Crack'n a perfect blank

[barrysj]

So you go through all of the work to get your blank perfect. TBC, Sand, Micro Mesh, multiple coats CA, sand, and polish. Now the critical step comes to get the fricken bushings off the beautifully finished blank and although you take great care, your CA finish cracks and the CA on the bushings pulls off a piece of CA on the blank so that you have bare wood..: {

I've slowly perfected (or nearly) every other part of pen turning but this final step.

I've tried the derlin bushings only to have similar issues, I even try to use a parting tool very lightly on the bushings to "separate" the bushing from the blank. I get the same outcome, and my derlin bushings keep getting smaller :wink:

Does anyone have a tried and true method?

Thanks,
Dude

 

[hunter-27]

Don't use the bushings for applying the finish, just put the barrel between centers with just enough pressure and finish as you usually would.

 

[hdtran]

So you go through all of the work to get your blank perfect. TBC, Sand, Micro Mesh, multiple coats CA, sand, and polish. Now the critical step comes to get the fricken bushings off the beautifully finished blank and although you take great care, your CA finish cracks and the CA on the bushings pulls off a piece of CA on the blank so that you have bare wood..: {

I've slowly perfected (or nearly) every other part of pen turning but this final step.

I've tried the derlin bushings only to have similar issues, I even try to use a parting tool very lightly on the bushings to "separate" the bushing from the blank. I get the same outcome, and my derlin bushings keep getting smaller :wink:

Does anyone have a tried and true method?

Thanks,
Dude

Wax the bushings before you start. Then, when you apply the CA, if you wait until each layer is completely cured, you can loosen the mandrel slightly, and break the bushing from the pen, then, retighten the mandrel and apply the next layer of CA.

I don't own Delrin bushings (yet). I am coveting the conical bushings that one of the members here sells (Johnny CNC if my memory serves me right; who was recently in an accident; we are all pulling for him).

Best,

hdtran

 

[ThomJ]

I use Johnny's conical delrins, love them

 

[soligen]

Don't use the bushings for applying the finish, just put the barrel between centers with just enough pressure and finish as you usually would.

+1

I end up gluing the blank to the centers, but I cut the glue before removing and then trim the barrels - before final sanding and polishing

 

[aggromere]

I haven't used a mandrel in years. but Johnny convinced me to get his mandrel finishing bushings. I have had no issues using them. I turn oon the steel bushings TBC. Then sand on the delrin TBC bushings and then move it to the mandrel with his finishing bushings for the CA finish. So far it works fine. I occassionally, but rarely get a white spot under the finish at the end of the tube. Sometimes I can drip some thin ca behind the ca (it has separated due to moisture) and it fixes it. But now i make sure I over lap my finish to the edges of the wood so that when I wet sand I dont get that problem anymore and then when I am completely finished I use a sanding mill and clean up the ends and then assemble the pen.

 

[barrysj]

Don't use the bushings for applying the finish, just put the barrel between centers with just enough pressure and finish as you usually would.

How do you sand off the "rounded" edges that get left by going bushingless? I've tried with my disk sander ( used for squaring the blanks), but it can cause cracks on the edge of the blank due to the high grit count and force.

 

[Mr Vic]

Here's what I use. UHMW cones. Cut a block, drill 1/4" hole, mount on the mandrel and turn into a cone. CA will chip right off as it doesn't penetrate or just soak in some acetone.

When you remove the pen section you will have some excess at the cone but they'll pop right out. I use a sandinig disk on a dremal to trim up. I use the same setup for buffing. The coned shape lets you get to the ends. I find a bags of assorted pieces at my local Woodcraft.

 

[hunter-27]

Don't use the bushings for applying the finish, just put the barrel between centers with just enough pressure and finish as you usually would.

How do you sand off the "rounded" edges that get left by going bushingless? I've tried with my disk sander ( used for squaring the blanks), but it can cause cracks on the edge of the blank due to the high grit count and force.

I guess I feel you answered your own question. Use finer grit paper, you are dealing with a very thin edge, unless you are gooping the ca on a lot thicker than me I see no need for "rough" paper to do the job. My opinion, others may vary, hope it helps.

 

[warreng8170]

I have an old oval skew that I never use for turning (never could use it as good as a flat skew) so I keep a good sharp point on it and use it similar to what you were doing with the parting tool. The good thing about the skew is it doesn't take down your bushings.

 

[barrysj]

Here's what I use. UHMW cones. Cut a block, drill 1/4" hole, mount on the mandrel and turn into a cone. CA will chip right off as it doesn't penetrate or just soak in some acetone.

When you remove the pen section you will have some excess at the cone but they'll pop right out. I use a sandinig disk on a dremal to trim up. I use the same setup for buffing. The coned shape lets you get to the ends. I find a bags of assorted pieces at my local Woodcraft.

Thanks for the replies so quick, what is UHMW?

 

[Nick]

I use Johnny's conical delrins, love them

I use Johnny's conical bushings as well. I keep them set up on an extra lathe.
They are not expensive and will solve the problem.

 

[lwalden]

Here's what I use. UHMW cones. Cut a block, drill 1/4" hole, mount on the mandrel and turn into a cone. CA will chip right off as it doesn't penetrate or just soak in some acetone.

When you remove the pen section you will have some excess at the cone but they'll pop right out. I use a sandinig disk on a dremal to trim up. I use the same setup for buffing. The coned shape lets you get to the ends. I find a bags of assorted pieces at my local Woodcraft.

Thanks for the replies so quick, what is UHMW?

UHMW = Ultra High Molecular Weight- very dense, slippery material similar to Delrin.

 

[jlmort1980]

I use my steel bushings to finish but before I remove the bushings I use an exacto knife and score the ca finish just off to the side of the finished piece. THen when i remove the piece and the bushing is stuck to it just a little gentle pressure and it pops off leaving just a little extra CA which is easily removed with some fine sandpaper

 

[Timbo]

Don't use the bushings for applying the finish, just put the barrel between centers with just enough pressure and finish as you usually would.

How do you sand off the "rounded" edges that get left by going bushingless? I've tried with my disk sander ( used for squaring the blanks), but it can cause cracks on the edge of the blank due to the high grit count and force.

I apply CA between centers without bushings also. I clean up the edges using a barrel trimmer. I don't use a drill...I do it by hand. Mount the finished blank on the trimmer (with the appropreate sleeve of course), press it lightly against the trimmer as you rotate it. I do this with increasing force as the edge of the blank gets cleaned up. You can feel the rotation getting smoother, and you'll know when it's done. If your trimmer is sharp, the CA wont crack, it will be sliced off leaving a clean edge. I have not ruined a single blank using this method. Takes about 30 seconds to clean both ends of a blank.

 

[robutacion]

Don't use the bushings for applying the finish, just put the barrel between centers with just enough pressure and finish as you usually would.

How do you sand off the "rounded" edges that get left by going bushingless? I've tried with my disk sander ( used for squaring the blanks), but it can cause cracks on the edge of the blank due to the high grit count and force.

Hi barrysj,

You could look here for the answer to your question...!

Disclaimer: I have no financial game or any other reward of any kind from suggestion this site...!

Cheers
George

 

[chrisk]

+1 on Johnny CNC's conical Delrin bushings and between centers finiishing. Never had CA issues since.

 

[barrysj]

Thanks for all the great info. I think I'm going to go with the eliminator bushings from Johnny and make a pen sanding mill to trim it up (but I will try the barrel trimmer idea, sounds interesting)

thanks

Dude

 

[Drstrangefart]

I made a small skew by forging a huge galvanized nail into the shape I wanted and tempered it, then sharpened it. I use it to cut through the CA at the bushing/barrel joint, and then break everything loose before I Micromesh. I also clean off the bushings if they're bad to avoid the jagged edges beating up the MM pads.

 

[barrysj]

Ok,

I turn between centers and couldn't find a conical bushing for TBC on Johnny's site. It looks like there is only the eliminators that you put on the 7mm mandrel. Do they have conical bushings for TBC? I'd rather not have to change my chucks out....

 

[sbwertz]

I have the delrin bushings, and like them for larger pens. For 7mm pens I simply remove the bushings and replace them with pieces of brass tubing. I have had no issues with the ca sticking to the brass tubes because they are so much smaller than the pen blanks. And the brass doesn't transfer the gray discoloration like the steel bushings do when sanding. After removing the blanks from the mandrel I give them a couple of turns with my hand pen mill (barrel trimmer with a wooden handle) to remove any remaining CA on the ends.

 

[Drstrangefart]

I have the delrin bushings, and like them for larger pens. For 7mm pens I simply remove the bushings and replace them with pieces of brass tubing. I have had no issues with the ca sticking to the brass tubes because they are so much smaller than the pen blanks. And the brass doesn't transfer the gray discoloration like the steel bushings do when sanding. After removing the blanks from the mandrel I give them a couple of turns with my hand pen mill (barrel trimmer with a wooden handle) to remove any remaining CA on the ends.

I like that idea as I already have the requred materials on hand for it! Thanks!!!

 

[barrysj]

I have the delrin bushings, and like them for larger pens. For 7mm pens I simply remove the bushings and replace them with pieces of brass tubing. I have had no issues with the ca sticking to the brass tubes because they are so much smaller than the pen blanks. And the brass doesn't transfer the gray discoloration like the steel bushings do when sanding. After removing the blanks from the mandrel I give them a couple of turns with my hand pen mill (barrel trimmer with a wooden handle) to remove any remaining CA on the ends.

Sharon,
Thanks for the idea.....i have cut small pieces of brass tubes for the jr gent etc and slid them on johnny cnc's bushings and finished with ca. Havent had an isue since. I dip gthem in wax to help keep the ca from sticking and drop them in nailpolish remover after three or so finishings....thanks again.

-Dude

 

[seamus7227]

I just always use my x-acto knife with the lathe off, spin it by hand, and using a new blade, cut right on the edge between the bushings and the blank. I've been doing that for 2 years now and never had a problem. but I want my edges to match perfectly with the pen kit and not be slightly rounded over which is what i get when going between centers.