Blanks Blowing Out

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Mike_in_CA

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I'm new, this is my first post. I should've realized there'd be a forum devoted to pen turning. I looked back a little to see if this question had recently been addressed, but didn't see it.

I've turned about 30 to 35 pens and recently I've had some bad luck, or poor technique. Just before final turning, some blanks are blowing out. The piece comes off and I can clearly see the tube. I thought I was succesful changing from CA to Polyurithane. I've glued up blanks both wet and dry. I insert the sanded tube from both ends to make sure the glue is distributed. Although I'm never confident that when the tube is shoved to the other end of the blank, the glue has rubbed off? What should I check, or change in my proceedure?

It's probably old question to many experienced turners. Any comments and ideas are welcomed.
Thanks,
 
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Mikey

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If the blank is blowing off, ie. cracking apart, it's not the glue you are using. The only times I ever have blow outs are when I am trying to take too big a cut, or when I am forcing the tool to do something it wasn't designed to do. Are your tools sharp?

Last blowout I had was caused by the fingernail gouge when I tried to take too much out of a cut. I cracked a nice burl.[:(]
 

Rifleman1776

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You're the only person that has ever happened to. [:p][;)]
Seriously (which we rarely achieve here [:D] ) blowing out blanks is a curse of the avocation. It happens and for a variety of reasons. Some woods, particularly hightly figured stuff, is very prone to flying apart as it just doesn't have the grain structure of non-figured or burled woods. I have some big leaf maple burl a/k/a BLMB that just wouldn't turn without self-destruction until I had it stabilized. Now it makes beautiful turnings and holds together. Sometimes technique can be the culprit. Yesterday I ruined a blank of cast poly-resin material because of a lapse in focus and allowed the point of a skew to hit the turning. As you experiences, sometimes just the type of glue you use makes a difference. It happens, with experience you will reduce these dissapointments. When you have stopped blowing blanks, you have stopped turning. Good luck.
 

Efletche

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I used to get a lot of blow outs when I first started as well. My mistake was I was taking too much off with each pass and using too much pressure to boot. I also stop periodically when doing burls and antler to make sure I am not tearing too much out of the remaining material. If I am, I fill to spots with CA and continue.
 

alamocdc

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[:0][:0][:0][:0] Frank used an acronymn!







Okay, I'm back, I had to run outside and see if the sky was falling. [}:)][:p] First, Mike, welcome to the group!!! Secondly, see above. Both Mikey an Frank gave you some good advice. To date all of my blowouts have been my fault. Either by being too aggressive, or trying to use a wood that needed a little assistance in strength w/o giving it, i.e. stabilization.
 

gerryr

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Like everyone else, I've also experienced blowouts and they can be pretty disheartening when you getting started(or any time for that matter). I used to do all my turning with a gouge. I have since learned, more or less, to use a skew and that has made a big difference. Now I only use a gouge for rough turning to mostly round. I recently bought a heavy duty round nose scraper for antler and gave it a try on some burl, it worked great. My gouges are getting less and less use on pens and I'm having fewer wood failures.
 

ctEaglesc

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Just a SWAG but you said you"sanded" your tubes.
I take that to mean a cursory pass with a piece of sandpaper to brighten them up.
The purpose of the "sanding" as you put it is to creat more rlue surfaces to adhere to.
I use only CA on my blanks and glue ups and I get my dhare of catches.
I suggest you SCUFF the tubes more aggressively.
I use a long screw driver and my bench sander and watch them BOUNCE and vibrate.It takes all about ten seconds for both tubes.
When finished the surface is bright shiney and ROUGH.
The other thing I suggest is you seal the INSIDE of your blanks with CA and redrill prior to gluing.
Even with the intricate glue ups I Do I don't get many blow outs and can't remember the last time I had one(not including my truck)
 

JimGo

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Yup, you're certainly not alone. Welcome to IAP, and to the group of those frustrated by blow-outs!! I've reduced the percentage of blow-outs by doing a few things:
1) Make sure the tube is scuffed before you coat it with glue.
2) Clean the inside of the hole and the tube with DNA before you coat either with glue. This can be especially important in resinous woods like any of the Rosewoods (e.g. Cocobolo, Rosewood, African Blackwood), Lignum Vitae, Pine, and Olive. Depending on the glue you use, it may not want to bond too well with any resinous spots
3) Make sure you get good glue coverage (sounds like you're already doing this); if a section of 1/32" thick wood isn't well bonded to the tube but the adjoining section is, the poorly bonded section won't survive the same abuse that the well-bonded section will.
4) Make sure your tools are sharp, especially at this stage. I have a tendency to try to turn at least a whole pen without sharpening, and I'm trying to overcome that now. I find that if I rough-shape, then go back and re-sharpen before I make my final cuts, I get cleaner cuts and fewer blow-outs (except the handle is bumped by my stomach as I move around in front of the lathe and digs the skew into the blank - not that this has ever happened to ME).

Good luck!
 

ldimick

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The two biggest things I did that DRASTICALLY reduced my blow outs were:

1. Turning with a skew so you are actually slicing off the wood instead of ripping it off with a gouge.
2. Sharpening the tools with a diamond hone at least twice per pen.

The wood will often tell you when you are getting into dangerous waters. Watch for the tell tale chattering.
 

Mike_in_CA

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Many thanks to all who replied. Some good suggestions. For clarification by "sanding" I mean scuffing to remove tarnish & for glue to adhear to.

Some points of tool technique has me curious. It sounds like most of you use a skew to turn most of the blank. I use a roughing gouge to get it round, then a smaller spindle gouge to shape down, then a skew to get it flat or smooth. I've never thought of doing more with a skew. humm? I'm a little skidish of the skew, I'll have to practice.

I'll have to reconsider my tool choice & technique. Do most use CA? Does anyone use polyurithane? BTW- all the blow-puts have been with stabilized burls.
Thanks Again.
 

JimGo

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Mike,
If all you're doing is removing the tarnish, then you may not be scuffing the blanks enough. I use coarse sanding blocks I got from Harbor Freight, and rub the tubes across that until they have lots of scratches.

I use Gorilla Glue (a form of poly glue) when I know I'll have a few days in a row in my shop (and thus the time to allow the blanks to dry). I like it better than CA for tube gluing, especially with my "inexpensive" (i.e. cheap and not all that accurate) drill press that has a fair amount of run-out. The poly glue expands to fill any gap between the blank and the tube, whereas CA won't really do that for you. But, if you're careful with how you drill, CA does a fine job.

Yep, I turn my wood pens from start to finish with the same tool, a skew. I use a round-nose scraper on my non-wood pens.

Good luck!
 

gerryr

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If you're blowing out stabilized burl, my guess is that you're trying to cut way too much at a time. A skew works best on wood with relatively straight grain. I've tried a skew on burl, but my scraper is easier to use on burl that I don't even bother with it on burl now. I've used CA, epoxy and polyurethane to glue the tubes. If I'm not in a hurry, I generally use polyurethane since it's more flexible. If I'm in a hurry and want to start turning right away, I use CA.
 

Dario

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Mike,

I use Gorilla glue 99% of the time. Two part epoxy when I need one quick. Had a couple of blow out early on with GG but it is due to operator error [V]...I was using a dull roughing gouge!!! [:D].

I still use roughing gouge to round my stock then use the skew. My pen turning tools are the cheap HF HSS set...mainly using 2 out of that set (roughing gouge and skew) but every now and then I use the parting tool for tennons when needed.

I wish I can say that I sharpen as often as Lynn said but I don't. With these cheap tools I only touch them up every 20 or so pens...and still works. Best way is to feel the cut and sharpen when needed. Note that different material (that includes various wood species) may change your mileage.

I will encourage you to use your skew more...I think that is the best way to go.

BTW, here is how I apply my gorilla glue.

drill hole
roughen tube with sandpaper
place newspaper on work area (VERY IMPORTANT [:D] )
put on gloves (I use medical gloves from Walmart)
put some GG in the hole
(yes I don't wet the wood anymore...still bubbles but less, stronger bond too)
with a bamboo skewer (BBQ stick) spread the glue in the hole throughly
repeat last 2 steps from the other end of the hole
insert the tube partially in the hole
apply more GG on the length of the tube
slowly insert the tube rotating tube along the way
watch for glue build up where tube and hole meets...it should be even all around
(add more glue if there is no build up)
lay tubed blank on the newspaper
move to next blank (I ususally try to do 10 pens per batch)
next morning, I clean up the bubble over with a knife also clean inside the tube (can be avoided by plugging the ends with wax, potato, etc.)

Hope this helps
 

TomServo

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Grand Forks, ND, USA.
I personally like to use scotch brite to rough up the tubes - gets it done nice and fast and uniformly :)

Dario: I agree wholeheartedly, no matter what glue you use, coat the outside of the tube and the inside of the blank. Also to rotate the tube while inserting, and there's nothing wrong with being a little generous on the glue - any squeeze out can often be reused. I had lots of blowouts because of little air pockets between the blank and the tube.. particularly with some ebony :)
 
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