Acrylic Shell Shock

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Hula daddy

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Jan 3, 2012
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Livonia MI
I am trying my first attempts at turning some acrylic pens. I bought 5 blanks from the $1.89 bin at woodcraft. I have tried 4 of the and all 4 shattered while turning.

I have used new blades on the woodchuck so I am sure the blade is shape. each one is getting closer as I use lighter and lighter touches.

My question is could it just cheap acrylic or is it me?

thanks Brian
 
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There is no way anyone can know that.

Do you have any friends who bought the same material?
OR, if you want to send me one, I will video the turning of it, for you.

I should clarify, I would not use a carbide tool---someone else would be a better choice for that tool.
 
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I've never used a Woodchuck Brian, but acrylic is a fickle beast no matter what you use!!! You can tell when you're in "The Zone" when you don't hear anything but the lathe running and wispy ribbons are flying everywhere! If you hear a crackle or crunching or chipping...check the sharpness, angle and speed.
 
When in the process is it breaking? While you are rounding off or beyond that point?

The woodchuck or any of the carbide tools are definitely capable of doing the job however I will typically round off using a gouge well above center in more of a shearing cut than a scraping cut and then switch to the carbide when others would switch to a skew to do the final dimensioning and detail work. The only time I've ever had a problem is if I catch a corner of the tool instead of presenting correctly.
 
What Jim said. When Are they shattering? I have only had one shatter and it was in the initial rounding stage. I now take most of the corners off with a belt sander. This includes the ends sometimes. Light cuts are important.
 
Never had them shatter when rounding them off. Mostly when shaping and nearing the finish line making it more frustrating. last one shattered near the end of the blank with about 1/16" to go.

I could clarify my question. Is there such a thing as poorly made or more brittle acrylic blanks? I would not mind trying a more expensive blank but I am a little reluctant to watch $10 or more blow up in my face.
 
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Hula daddy said:
Never had them shatter when rounding them off. Mostly when shaping and nearing the finish line making it more frustrating. last one shattered near the end of the blank with about 1/16" to go.

I could clarify my question. Is there such a thing as poorly made or more brittle acrylic blanks? I would not mind trying a more expensive blank but I am a little reluctant to watch $10 or more blow up in my face.
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Is your hole large? With some kits you are directed to drill a hole that leaves VERY LITTLE material. It is easy to break these near the ends, if the brass tube is slightly skewed.

ABSOLUTELY!!! Acrylester is much more brittle than Alumilite (opposite ends of the "brittle-meter"). But they both can be persuaded to be a pen.
 
Lots of good advice and things to look at and try. Not all acrylic is the same. Some of it is very brittle and some of it is soft. Some of it you should not use a Woodchuck on. If I remember correctly the Acrylic Acetate will dull the carbide bits pretty quickly, more so than tru-stone. If your first attempt is with the Acrylic Acetate, then that is not always a good starting point. Find someone on here that does some home pours and try a poly resin from them first first. Much easier to work with. The stuff comes off your tool all light and fluffy and polishes very nice too. A much more forgiving medium to cut your teeth on.
 
InvisibleMan said:
Leatherman1998 said:
Check when you are drilling so heat will not build up. I use water, some use a air blower, and others drill super slow. I drill in my lathe so I don't have any trouble with blowout and such. 103 acrylic blanks - YouTube watch this, I have not blown up a plastic blank yet.
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Now you've done it. Good luck with your next one.:biggrin:
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I have done a lot of acrylic blanks and I still have a good record of not blowing any up.
 
Don't know if this will help as our local Woodcraft bin has been a downfall as I approach the check out. I have bought a lot of them , haven't had time to turn any yet. The ones locally are all bear tooth woods a lot have a sticker on them.
Bear Tooth Woods here is their page. Other than acrylic's I couldn't find any more of a description. I will be looking forward to the answers in this thread to stop any problems/bad habits before they start!
:clown:
 
Make sure you are not presenting the Woodchuck blade "flat", that is at 180 degrees. Present it at about a 45 degree angle to the blank and just barely "tick" off the corners for a while. Get the feel by doing that. Just "ticking" them down slowly.

As you get the blank closer to round you'll be able to lean into it a little more, but still keep low pressure on the cut.

Make sure you are turning at AT LEAST 800, better would be 1000-1200. You feel much more secure at higher speed because the high-spinning blank won't let you put much pressure into a cut.

So two things: 45 degrees and 1000 rpm.
 
Just thought I better clarify: by 45 degrees, I mean twisting the tool to a 45 degree prsentation angle.

I also like to present the tool at a little less than "staight" into the blank; that is, the tool blade is a little to the right of the spot where the tool shaft rests on the the tool rest.
 
I'll take a different advice route.....don't use the Woodchuck. There are some materials I like the woodchuck for and others I prefer a skew, scraper or gouge. Turning is a style thing and what works for some may be a nightmare for others.
 
You might want to try some Urathane glue such as gerilla or elmers Urathane. Just need a touch of water to dip the tube before inserting with the glue. The Urathane will expand and fill any gaps and make it more solid. Just make sure the tube doesn't push out, and to stop that, stand the blank on end and that keeps the tube in place. Also roughen up the tube with 220 grit for the glue to have something to grip. I've done this and never had a blow out as of yet. Most of my blow outs are operator error. Pushing too hard or over using a tool to where it gets dull.
 
Learn to use a skew and use it on all materials. For my money the skew is my tool of choice: for wood, antler, all plastics and acrylics, truestones, hard rubber, corncobs...well, you get the idea. Carbide tools are nice but they are not some magical solution that works for every blank. I have several and rarely use them...for pens, that is. And, different materials require different techniques no matter what tool is being used.
Do a good turn daily!
Don
 
Just wanted to follow up. Lyle AKA Invisible man was kind enough to send me a blank he poured. I can say that the I did turn it with out it shattering. But unfortunately I severely under cut the bushings. So assembly was pointless. but I did get practice finishing the blank.

A few things that I did learn for this thread.

1. the difference between the woodcraft blank and the the one sent to me was completely different. the wood craft is much more fragile and Glass like

2. I believe part of my problem was small gaps between the brass and the blank along with possibly building up to much heat while drilling.

3. Personally for PR I like using the skew VS. the wood chuck. I just could not get a constant clean cut with it. It would always bit. It is probably just me but I did not have that issue with a sharp skew.

thanks again for all your help.
 
I use a Woodchuck or skew to turn all pen materials with very few problems. I have only had one blank that was not usable and I may not have had the best glue adhesion on this blank. The skew is great if you have mastered it's use; the finish if used properly is ready for 400 grit sandpaper.

As others have said rotate the Woodchuck approximately 45 degrees ccw and make very shallow passes the length of the blank from right to left. The lathe rpm should be as fast as it will run. For me that is about 3400 rpm. The less time that you have "air" between contact with the four corners the less chance of the tool grabbing. I place my left hand on the tool shank at the toolrest and sort of use it to maintain a shallow cut as I make the cuts. The hand holding the tool and the rest, keeps me from taking too large a bite out of the blank. I can even turn acrylester blanks using this method and they are probably the most difficult of the plastic blanks. Keep trying, making shallow passes until round and with the rpm's high and your skill turning plastic blanks will improve.

If your first blank turned out perfect, where would the challenge and pride in mastering a process come from?:beauty:
 
Once my acrylic blank is turned round with my carbide tool, I use a 1/4" parting tool. When those things are sharp they will throw better curls and will not put pits in the blank. Try that next time you are turning your acrylic blanks and let me know what you think of that. It outshaves your carbide tools.
 
Hula daddy said:
I am trying my first attempts at turning some acrylic pens. I bought 5 blanks from the $1.89 bin at woodcraft. I have tried 4 of the and all 4 shattered while turning.

I have used new blades on the woodchuck so I am sure the blade is shape. each one is getting closer as I use lighter and lighter touches.

My question is could it just cheap acrylic or is it me?

thanks Brian
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Rather than trying to figure out what you are doing wrong, which I suspect is likely the problem, call your local Woodcraft and find out when the next pen making class is being held. The Woodcraft where I used to live had classes of one type or another every month and even when there weren't classes, all you had to do was walk in and talk with the folks working there.

Contrary to the constant bashing they receive on the forum, most Woodcraft stores I have frequented have some pretty decent folks working there, always willing to help out.
 
Have to second that the one locally here in Sterling Heights, has a great staff. they also have a beginning free pen turning class every so often in addition to the pay for ones. They all have been very helpful.
:clown:
 
Texatdurango said:
Hula daddy said:
I am trying my first attempts at turning some acrylic pens. I bought 5 blanks from the $1.89 bin at woodcraft. I have tried 4 of the and all 4 shattered while turning.

I have used new blades on the woodchuck so I am sure the blade is shape. each one is getting closer as I use lighter and lighter touches.

My question is could it just cheap acrylic or is it me?

thanks Brian
Click to expand...
Rather than trying to figure out what you are doing wrong, which I suspect is likely the problem, call your local Woodcraft and find out when the next pen making class is being held. The Woodcraft where I used to live had classes of one type or another every month and even when there weren't classes, all you had to do was walk in and talk with the folks working there.

Contrary to the constant bashing they receive on the forum, most Woodcraft stores I have frequented have some pretty decent folks working there, always willing to help out.
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Hmmm...I dont think I bashed any one and have had numerous discussions with the woodcraft folks. I agree they are very helpful.
 
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Hula daddy said:
......

Hmmm...I dont think I bashed any one and have had numerous discussions with the woodcraft folks. I agree they are very helpful.
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After reading my post again, I think I did a poor job of conveying my thoughts. Let me try it again.....

Since none of us really know what your problem it's rather difficult trying to diagnose what's going on then giving you some valued solutions. I merely suggested visiting the Woodcraft folks, even take your carbide tipped tool in and let them see if they can help you out. I remember after joining a local wood turning club and spending one day with one of the better turners, I learned more in a few hours with him than I did in three months trying to teach myself and learning from my cyber friends because he could SEE where I was doing things wrong and could SHOW me the correct ways.

As far as the Woodcraft bashing goes, it's not you I was referring to, now and then threads will pop up bashing either Woodcraft or Rockler either complaining about poor service, ignorant sales staff and/or high prices when actually from the folks I have dealt with in these stores have generally been very helpful, especially with hands on help.

If I were you, I would grab the woodchuck and a blank and take it down to the store and ask someone to show you how to best turn it down.
 
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I have somewhat the same problem. Mine dont shatter, but I do end up with the surface looking "cratered" with little salt sized craters in the finish. I know it is a result of the tool chattering, but how do you prevent it. (using 1750 rpm, and sharp tools)
Stan
 
biednick said:
What speed are you at? I would turn it all the way up. I turn all my pens at around 3700 rpm.
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What he said. I shattered a few Acrylester blanks, and stuck to acrylic acetate after that for a long time. I finally got my confidence back up and gave them another try.

"Faster, faster" seemed to be the rule for success on mine.
 
sthoover47 said:
I have somewhat the same problem. Mine dont shatter, but I do end up with the surface looking "cratered" with little salt sized craters in the finish. I know it is a result of the tool chattering, but how do you prevent it. (using 1750 rpm, and sharp tools)
Stan
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Crank that bad boy up. I use the fastest speed my lathe goes - I think 3900 RPM or so. I have problems when I slow it down.

Also, don't rush the side-to-side movement. Let the tools do the work.
 
Brian; I would give you several suggestions. Rough up the tubes with sandpaper before gluing. Knock off the corners with a drum sander before spinning on the lathe.

Examine the blank that shattered, is the tube bare of glue? Poor blank adhesion. If the glue is on the tube and not the blank, the glue didn't stick to the blank.

Carbide is useful for turning, but there are two "families" of carbide bits. Look at the bit from the side. If the angle between the top and bevel is from 40 to 50 degrees, use for wood. If the angle is from 75 to 85 degrees, use for acrylic. The wood bit is too grabby for acrylic, the acrylic bit will leave tear out on a wood blank.
 
randyrls said:
Carbide is useful for turning, but there are two "families" of carbide bits. Look at the bit from the side. If the angle between the top and bevel is from 40 to 50 degrees, use for wood. If the angle is from 75 to 85 degrees, use for acrylic. The wood bit is too grabby for acrylic, the acrylic bit will leave tear out on a wood blank.
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I'm not talking to myself!:biggrin: (That's my story and I'm sticking to it!)

I received a PM asking for clarification, so I thought to post it to the thread too.

These are two of my carbide tools.


Notice the difference in the front bevel angle. The upper bit is great for wood. It will peel wood from a blank faster than you can push the tool into the wood. BUT it is "grabby" and will leave a pitted surface in brittle acrylics.

The lower bit will peel endless ribbons from the most brittle of Acrylester, the hardest of the Trustones and M3 blanks. BUT the lower bit will leave a ragged, torn surface on wood blanks.

I hope this makes it clear.

Off to help with Habitat for Humanity now.
 
Out of curiosity, I am relatively new with the Woodchuck. I've done been through one R2 and one R4 (just ordered more R4...seemed to work better for me). Love the tool...even managed a few of the "harder" (probably moderate) TruStone and numerous antler and acrylic blanks. I did a demonstration last weekend and so "cheated" and bought some pre-cut, pre-drilled blanks from PSi (Bocote). Fortunately, I tried a few before the "show" and blew-out 2 of the first 3 blanks on my first "swipe" with the penpro, R4 insert, (rounded with a gouge first). The blade caught and the blank blew apart in chunks in both cases. Since then I've been hesitant to try the penpro on wood (I have had a few successes previously with other woods (olivewood, lignum vitae, indian rosewood are a few). In the the few hundred pens I've made, I've had very few blow-outs like this and those usually to impatience or the osage orange branch from the ditch didn't like being turned. I've gone back to the skew on wood for now. Is this somewhat normal for the penpro? Is the R4 the wrong insert for this? I'm more than willing to admit it's me...I just read that folks turn ALL their pens with the penpro and thought i would too (less sharpening for the skew). Is wood the exception? Thanks for the help.
 
randyrls said:
......Carbide is useful for turning, but there are two "families" of carbide bits. Look at the bit from the side. If the angle between the top and bevel is from 40 to 50 degrees, use for wood. If the angle is from 75 to 85 degrees, use for acrylic. The wood bit is too grabby for acrylic, the acrylic bit will leave tear out on a wood blank.
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Something to consider

Randy, I understand what you are saying about the degrees of the different cutters but..... I would like to add a comment so those new to turning or just haven't thought of this, won't take these angles as "gospel".

If the cutting tool is held at a perfect 90 degrees to the blank then the angles will function as described above BUT..... if the user tilts the cutting tool either up or down based on his/her height to the lathe or tool holding stance, then the stated angles are going to be way off and the aggressive cutter becomes really radical and the tame cutter switches from mild to wild.

So, just how a person holds the tool handle will cause one with a mild cutting tip to start taking aggressive cuts so back to blanks blowing out by those who didn't consider the angle change.
 
I've done several acrylic pens and only broke the first one from taking to big a bite. I have great luck using EWTs "Pen Turner" from Craft Supplies and it is a square carbide tool with a 2 in radius. When done turning I Micro Mesh and use Hut's Ultra Gloss. You could be drilling too fast or running to high a speed on the lathe. Try around 2000 rpm. You can't take to big a bite or build up very much heat. Take your time, it's supposed to be fun.
 
I always use my woodchuck for acrylic! I was having the same problem and someone here told me to use the round cutter for acrylic. I switch to it and don't have any issues with acrylic now. Also try turning the cutter up on its side a bit and see the steady stream of acrylic just peal off. If you use the woodchuck like a scraper it doesn't cut as well as far as I am concerned. I just love the Woodchuck!
 
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Hula daddy said:
I am trying my first attempts at turning some acrylic pens. I bought 5 blanks from the $1.89 bin at woodcraft. I have tried 4 of the and all 4 shattered while turning.

I have used new blades on the woodchuck so I am sure the blade is shape. each one is getting closer as I use lighter and lighter touches.

My question is could it just cheap acrylic or is it me?

thanks Brian
Click to expand...
When I pck-up acrylic blanks I look at the edges where they were cut apart. If there are a lot of chips along that edge I know that the blank is VERY brittle and very easy to shatter on the lightest of catches. I have a little better luck on these blanks using a scew chisel.

Rhino Plastic blanks turn and polish very nicely.
 
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