Roughing out acrylics

[crabcreekind]

I have turned a couple acrylic pens now and turning the pen takes me an hour most of time is roughing the pen blank out, i use a gouge to rough it out and doesnt work very well but it works great when i have the blank round. So i am wondering if i am doing something wrong.

 

[soligen]

I do basically a planing cut with a gouge. Scary sharp helps, but depending what type of material (ie how brittle) I think better safe than sorry so go slow. I can rough alumilite faster than PR, but the danger in goign faster on the easier kind of blank is that when I switch back it is hard to slow back down, then the PR pits and/or cracks.

You _could_ buy round blanks, or see if you can make a jig to knock the corners off on the band saw.

 

[Seer]

Round off the corners with a sander helps prevent chipout. I use a carbide tool I made to do acrylics works like a dream.

 

[alphageek]

James,

I wouldn't say 'wrong', but I can round an acrylic just about as fast as wood...
A couple of questions:
1) what kind of gouge?
2) what speed on the lathe?
3) what kind of acrylic (there is several)

and can you tell a bit more about "not working well" - what is happening.
Can you maybe have someone snap a picture while you are roughing? That may help diagnose a bit too.

 

[Ruby pen turning]

You probably are not doing anything wrong. A square acrylic blank will throw chips flying everywhere. Maybe you need to be more forceful but not to forceful or you will start taking chunk out.
I have found that holding the gouge in a way with your hand up against the tool rest that will allow you to put good pressure on the blank but not let the gouge dig in on the softer spots. Also , if you have a carbide insert type of gouge, you can cant or angle it slightly and standing off to the side pull it toward you. At least I have found this to work very well for me.

 

[ed4copies]

James,

Watch the first few minutes of this:
http://www.youtube.com/watch?v=xikciU16Fts

It might help your technique.

 

[Lenny]

SHARP tools are a must! If your tool is really sharp you should get nice ribbons coming off the blank.

 

[Ruby pen turning]

SHARP tools are a must! If your tool is really sharp you should get nice ribbons coming off the blank.

He is talking about getting it to the point of being round. then he said all goes well.

 

[crabcreekind]

I think it is a 1/2 spindle gouge and about 900-1200 rpm on the lathe. acrylic is AA or whatever you get from PSI.

 

[ed4copies]

I think it is a 1/2 spindle gouge and about 900-1200 rpm on the lathe. acrylic is AA or whatever you get from PSI.

It would be good to turn up your speed, if it does not make you uncomfortable.

Removing the "square corners" with a belt sander is also a great suggestion.

 

[crabcreekind]

What speed should i turn it up to?

 

[ed4copies]

Most importantly, you have to be comfortable---if it looks like it's moving FAST, you will make mistakes.

I turn at 4200rpm--there's no such thing as too fast--but I worked up to that---stop when you think, "wow, that's cranking!!" (In two weeks or less, you will turn it up)

 

[alphageek]

What speed should i turn it up to?

Since I asked the questions... I'll give you my views.

1) Speed - I agree with Ed.. My lathes top belt is 3900 rpm - I turn pens at that! Its not for everyone, but I will tell you that turning at under 1800 rpm with acrylics gives me fits.
2) AA is nice, but I suggest you try one of the new turner friendlier PR blanks out there.
3) Gouge... I'll assume its really sharp.. if not - make it sharper! Personally if I use a gouge, the bigger and "firmer" it is, the better for me.

(all my opinions.. try what you want.. Be VERY careful when you try new things, but then see what gets you further, faster, better!)

 

[crabcreekind]

ok ill turn the speed up but my lathe maxes at 3200rpm thanks for the advice

 

[ed4copies]

MAKE SURE YOU WEAR EYE PROTECTION!!!

Face shield is even better, but the little pieces of plastic can damage your sight!!!

 

[crabcreekind]

Problem solved, Dont worry ed i have a full face shield

 

[lorbay]

SHARP tools are a must! If your tool is really sharp you should get nice ribbons coming off the blank.

Of course this is after you get it round.

Lin.

 

[ed4copies]

Problem solved, Dont worry ed i have a full face shield

Yeah, I HAVE one too!! It only protects you if you WEAR it--I know I didn't when I was younger and invincible--just trying to convince you to be smart!!

(No offense meant--just emphasis!!)

 

[crabcreekind]

I totally know what you mean, I were eye protection for pretty much everything. And i got a respirator for doing ca finishes.

 

[azamiryou]

Personally if I use a gouge, the bigger and "firmer" it is, the better for me.

+1 I bought a small gouge for pens, thinking it was more "pen-sized". It gathers dust except for small beads and coves (very rare), the big gouge is much better in general for even the smallest projects.

 

[JMT]

Third the belt sander process.

 

[Rob73]

I've been taking acrylics and rounding them down pretty far with my belt sander. Then I take them to the lathe and use a round nose scraper or the new round carbide tool I got a couple weeks ago. Been working very well for me so far, except on some acrylic acetate blanks I got from woodenturnigz. They look nice but man alive I can't stop these things from blowing out no matter what I do. I got so tired of it I decided to not use them on pens to just use them on bookmarks and they still blow out like crazy.

 

[ed4copies]

Hey Rob!!

I'll trade you, a couple of mine for a couple of theirs that are giving you difficulties!!

(I can't answer questions unless I know what is "out there"--PM me if interested, please!)

 

[sfallsguy]

My 2cents worth, as one not as experienced as most of the others.....just finished an acrylic - some are harder than others, and this one was a beaut! Acrylester(?) is worse. But to the point, round off the corners. I have a jig to use with the band saw that will do that. It makes it much easier. And scary sharp is the rest of the story.

This will help, and good luck. Just perservere.


John

 

[le_skieur]

SHARP tools are a must! If your tool is really sharp you should get nice ribbons coming off the blank.

Lenny is right and I will say with the good angle at 3000rpm

 

[Chasper]

I've turned over 100 acrylic pens in the last week, only 15 were Sierras so that is 185 half blanks. That is at least 50% more that I typically turn in a week, but not too unusual. One of them broke while turning. I suspect that I cracked it while drilling and I didn't notice until a big chunk flew off.

Every one of them was rounded off with a round nose scraper, including a lot of Inlace Acrylester. Most of them were turned down to near finished with the scraper, then finished off with a skew, quite a few of them were finished entirely with the scraper. On Inlace Acrylester I pick up the skew much sooner than on any other material.

Sharp tools and high speed are needed, but most important is technique. I turned a few thousand of them before I stopped tearing them up. Practice, practice, practice.

 

[crabcreekind]

Chasper: i have turned up the speed on my lathe and my tools are sharp, I did this and it came out perfect on my first try with a gouge i just touched it up with a skew.