Blank blow-outs

ryanbp01 · Post by **ryanbp01** » Mon Mar 03, 2008 11:16 am

Well, for the first time I had something occur I have never had happen before: I turned ten separate pen blanks yesterday using hard maple and every one of them fractured on the lathe. I was able to save the pen tubes. I have used the same glue (gap-filling CA) I have used previously with no results. Does anyone out there have a possible solution/remedy to this?

BPR

Ed in Tampa · Post by **Ed in Tampa** » Mon Mar 03, 2008 11:51 am

ryanbp01 wrote:Well, for the first time I had something occur I have never had happen before: I turned ten separate pen blanks yesterday using hard maple and every one of them fractured on the lathe. I was able to save the pen tubes. I have used the same glue (gap-filling CA) I have used previously with no results. Does anyone out there have a possible solution/remedy to this?

BPR

Ryan
A few things I can't think that might cause this problem.

First is the drill your using getting old? It is possible the bit is worn and diameter is reduced and the hole is slightly too small? Force in a pen tube and you have enough pressure to split the wood when it gets thin enough.

Second how is the sharpness of your tools. If they are getting dull they could be sitting up tension that is causing the wood to crack with it gets thin enough. There is quite a bit of heat generated in lath turning with dull tools, this heat can heat up the pen tube making it expand which may crack the wood.

As parting idea could the wood itself be at fault? Some wood grows under unusal stress and when the wood gets thin enough these stresses causes the wood to split. I have seen this ripping wood where a thin ripped piece will actually curl and split while being ripped off a much thicker piece.
Ed

ryanbp01 · Post by **ryanbp01** » Mon Mar 03, 2008 12:30 pm

The bit hasn't been used often enough to merit sharpening. The tools have all been sharpened. As far as the wood is concerned, there didn't seem to be any effects that I observed. I was turning all of these blanks on the slow setting. It was down towards the end of the turning process when things came apart. It was irritating, to say the least.

BPR

ldh · Post by **ldh** » Mon Mar 03, 2008 12:32 pm

ryanbp01 wrote:Well, for the first time I had something occur I have never had happen before: I turned ten separate pen blanks yesterday using hard maple and every one of them fractured on the lathe. I was able to save the pen tubes. I have used the same glue (gap-filling CA) I have used previously with no results. Does anyone out there have a possible solution/remedy to this?

BPR

Ryan,
I use quick set epoxy. I have found that it works much better for me than
CA. Using a bit lighter touch with your lathe tools may help also.
ldh

mtobey · Post by **mtobey** » Mon Mar 03, 2008 1:31 pm

Another "flexible" alternative, Gorilla Glue never gets quite hard, but is hard enough. It will provide an undetectable cushioning between blank and tube. I might note that I have had good luck at 1500 rpm with split or brad bit drills. Slow will gouge sometimes.

paulmcohen · Post by **paulmcohen** » Mon Mar 03, 2008 2:35 pm

ryanbp01 wrote:I have used the same glue (gap-filling CA) I have used previously with no results. Does anyone out there have a possible solution/remedy to this?

BPR

Is the CA old, my experience is the stuff has a relatively short shelf life once opened. I keep unopened bottles in the fridge but once opened I was told you don't want to do that.

If the CA bond is solid I can't imagine being able to reuse a tube because every surface would be covered with wood. I have had a tube separate from the wood (tube spins but wood does not) but that was because of bad glue.

paul269 · Post by **paul269** » Mon Mar 03, 2008 5:10 pm

Check the warble of the drill bit. Not all drill bits are made the same. If there is a noticeable warble then your hole is too big creating a space between the wood and the pen tube.

I use CA in the course of my employment and when I make pens. At work I buy CA by the quart. When not in use it is in the refrigerator. I have no problems taking it in and out of the fridge. Just let it return to room temperature before using.

paulmcohen · Post by **paulmcohen** » Mon Mar 03, 2008 7:52 pm

paul269 wrote:I have no problems taking it in and out of the fridge. Just let it return to room temperature before using.

I may have misunderstood the fridge issue, thinking about it room temperature must be the key.

charlese · Post by **charlese** » Tue Mar 04, 2008 12:05 am

Having no experience with pens, I can picture turning small, hollowed out maple sticks. My guess is that your lathe tools need to be sharpened. Have you used maple previously? The fibers are very hard, also brittle and subject to fracture when struck at the right angle with a dull tool. A sharp one will have a greater tendency to slice, rather than rip.

charlese · Post by **charlese** » Tue Mar 04, 2008 12:05 am

Having no experience with pens, I can picture turning small, hollowed out maple sticks. My guess is that your lathe tools need to be sharpened. Have you used maple previously? The fibers are very hard, also brittle and subject to fracture when struck at the right angle with a dull tool. A sharp one will have a greater tendency to slice, rather than rip.