Help and advice

[wwillimon]

I am new to the site and pretty new to pen turning. Just started trying some acrylics and I need help. Two of the blanks I cut fine but on the third one was a complete disaster. I am placing a photo of this blank so you can see. I have wondered if maybe got a bad blank.

 

[hewunch]

Hey! I used to live in Ware Shoals. Looks like you may have been a bit aggressive with your turning. Also, not all acrylics are the same. Some are more brittle than others. Sharp tools, light cuts. If you have more issues check out Bruce at the Pathway House there in Greenwood. He is a wealth of knowledge.

 

[wwillimon]

Hey! I used to live in Ware Shoals. Looks like you may have been a bit aggressive with your turning. Also, not all acrylics are the same. Some are more brittle than others. Sharp tools, light cuts. If you have more issues check out Bruce at the Pathway House there in Greenwood. He is a wealth of knowledge.

Thanks. Does it look like I need to turn up rpms. Cutting only at about 300. Waiting on live center to turn up to about 500

 

[KenB259]

Thanks. Does it look like I need to turn up rpms. Cutting only at about 300. Waiting on live center to turn up to about 500

That is way to slow, you need to be turning as fast as your lathe can go, probably 3000 - 3500 rpm.

 

[egnald]

Greetings from Nebraska.

KenB259 is spot on, I usually turn my blanks as fast as my lathe will go typically 3600 RPM if one can believe the tachometer on the lathe. Also as already noted by hewnch, not all "Acrylics" i.e. Plastic Blanks are the same. Some are true Acrylic, but some are Polyester, Urethane, epoxy, etc. and they all have some unique characteristics, the most pertinent of which is their level of brittleness. The worst in my opinion is Inlace Acrylester as it is very brittle and "chippy" when it is being turned.

Try the suggestions, speed up your lathe, make sure you have a very sharp tool, and take light passes. I have had the best success using a cutter with a negative rake grind. Good luck finding the right combination as the Plastics can result in very beautiful pens.

Regards, Dave

PS A final word of caution, for plastics that are translucent, you will have a much more satisfying result if you paint the inside of the blank after drilling so that the brass tube doesn't show through - unless that is a look that you are going for of course.

 

[howsitwork]

The advice above should sort it but you DO need to use a revolving tail centre or you're in melting territory which is not good. Unless I'm reading your reply wrong of course

 

[tomtedesco]

That is way to slow, you need to be turning as fast as your lathe can go, probably 3000 - 3500 rpm.

Good advice here. It can get a bit scary at first but the speed in this case is your friend, good luck.

 

[qquake]

Thanks. Does it look like I need to turn up rpms. Cutting only at about 300. Waiting on live center to turn up to about 500

I turn everything, acrylic and wood, at 2000rpm.

 

[wwillimon]

The advice above should sort it but you DO need to use a revolving tail centre or you're in melting territory which is not good. Unless I'm reading your reply wrong of course

I just have an old sears lath and had a hard time finding a live center that would match up. It has no morse taper tail stock. Finally found one. I do this as a hobby and do appriciate all of the advice. Was a machinist for years and retired. Couldn't hardley afford a metal lath. Just enjoy making pens, tops,and yo-yo's. The one piece that I made a mess on was the Acrylester.

 

[qquake]

Acrylester is one of the more difficult acrylics to turn. It's very brittle. I've ruined quite a few of them. I used to avoid them at all costs, until I started using a carbide chisel and shearing cuts. Now I don't mind turning them.

 

[qquake]

This is acrylester. The results are worth the extra effort.