Thread: Aussie Acrylic Blanks - Blowout

Check to see if you have a good enough bond to the tube? what glue are you using and how are you applying it?? what chisel are you using? more info will help us give a better answer.

Cheers
Tony.

When you say you turn it slow do you mean the speed of the lathe, or the length of time to get it to size. Do you hold the chisel to loosely or grip on like no tomorrow. Your grip determines your tool control and also how light and heavy you make cuts

Need more detail- what glue for tube, what was fit on tube like, what tool are you using, what approach to blank, what speed of lathe, plus what ever you can think of that you did.

ps I doubt it was the blank

Try turning from the ends in.
David

I have the tools that came with the lathe. They are not branded and probably Arnt the best. I'm using gorilla glue and I leave it set for two hours like the bottle says. The lathe is on its top speed and I cut into the blanking slowly to reduce the heat.

Make sure your tools are razor sharp or invest in a Woodchuck Pro for turning. It seems it might be cheap, jagged or blunt tools catching on the blank. That will do it every time. I have not tried Gorilla glue so can't comment other than to say that the tube must be covered in the glue so every part of the blank is glued. Someone will comment on the lathe speed - maybe it should be a bit slower.

Acrilic to brass, the only glue I would trust is epoxy...others may like CA.

Did you scrub the tubes.

OH...if you get over zelous during drilling you may cause micro fracturtes that open up.

cheers

Awesome. Thanks for that I will try a bit of everything.

Though I haven't been pen turning for very long, I might offer my thoughts. Barring any gluing or drilling problems, my novice experience might help. I've done a few of these and yes I have had some problems with them, big blowout drilling one, catching with a chip-out down to the tube.

I've found the Australian Made PR Blanks are very hard/brittle compared to acrylic blanks. They are very unforgiving of catches. Having said that, once you get them to round, using a skew produces lovely ribbons and they turn very well.

When drilling I use my lowest speed on the drill press and only drill about 5mm per plunge. I use brad point drills as they seem to cut better into PR,acrylic and wood. I also think that the side blades/wings reduce blowout when you drill through the bottom. I now check to see if the drill bit is too hot (can't touch it without burning myself) every so often. If it is I'll wait a while for it to cool before continuing. I haven't tried spraying water on the bit when doing acrylics and PR.

When turning I find I need to have a light touch and only take small amounts of material off each pass. They take a lot more time to get to shape than wood, but finishing is faster (CA finish on wood) so it balances out. I've found I need to hone the edge of my tools a few times during turning. Just a light going over with a diamond hone.

I use a medium turning speed on all PR/acrylics and haven't had any problems with heat. Lately, when I get close to the bushing size and final shape I use an "old" skew as a scraper taking off slivers of material (the skew has a curved edge instead of straight to minimise catches). This way I can get right to the bushing and fine tune the shape.

You could also try "cheating" by doing the final shaping with coarse wet and dry (240 or 320) wet sanding. Shaping this way takes a bit longer but you shouldn't have a blowout. You can then wet sand using 400, 600, etc to remove the coarse sanding marks. I usually wet sand starting with 400, 600, 800, 1000 and progressing through the micromesh, brasso, polish for all my pens.

These blanks can be a pain to turn but always produce beautiful results.

Well, that's my 2c worth. Hope it helps

Very well put Switch, pretty much covers range of procedures that can be used ,and probably should be cheers ~ John

The other thing to think about is that, the character of acrillics can vary with so many factors.

Just a change in colour can change the texture of the material and the way it cuts.

We also have to be mindfull of the way that particular acrillic has been cast.

Very few blanks are homogenous and consistent throughout.

Anything with a crystaline apperance, swirled, contains tape, chips or other foreign material will be structrualy compromised in comparison to a smooth single colour.

Also remember anybody casting acrillic in this country will be doing so on a relativly small scale and wont have access to the large scale industrial methods used overseas....and will be trying to achieve different things.

cheers

Hi Shoey,
the resin used in making the Aussie blanks is far softer than the steel used in chisels. If the chisel is sharp it will cut the resin . If the chisel is not sharp and pressure is applied to the blank something has to give and the usual outcome is a chunk of resin on the floor. There can certainly be other contributing factors as other people have outlined like a gap between the tube and the blank or fracturing from the drilling process. I think using polyurethane glue could be an advantage here.
As a guide when I was using HSS chisel I'd give them a touch up half way through turning a barrel to keep the edge sharp. Now I use a tungsten tipped chisel from start to finish and can't speak more highly about them.
I've been turning between centres from bushes I bought from Fred here on the forums and love it , it helps to reduce vibrations and produces much better results than I was getting using a pen mandrel. The bushes are made beautifully made from stainless steel and are a delight to use .
If you would like any more of my advice please PM me.

Regards Bruce

Wood N Workshop