Thread: CA lifts when pressed or sanded

Sounds like you are squaring after turning.If so try squaring before turning your pen then when finished a couple of taps on the lathe bed or head stock should break the glue seal on the bushings then a quick sand to get rid of the sharp edges should do the trick. have a look at some utube videos & all will become more clearer

I square the blank before turning with a pen mill usually unless it's burl or something sensitive in which case i'll use a disc sander.

CA does not like end mills, aggressive sanding or heat, all cause debonding. Other causes are sanding too fine, you shouldn't go beyond 600 IMHO before applying CA, plus being too aggressive when cutting CA from bushes etc. Oilly timbers can be a problem and should be wiped down with metho before applying CA. Not sure what CA you are using either, but at least the first couple should be thin CA, t give a good bonded surface.

You can sometimes save the blank by holding the blank vertically above a drip of thin CA and let it get sucked up. I seal the ends of my blanks after final squaring in a similar way for all my blanks (before wet sanding/ploishing).

Hope this helps.

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.

If you can see that the CA is debonding after hand sanding then it sounds like it is happening when you are trying to remove the bushes. It doesn't take much force on the bush to cause the CA to let go.
I always apply my CA between centres so that there is nothing up against the ends for the CA to stick to. I apply a bit of WD40 or similar to the centres before fitting the blank in. That way if any excess goes over the ends and on to the centre it doesn't stick. By not having anything up against the ends, the CA automaticly seals the ends as you always tend to get a bit run over the end.

Originally Posted by Treecycle

If you can see that the CA is debonding after hand sanding then it sounds like it is happening when you are trying to remove the bushes. It doesn't take much force on the bush to cause the CA to let go...

Originally Posted by Tiger

..generally I sand up to 1200....

Thant's what I used to do too, now I know better

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?

I turn and sand only to 150 on the bushes, then swap to my Delrin cone bushes, then sand to 600 and apply CA. I cut CA edges with razer sharp home made pointed tool (from tool steel). Then I sand ends square using my specially designed head in the headstock and transfer punch to hold the blank in the tailstock (there is a thread on it some where). After squaring off the end I seal the ends and clear tube again and bevel edge with deburrer. Then I wet sand or provide buff finish and we are done.

I'll be back in Melb in a few days, perhaps we can get together, PM me your details

Thanks Neil, Treecycle etc, will go into shed tonight and try some of these suggestions.

Had another go tonight, result was better but still left with a slight discoloration at the end of the pen barrel after sanding square. Only sanded to 600 this time and used bushes made from some plastic chopping board, they definitely help. Forgot to seal the ends with CA, will try that next time.

How did you sand square? If with a decent disc sander, it will be too aggressive, likewise pen mill.

When I said sand the ends square above, it is only the CA sanded square, the blanks were sanded square before I started turning.

Yes it was a disc sander on low speed with 400 grit, light touch, also forgot to mention that i use a countersink hand tool on the pen barrel to ease assembly, i notice that this takes some of the brass tube off, maybe too much and as a result weakens the CA at the end of the pen barrel.

Not sure about weakening it, but if it was blunt at all, it would push the brass outward and debond the CA. I radius the tube too, but I use a hand de-burrer (~$10 at your local car parts store), achieves the same result but no risk to coatings.

Just a thought, but are you sanding the ends before the CA has fully cured ?
If the CA is still a bit soft it will lift a lot easier than when fully cured and hard.

I leave my CA finished blanks for 24 hrs before I do any sanding.

Originally Posted by dai sensei

Not sure about weakening it, but if it was blunt at all, it would push the brass outward and debond the CA. I radius the tube too, but I use a hand de-burrer (~$10 at your local car parts store), achieves the same result but no risk to coatings.

Countersink tool feels pretty sharp but I must remind myself that the tubes are only brass so don't need much to countersink it. Got one of those de-burrers somewhere, I'll give it a try.