How do I avoid THIS?!

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Zahnarzt

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Dec 2, 2012
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15
Location
Kingston, MA
I've been having trouble avoiding the CA lifting off the ends of the wood. Sometimes it happens as soon as I take them off the lathe, sometimes when I am assembling them (it typically worsens when I assemble) What can I do to avoid this!?
 

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Are you doing your CA finish with the same bushings that you turn with?? If so you need to cut the CA with a knife or something to score it so it will break free from the bushing. I would recommend using the Eliminator II or something like that and make sure you seal the end of the blank good before you assy.
 
For these I did score with an exacto and they came offf the bushings with little issue. I then lightly sanded the edges and assembled. Do you finish with different bushings on? What do you use to seal the ends and when do you do it (after flushing up the wood with the tubes or after finishing altogether)?
 
I don't really touch them but I do clean up the sawdust with some mineral spirits. I dry them thoroughly after but could some residue stick around a muck up the adherence?
 
You might try DNA instead of mineral spirits for cleanup/ sawdust removal. Also, if you put your CA finish on while using a 60degree deadcenter in the headstock, rather than a mandrel and bushings, then use a sanding disc instead of a cutterhead on a penmill, you can gently sand off any CA that laps over the edges while doing a final squareup of the blank. Since i started finishing between centers, I've not had any problem with the CA wanting to lift at the edges.
 
It seems to me that, the CA may no have adhere to the wood as it was suppose to. If the wood is oily, you need to wipe the wood with acetone before the CA is applied, making sure no fingers are rubbed on the bare wood.

The second issue, may be the CA that gets stuck to the bushings and with the attempts to separate them, have lifted the CA out of the ends.

BUT, what I thing the major problem is here is that, the ends of the barrels after the CA is applied, have not been sanded right, where some CA is still hanging over the wood edge and when you push/press the kit fittings tight, the CA is simply compress back and therefore separate from the wood.

This is even a bigger problem when the CA doesn't adhere to the wood as it should, it want take much the "flake" it, a simple pen drop or hitting hard surface will dislodge/separate the CA layers from the wood...!

Cheers
George
 
DNA, a pen mill sanding and perhaps even finishing between centers sounds like it should do the job. Thanks guys! Hopefully I'll post some good results soon.
 
I use the 60 degree dead center in the head stock and a 60 degree live center in the tail stock while applying the CA and and for sanding and polishing, I then take my barrel trimmer and turn the cutting edge around and stick 400 grit sand paper on the smooth side and sand the ends of the finished pen barrel with it until the ends are clear of all the ca and flush with the brass tube and then assemble the pen, also if the pen parts seem harder than usual to press together, I will lightly file the inside of the brass tube rather than forcing the parts together.
 
I use a fine metal file to take the sharp edge off the ends after finishing, and nail polish hardner to seal the ends of the blanks. Jim S
 
We just discussed this in another post, I believe. Anyhow, I use a sharp parting tool adn turn off the CA down to the pushing. They separate nicely and then I use the Beall wheels to buff them so there's no sharp edge.
Also +1 on the comment re mineral spirits. I use denatured alcohol or acetone to wipe down the blank prior to CA. Prefer the acetone because it evaporates faster and leaves no residue. There's some moisture in the DNA.
 
+1 on the DNA and the 60 deg centers. I also take the blanks off of the lathe and trim the excess CA off before I start the finish sanding. Since I started that I have not had this problem.
 
Ok I am a bit confused now. So are you flushing up the ends of your blanks after you apply the finish and before assembly or do you do it after gluing the tube in before turning? Or is it both?
 
It was happening to me a lot. Then I started giving the CA an extra couple of minutes to set once I was finished (like 5 while I set everything up to assemble the pen and prep the next one). Scoring and separating the bushing with a twisting motion is what helped me as well. But now I'm going to try finishing between centers.

Good luck to you and me both.
 
I wax the bushings before starting the finishing process. I also like to apply some thin CA to the barrel ends so that they are sealed, and give the finish something to bond to. After finishing, but before taking the barrel off the mandrel, I score with the skew. Then I reverse the pen mill and back it with a piece of sandpaper to sand down to final true up on the barrel ends.

If it's one of the more oily woods, then all bets are off. I just tried using sanding sealer to see how that works, and General Finishes Woodturners Finish seems to do well.

The CA finish is acrylic, and it's brittle. Therefore, cracking is always a possibility. Take steps to prevent that cracking like giving the glue something to bond to (CA on the ends, or Sanding Sealer). Waxing the bushing helps prevent the glue from bonding to the bushing. Scoring the finish before removing the barrel from the mandrel will help break it free of the bushing with less chance of cracking.

I just decided that this was a part of the process that it didn't pay to rush.
 
I was having similar problems, especially after I was using eliminator style bushings for finishing. I was getting a build up of CA on the corner of the barrels. When I pressed the hardware on it would compress that CA and cause the CA on the edge to lift from the wood or chip off.

I found that if I sanded back the CA on the ends it would stop this from happening. I just take the barrels off the bushings (before sanding/polishing) and place some 400 or 800 w&d on the ways and dry sand with an even motion. If I sand through to the wood/brass I will thinly coat the end with some thin CA. (A drop of thin CA on folded paper towel and place half of barrel edge on CA and rotate the barrel). Then finish sanding/polishing.

Before pressing the components together I also make sure there is no CA inside the brass tube or edge. I use a hobby knife and/or a deburring tool. Sometimes I find an ultra thin layer of CA inside the first few mm of the tube. It will cause you to use excessive force to press the parts which can also cause chipping.

TonyO
 
I think you are putting more pressure to the end of the blanks when wet sanding and you're sanding the finish off.
 
This happened to me on several occasions, but always with oily wood such as ebonies. That "lifting" drove me to try TBC - Turning Between Centers, and I have never looked back. That was in '07.

Lifting can be from:
1. Oily Wood;
2. Pressing too tight with the pen press;
3. CA residue inside the tube, which causes the brass and wood to expand;
4. CA stuck to bushings and not "breaking" evenly;
5. BLO on oily woods. BLO is not a good idea on oily woods as the wood is alreadsy oily and BLO is an oil base.


Good adhesion with CA on oily woods is best accomplished by cleaning/rubbing with DNA or Acetone or CA Accelerator. Acetone and DNA are sometimes linked to moisture in the wood and then cloudy finishes. Most of the time it is OK, but just beware of it.
 
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