Finishing with no Bushings

[Wheaties]

It was brought up in another thread that someone will turn the blank close to the final diameter and then remove the bushing and finish to final dimensions using a caliper to exactly match the kit. I have a couple questions about this:

1) Doesn't putting a blank between 60 degree centers cause the stress to act perpendicular the the brass tube? In other words, pushing out instead of longitudinally through the tube. Doesn't this greatly increase the likelihood of cracking?

2) If not, why do any of us use any bushings ever?

 

[Paul in OKC]

Overall, the greatest stress on the blank this way is at the ends. Yes, I think it could cause a crack to start, but generally would think it not too much of a problem, It will put a slight 60 degree chamfer of a sort at the each end of the tube. (I don't finish this way, just my thoughts)

 

[Monty]

This is true, but you need very slight pressure on the ends as you should only be making very light cuts (with a sharp tool) or sanding. You want just enough pressure to drive the blank without slipping.

 

[rjwolfe3]

I think if you don't over tightening and then lightly press when sanding, you should be all right. I least I haven't had a problem yet.

 

[mick]

Zach,I'll turn mine down to the bushings, checking frequently as I creep up on the final diameter. I do all my sanding and the first couple of coats of thin CA with the bushings in place. I THEN remove the bushings, sand the ends slightly on a perfectly flat surface using 600 grit paper, put the barrel back between centers and finish. This accomplishes a couple of things. I never have CA sticking to bushings. I always get the ends of the barrels sealed and most importantly I never have my finish "lift" on the ends. Minimal pressure on the tailstock is required to hold a blank for finishing so you be in no danger of distorting the tubes. I usually let my finish cure overnight so the next day I put the barrel back on the bushings and do my final sanding and buffing. Yeah I cracked a couple of barrels at first but once I realized not much pressure was needed that ended and I get much better finishes and no glue on my bushings...YMMV
Mike

 

[bitshird]

Zach, I turn close to my steel bushings and if it's a pen I've been to lazy to make delrin bushings for use a set of delrin bushings with a 40 degree taper and a (yuck, dare I say the word) Mandrel to sand to finish diameter and apply CA that way, Most of the kit's I use I have made between center bushings for with one twist, I've drill through them and reamed them to .248 so I can finish both pieces at once.

 

[Bree]

I turn with bushings until finished but there is a lot to be said for this technique. I just did a Cocobolo Sierra over the weekend. I was a nice piece of Coco... not the best but nice enough. It turned well and I started to do a CA finish on it. Not surprisingly, when I go to the end I had a beautiful hard finish with a cloud in there. I think I wet sanded some moisture into the CA which clouded it up.

Very annoyed about it, I turned it back down to wood and used another finish method. I inserted the back end of the Sierra and was shocked to find that I had a high edge on the wood. I looked at the bushings and lo and behold there was a substantial accumulation of CA on the bushings.

I turned down to the bushings but they had grown from the CA. It was like ice on a Bering Sea crab boat! I had to chisel off all the CA from the bushings (cutting my thumb in the process) and return the wood down to the real bushing level and refinish it yet again!

Removing the tube prior to finishing and putting it on centers or even switching to Delrin bushings would prevent the insanity and aggravation that I just went through. And probably yield a decent pen!!

 

[RDH79]

This is the way i finish mine. I just put enough pressure to spin the blank. I only sand I do not cut without bushings. I also make sure the ends are coated with Ca to seal the finish so moisture doesnt get under. Yes I still once in a while get that cloud spots on the ends but I just sand back down and apply Ca. Works for me.

 

[Texatdurango]

it was brought up in another thread that someone will turn the blank close to the final diameter and then remove the bushing and finish to final dimensions using a caliper to exactly match the kit. I have a couple questions about this:

1) doesn't putting a blank between 60 degree centers cause the stress to act perpendicular the the brass tube? In other words, pushing out instead of longitudinally through the tube. Doesn't this greatly increase the likelihood of cracking?

I turn between centers on all the kit pens i do and have never had a problem, of course i don't crank the tailstock so tight it wants to split the blank to pieces!

rather than focus on reasons it won't work, why not give it a try, i have yet to meet a turner who tried it and went back to finishing with bushings. All you are doing is sanding and applying ca or finish of your choice and you would be suprised how little holding power you need to keep a blank from slipping.

2) if not, why do any of us use any bushings ever?

Good question! I use bushings to get close and that's it. I have turned pens without any bushings and they came out just fine. Tools i thought i was "supposed to use" like pen mandrels, pen presses, bushings, tube insertion tools, and blank drilling vices are now just collecting dust in the shop.

...

 

[JimB]

Bree - next time yoiu should just soak the bushings in aceteone to get the ca off.

 

[Bree]

Bree - next time yoiu should just soak the bushings in aceteone to get the ca off.

I thought about that but the sheer volume would probably have taken a lot longer to dissolve through than just getting under the layers and chipping them off! But at least I wouldn't have poked a super sharp chisel into my thumb!!! OUCH!!!

 

[JimB]

I thought about that but the sheer volume would probably have taken a lot longer to dissolve through than just getting under the layers and chipping them off! But at least I wouldn't have poked a super sharp chisel into my thumb!!! OUCH!!!

Yeah, it will take a few minutes. I have a very small jar I keep full of acetone. I use it to soak bushings and sometimes my live and dead centers (just the tips) when they get coated. Usually I just let them soak for a minute or so and then use a cloth, not paper towel, to wipe off the ca. Sometimes it needs a second soaking. It's better than the OUCH process.

 

[bitshird]

Yeah, it will take a few minutes. I have a very small jar I keep full of acetone. I use it to soak bushings and sometimes my live and dead centers (just the tips) when they get coated. Usually I just let them soak for a minute or so and then use a cloth, not paper towel, to wipe off the ca. Sometimes it needs a second soaking. It's better than the OUCH process.

I hate to bring it up, but you can also get a buildup of CA on Delrin, it's just easier to get off, I also keep a small pimento jar over my lathe with Acetone for stripping CA.

 

[workinforwood]

If I'm building a pen that will be CA finished, I turn the pen to size with the johnny bushings, then remove the bushings, mount the pen directly between centers, sand just a little bit and then apply the CA. It will not hardly damage the tubes, it will chamfer them a bit right at the end which effects nothing. Just don't over tighten it or you will obviously split and crush the pen. I sand the pen after applying the finish while between centers, polish it, whatever needs be done. Then I remove the blank, I'll sand down any large overhanging pieces of CA off the ends by hand and finally use a barrel trimming sander to clean up the ends and ensure they are flat and square. I use a mic as I go too. Over time CA builds up on the centers. The CA is easily scraped off the centers too..just fire up the lathe and touch it with a skew and the CA is gone.

 

[RussFairfield]

The only reason you will need the extra gripping power of the bushings and mandrel screw will be for the high stress of the intermitent cut while tuning the square blank to round and removing a lot of wood between round and finishen pen diameter.

I usually turn the blanks to round between centers BEFORE drilling them. This removes all of the excess wood, and the round blanks can be held with less pressure, both with a mandrel or between centers. Also learning to use a skew chisel for this rounding will have less cutting force than any other tool you could use.

After the wood is round, holding it between centers can be a better way to hold the pen, the cutting stresses are less after it is round, and the outside will always be concentric with the tubes.

You should ALWAYS be taking those light finishing cuts with the turning tool AFTER it has been removed from the mandrel and put between centers. If you only sand and finish between centers, any oval shape from the mandrel will still be there and you have accomplished nothing.

If you have to use enough pressure to expand the brass and crack the wood, you are using a dull tool or the wrong tool, trying to remove too much wood with each cut, or you are using way too much pressure on the sandpaper and need to loosen your grip.

Also be aware that heavy sanding can cause an oval pen barrel because of differences in the wood grain, and that sanding between centers will not solve this problem.

 

[Bree]

The only reason you will need the extra gripping power of the bushings and mandrel screw will be for the high stress of the intermitent cut while tuning the square blank to round and removing a lot of wood between round and finishen pen diameter.

I usually turn the blanks to round between centers BEFORE drilling them. This removes all of the excess wood, and the round blanks can be held with less pressure, both with a mandrel or between centers. Also learning to use a skew chisel for this rounding will have less cutting force than any other tool you could use.

After the wood is round, holding it between centers can be a better way to hold the pen, the cutting stresses are less after it is round, and the outside will always be concentric with the tubes.

You should ALWAYS be taking those light finishing cuts with the turning tool AFTER it has been removed from the mandrel and put between centers. If you only sand and finish between centers, any oval shape from the mandrel will still be there and you have accomplished nothing.

If you have to use enough pressure to expand the brass and crack the wood, you are using a dull tool or the wrong tool, trying to remove too much wood with each cut, or you are using way too much pressure on the sandpaper and need to loosen your grip.

Also be aware that heavy sanding can cause an oval pen barrel because of differences in the wood grain, and that sanding between centers will not solve this problem.

Those are some pretty darn good tips! Thx!!
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