Turning Acrylics #@!

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gwlundgren

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Mar 15, 2014
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I had turned a few and they turned out fine. Now I seem to run into more troubles.

Perhaps I'm getting too aggressive. Wrong angles with my lathe chisel, or . . ?

For now I'm a hobbyist. Not into selling my work yet.

I sharpen my chisels each time. Have the Worksharp 3000 with the Tormek adapters to get the right angles.

I use the roughing gouge a lot. Like a 3/4 in? That's what I see in videos a lot. Somehow that seems too big once the blank is round. Should I be stepping down to a smaller chisel? What type of chisel?

I have a seemingly complete set, 8 chisels, PSI's Set of 8 Benjamins Best HSS Lathe Chisel Set Item #LCHSS8.

Also have a smaller set of 8. The Woodcraft WoodRiver HSS "Mini" Turning Tool Set 5 piece #143718.

Any tips or advice appreciated.

Thx, Gary
 
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eranox

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My two best pieces of advice are turn at high speeds, and knock the corners of the blank off with coarse sandpaper before getting chisels involved.

Acrylic is a finicky material. I use a round-nose scraper to work mine, and I make light passes and move very slowly to start. This causes the acrylic and the tool to warm up, and this makes the acrylic cut much more easily and chip much less. Once you get to a cylinder, things become easier, and you should have more or less one long continuous shaving coming off the blank. I have actually found that ultra-sharp tools are not a strict necessity (others will strongly disagree), but I do not recommend that you use a tool with a burr to cut your acrylic. The burr will agressively pull the tool into the material, and you will cut/chip far too much away in a very short time.

Since heat softens acrylic, you'll want to take the opposite approach to sanding. Set the lathe on a slow speed, and wet sand when you can. Keep the sandpaper moving, and don't apply too much pressure. It's really not difficult, and you'll get a feel for it pretty quickly.
 

1080Wayne

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Did you get your new pieces from a different source ? There are several different acrylics , and unfortunately to make it more confusing , different plastics called acrylics which are not acrylics . They do not all turn the same .
 

randyrls

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Gary; The term Acrylic describes a family of materials that can vary greatly from soft and gummy, to, hard as nails.

Can you be more specific as to the problem you are having? What acrylic are you trying to work with.

With all acrylics, heat is your enemy. This includes while drilling, turning, and sanding.
 

Rchan63

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Apr 17, 2009
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What speed do you turn when turning acrylics? I turn mine around 1200rpm. I use a large spindle gouge from Harbor freight. It needs sharpening often but it works for me.
 

keithbyrd

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I set my speed to 3500 and do acrylic rounding with a large bowl scraper! Light passes until the corners are knocked off then a little more agressive - happens pretty quickly then switch to my pen pro carbide - rarely have any problems even on the various types of acrylics!
 
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ed4copies

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"Acrylic" is used for nearly any plastic, resin, etc.

Inlace acrylester is difficult, Acrylic Acetate is much easier. So, what you are trying to turn could be two very different products.

Picture?
What is the material called?
Either would help,
Ed
 

kovalcik

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Barrington, NH
Use whatever tool feels comfortable for the job. If the 3/4" seems too big, move down a size. Make sure you are rubbing the bevel. This will keep you from taking too big a bite.

When I get close to size, I move to a skew chisel to get the best finish. If the blank is one of the brittle ones, I move to the skew sooner. I would definitely recommend learning the skew with a planing cut. Nothing will give you a better finish.
 
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gwlundgren

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Did you get your new pieces from a different source ? There are several different acrylics , and unfortunately to make it more confusing , different plastics called acrylics which are not acrylics . They do not all turn the same .
Thanks. Have been getting my acrylics from PSI.
 

gwlundgren

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Thanks. Using acrylics from PSI. Stars & Stripes blanks (not the ones where you glue the stripes & stars in). Also camo blanks.
 

juteck

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Dec 10, 2008
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I used to use a bowl gouge, but I turn all of mine start to finish with a Crown 3/4" roughing gouge. I use the same technique for wood, various plastics, antler, etc. The only time I veer from the roughing gouge is on laminations, especially laminations with metal separators. The 3/4" size should do fine, even at the smaller diameters. Keep it sharp is key, and ride the bevel. If you raise the handle, you end up scraping. If you do this like a scraping mode (although not the preferred way of using this tool), make sure the point of contact on the edge is on the center line, or just slightly below it.
 
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Tom T

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May 12, 2012
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I use a 3/4 roughing gauge also and have turned many acrylic blanks. It is easier if you take off the long corners on a disc sander prior to turning. Mostly though I am wanting to turn so I do not take of the corners.
A big change for me came when I went to the PSI mandrel saver and lost the brass nut.
If I get a catch it spins freely and does not blow up the blank.
I have also found it necessary to readjust the tool rest after the blank is round and the diameter is smaller. Keep the rest as close to the blank as you can. I went from a 11inch long tool rest to a 4 inch tool rest for pens and like it much better.
Also I cut acrylic at 1200-1400 rpm no more but for sure no less. Real slow rpm has been an issue. Also cut the corners of the blank when turning from just on the blank to off the blank. Never cut into the corner from the out side. Also I some times roll the roughing gauge on edge if it it giving me to much grief. I get real close to the bushing an then stop and measure with the calipers to check the diameter and then start sanding dry paper strips from Wood Craft (WC). Usually about 240 grit they come in a turning pack. When I am with in 10, 10s of an inch I switch to wt micro mesh. Go through all sizes. Then when real close go to beal buffing system. Triply(spelling) and then white diamond. Use a jewelers loop no scratches any ware. Round the ends very gently with micro mesh by hand then put kit together and impress all my co-worker and friends and some times the wife.
I most likely left out a few things but this is a quick coverage.
Side note, computer pens is a whole other story. Lots of sanding and filling.
 

robutacion

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Australia - SA Adelaide Hills
And off-course, you have the "Flap Disk System" here :wink::biggrin:

Cam'on guys, you knew that was coming, huh...???:)

Good luck,

PS: I use all the tools mentioned above + the flap disk system, when the situation requires/calls for....!:biggrin:

Cheers
George
 
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