CA vs Epoxy

Signed-In Members Don't See This Ad

dalemcginnis

Local Chapter Leader
Joined
Apr 18, 2007
Messages
1,027
Location
Daphne, Al. USA
A question for those of you that use epoxy, especially if you have or also use CA to glue your tubes. Do you think that the epoxy helps to prevent blanks from exploding off of the tubes while you are turning them?

I just blew up a beautiful burl today. Three large pieces flew off the tube. It seems to me that if the glue did a better job off holding the wood to the tube that would be less likely to happen. I know the one time I did use epoxy because my tube had a sloppy fit that it did prevent a blowout. I didn't notice it while I was turning it, but after sanding it I saw that at one end there was a spot that had no wood just epoxy.
 
Signed-In Members Don't See This Ad

Dario

Member
Joined
Apr 14, 2005
Messages
8,222
Location
Austin, TX, USA.
I mostly use Gorilla Glue for tubes but also use epoxy when I am in a hurry.

I used CA once then stopped, just say we didn't like each other :D so I cannot comment about it. I do use CA to stabilize soft wood or fill voids of blanks after drilling. After the CA cures, I re-drill again then glue the tube.

When gluing (with Gorilla Glue or Epoxy), I always spread the glue inside the hole with a bamboo skewer (BBQ stick).

Before inserting the tube (no matter what glue I use), I fill one end of it with clay/putty (I usually raid my daughter's play-do [:I])

Of all the pens I turned, I never lost a pen through blowout using this method.
 

Aderhammer

Member
Joined
Dec 4, 2007
Messages
541
Location
Allentown, Pennsylvania, USA.
I use straight epoxy, never have had a blank gone bad, I use a slower cure epoxy and then heat cure it w/ a heater and metal shield, this way the epoxy is ready for milling in about an hour after gluing and heating. But the epoxy is still good If i wanna glue up some other blanks a little bit later.
 

dalemcginnis

Local Chapter Leader
Joined
Apr 18, 2007
Messages
1,027
Location
Daphne, Al. USA
Thanks, you've confirmed the direction I was heading. Looks like I'll be using a lot more epoxy. I had been sticking with CA because I could go into the shop and then decide what kit and wood I want to turn that night. Now I'll have to decide today what pens I want to turn tomorrow.:D
 

mrcook4570

Member
Joined
Mar 27, 2005
Messages
4,098
Location
Mason, WV, USA.
The key to preventing blowouts is to make sure you have 100% glue coverage. Check your blowouts. Is there glue residue on both the tube and the inside of the blank? Or is the coverage spotty?

As you push the tube into the hole, the blank will remove glue from the tube. This gives less than 100% glue coverage and thus leads to blowouts. As Dario said, coat the inside of the blank with glue. Also coat the tube with glue. Plug one end of the tube and insert with a twisting action. This will provide the best possible glue coverage.

That said, I use epoxy or GG. Epoxy for small batches that must be turned the same day. GG for large batches that do not require immediate turning.

I have had too many failures with CA for gluing in tubes. Most notably, when disassembling a slimline or euro. Attempting to knock out the transmission frequently results in the brass tube becoming dislodged from the blank and the transmission is still stuck in the brass tube.
 

leehljp

Member Liaison
Joined
Feb 6, 2005
Messages
9,314
Location
Tunica, Mississippi,
I agree with all of the above. I don't have GG, can get it but it is expensive and I have to travel far to get it. SO, I use epoxy, 5 minute if I am doing 1 or 2 blanks; 30 minute if I am doing 3 to 10 blanks. I do find that epoxy seems to fill more space and grip better than CA. One other problem that I have had even with medium and thick CA is the occasional quick setting of even those before I can get the tube in precisely.
 

Tonto

Member
Joined
Oct 2, 2007
Messages
59
Location
Fridley, MN, USA.
The other variable in this discussion is sharp tools. Amazed at how a quick touch up on the wheel changes the speed and shape of wood curls and I suspect reducing the grab that causes the blow out
 

RussFairfield

Passed Away 2011
In Memoriam
Joined
Feb 10, 2004
Messages
1,522
Location
Post Falls, Idaho.
For what it's worth, this my personal experience with glues and glue joints. Othere will have different experiences and reach different conclusions.

A bad piece of wood will crack or explode when it wants to, and it doesn't matter which glue was used for the tube.

For most wood, the glue joint only has to be strong enough to hold everything together until after it has been turned, sanded, and finished. After that the metal ends are pressed into the tube, capturing the wood, and there is no longer any need for a glue joint. Any glue in the joint only acts as a filler to keep the wood centered on the tube. Think about that.

The hardest stress on the wood and the glue joint is the pounding it takes from the intermittent cut while the wood is being turned from square to round. I tend to take big cuts suring this rounding to get it done faster.

There will be a lot less stress on the wood and glue joint if the square-to-round is done between centers BEFORE the the blank is drilled and the tube is glued in. Doing this solves 2 problems. It removes the stress from the glue joint, and it takes a lot less pressure on the bushings to turn a round blank than it does a square blank. There will be fewer blowups, and those that do happen will be before the blank is drilled, and we will have a better chance to glue them back together. Less pressure on the bushings means less opportunity to bend the mandrel and cause all sorts of alignment problems later.

Except for one specific type of wood, I use CA glue for gluing all tubes, but this wasn't always this way. My first pens were glued with epoxy, and were then followed by various brands of Polyurethane glues, but I still used epoxy when I didn't want to wait overnight and I used the 5-minute variety when I wanted a faster cure.. I never used CA glue because I has always thought it was too brittle - until one day when I needed some pens in a hurry while I was making a video.

When one of the tubes got stuck about 1/2 way into the hole, I thought it would be very easy to get it out. After all, it was a brittle and weak glue joint. Everyone knew that. One good hammer blow would break it free. Several hammer blows later the tube and the wood were totally destroyed - - and the brass was still stuck firmly to the wood. So much for CA being a weak glue joint. I have used nothing but a medium CA glue, Hot Stuff "Super-T", ever since. That was 4 years ago.

The one exception is wood that I suspect or know will crack. I drill the hole slightly oversized with the next larger drill in whatever fractional, letter, number, or decimal size is available. As an example, I use the larger 9/32" drill instead of the 7mm or "J" size for the 7mm tubes. Then I use the Polyurethane glue because it will expand and fill in the gap, and the foam is strong enough to hold it together yet flexible enough to allow for expansion of the wood. I went from 100% failure due to cracking to 80% success with pens turned from Ebony when I did this. I have always suspected some combination of internal stresses and moisture in the wood that resulted in movement and shrinkage as the cause of the cracking. Using a somewhat flexible glue joint allowed for this movement and reduced the cracking.

The only problem I have had with the oversized hole and Polyurethane glue has been with pens where the wood was not captured between two metal parts that had been pressed into the tubes. The solution was easy - never make a closed-end pen from a species where I would be useing the Polyurethane glue for the tubes.

I have used all of the Polyurethane glues over the years and have settled on Titebond brand as my preference. It keeps longer that the others after the bottle has been opened, it foams less and doesn't push the tubes out of the holes as much, cures faster and without having to use water on the wood, the bond is just as strong as the others, and it is less expensive than Gorrila brand.
 
Joined
Jan 18, 2004
Messages
163
Location
madison, wi, USA.
I use polyurethane (GG) to glue the tubes. I drill the blanks with a 9/32" drill. The glue is put on the tubes which are then twisted as they are inserted. I have had no problems with "blow-outs".

When I turn cherry burl blanks, I drip CA into the drilled blank before gluing in the tubes with polyurethane. I also drip some on the blank as I turn. Again, no problem (hardly ever) with blow outs.

The overnight wait is good training for being patient and planning ahead.

Larry
http://webpages.charter.net/lgottlieb2/
 

drawknife

Member
Joined
Aug 8, 2007
Messages
141
Location
Smyrna, Tennessee
I guess I'm sitting on the amen seat, I think coverage is the key no matter what the glue is. I almost use the fit of the tube as what type of glue to use. If it's a nice tight fit then CA is fine, there shouldn't be any centering problems with the tube in the blank. Use medium Hot stuff Super T. Use epoxy if I want to darken the tube using pigment dyes turning acrylics or corian, 5 min stuff. If the blank turns out a little sloppy on the tube I use urethane to center the tube, just have to go back in an hour or so and push the little suckers back into the blank if they're pushed out. You can drill them larger to accommodate the foaming, but other than a slimline its more difficult to find drill sizes a few thousandths larger than the recommended drill size. It's easier I think to just go back and look at them a little later, and it gives you a chance to go back out and fool with something else :D
 

edstreet

Member
Joined
Aug 12, 2007
Messages
3,684
Location
No longer confused....
I use loctite 324 speed bonder on the tubes :) Once it's set it takes an act of congress to come out. The biggest advantage is clean up is super easy, no junk to scrape off and nothing to clog up inside the tubes, it's anerobic so anything in the presence of o2 will not harden meaning just wipe off the excess. It is a 2 part system with a spray on part then the liquid glue itself. Super strong something like 14,000 psi shear strength and best of all it sets in under 5 minutes.

You can take 2 strips of metal glue them together into an L shape and suspend a 100 pound bucket at the end before the bond will break.

Ed
 
Top Bottom