Advice for turning celtic knot blank

[bwg]

I have a problem with turning blanks with celtic knots. I'm not sure if I'm using the wrong tool or its not sharp enough, or whatever.
More times than not when I am turning a celtic knot blank, I tend to blow it apart when I start getting close to the tube.
At first I figured that I was just getting a catch with my skew, so I quit using the straight skew and started using one with rounded edges...same result.
I am taking the lightest cuts (I believe) that I can.
Maybe I should use a scraper or EasyWood tool?
Any help would be appreciated.

 

[Bill in Buena Park]

The first thing I would check is if you are getting a good glue bond between your tube and the blank. I seem to recall poor glue coverage being the most significant factor, and possibly glue choice - many opt for epoxy in this case, although I've never had an issue using CA.

 

[jttheclockman]

Hello Bruce

Are these blanks you made and if so what is the materials used??? What is the glue of choice if these are your blanks???

Presentation of the tool to the material is also a key factor, not only sharpness of the tool. Control of the tool is important too. As you move the tool along the rest you need to keep it solid and at the same angle. Any dip in arm angle or tool dip will cause problems. I am a firm believer in the use of the skew.

 

[duncsuss]

I treat all segmented and laser-cut blanks the same way I treat burls -- I stop frequently and apply thin CA to fill any small voids and fix the places where segments weren't glued together perfectly.

Bill's comment about glue coverage between the brass tube and the blank is correct -- a small patch where glue is missing allows the blank to flex under the cutting edge of your tool. When it bounces back, you have a chunk torn out.

 

[Brian G]

I'll probably be admonished and risk handfuls of offcuts thrown at me, but I say there's nothing wrong with switching to sandpaper when you're close to the finished dimension. If it's a blank you have made, you've invested more time in making the blank before turning than you will invest in the actual turning.

Why let pride or stubbornness of the need to use a turning tool get in the way of finishing a beautiful pen?

As mentioned, make sure you have good adhesive coverage on the mating surfaces.

I used sandpaper for the last three or four thousandths before the finish on this pen.



If I handed it to somebody and said, "here, it's yours," should they care that I didn't use a turning tool right to the end?

 

[jmm666]

I have made several celtic knot pens and some have had accidents. I believe the problem is the tiny pieces that result from a completed knot. Where the lines cross, there are some tiny pieces trapped between them. There was a previous comment about glue and that is the major issue. If there is no glue holding these little pieces to the tube and they are not held firmly to each other, then they will break free.
The solution is to ensure good glue coverage when assembling the segmented pieces and again when inserting the tube.

 

[leehljp]

On thing not mentioned yet is speed. Slower turning speeds will catch more if consistent and slow movements are not rigidly adhered to. Faster turning speed means smaller bites will be taken for any given movement.

For me, I added CA as mentioned above, turned at 2400 or greater speed, moved the tool very slowly, added CA and repeated.

For my chisel, I also had a 1/4 sheet of 800 sandpaper, 1/4 sheet of 1000/1200, 1/4 of 2000 or higher SP. After 3 or 4 bites, I took a couple of swipes on the highest SP. (IF you are using carbide, skip that.)

I keep my tools freshly sharpened moment by moment.

BRIAN G: Not throwing anything here :biggrin: but I do have a question about sanding the last few micro mms. I do that on most blanks, but not on segments, as I get plenty of metalic sanding dust ground into the wood (400/600 SP). How do you keep it out? I sure would love to see a tutorial on that as in general I like to sand the last few micro mills. Thanks.

 

[Charlie_W]

All good advice!
I just wanted to add that you may want to use some thin CA inside the drilled hole before gluing in the tube. I also would glue the tube in with epoxy....placing epoxy inside the blank as well as on the tube being inserted.

Good luck!

 

[Brian G]

BRIAN G: Not throwing anything here :biggrin: but I do have a question about sanding the last few micro mms. I do that on most blanks, but not on segments, as I get plenty of metalic sanding dust ground into the wood (400/600 SP). How do you keep it out? I sure would love to see a tutorial on that as in general I like to sand the last few micro mills. Thanks.

Hank, I try to restrict the sanding to the ends so that I avoid metallic dust. Whatever I create, I use a tack cloth, then compressed air, and DNA lengthwise to remove as much as I can.

Using dark woods helps, too. :biggrin:

 

[GaryMGg]

That's one mighty fine Celtic Knot pen Brian.

 

[jttheclockman]

Do you think the answers found a home?? Once again

 

[Brian G]

Thank you, Gary. It was a backup entry for the 2016 BASH Ballpoint Contest. The piping on the lower barrel was supposed to be 8 stripes to complement the 8 loops in the knot, but I made a mistake cutting the grooves and had to settle for 4 stripes.

 

[bwg]

Thanks

Thanks for all the thoughtful replies. I will apply these to my further attempts and let you know the results.
I think the idea about better gluing to the tube make good sense and just might be appropriate for my efforts

Thanks again to everyone