Turning Acrylic

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ghansen4

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Tonight I tried to turn my second ever acrylic blank, and let's just say that it didn't go as planned. This blank was different from the first in that it seemed to come off in small sharp shards until it broke off of the tube in a large chunk. It reminded me of smashing a piece of hard candy like a jolly rancher.

Is this normal? My first acrylic blank was a little like this, but definitely not as bad. Do different acrylics turn differently? Could age have had something to do with it? Any suggestions for turning acrylics so this doesn't happen again?
 
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OZturner

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Hi Greg,
As Wayne commented, there are so many reasons that could have caused your Blank to shatter.
Please give a run down on a step by step of what you did, and what you used.
How did you drill, Speed, Drill type, Sharpness?
How frequently did you clear and cool the Drill?
What adhesive used?,
How did you roughen the Tube?
The Method and tools you used to turn?
What speed?
Where did you start? What sequence did you turn the blank? e.g both ends to round then the center down, or right to left along the whole blank, or what ever?
Was there any adhesive on the tube, where the pieces came off?
Some pictures may be helpful.
Or better still would be take the remnants to a local group of pen turners, and let them see what they can suggest.
Regards,
Brian.
 
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My first few experiences with the various plastic blanks had me swear off turning anything but wood for quite a while. These days I appreciate the fact I don't have to apply a finish and over time I've learned which ones I can turn with carbide and which ones need the skew. When I blow up a blank it's usually because I'm trying to take too much off at once. For most polymer blanks, patience and light cuts are key. If you're turning acrylester just go ahead and put the carbide down.
 
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The tools can never be too sharp, and each blank tends to cut differently. The mix when poured makes a difference, some are just more brittle than others, and some days just work better than others. I swear that some of my blanks have a "grain" pattern and cut better in one direction than the other, but it is likely my "feel" for the day or the sharpness of the two sides of the tool. Keep practicing, it will get better, and the results are worth it.
 

WriteON

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Tonight I tried to turn my second ever acrylic blank, and let's just say that it didn't go as planned. This blank was different from the first in that it seemed to come off in small sharp shards until it broke off of the tube in a large chunk. It reminded me of smashing a piece of hard candy like a jolly rancher.

Is this normal? My first acrylic blank was a little like this, but definitely not as bad. Do different acrylics turn differently? Could age have had something to do with it? Any suggestions for turning acrylics so this doesn't happen again?

Welcome aboard and welcome to the acrylic club. Nothing is wrong...you are learning. Most of us have experienced what you are going through. I broke, chipped, cracked a few until I got the touch. Sharp tools and speed are your best friend. Take your time. Light strikes. You'll get there. Some acrylics are more brittle than other. I do not like working with certain types. You'll figure it out. Stay with it...just take your time.
 
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eharri446

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Greg, from what you described leads me to believe that you were trying to turn Inlcae Acrylester. If that is so, then you need to have very sharp tools, carbibe will work also, and take very light cuts.

I use a Sorby spindle gouge, a round carbia, and a R2 carbide. Once you get the hang of turning them, they finish beautifully.
 

eharri446

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That will turn a lot easier than Inlace Acrylester. I have turned several of those blanks and they have all been a pain. I can turn a regular acrylice acetate blank in about 30 minutes, but it will take me close to 2 hours to turn the Inlace blanks.

If you have a Woodcraft near you, check and see if they have a box with acrlic blank cutoffs. Mine has one and they sell 2 1/2 inch blanks for $1.99. That is a fairly cheap price for something you can learn with. That size will make a nice Sierra style pen.

Also, you can purchase some alumilite blanks and it turns almost like butter. The only thing that I found that you need to look out for with Alumilite and the new Liquid Diamond blanks if the shavings that come of as you are turning can get real long and then they want to wrap around your blank. When that happens, I just turn them off or stop the lathe and pull them off. Not a major problem just a little inconvenience.
 
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Wow, you guys were spot on. Turns out it was in fact Inlace Acrylester with a carbide tool. What are some of the easier acrylics to turn with carbide?

How about something like this?
https://www.exoticblanks.com/Maroon-and-Black-AA-39.html

That's because we've been there before ;) I will say this, the Acrylester is worth the effort but there IS a learning curve. I'd suggest practicing on some single tube pens with short tubes so you don't feel the pain as much when you blow one up. Go ahead and get yourself a nice skew chisel. The carbide tools are great and I laid my skew down when they got popular several years ago.. but.. it's worth picking it up to do some things the carbide can't. When you've got soft spalty wood or blanks like acrylester you'll appreciate being comfortable with the skew.
 

ed4copies

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MRDucks2

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I turned my first piece of the inlace acrylester last week. Woodturningz told me to avoid the carbide and if I used a gouge to keep it vertical until I got a feel for it (see First, First, First under other things). Started with the ornament so I could freestyle. Approaching round was tough and after "knocking" the corners off a little I went with a sharp skew that I honed on a stone halfway through. Again, staying very upright on the approach as I got a feel for it.


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randyrls

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Greg; All the other suggestions are good ones. The post by Brian (OZturner) is especially complete. You need to figure out what went wrong. Some materials are easier than others, but all can be done successfully with the correct technique. Especially examine the broken pieces of the blank, where did the glue joint fail, is the glue on the blank or the tube. If the glue is on the blank, you need to scuff the tube with sand paper and wipe down the tube with denatured alcohol.

There is a "best practices" Wiki page on Blank preparation. Try to round off the blank corners on a power disc sander before you start to turn. Mount the blanks on a mandrel and use it to hold the blanks.

Hope this helps.
 
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thawkins87

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Here's a related question perhaps someone could answer... I finally procured a skew after failing miserably with IA and carbide tools, and it worked phenomenally. Only problem was, I found myself needing to re-hone the edge every 2-3 minutes. Is this normal, or did I perhaps put a poor edge on it to begin with?
 

MRDucks2

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I'm new this this, too, but picked up on decent skew results pretty quick. I use the HF set and found I must sharpen about half way through on acrylic. Also noticed that, depending on what I am trying to accomplish I may develop a "dull spot" sometime near one end or the other, sometimes in the center and sometimes only where I hit metal. Lol.

I switch between left hand cutting and right hand cutting and found that will quickly show if I sharpened poorly by cutting well in one direction but not the other. Except for that situation I typically get 10-15 minutes minimum between sharpening with cheap HSS in the worst situations.


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mark james

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I'm new this this, too, but picked up on decent skew results pretty quick. I use the HF set and found I must sharpen about half way through on acrylic. Also noticed that, depending on what I am trying to accomplish I may develop a "dull spot" sometime near one end or the other, sometimes in the center and sometimes only where I hit metal. Lol.

I switch between left hand cutting and right hand cutting and found that will quickly show if I sharpened poorly by cutting well in one direction but not the other. Except for that situation I typically get 10-15 minutes minimum between sharpening with cheap HSS in the worst situations.


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"Cheap HSS" tools will need to be sharpened more often, but are perfectly fine! Just keep your grinding jig adjusted, use it frequently, and the HSS gouges will be fine.
 

Noot17

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I've had good luck turning the Italian Lucite and madreperlato blanks from exotic blanks.

Granted I've only turned two, but I did one with cheap HSS and the other with a nice carbide and both came out fine, with minimal to no chipping during the process.


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