Dumb closed end ???

[bobleibo]

I have this feeling I am missing something or this is just too simple…. especially if it actually makes sense.
I started doing my homework on turning my first closed end pens and kept focusing on the need for various sizes of pin-chucks. I have paid close attention to the tutorials available then started thinking – I hate when that happens – why can't the drill bit also be the mandrel? I'll try to explain it so it doesn't give anyone a headache.
- Mount the blank to drill it on the lathe
- Mount my drill chuck in the tailstock with the appropriate drill bit and drill the blank making sure to leave plenty of extra blank for the closed end portion as well as a portion that will become a waste block. Drill only as deep as needed.
- Take the drill chuck with the bit still inserted and mount it in the headstock of my lathe. Mount the blank on the drill bit inserted only as deep as needed.
- Loosen the chuck and slide the bit into the chuck deep enough so that the blank now rests against the jaws of the chuck which will prevent the blank from being drilled any deeper.
- Bring the tailstock up to the waste end of the blank and secure.
- Turn the blank to the desired shape and length and eventually part off the waste block.
- Remove the tailstock and use blue painters tape to secure the blank to the chuck and finish the closed end portion of the blank.
- Once the blank is finished, it can be removed from the chuck and bit and the brass tubes could be inserted as needed.
Am I missing something that should be blatantly obvious to someone like me? Hopefully I will get a chance after the holiday to try this out but thought I'd get some input first.
Please be kind…….
Cheers
Bob

 

[kirkfranks]

You can try, but I would think of a couple possible problems.
1. without the brass tube the thinness of the wood will probably split/explode. I konw it would with my poor skew skills.
2. you cannot get the bushing on the drill bit like you could with the closed end mandrel. I still like bushings. I do realize many don't use them much.

 

[BRobbins629]

The only thing I see wrong is that unless the brass tube is a perfect fit, you will have an off center pen. Pin chucks are fairly easy to make. I've even used the Harbor Freight transfer punches. You can usually find one that fits. If too loose wrap a piece of tape.

http://www.harborfreight.com/28-piece-transfer-punch-set-3577.html

 

[soligen]

A thought is to go ahead and glue in the tube first, then instead of the drill use a HF transfer punch or a cut off bolt as a mandrel. 1 layer of blue painters tape carefully applied can often make up for the slight size difference.

I did something similar on my recent closed end. Used a bolt with the head cut off and one layer of painters tape with a Jr Gent. However, I step drilled the hole and the threads of the bolt engaged, so I needed no tape to hold the blank on while I finished the closed end. Quick and easy - made the mandrel in the amount of time it took me to cut the head off the bolt, which I did by chucking in the collet chuck and sawing with a hack saw while it spun. Took maybe 2 minutes max.

Having the threads actually engage was serendipity. I didnt plan for it, it just worked out.

 

[steeler fan1]

Bob,

I don't think its too far fetched at all. I was watching a dvd I got from CSUSA on woodturning projects, with Rex and Kip.They made a bud vase using that exact method. After the vase was turned to form the mounted a drill chuck in the tail and drilled the cavity for the test tube liner. Then put the drill chuck in the head section and finished the bottom of the vase. They applied some blue tape to the bit to make it fit snug.

Seemed to work well for what they were doing. Always more than one way to do any project. As they say, YMMV

Carl

 

[aggromere]

I would imagine some one with good attention and good skills might be able to make that work. i make a lot of double closed end pens and they present problems at every step.

1. I have to get the blank as exactly cylindrical as I can cut it in half and then drill the appropriate depth holes starting at the inside joint were they were cut, so the grain will match up later.

2. I glue in the tubes, square them on the lathe, then remove them. I have a jig I call a coupler jig for each size pen i do closed ends with. Johnny made them. It is simply a double long steel bushing with the insdie the tube part of each tube. I use this to recouple the pen back together, remount the centers in the original holes from turning it rounf and spin it to see how out of round it is. Sometimes the holes in the two blanks don't line up perfectly straight. If it seems straigth enough I take it down to size tightly pressed in the lathe with the coupler in place so it is like I am turning one piece of two, not two. Once i get it to size. I often remove it from the lathe and spin the blanks around the coupler to check for out of round in relationship to the tubes. It happens some.

I then mount each tube on a closed end mandrel spin it and check for out of roung again. If it is only slightly out I clean it up some with my skew and sand paper and shape he end. The repeat on the other blank.

At this point i am ready to sand. I put a delrin washer or scrap washer on the mandrel following the blank so it buts up against the edge. Thjis protects the end for getting a slight indentation for the sanding. Once sanded, I clean and remount on the closed end mandrel without the washer and do my ca finish. Once I am happy with it. I remove it from the mandrel, replace the washer and then web sand with 1500 to 12k MM. If I have a lot of grooves and ridges I will start with 600 grit.

I then polish and repeat the process on the other blank. Theoretically I should have two perfectly matching ends. I sometimes glean the ends up with a sanding mill with very vine grit sandpaper. Sometime glues gets on the edge and can mess up the fit.

After that I assemble the pen. 6 or 7 out of ten turn out perfectly while the others have a variety of issues all stemming from the two tubes not being perfectly straight in relationship with each other (hole drilling issues I guess). Sometimes I can save the pen, if not, i simply cut all the finish off and move it to the metal lathe to do a controlled turn down while the two pieces are still coupled together. Once I get it exactly round, i transfer back to the wood lathe and finish shaping or sanding and finishing and sanding.

Sometimes to curcumvent the aggravation I will make the double closed end, no ceneter ring pen by doing open ended tubes. I then glue on a section of wood I iwll use as cigar ash and form it with the pen and put a head piece matching the pen on the other end and cover the seam with the cigar band. That is about the esaiest way to make them in my boo.

At that point you should have a single piece of wood with one central joint that lines of perfectly. I continue to test fit with the jig to see if I need to make adjustments.

 

[bobleibo]

LOTS of great tips to think about, I knew it wouldn't be that easy. I'm going to give it a try when I get some time and see what happens, probably use a bunch of the tips that all of you suggested as I move along. I figure the worst that can happen is I go back to square 1 but you never know unless you give it a try.
Merry Christmas everyone!
Bob

 

[wb7whi]

LOTS of great tips to think about, I knew it wouldn't be that easy. I'm going to give it a try when I get some time and see what happens, probably use a bunch of the tips that all of you suggested as I move along. I figure the worst that can happen is I go back to square 1 but you never know unless you give it a try.
Merry Christmas everyone!
Bob

Use a replaceable mandril and with a small triangular file cut slots in the thread so it is now like a tap.
After drilling your blank drill another quarter inch with a quarter inch drill.
Insert the mandril into an adjustable morse taper so you can adjust how much mandril you will need.
Add the proper size bushing onto the mandril.
Insert the blank onto the mandril and bushing.
Bring up the tailstock then tighten the mandril.
Turn away.

Wayne