Problem with acrylic blanks

Signed-In Members Don't See This Ad

Firebucket53

Member
Joined
Apr 19, 2017
Messages
23
Location
South Carolina
I am starting to get into turning acrylic pens. The problem I'm having is pitting. part of the pin blank when I'm finished sanding and buffing there are little pit marks on part of the pin tube. Any suggestions?
 
Signed-In Members Don't See This Ad

Wagner11

Member
Joined
Jul 8, 2017
Messages
128
Location
Indiana
Sounds like maybe the blank is chipping off small hunks due to a dull tool or aggressive cut. Then during sanding these small chips don't get fully removed.

If you have a picture of this pitting it might help to identify the issue.

Sent from my SM-S975L using Tapatalk
 

MRDucks2

Member
Joined
Jul 17, 2017
Messages
1,844
Location
Franklin, IN
I don’t have a ton of experience by have made plenty of mistakes. If it were my pen it would be what Doug pointed out, chipping of the blank. Guessing that because pits are irregular shape (not casting bubbles) and kind of in a band around the pen.

I tend to get these if I change angle slightly while turning either as I shape the blank or move my hands. Things that help me is to “ride the bevel” of my Skew more as I get close to the final shape and move my body instead of my hands/arms as I move across the blank.

If you are using carbide (which I have less experience at) try more of a cutting angle and not a scraping angle. Some resin does not like carbide as well so lighter, angles cuts.


Sent from my iPhone using Penturners.org mobile app
 

More4dan

Member
Joined
Mar 17, 2016
Messages
1,485
Location
Katy, TX
Also try to keep the cutting edge at or above the centerline of blank. This happens more with inlace acrylister vs AA. You can clean the blank well and fill the pit with a drop of medium to thick CA and let it dry. Skim with A sharp tool and re-sand and polish.

Danny


Sent from my iPad using Penturners.org mobile app
 

TonyL

Member
Joined
Mar 9, 2014
Messages
6,759
Location
Alpharetta, GA 30004
You'll get past that. I think it's a matter of touch. Use sharp quality tools. Slow and light pressure as you get to the end stage to turning the blank.
What he said ^
Ed of Exotics has an excellent video on turning acrylics on YouTube
 

Dr_N

Member
Joined
Jan 19, 2018
Messages
175
Location
St. Charles, MO
In my very limited experience, all of the above advice is spot on. The type of acrylic and tool used may be helpful for more precise advice. As many have said, when I get those pits it is typically too aggressive of a cut...I'm not very patient and want to see the finished pen too quickly!
 

Curly

Member
Joined
Nov 20, 2010
Messages
3,540
Location
Saskatoon SK., Canada.
If when you turn you hear what sounds like ripping and getting covered in tiny chips or flakes instead of long ribbons of plastic you are too aggressive, using dull tools, presenting the tool wrong and stuff that isn't coming to mind. :rolleyes: When you get it right the barrel will be smooth requiring very little sanding and the shavings will be like fine ribbons or hair. Practice with inexpensive blanks turning, them to nothing, that you don't care to make a pen from.
 

MRDucks2

Member
Joined
Jul 17, 2017
Messages
1,844
Location
Franklin, IN
Only living across Indy from WoodTurningz I started out on Inlace Acrylester. Glad I had a face shield on. First few I thought ripping the corners off in a rain of shrapnel was the way it was supposed to work. Then watched some of Captain Eddie’s videos on sharpening, read some things on here about turning IA and now love it, normally turning the entire thing from square to finished with a sharp Skew. Though I can now use carbide to finish (just because the guys at WoodTurningz said not to try using carbide on it). Beautiful shine.


Sent from my iPhone using Penturners.org mobile app
 

Herb G

Member
Joined
Nov 13, 2015
Messages
1,453
Location
Southern Maryland
Some great advice has already been given, but nobody has mentioned that sometimes acrylics are just crappy to begin with.
Either they had too much catalyst added when they were poured, or they set up too fast, or it was too cold to set properly or, or, or.

I turned some AA blanks & they just delaminated all by themselves.
One was sitting on my desk when it went *POP* and split away like peeling an onion. I had turned it a few days before, so it had been sitting for a few days when it did it.

I still have no idea why it did it, it just did it all by its self.
 

turncrazy43

Member
Joined
Apr 22, 2012
Messages
1,041
Location
Marietta, GA
Have turned both of these blanks (7/8 from PSI) and the 3/4" from Exotics. Never saw air bubbles in either one. They did not seem brittle at all. I agree with others the problem may be need for sharp tools and small cuts.
Turncrzy43
 
Top Bottom