cracked edges

[sigge]

Hi everyone...

I am fairly new to pen turning but have done a few good ones lately... But i seem to have a recurring problem. I have mostly turned acryllics lately and onall the pens I seem to get cracks at the edges near the bushings on the finished product. Before assembling the pen so it is not due to exessive force on the drill press. The crack/s can be anything from 2-3 mm up to a cm.

Any ideas what I am doing wrong?

 

[mickr]

are your tools sharp? How hard are you pushing on the blank? The ends are usually the thinest..take it slow & keep the tools sharp

 

[tseger]

Did you make sure you cleaned ALL the dried ca from the ends of the tubes? Sometimes this residue left inside the tube ca cause splitting during assembly.

 

[David M]

is the blank cut flush with the brass tube and the bushing not tightened up on just the blank. to much puessure ?

 

[sigge]

Hi everyone...

The tools are brand new so they are sharp. MudPuppie, the blank is cut flush with the tube. I square the ends before i start turning. But how do you mean not tightened up on just the blank? How do you mean? I thought that maybe i tightenened the knob on the mandrel to much but i tried looser and still i got a small crack.

Regards
Johan

 

[el_d]

Hi Johan, I have had this problem happen to me before and my problem was that when turning I cut from the center of the blank out towards the edges of the blank. I guess the cuting force broke the acrylic as I moved towards the thinner/weaker ends of the blank. Try working from the ends towards the center and see if it stops the chipping.

 

[mickr]

Hi everyone...

The tools are brand new so they are sharp. MudPuppie, the blank is cut flush with the tube. I square the ends before i start turning. But how do you mean not tightened up on just the blank? How do you mean? I thought that maybe i tightenened the knob on the mandrel to much but i tried looser and still i got a small crack.

Regards
Johan

Just because the tools are new, doesn't mean they are sharp!!! Not tightened on the blank question: Does the material extend past the brass tube? even a little? then the bushing is pushing the material & can crack

 

[miket812]

Make sure that you are not applying too much pressure when you use your pen mill and that it is sharp. The pen mill can be your friend or your enemy. That is why a lot of people don't use them. They can cause chipping that can not be seen until it is turned down. Just my .02. Hope this helps.
Mike H.

 

[snyiper]

Ed told me the secret was to round over the ends first to knock off the edges....dang guess the cat is out the bag now!!!

 

[programmergeek]

New tools are usally not really that sharp and have a very course grind. get a little diamond hone also to just touch them up by hand.

Is the cracking when you are done and assembled or on the lathe?

 

[THarvey]

Hi everyone...

The tools are brand new so they are sharp. MudPuppie, the blank is cut flush with the tube. I square the ends before i start turning. But how do you mean not tightened up on just the blank? How do you mean? I thought that maybe i tightenened the knob on the mandrel to much but i tried looser and still i got a small crack.

Regards
Johan

New tools rarely arrive sharp. Most tools need to be honed. Acrylics are more sensitive to sharp tools. Wood is a little more forgiving.

Are you seeing the cracks more on one end of the blank? Are they toward the head or the tail of the lathe? Or, along the center bushing? Is it possible that your mandrel is slightly bent?

 

[sigge]

Hi everyone... Thank you for all the help. Most of the ideas you had I tried on a tru-stone today and I got even more cracks... I will sharpen my tools and see if that helps... Also might be the pen mill that makes it. The problem occurs before assemply. On the lathe.