Thread: Chips/cracks on end of blanks

It's been a while since I've done a wood pen, but I know when I do acrylics, I always cut from the centre of the blank out to the ends.

That's about the only suggestion I have - over to others...

Cheers,
Andrew

Tiger are you coming to the get together in tooradin?
It'll be good.

I have never had a problem with olive wood, normally its a bit oily (which doesn't like CA) Only thing I can think of is you have your mandrel too tight when finishing ,try sfter you have rounded the blank to ease off on the pressure ,doesn't take much ,if it does spin just tighten slightly , The timber sometimes expands a bit as you work it ,,so could be pushing on the wood near your bushes this pressure can crack or damage the ends ,easy to check if that's the problem ,after you have rough turned ,take out the blanks and see if the wood is still flush with the end of the tube ,if not a quick rub on some sandpaper with the blank held vertically and a cicular motion till you just touch the brass tube , that usually fixes that problem Remember any woodturning does relieve stresses in the timber so movement is possible , cheers ~ John

Thanks for the suggestions.

Andrew, this is a controversial point, some say sand toward centre, some say away from centre, not sure which way will work best to avoid chipping.

Fly, not sure about Tooradin, I've been down before and always great, but weekends at our place is full of sporting and other commitments, I'll see how I go.

John, it's funny that you say you don't have many problems with olive wood, I don't usually have problems with other wood but have found olive wood a little temperamental. Also I have the mandrel fairly loose and often the barrels spin so I end up tightening just a little. Must try your suggestion of rubbing the blanks on some sandpaper, I tried this before and found that I couldn't quite get the barrel perpendicular to the sandpaper and it created a small gap when I assembled the pen to the centre band.

Tigar you need to hold the barrel as close to the end on the sandpaper as you can, you can feel when its flat or if its tipping slightly , A little practice and it will become second nature cheers John

Tiger, if the wood is the "chippy" type, then maybe the last 2mm with coarse sandpaper, and then finish with the different grades.
There is a good point in sanding out away from the centre--if it is a light coloured wood--sometimes the metal filings will stain the wood if you go from the bushing towards the centre;-----, whereas if you start centre and move outwards you can avoid staining the wood. Amos

Good point Amos, I've stained blanks in the past so I'll remember to sand from the centre (also done this with black wet n' dry sandpaper which seems to stain the lighter woods).


John, I'll keep practicing that move to sand the edges of the barrels, good tip.

This is a new one on me. I have had chipping from blanks when I am cutting with the skew, but never with sandpaper. Your method of sanding from the outside in is better for preventing chipping, when you go the other way the last bit of wood is unsupported and can chip. This outside in direction of sanding will carry dust from the bushing onto the blank, but a wipe along the grain with a dish scrub pad will clear the sanding dust.
I suspect the cracking is due to the loose bushings you mentioned in one post. If the blank spins against the bushing, it is possible for a bump in the blank to catch on a nick in the bushing and pull a chip out of the blank. I worry that you talk about the blank slipping during sanding. You might be pressing too hard on the sandpaper if you are getting slipping. A light touch, with the sandpaper always moving is prefered. Let the paper do the work. I recommend every penturner read Russ Fairfield's 5 rules of sanding:
FS-102

It is also possible to clean-up the end of non-stepped bushings with a disk-sander blank-squaring jig.

Hope this helps,
Brad Harding
HardingPens.com

Originally Posted by HardingPens

This is a new one on me. I have had chipping from blanks when I am cutting with the skew, but never with sandpaper. Your method of sanding from the outside in is better for preventing chipping, when you go the other way the last bit of wood is unsupported and can chip. This outside in direction of sanding will carry dust from the bushing onto the blank, but a wipe along the grain with a dish scrub pad will clear the sanding dust.
I suspect the cracking is due to the loose bushings you mentioned in one post. If the blank spins against the bushing, it is possible for a bump in the blank to catch on a nick in the bushing and pull a chip out of the blank. I worry that you talk about the blank slipping during sanding. You might be pressing too hard on the sandpaper if you are getting slipping. A light touch, with the sandpaper always moving is prefered. Let the paper do the work.

I meant to say when cutting rather than sanding from the centre out. I think the blank spun because the glue didn't adhere well. Still unsure of whether to cut centre out or outwards in but I think I'll try the latter and gauge its effectiveness.

Personally, I never drill through the end of the blank. I cut each blank longer than it needs to be, and drill about 5mm longer than the brass tube. Then cut off the end. That way you run much less risk of chipping or cracking on the end.

Tiger

Try the Sika Poly glue. It remains slightly elastic and allows a bit of give which might prevent chipping of the ends of the blank. CA goes rock hard and I have had problems with that.

Even taking all the precautions mentioned above still got some chipping but it has been reduced somewhat. It's possible that there's some microscopic cracks in my timber that may be the cause but I'll cut until the last mm or so and then use sandpaper. To prevent the microscopic cracking from ruining the piece should you apply CA just before sanding, or is there a better way to deal with this situation?

if you think it is going to chip it doesn't hurt to apply CA through the turning process as long as you don't glue your bushes to the tube. You shouldn't need to apply CA before sanding.