CA separation on ends after assembly

[flip]

As described, I have done several pens with CA and about half of the time it seems like the CA delaminates. My usual routine is sand to 600, wipe down with DNA, wax bushings lightly, 2-3 coats of thin stick fast, 3-4 of medium, wet sand with mm through 12000, plastic polish, assemble.

There are times when I use the skew to separate the tube from the bushing but not always, doesn't seem to matter. Always knock off excess from ends of tubes and sometime will use some thin CA to seal too.

It seems like when the parts bottom out the pressure causes the CA to separate from the tube OR the layers of CA are delaminating. It looks like a half moon on the edge. Sometimes I can put a drip of thin on the area and it will wick in and make it disappear, sometime not.

Cleaned out tubes to eliminate bulge blowout and only used enough pressure to close gap between tube and part being pressed. Ideas?

 

[OLLIEwinz]

hmm not 100% sure but i use non stick bushings and have never had an issue with my finish delamination or splitting at the ends, just a thought
-oliver

 

[tjseagrove]

I use a bit of thin and seal the ends before applying the CA finish. If you wet sand, moisture can get into the wood on the ends and cause issues.
32

 

[jttheclockman]

Welcome to the site. I see your very first post is a problem that many new pen turners face as they get started perfecting that perfect finish.

There are a few factors that can cause what you are seeing and it is documented throughout this forum many times but hopefully I will touch on the basic and more familar ones. The first is when using CA for the finish and using the regular bushings will always give you a tendency to get ca on the bushings and more or less glue them to the ends of th blank. Now you have to seperate them and with the CA being fresh and not cured enough it can fracture the ends. Some times you will not notice this until you press parts in because you are now putting pressure on that CA and not being flexible enough it will fracture.

To conteract this many people do their finishing without the regular bushing and switch to delron bushings or finish between centers. I included a link that touches on this. www.penturners.org/forum/f14/ca-finish-tips-tricks-135309/

Many people also file the inside of the tube down a bit so that pressing in of the components is not too tight. They may even go as far as using some blue locktite to hold them in. You do need to debur th edges and make sure no glue has entered the tube. Also press in the componets as straight as possible. Any angle will apply undue pressure and cause fractures in the CA.

Finally the CA of choice. It has been documented here many times that Stickfast CA can cause problems so not my choice of glues.

Others will chime in and add some more but good luck and again welcome to the site. Hopefully they will mention the use of a barrel trimmer VS the use of sanding disc and the do's and don'ts of both.

 

[JimB]

You say you are knocking off the excess from the ends but you don't say how you are doing it. You may still have some there and that can cause the problem. It doesn't take much.

 

[flip]

You say you are knocking off the excess from the ends but you don't say how you are doing it. You may still have some there and that can cause the problem. It doesn't take much.

Generally, 600 on lathe bed and "spin". Tried 1200 MM wet too and have not seen much difference in failure rates. What is odd is that some pens/woods have given me no issues at all, some I can't make one that looks right. Ordered the non sticks so let's see what that does. My concern, and may still be, is that the medium is not biting into the thin.

This is driving me nuts and making my "reject" pile look like a collection. Maybe I should call it the "Hall of Shame".

 

[JimB]

You say you are knocking off the excess from the ends but you don't say how you are doing it. You may still have some there and that can cause the problem. It doesn't take much.

Generally, 600 on lathe bed and "spin". Tried 1200 MM wet too and have not seen much difference in failure rates. What is odd is that some pens/woods have given me no issues at all, some I can't make one that looks right. Ordered the non sticks so let's see what that does. My concern, and may still be, is that the medium is not biting into the thin.

This is driving me nuts and making my "reject" pile look like a collection. Maybe I should call it the "Hall of Shame".

I tried the sandpaper on the lathe bed when I started and didn't like the results so I made myself a little jig for sanding the ends. I never had an issue with one coat of ca not adhering to another but I also usually use either thin or medium, not both.


View in Gallery

 

[flip]

You say you are knocking off the excess from the ends but you don't say how you are doing it. You may still have some there and that can cause the problem. It doesn't take much.

Generally, 600 on lathe bed and "spin". Tried 1200 MM wet too and have not seen much difference in failure rates. What is odd is that some pens/woods have given me no issues at all, some I can't make one that looks right. Ordered the non sticks so let's see what that does. My concern, and may still be, is that the medium is not biting into the thin.

This is driving me nuts and making my "reject" pile look like a collection. Maybe I should call it the "Hall of Shame".

I tried the sandpaper on the lathe bed when I started and didn't like the results so I made myself a little jig for sanding the ends. I never had an issue with one coat of ca not adhering to another but I also usually use either thin or medium, not both.


View in Gallery

As a rule, how many coats of thin or medium do you use? There has to be a good median between too much and too little and I don't know where that is.

 

[lorbay]

One thing to do is get rid of the bushings before applying CA.

Lin.

 

[mecompco]

One thing to do is get rid of the bushings before applying CA.

Lin.

Yes, remove bushings and apply CA between centers. I put a little wax on the centers first. If you do get some adhesion, it is easy to get a razor blade in there and unstick the blank.

 

[JimB]

You say you are knocking off the excess from the ends but you don't say how you are doing it. You may still have some there and that can cause the problem. It doesn't take much.

Generally, 600 on lathe bed and "spin". Tried 1200 MM wet too and have not seen much difference in failure rates. What is odd is that some pens/woods have given me no issues at all, some I can't make one that looks right. Ordered the non sticks so let's see what that does. My concern, and may still be, is that the medium is not biting into the thin.

This is driving me nuts and making my "reject" pile look like a collection. Maybe I should call it the "Hall of Shame".

I tried the sandpaper on the lathe bed when I started and didn't like the results so I made myself a little jig for sanding the ends. I never had an issue with one coat of ca not adhering to another but I also usually use either thin or medium, not both.


View in Gallery

As a rule, how many coats of thin or medium do you use? There has to be a good median between too much and too little and I don't know where that is.

Just for full disclosure I don't make a lot of pens any more and what I do make only a few have a ca finish. In the past 6 months I have only made 5 pens and 4 of them have a ca finish. Actually, ca/BLO.

If I use thin ca I put on about 10 coats. Medium ca about half that. I say 'about' because I don't count the coats. I keep going until it looks the way I want it. I also don't use bushings at all when applying the ca. I mount the turned barrel directly between the live and dead centers so the centers make contact with the brass tube. Don't over tighten or you will flair the tube or crack your blank.

Once the ca/BLO finish is done I put it aside until the next day to let it cure before I do any sanding, trimming or polishing.

 

[robertkulp]

As mentioned, there are a number of things that can cause your problems. Basically, it's some sort of pressure or shock that is causing the CA to release from the wood. This can be caused by the blank not being trimmed perfectly flush against the tube. If the wood is protruding slightly, then pressing in the hardware will press on the wood; putting undue stress on the finish & causing cracks. It can also be caused by removing the bushings if they are CA'd to the blank after finishing. If a little bit of CA gets down on the end of the blanks, then that can interfere and cause problems during assembly, too.

One tip to help increase the bond between the wood and the CA is to first use a couple of drops of BLO or accelerator, then apply thin CA. BLO acts as a mild activator and can help with curing of the CA within the wood.

Also, there are different viscosities of "thin" CA. To really soak into the wood, you want the CA to be as thin as water, about 5cps. Some thin CA is up to 20cps and it might not soak in quite as effectively.

As was also mentioned, Stick Fast has a strong reputation for cracking. It seems to be more brittle than other brands of CA, especially when used with their Acetone accelerator. I recommend against using an accelerator that is based on Acetone. Heptane or Naphtha are much better.

Sometimes, the simple solution is to change your CA.

 

[flip]

As mentioned, there are a number of things that can cause your problems. Basically, it's some sort of pressure or shock that is causing the CA to release from the wood. This can be caused by the blank not being trimmed perfectly flush against the tube. If the wood is protruding slightly, then pressing in the hardware will press on the wood; putting undue stress on the finish & causing cracks. It can also be caused by removing the bushings if they are CA'd to the blank after finishing. If a little bit of CA gets down on the end of the blanks, then that can interfere and cause problems during assembly, too.

One tip to help increase the bond between the wood and the CA is to first use a couple of drops of BLO or accelerator, then apply thin CA. BLO acts as a mild activator and can help with curing of the CA within the wood.

Also, there are different viscosities of "thin" CA. To really soak into the wood, you want the CA to be as thin as water, about 5cps. Some thin CA is up to 20cps and it might not soak in quite as effectively.

As was also mentioned, Stick Fast has a strong reputation for cracking. It seems to be more brittle than other brands of CA, especially when used with their Acetone accelerator. I recommend against using an accelerator that is based on Acetone. Heptane or Naphtha are much better.

Sometimes, the simple solution is to change your CA.

What is your go to brand(s)?

 

[robertkulp]

As mentioned, there are a number of things that can cause your problems. Basically, it's some sort of pressure or shock that is causing the CA to release from the wood. This can be caused by the blank not being trimmed perfectly flush against the tube. If the wood is protruding slightly, then pressing in the hardware will press on the wood; putting undue stress on the finish & causing cracks. It can also be caused by removing the bushings if they are CA'd to the blank after finishing. If a little bit of CA gets down on the end of the blanks, then that can interfere and cause problems during assembly, too.

One tip to help increase the bond between the wood and the CA is to first use a couple of drops of BLO or accelerator, then apply thin CA. BLO acts as a mild activator and can help with curing of the CA within the wood.

Also, there are different viscosities of "thin" CA. To really soak into the wood, you want the CA to be as thin as water, about 5cps. Some thin CA is up to 20cps and it might not soak in quite as effectively.

As was also mentioned, Stick Fast has a strong reputation for cracking. It seems to be more brittle than other brands of CA, especially when used with their Acetone accelerator. I recommend against using an accelerator that is based on Acetone. Heptane or Naphtha are much better.

Sometimes, the simple solution is to change your CA.

What is your go to brand(s)?

Flip,

First, let me give a disclaimer... I sell CA from Mercury Adhesives.

Now, having said that - obviously it's my favorite, but I have a lot of customers who have tried it and told me that it's much easier to apply than others and has solved a number of their problems.

In addition to Mercury, there are other brands that are popular with pen turners with BSI (Bob Smith Industries) being one of the more common.
--Robert

 

[jttheclockman]

Satellite Hot stuff best on the market in my opinion. They are a vendor here. Check vendors. I like to use 2 to 3 coats thin and then 4 to 6 coats med. Never thick and i never use accelerator. I have to say I probably been pretty lucky that from the very first wood pen I made i never had a problem doing a CA finish. When I first joined this site I did more reading and kept to myself and learned so much from those that pioneered this site. Lots of good info in these pages on th best pen turning site on the net. We do not know how fortunate we are to have this vast array of knowledge and stored info in one place.

Keep them lathes spinning.

 

[Monty]

I believe everybody has their favorite brand of CA. I would suggest you try different brands until you find the one that gives you the best results.
That said, I've been using EZ Bond CA for over 10 years with no problems. I usually apply up to 5 coats of thin, 5CPS, CA and if I do use accelerator, I use acetone based accelerator from a refillable pressurized spray can held 12-18 inched away from the pen blank. I found that accelerator in a pump does not deliver consistent size droplets of accelerator which can cause uneven curing in the CA which causes a rough finish that takes more sanding to smooth out.
Both EZ Bond and the refillable bottles can be purchased at Exoticblanks.com. Classicnib.com sells both EZ Bond and BSI CA.

 

[CREID]

I agree with Monty about the fact that everyone has their favorite brand of CA. I have been using Stick Fast for years without any failures of the CA, either in finishing or gluing of tubes. Having said that, someone talked me into trying BSI's flexible, so I bought some and will try it one of these days. I mostly have been doing acrylic pens lately. But yes, try a brand or two or three or whatever and use what you like and believe in. Believing in it is the most important, because if you think it will fail you will subconsciously make it fail.

 

[flip]

I really appreciate the hints and feedback. Ordered some non stick bushings and different CA so we will see if that helps. The funny part about this is we originally bought the lathe for our youngest son as a Christmas gift because he wanted to start doing small bowls. Ran into the pens accidentally while picking up some accessories for the lathe and now both of us are addicted. I am a hobby woodworker and never saw turning as something I wanted to try because I am not overly patient nor really saw it as a skill set I needed. Oh well, shows you what I know. It's my sons fault, I swear!:wink:

 

[waterboy]

Most of the time water and wood do not mix. Try finishing without the wet standing, just dry sand for a few blanks and see how that works. Water can wick between the bushings and then soak into the end of the blank.

 

[wob50]

Usual 5 thin coats...and 5 medium coats...of CA

 

[flip]

Most of the time water and wood do not mix. Try finishing without the wet standing, just dry sand for a few blanks and see how that works. Water can wick between the bushings and then soak into the end of the blank.

Are you suggesting dry sanding the CA with mm after it has been applied. I dry sand the blank prior to CA application. if it is an oily wood I wipe down first with DNA and let it spin on for awhile to make sure the DNA is completely evaporated. I do thoroughly wipe the blank down before finishing to make sure the dust is not causing adhesion issues with the ca or mylands.

 

[JimB]

Yes, you can dry sand with MM. It will start to polish the ca as you get to the higher grits. Be careful as dry sanding can heat up the MM so light pressure only.

The best thing to do is take a piece of wood and turn it down to a pen blank size between centers. No drilling, tubes or bushings needed. Then try a few of the methods suggested to see what works for you.

 

[flip]

Yes, you can dry sand with MM. It will start to polish the ca as you get to the higher grits. Be careful as dry sanding can heat up the MM so light pressure only.

The best thing to do is take a piece of wood and turn it down to a pen blank size between centers. No drilling, tubes or bushings needed. Then try a few of the methods suggested to see what works for you.

Will try this. As a follow up, I did a few pens over the weekend and used the Mercury CA without issues. Same finish schedule, different CA, no cracks.

 

[robertkulp]

Yes, you can dry sand with MM. It will start to polish the ca as you get to the higher grits. Be careful as dry sanding can heat up the MM so light pressure only.

The best thing to do is take a piece of wood and turn it down to a pen blank size between centers. No drilling, tubes or bushings needed. Then try a few of the methods suggested to see what works for you.

Will try this. As a follow up, I did a few pens over the weekend and used the Mercury CA without issues. Same finish schedule, different CA, no cracks.

Glad the Mercury CA worked well for you. Let me know if you have any issues or questions.