Thread: CA lifts when pressed or sanded

Originally Posted by Tiger

I generally wait for a few minutes after applying CA, once it feels set, I micro-mesh. Always done it this way and have not had problems in the past.

I have found that CA takes some time to harden fully, especially when it is a bit thicker.
Since I have been giving them time to cure properly before taking the sandpaper to them, I have found I have been getting a better quality finish.
Your mileage may vary of course, so do what works for you.

Originally Posted by Tiger

Thanks Neil, appreciate your thoughts. For the record I use thin CA, wipe down with Metho before applying CA. I haven't as a rule sealed the ends of the blanks with CA but will give that a try, just to clarify you do that before you wet sand and you only do it once?

If I had to make an educated guess it does look like the CA has not bonded properly, generally I sand up to 1200 but will only go to 600 next time and see how that goes. Always thought that the smoother the surface the easier the CA would go on.

I agree sand to 600 on the lathe then stop and hand sand along the grain with 600. Much better finish than 800 on the lathe IMO. I have had similar separation problems with sanding too fine with Minwax Wipe-on-Poly. Any finish must be able to key into the surface of the article the finish is applied to.

Tiger

Use the finishing lathe sander I sent you the plans of. It does work, but if you don't use it then .......

Made another pen last night and results were better but still some lifting of the CA, the plastic chopping board bushings really help and I used a sharp skew to sever the pen barrels from the bushings. The excess CA was only tiny and so I resorted to softly sanding it on some 400 grit sandpaper on a flat surface, there was still some debonding of the CA. For whatever reason I suspect the CA is not bonding properly to these blanks even though I'm sanding to just 600. Going to try another pen tonight, this time I'll wait an hour or so before I remove it from the mandrel and see if that makes any difference.

Is it just one particular species of wood you are doing all these trials on?
Are the blanks new ones you are making, or are you trying to redo previously completed ones?
In your initial post you said the bushes are waxed. Could you be getting any wax on to the ends of the blank before applying the CA?
Why do you chamfer the inside of the brass tubes after applying the CA? I always do this before putting them in to apply a coating of whatever.

Originally Posted by Treecycle

Is it just one particular species of wood you are doing all these trials on?


Are the blanks new ones you are making, or are you trying to redo previously completed ones?


In your initial post you said the bushes are waxed. Could you be getting any wax on to the ends of the blank before applying the CA?


Why do you chamfer the inside of the brass tubes after applying the CA? I always do this before putting them in to apply a coating of whatever.

Yes, all Redgum with some fiddleback, I'm using the same timber so keeping that part of the process constant. All new blanks. Last night I did not apply wax as I was using the plastic bushings. The chamfering is to assist the assembly process, last night I did it before turning, I made sure that the blanks were square via my pen mill.

Removing the blank from the bushings while the CA is still soft/not cured will cause the CA to separate from the ends 90% of the time even if you try and separate the bushings by using a sharp blade to cut around the bushings.
I TBC and wax the ends of my dead center and live center and never have a problem with CA separating from the blank ends.
Disk sanding or Milling the ends of the blanks after applying the CA will cause the CA to heat up and separate from the ends of the blanks.


Les

Originally Posted by Les in Red Deer

Removing the blank from the bushings while the CA is still soft/not cured will cause the CA to separate from the ends 90% of the time even if you try and separate the bushings by using a sharp blade to cut around the bushings.
I TBC and wax the ends of my dead center and live center and never have a problem with CA separating from the blank ends.
Disk sanding or Milling the ends of the blanks after applying the CA will cause the CA to heat up and separate from the ends of the blanks.


Les

Thanks Les, I've tried just about everything else so may as well try TBC. I have always turned pens the way I'm doing it now and this has not happened with other timber, it has been cold in Melbourne lately and maybe that is a factor.

I take it we are all reading this correctly and the debonding is appearing before any of the fittings are pressed on to the blank, not afterwards?

Originally Posted by Treecycle

I take it we are all reading this correctly and the debonding is appearing before any of the fittings are pressed on to the blank, not afterwards?

I've turned a few pens recently, sometimes the debonding is occurring (or I'm only noticing it) when assembling, the majority of the time it seems to occur when squaring the CA residue.

Had another go tonight, this time i waited an hour after applying CA before assembling, this time no CA lifting. Used plastic bushings, no wax and forgot to sever the bushings, it would appear that with some timbers at least you need to wait after applying the CA. I've turned many types of timbers and never needed to wait, on Redgum you will need to wait if only for an hour to be safe when separating bushings.

Good news. Hopefully with all the input to this thread, a number of people have picked up some little thing to help them in the future.