Problem with CA finish on ends of pens

[Jeremy Killingbeck]

I have been using a CA (Super glue) finish on all my pens recently, but I keep having imperfections on the ends of the pens. I have tried many different techniques, but have not seem to find one that works well 100% of the time. Does anyone know any good tricks that will help prevent the problems that I am having? See attached pictures:

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[Mike Cruz]

Jeremy, I'm not a CA finish guy, but I do have a question that might help someone give you an answer... Is that "bubbling up" or is that filling in what might have been a chip out in the wood?

[Marty Eargle]

Can't tell exactly from the photos, but it looks like distortion in the finish that can be cause when you have to break your bushings free from your pen. If this is your problem, a then coat of wax on your bushings could help, or a light tough with a scraper to remove all the CA overflow.

[Jeremy Killingbeck]

It is kind of like the coating is separating from the wood. There are not any defects with the wood under the problem areas & the coating is not bubbling. I am thinking that either the bond strength is not strong enough, or it is some how fracturing and causing separation to the wood.



Jeremy, I'm not a CA finish guy, but I do have a question that might help someone give you an answer... Is that "bubbling up" or is that filling in what might have been a chip out in the wood?

[Jeremy Killingbeck]

I thought that it might be happening when breaking the bushing off, so I made some undersize bushing out of a 7mm pen tube that I use when applying the glue. That way the glue does not attach to my bushing & cause a fracture. Even after doing that I still seem to get imperfection in just about every pen I make.


Can't tell exactly from the photos, but it looks like distortion in the finish that can be cause when you have to break your bushings free from your pen. If this is your problem, a then coat of wax on your bushings could help, or a light tough with a scraper to remove all the CA overflow.

[Greg Bolton22]

Hi Jeremy,

Do you see the imperfections before you press the pens together? I have had problems like this when the glue protruded past the wood on the tube and therefore made contact with the kit when pressing together. I have started sanding the ends of the finished tubes after they come off the mandrel. I just put a piece if 320 flat on the ways of the lathe and lightly swirl the end of the tube around while holding it vertical. This leaves a nice flat surface to make contact with the kit components. The other issue I have had is actually pressing the kits together with too much pressure and buckling the finish.

If you are seeing the imperfections right off the mandrel I don't know what to tell you.

Good luck!

Greg

[Jeremy Killingbeck]

I usually see the imperfections right off the mandrel. I have started sanding the ends before I do a finish sand / polish on the finish, but again the issue has not gone away.

[Jim Burr]

You may want to try delrin or another bushing material made just for finishing. Let's run through your entire process, see if there is something that sitcks out.

[Dave Fritz]

How about trying to finish between centers? I sometimes use bushings to turn, then remove and finish between centers. Before assembling lightly sand the ends.

Curious what you find out as you try different methods.

Dave F.

[Jim Burr]

How about trying to finish between centers? I sometimes use bushings to turn, then remove and finish between centers. Before assembling lightly sand the ends.

Curious what you find out as you try different methods.

Dave F.

That just caused a light bulb to go off, If you are using a mandrel to turn, you have a concentric blank so your finish will be thinner on two sides. BTC is a great idea for no only finishing, but turning too!

[Brian Brown]

Just prior to your first coat of CA, are you washing the blanks thoroughly with acetone, and if so, are you allowing the acetone adequate time to evaporate? Oil from your fingers (you always rub the ends to see how close they match the bushings right?) or loose sawdust can cause the CA to adhere poorly. Also, how old is your CA. Try some fresh, and see if it bonds better. Also what is the temperature of your glue and shop? CA Bonds poorly when it is cold.

[Carl Civitella]

Perhaps you are spinning your blank to fast, causing the blistering on the ends. Sanding to much, when i get down to just sort of the profile i want, i back off the speed both with the tool and sand paper. Also when sanding between coats of c/a i go slower. Maybe that is the problem..Good luck, Carl

[Steve Doerr]

Jeremy,
I have had the same thing occur in the past when doing pens. There are a couple of issues that cause the problem.
1. Do not use the regular bushing to support your blank when applying CA. As Jim stated get some delrin bushings that are tapered. You can either make them or order them at Wooden Wonders.
2. After you apply the CA take the blanks off the mandrel and use a sharp utility knife to trim any excess CA off the end of the barrel. Then sand end smooth. Make sure the sanded end is perpendicular to the tube. You want it flat and smooth so that when you assemble the pen the fittings are putting pressure on the blank in an even and constant manner.
3. DO NOT apply excessive pressure when assembling the pen. This excessive pressure along with a none perpendicular face is what ultimately causes the CA layers to separate. The separation of layers is what is causing the milky white appearance on your blanks.

To get ride of the bad spot, unfortunately, you have to remove the finish to where the layers have separated. Sand and then reapply your CA.

Hope that helps. Good luck and happy turning.
Steve

[James Combs]

... I have started sanding the ends of the finished tubes after they come off the mandrel. I just put a piece if 320 flat on the ways of the lathe and lightly swirl the end of the tube around while holding it vertical...Greg
+1 on sanding the end after finishing. I have a piece of adhesive back sand paper at my assembly station and every barrel gets several "twirls" on each end before assembly. I have never seen the same issue and I only use CA finish.


...Let's run through your entire process, see if there is something that sitcks out.
As Jim says, give us some more detail of each of your processing steps, maybe something will stand out.

Someone else above mentioned acetone cleaning of the blank, a mandatory process for the oilier exotics. Don't know your exact CA process but I always use thin CA for the first coat because it penetrates the wood. I then switch to thick. You might add the thin as a first step if you aren't using it already but UMMV.

[Jeremy Killingbeck]

Thanks for all the advice. I tried a few pens last week and changed a few things which seemed to be successful. The first thing that I did was clean the wood with Acetone, and the 2nd was to start with 2 coats of thin CA before finishing with med CA. It made a big difference & I did not have any imperfections on the pen. Thanks again for all the help.

[Jim Underwood]

I had problems with this as well. Waxing, sanding the ends, washign down with acetnone... nothing seemed to help.

I think I finally hit on what was causing the problem. If you put enough CA glue on your pen body to be able to sand and polish it to a high gloss, it also gets that much on the bushings. If the mandrel has any wobble whatsoever then it means that the CA is flexing as it turns...
I believe this flexing between the bushing and pen body is what destroys the bond at the ends of the body. I would be willing to bet there are very few lathes whose headstock and tailstock line up exactly, which means no amount of special tweaking of the mandrel will fix the problem.

Ever since I started turning between centers, I haven't had the problem one single time.

[Steve Trauthwein]

Looks to me like you are sanding the finish off. Put more ca on and start sanding it with a lighter grade paper.

Steve