. You need to learn to use your tools better and in particular a skew. I go from skew to MM and never toch with sandpaper. If you can not or are not getting a blank that is baby bottom smooth and ready for poishing then tools need to be sharpened and learned to use better. When you use sandpaper and especially starting at 150 grit you are introducing such huge scratch marks it will take forever to get them out. Stop doing that!!!!

You are using the wood mentality on acrylic and that is no good. I would not even start with 150 grit on wood. I start with 400 grit and if it is abit corser I might go as low as 220grit.

Now when sanding do not hold in one place always keep the paper, mm or whatever moving side to side. No need to go lengthwise with acrylics. There is no grain to fight. One other thing and is very very important wipe the blank down after each grit. I use white viva towels on acrylics because I found the blue shop towels to add scratches especially when polishing. As some said you can also turn to the polishing wheel and there are tricks there too. Remember heat is your enemy at all times on all type blanks. Good luck.

Question....how fast from side to side should you be moving the MM or sandpaper? Would the heat from the sanding cause scratches to be more evident or cause other problems?

How fast you ask?? the best I can describe is constant motion. Never stop in one place. You don't have to be lightning fast. You want the MM to do what it is suppose to. I am a big believer in use a lubricant for whenever Iand sanding out a finish and that includes flat work. There I use lemon oil. I always use water and that will never let your blank heat up so you eliminate the heat problem with acrylics. Remember wipe after each grit. Does heat cause scratches. It is the sandpaper that causes scratches. You never want to push so hard either because you will bend the mandrel. Light even pressure and your sanding scratches will go away. It does take some learning experience but not hard to pick up. The first 3 pads in the MM series are the most important in my opinion. These leave the largest scratch pattern. Get these conquered and you are golden.

 

[kludge77]

Thanks everyone for the advice!

I'll try a planning cut on the last pass and start with the MM. We'll see how I do...


Cheers!

That is a start and you will see a difference. Remeber though sharp tools!!! Report back with your findings please.

Success!

Shaped with a gouge. A final planning cut with the skew on the blank, and then straight to the wet MM.

What a DIFFERENCE. Thanks for the help everyone. Not only does it look great. It was much faster.