Was this my fault?

[LK&T]

So, this happened. My first go at turning a resin blank and I blow it up I wasn't exactly going at it full blast, but I wasn't messing around either. I was using a roughing gouge. You can easily see that it fractured along a line of "stuff" in the blank. Definitely made for a weak point in the blank. For the record, I did successfully turn three more resin blanks (same patterning) after this one blew up.

Questions: Did I do this by being too aggressive wasting away material? Are some blanks just duds because of the "stuff" that makes them pretty/cool/ugly? Obviously I should read up a bit on turning resin; it sure don't act like wood.

 

[EricRN]

Welcome to the club. This happens to us all at one point or another. Possible causes--Could be a blank defect. More likely, you were too aggressive with a tool that was too dull. Or you had a glue failure.

 

[LK&T]

Welcome to the club. This happens to us all at one point or another. Possible causes--Could be a blank defect. More likely, you were too aggressive with a tool that was too dull. Or you had a glue failure.

Thanks Eric. All three sound plausible, or a combination thereof. Unless some blanks are just gonna be duds, I think I got a little too aggressive with a blank that had a weak spot. My tool sharpness would not be an issue; I had just sharpened.

 

[Paul in OKC]

If turning between centers, be careful not to push too hard with the center. Could be causing the tube to spread slightly adding to the issue.

 

[socdad]

I try to turn my failures (more than I care to admit to ...) into opportunities. Turn the broken part down to the brass, find a scrap piece of acrylic (I like black), drill a hole, epoxie it on the tube & have at it ...

 

[ccccchunt]

I have had this happen because of heat buildup during drilling. Small invisible crack becomes readily apparent while turning.

 

[bsshog40]

Not sure if it's the pics but it almost looks like a spot with no glue! I always drop glue into each end of the blank and then coat the tube with glue and then twist it as I insert the tube.

 

[Kenny Durrant]

Just to add to the suggestions when roughing out the blank start from the ends and work toward the center. That way any pressure your putting on the blank has some backing to it rather than pushing it to the edge. I'm not saying that was the problem but it could help keep it from happening.

 

[leehljp]

Not sure if that is a streak of CA on the end on the brass or if you put too much pressure on the tube with the live center and causing the tube to maybe crimp, similar to what Paul in OKC said. That will rupture/fracture the blank enough for it to have a blowout.

Unless one is very experienced with a roughing gouge, I personally don't see the need for one on pen blanks. Some people do, but pen blanks are small enough that such large tools are a bit of overkill and can quickly become too aggressive.

If you did not put too much pressure with the live center/tail stock, then the problem is very likely to be too aggressive. On pen blanks, patience and feel of the blank become your friend. The difference between a blow out and finely turned blank is often just taking one minute longer.

 

[Roly]

I use a 8mm bowl gouge with a light touch to round the blanks and then immediately go to a skew. It has stopped the blow outs I used to get on a regular basis.

 

[SpiritRider]

I turn mine like that in to beads in my spare time and sell them for a few dollars

 

[LK&T]

If turning between centers, be careful not to push too hard with the center. Could be causing the tube to spread slightly adding to the issue.

Good advice. I start with the centers barely snug and tighten them as I turn until I can take a decent cut without stopping the blank.

 

[LK&T]

Not sure if it's the pics but it almost looks like a spot with no glue! I always drop glue into each end of the blank and then coat the tube with glue and then twist it as I insert the tube.

That, Bobby, is an astute observation. I think that may be part of the problem!

 

[LK&T]

Not sure if that is a streak of CA on the end on the brass or if you put too much pressure on the tube with the live center and causing the tube to maybe crimp, similar to what Paul in OKC said. That will rupture/fracture the blank enough for it to have a blowout.

Unless one is very experienced with a roughing gouge, I personally don't see the need for one on pen blanks. Some people do, but pen blanks are small enough that such large tools are a bit of overkill and can quickly become too aggressive.

If you did not put too much pressure with the live center/tail stock, then the problem is very likely to be too aggressive. On pen blanks, patience and feel of the blank become your friend. The difference between a blow out and finely turned blank is often just taking one minute longer.

All excellent advice Sir, and thank you. The "streak" on the end of the tube is chips(?) from the blank, not glue. I'm pretty careful with the pressure on the centers, starting loose and tightening as I go until I can take a good cut without stalling the blank. As for the roughing gouge, it seems controllable to me. What tool do you recommend when turning the blank from square/round to close to final size? After the RG, I'm using a skew with scraping cuts to get the final dimension.

 

[PreacherJon]

If you find the piece that popped out... you can CA it back into place... but yea... happens to everyone.... I find I'm to aggressive or... to lazy to sharpen tool... with acrylics... they have got to be sharp.

 

[LK&T]

Obviously I'm doing something wrong. I seem to be right on the edge of whatever it is, because I've turned three acrylic/resin/whatever it is blanks with no problem. Then, this happens. D*$N, that was an expensive blank.....

 

[leehljp]

All of the "white" and ring scratches to me indicate that you are being too aggressive and using more of a dull tool than you know. A skew, as JohnT and others say would eliminate that. I am not good with the skew, but use a "slightly" rounded scraper, and still get very very smooth cuts on acrylic and wood, even if roughing it down. "Rough" on already round blanks is indicative of either dull tools or too aggressive, or both.

Off Topic but relevant: I used to be good at basic woodworking and making things, but spent very little time on the finish. And I saw / see much of this mindset among some peers. We easily spend 40 hours making something and 2 - 3 hours on the finish. It took me a while to learn that I needed to spend almost as much time on the finishing as the making. That improved my projects' look and value by multiple fold.

That example relates to pen making in the "sharpening" aspect - more that one might think. One can tell the sharpness of a tool by looking at the turnings. Sharp tools are as important as the lathe. It is easy to understand the desire to do a pen, and another, and another, but at some point, the use of the turning tool catches up with us. I personally "sharpen" my tools about once every 30 to 40 pens, but I swipe it across a .3micron sand paper 3 to 4 times per pen (similar to honing). About every 3 to 4 pens, I swipe the edge of the tool two or three times across 3 or 4 micron SP (forget which exactly) then 1 micron and then .3 micron sandpaper. Tools stay sharp this way.

This is my opinion only: new pen turners should stay away from roughing gouges. They are made to rough in bowl blanks and are too aggressive on something as small as a pen blank - unless one is already an expert/professional in the use of a roughing gouge. In the case of being an expert, they generally can finely turn a pen with a roughing gouge. But for New Turners, it can easily be deceptive, kinda like giving a Porsche to a new driver!

If one is not adapt at sharpening, or does not have the proper tools for sharpening, carbide insert tools is recommended. They do not have to be sharpened (but can be). When streaks begin to show, simply turn the insert. And I would suggest searching on this forum for "inserts". Some, from my reading of different threads, seem to be more finely sharpened than others. They tend to cost More, but sharpness is worth it.

 

[PreacherJon]

Obviously I'm doing something wrong. I seem to be right on the edge of whatever it is, because I've turned three acrylic/resin/whatever it is blanks with no problem. Then, this happens. D*$N, that was an expensive blank.....

View attachment 292981

Try saving that... put layers of CA over that broken end. After all that is was CA is... a liquid Acrylic.