Splitting Pen Blanks

[Terry Hayes]

Hi everyone,

I recently purchased a "grab bag" of pen blanks from my local woodworking store. For some reason they all are splitting on me while I am turning. My tools are sharp and the mandrel is not overtightened. Any suggestions would help. I have been through two bags of tubes already and I am getting frustrated. They are 7mm slimlines. Is it possible that the blanks are too dry??? Any suggestions would be appreciated !

Thanks,

Terry

[Michael Armstrong]

Terry:
It's hard to tell from the photo but it almost looks like there was no glue under the part that blew out. What do you use to glue the tubes in? I know some people have great success with CA but I have become a firm believer in the use of 2 part epoxy.

Michael

[Terry Hayes]

I have been using the green satellite city ca. I am applying it quite liberally. The blank won't spin off or around when it cracks so I think I have enough glue on it.

[Richard Coers]

I agree with the glue suggestion. CA is not the best material to use. It would only take a drop or two to keep the tube from slipping, but not have complete coverage between the tube and the wood. I use epoxy as well. I also sand the brass with 80 grit before gluing. It lets the glue get a mechanical bond. What tool are you using? A skew is the tool of choice for smooth finish and gentle cutting. Are you using CA for a finish? If so, and you want to continue using CA for gluing up the tube, I suggest using some thin CA to stablilize the blank when you get to less than 1/8" wall thickness. Wood can't be too dry. The only problem with drying and blank blow outs, would be if it was dried too fast and some checking occured in the kiln. One last suggestion, would be to take really light cuts and slow up your tool motion when you get thin. Let the tool cut, don't force it.

[Robert McGowen]

CA is not the best material to use. It would only take a drop or two to keep the tube from slipping, but not have complete coverage between the tube and the wood. I use epoxy as well. I also sand the brass with 80 grit before gluing. It lets the glue get a mechanical bond.

Excellent advice here.......

[Terry Hayes]

I have been preparing the tube and blank by sanding the brass and applying full coverage of the thick ca. The thing that concerns me is the blank splits after I take off about 50% of the material. I am not even getting down to sanding depth. I could try using the skew. I have been using a small gouge. I never had these problems with my own blanks (walnut, maple, etc..)

[Terry Hayes]

Thanks for the quick advice everyone. I will try using the epoxy and hope for better results!

[Dan Forman]

The only time that's happened to me was when I used ca glue, never with epoxy. If it was well glued, it might split, but not fly off the tube like that. I don't think a blank could be too dry, however it's possible that they have micro cracks from being dried improperly, and tend to split easily in the turning process. Some of the exotics are prone to cracking, such a s snakewood, pink ivory, and ebony - they tend to crack when heat builds up, like when drilling. Even so, they wouldn't fly apart like that if properly glued - you would just see a crack. Try the 5 min epoxy. You can work the blank after a half hour or so. I use a bamboo bbq skewer to apply the epoxy to the inside of the blank and the outside of the tube, and use PlayDoug to plug the tube end so that the glue doesn't get inside the tube.

Dan

[Jim Burr]

Remember too Terry that pressure and heat from drilling can cause a fracture in the wood on occasion. Grain also plays a factor as does the tool and angle of attack you use. Out of about 800 pens, I've had that same split about 15-20 times. Cut off the remaining wood and add an contrasting band...might as well make lemonaide!

[Lee Koepke]

A side note (after Jim posted the idea ...) dont toss the broken blanks, square off the broken piece, find a small piece of complimentary or contrasting wood, drill a 7mm hole and epoxy it to the blow-out, and you have a 'segmented' repaired piece that nobody else will know about.

I fixed this with a piece of Corian ...

187222

[Ken Garlock]

Hello Terry, and welcome to the creek. Do stop by frequently and wade in the warm waters.:)

I haven't made many pens, but I have found that using medium density CA on the brass tubes works just fine IF you properly glue the tube to the wood blank. By properly I mean, one use sandpaper to clean the tube so the glue has a surface to adhere to. Second, when applying the CA, make sure you coat the brass at least 70%. Three work FAST when sliding the tube in place. Don't worry about CA running off the end of the blank, you will be cutting it away during the squaring & trimming of the blank prior to mounting on the lathe.

Always wear Nitrile Gloves. De-bonding agent is handy to have if by chance you get a hole in the gloves.

[Bernie Weishapl]

Welcome to SMC Terry. I have found thru the many pens I have made that I do not like CA. I use epoxy on all my pens acrylic or wood. I make sure I coat the brass and twist it when inserting. I have never had one blow out since in the last 3 or 4 yrs.

[Darren Jamieson]

Alot of good advise here. I haven't done tons of pens but in the beginning I had a couple do just what yours did and I found it to be to agressive of a cut with a tool that I thought was sharp but latter learned how to sharpen much better. Since then I have never had that problem and I could literally stop my lathe with an agressive cut if I choose to. Maybe not with a pen but certainly with a bowl.

[Kenneth Hertzog]

Very nice pen blank and had it made it thru the turning it would of been nice
I use gorilla glue with all the pens I make.
If you look closely at the grain you can see that it went the direction of the split
a number of problems could occur. when drilling the bit could of followed the grain a bit
and stressed the blank or there was a problem with the batch and they put it in a grab
bag for different projects.
what I do when it blows out like that is make a key chain out of the good piece that is left
or turn the tube around and make a comfort grip pen
you lose about an inch to put in the rubber grip
just a thought
Ken

[Augie Murgillo]

Terry sharp lathe tools make a world of difference.

[Brian McInturff]

Here is what I think may be happening. Since a piece came completely off and never was adhered to the brass tube then I suspect the hole ovaled(is that a word?) during the drilling. Hence no glue on the one site. That can happen on denser woods if the bit heats up while drilling. I retract the bit constantly and feel the blank. If the blank is hot to the touch then stop. Let it cool down and come back to it later and finish drilling. I use Medium CA and have never had a problem with it. Sand the tube like you are doing, and the CA in 23 lines along the length of the tube, insert, spinning and running it back and forth to ensure complete coverage. Then let it set. If you think it's bad blanks, take the bag back and ask the owner if he wouldn't mind turning a couple pens. If they blow out then you indeed did get a bag of bad blanks.

[Keith Christopher]

I scuff the tubes with 100 grit and put a poly resin like gorilla glue. works quite well and surely gap filling

[Don Alexander]

it looks like the wood split along the grain line .............. i have found that blanks with this type of grain pattern are susceptible to splitting out in exactly the manor shown in your picture and a very simple solution to this problem is to soak it with thin CA after gluing in your tube and before turning then turn it round and roughly 50% of the way to the goal then remove from the lathe and soak it in thin CA again (i use medium CA for gluing in the tubes ) my method for soaking it in thin Ca is to just slowly apply the CA to the rounded blank slowly letting it soak in all it will take
i use some thin dowels thru the tube to keep my fingers out of the way and let me roll the tube aroundon a folded paper towel that way i control the mess potential ........ i like to do several pens of the same type at a time which makes for zero downtime while i am letting one set of soaked blanks sit and cure for afew minutes i repeat the process on the next set of blanks
soaking the blanks in thin CA not onlyhas eliminated the type of splits in your picture but it also helps prevent later cracking on things like Cherry Burl (which will split seemingly if you breath near it)
apply the thin CA slowly and let the blank soak up all it will take , my results doing this have been very good HTH

[Dave Wagner]

I have had that happen only a couple times. I have glued them back to together, re machine them, and you almost can't tell.
I believe they were really dried out pieces.

I use the 2 part epoxy also, rough up the tubes with 80-100 grit, mix it good, I alway turn them back and forth when entering the wood to make sure they are coated good and leave to dry at least overnight. :)

[Bruce Sanders]

I use thick Ca glue exclusively and have no problems. I did blow your picture up and as others have said it looks short on glue. What speed are ypou turning at as this can cause it as well. A good soak in CA for the blank or in a bath of poly. I use Minwax wipe on poly for any blanks that look sus. You can still save the blank by filling the split out piece with an acrylic or such to make a feature out of it. I have used opals in a piece that had a natural split in it but the rest of the piece was an excellent piece of timber

[Terry Hayes]

Had good luck today by only using the roughing gouge and nothing else. Before I would finish with a smaller bowl gouge. I put no contours on the pen at all and it came out fine. My technique and tool choice must be the deciding factor when turning these slimline pens. I guess with such little wood left on the barrel you have little room for creativity!

[Lee Koepke]

Terry,

I have also used my small parting tool on woods that look like blowout material. Start from the outside and work your way in. With the gouges, you tend to start in the middle and push your way to the unsupported end. Take the parting tool to close to final, then work your skew for final shaping.