# acrylic blank help needed



## ripjack13 (May 12, 2015)

Ok...I sharpened my carbide cutter on my diamond pads. Took very very light cuts. Yet it still caught and took chunks out...down to the tube. I filled the "hole" with some thick ca and will let it sit over night.
So...the question is....how do I go about getting a smooth cut? Is just lots of practice and ruining blanks?


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## manbuckwal (May 12, 2015)

ripjack13 said:


> Ok...I sharpened my carbide cutter on my diamond pads. Took very very light cuts. Yet it still caught and took chunks out...down to the tube. I filled the "hole" with some thick ca and will let it sit over night.
> So...the question is....how do I go about getting a smooth cut? Is just lots of practice and ruining blanks?




I have had similar chip out issues . I have had better success w Alumilite resin blanks tho. The key for me has been very light passes w sharp tools .

Reactions: Like 1 | Agree 2


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## Final Strut (May 12, 2015)

Try light cuts with a scraper with a good hook on it. 

It sounds like you got a brittle blank. This can happen when there is to much heat present when the blank cures. To much heat can come from to much catalyst in PR or an imbalance of the two part mix with Alumilite or higher ambient temps during the curing period.

Reactions: Thank You! 1


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## Schroedc (May 12, 2015)

Try jacking up the speed, Some of the blanks I work with are really chippy and going at a crazy high rpm and taking a really light pass can help.

Reactions: Thank You! 1 | Agree 1


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## ripjack13 (May 12, 2015)

I had it mid way on the gear/pulley. Not sure of the speed. But I'll jack it up tomorrow...


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## JR Custom Calls (May 12, 2015)

What kind of acrylic? If its PR or Alumalite, dull cutters work best IME. Any time I turn a hybrid or poured blank, I swap out to an old dull cutter I have. For machine grade acrylic, sharp works better.

Reactions: Thank You! 1


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## ripjack13 (May 12, 2015)

I'd have to look to see what kind.


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## Bean_counter (May 12, 2015)

Yep do you know what kind of acrylic it is? Some are much chippier than others. Also what cutter are you using. I find my radius squatr cutter works best for finish work

Reactions: Agree 2


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## ripjack13 (May 12, 2015)

I wonder if they would send me a replacement blank. It's not like I was total n00b trying to turn for the first time....so...can't hurt to check.


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## ripjack13 (May 12, 2015)

It's a PR blank....

http://www.beartoothwoods.com/catalog/product_info.php?products_id=4047


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## JR Custom Calls (May 12, 2015)

PR chips out much easier than alumalite or cast acrylic rod. Try a dull cutter next time. And definitely take light cuts

Reactions: Thank You! 1


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## ripjack13 (May 12, 2015)

Dull...ok...will try it.

Thanks fellerz!


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## ripjack13 (May 12, 2015)

Bean_counter said:


> Also what cutter are you using. I find my radius squatr cutter works best for finish work



I was using my round cutter to rough it to size...but it's almost there. So i can switch to my radius cutter. It's a lil dull at the moment...

Reactions: Like 1


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## Bean_counter (May 12, 2015)

That's a cool blank, never seen those before. Yeah PR can def be chippy if too much mekp is used or lots of heat like Scott said.

Reactions: Thank You! 1


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## Tclem (May 12, 2015)

I don't use my carbides on them. I use a spindle roughing gouge and get it sharp and take light cuts

Reactions: Thank You! 1 | Agree 1


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## manbuckwal (May 12, 2015)

I have found high speed works best . I use the round carbide on pretty much everything .

Reactions: Thank You! 1


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## rdabpenman (May 15, 2015)

Minimum of 3800 RPM using a 1/2" spindle gouge and cut up hill.
Works great for me.

Les

Reactions: Thank You! 1


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## Treecycle Hardwoods (May 15, 2015)

I agree with bean on the sqare radius cutter it is the only tool I have found to work well on the finish cuts. As far as roughing it there is only one tool in my book and that is my skew. I use the skew for all pens except on 100% acrylics on the finish cuts. If i remember I will post pix of the grind i use on my skew and try to see if i can.

Reactions: Thank You! 1


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## ripjack13 (May 15, 2015)

A skew? Hmmm....i have one...

Uphill? Please explain this?


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## TimR (May 15, 2015)

I just got done posting a pen from acrylic and I almost exclusively used a roughing gouge at high speed. I got a little too aggressive and did have some chipping on the ends but with plenty of material left to clean up. I also do what Les brought up with a spindle gouge, in a shear scraping orientation, when I nedd finer control at the ends. Throughout the mid sections...all SRG.

Reactions: Like 1


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## NYWoodturner (May 15, 2015)

I agree with the folks who don't use carbide on the acrylic. I use a detail gouge. I have have used a roughing gouge but find then too bulky for pen banks. If you just aren't comfortable using traditional gouges use a negative rake scraper. They are practically fool proof. The only problem you might run into is if you allow it to get dull and start pressing too hard. 
That reminds me - I promised a crazy call maker I would make him one...

Reactions: Thank You! 1


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## ripjack13 (May 15, 2015)

Well...it blew up on me. Looks like I'll have to get another and try again. 
Don't have much in way of tools. Gonna have to go look for some new stuff.....


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## ripjack13 (May 15, 2015)

This is the set of tools I have....very limited...





I also have a roughing carbide scraper I made and a carbide radius square cutter I made also....
That's it....I wonder if I can make negative rake one....


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## ripjack13 (May 15, 2015)




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## Tclem (May 15, 2015)

I have used the square cutter. Instead of running length ways I would come in from the front till it was close to size then use the skew but I'm find of traditional tools now days

Reactions: Like 1


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## ripjack13 (May 17, 2015)

NYWoodturner said:


> I agree with the folks who don't use carbide on the acrylic. I use a detail gouge. I have have used a roughing gouge but find then too bulky for pen banks. If you just aren't comfortable using traditional gouges use a negative rake scraper. They are practically fool proof. The only problem you might run into is if you allow it to get dull and start pressing too hard.
> That reminds me - I promised a crazy call maker I would make him one...



Hey Scott, have you seen one of these before? is it a gimicky tool, or is it a useful one?

http://www.amazon.com/SB-Tools-004310-Negative-Scraper/dp/B00GJYDLR0







_"This Negative Rake Skewed Scraper from SB Tools includes a double ended blade with the same edge profile on each end. Note that the edges are slightly radiused to make it easier to traverse long cuts. It can be used either side up. The scraper includes a mounted Taper-Lock Bolster and will work with any SB Taper-Lock Handle. Scraper is 1" wide. It has a blade length of approximately 7" and an overall length of about 11". Recommended Handle Lengths: For Maximum Overhang - 20"; Minimum Length for General Use: 9". USA SB Tools Negative Rake Scrapers are the first of their kind ever produced. All scrapers have a 1/2" thick substrate (5/8" for the deep bowl version) which fully supports the replaceable blades along their entire length. Only the very front of the replaceable blade is exposed and can be easily resharpened in seconds. All scrapers come with one CPM 10V® (vanadium carbide powdered metal) double-ended replaceable blade. Negative Rake Scraping is a neutral technique. When done correctly, will improve your shapes and dramatically reduce your sanding time. It neither draws the wood in like Conventional Scraping does, nor pushes it away as would a gouge. This makes it an exceptional technique for working very thin walled pieces or broken surfaces, like square bowls or natural edge. Negative Rake Scraping works best on medium density temperate woods and the densest exotic woods. It is also the very best tool on acrylics, plastics and acrylic impregnated woods because it will not grab at them. It can produce an unmatched finish on end grain or around the mixed grain surface of a side grain bowl. Made in USA!_"


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## NYWoodturner (May 17, 2015)

Never heard of them or it before. I will tell you that you don't need to buy a tool. Take one of those beginner chisels you got that you swore off of and make your own. These folks sell replacement blades - Thats their bread and butter. Make your own. You can Google it but I believe the combines angles of a negative rake scraper are 50 to 60 degrees. 40 and 20 are most common. if you do a 30 30 you can just flip it when it gets dull. . In fact you can flip any angle combo. You just have to move it to find the "sweet spot". You will have to re-sharpen it multiple times in one pen blank, but the results are phenomenal.
OK - That sounds a bit like rambling  Let me clear it up a bit. 
If you have ever used a cabinet scraper you will understand how a negative rake scraper works. It uses a burr to cut / scrape with a razor sharp edge. A negative rake scraper is simply a "V" shaped edge with a burr. As soon as the burr is gone the magic is gone. You touch it to a grinder and re-establish the burr and you back in action. People adjust the angle combos to tweak the thickness / angle of the burr to prolong its life. I have never seen a discernible difference. 
You already have turning tools so I assume you have a grinder to resharpen. Take an old chisel or $2.00 worth of steel and make you own. You will love the results.

Reactions: Like 1


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## NYWoodturner (May 17, 2015)

I just looked at the link. $84 for that. Im speechless. Buy me $2.00 worth of steel and I'll make you one for $40 and save you half the cost

Reactions: Like 1


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## Treecycle Hardwoods (May 18, 2015)

With that radius square one you should be able to do the whole pen start to finish. Or get the spindle gouge from the 3 piece set and rough it with that then move to the square radius tool. Instead of pushing the radius tool into the pen blank come at it from either end gently leading with the corner. Make one motion the whole length of the blank and the start another cut. You will slowly work off a few thousandths at a pass. Once it is round start with light passes near each bushing and work it to the final shape. I have learned to be liberal with my glue when working acrylic. Most of my acrylic blow outs were in areas that I lacked glue coverage between the tube and the blank. That combined with too much pressure will cause you grief. Take a look at your hands next time you are turning one, if it looks like your taking a white knuckle ride at the lathe you might be pushing it too hard. If I lived closer I would drop by for a quick lesson.

Reactions: Thank You! 1


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