Pen Turning newbie problem

[Lee J]

I've just started turning some pens, relatively straight forward job but sometimes when I've turned down to size I notice a crack on the ends or splits ? what causes this ? lathe to fast? heat? I'm lost because it happened on 3 out of the 6 blanks I turned, 2 were spalted birch and the other was maple.

 

[Spindle]

Hi

Probable candidate will be overheating during the sanding phase - could also be caused by heat generated during drilling. Are you using a lip and spur, (brad point), bit? probably the best tool for the job.

Regards Mick

 

[woodyturner]

It could one of several things sanding to fast causing heat build up to split the wood, glue overflows inside the tube and dries, the wood may be slightly longer than the tube and being crushed when you assemble, parts not straight when being pressed in or they could be there all the time from when you exit when drilling out some woods will drill with no problem some may just crack some will split wide open try a more gentle approach or cut your wood to long don't exit when drilling and cut the end of after but make sure the extra wood is on the end part not the middle or the grain wont match I hope this is of help to you and good luck we have all experienced the same problem at some time when making pens

 

[nev]

probably heat as above plus...
is yer 'ole too tight? if you need to force the brass tube into the drilled blank, when you take all the wood away the first thing to give will be the end of the freshly turned blank.
or
Pen mandrel too tight?

possibly the lathe too fast when sanding? full whack is fine for cutting but i go to slowest or stationary for sanding with the grain.

hth

 

[Tazmaniandevil]

^^What they said^^
I had one blank split on me while turning it which I believe was caused by gaps in the glue. If it's just fine cracks though I would blame heat.

 

[Neil Farrer]

I'll add my tuppenny worth to what's been said and suggest that it could be that if you have been cutting your own blanks or if the wood is part seasoned the heat issue could be exacerbated by a high moisture content in the blank. I would do exactly what you have previously done with some known kiln dried heavier fine grained woods and see if the same thing happens. I have turned a couple of thousand pens but don't recall turning Birch.I used it once in the day job (Architectural woodwork) - about three tons of the damn stuff. Left the factory having been properly dried, straight as a die, turned up on site next day looking like it had come from a banana plantation. Bloody rubbish, horrible stuff, the only use for the stuff is for hardwood lippings on drawer fronts, - stuck to something else that's not going to move like Mo Farah.

Bin the birch and try again!

 

[Lee J]

I'm using a brad point drill bit, a trimmer to trim the blanks once the tube is inserted. I think it was heat during sanding. I tried again with some more woods , applied less pressure on the wood whilst sanding and all of them were fine...

 

[woodyturner]

Well done top marks what finish do you use

 

[cornishdave]

Very nice selection of pens always good to see real wood. regards Dave..

 

[Lee J]

Well done top marks what finish do you use

I sanded down to about 1000 then used a sanding sealer, friction polish and then canabura wax (or whatever it's called).