There is nothing earth-shattering or new here – I wanted a place to post some pictures with text for a friend of mine.
Turning pens with the standard mandrel:
I use a mandrel to turn pens when they are “7 millimeter” size. When they are larger than that I may or may not use a mandrel. There is a larger mandrel that is used for some larger pens from Berea hardwoods.
When I use a mandrel, I drive the mandrel with a 2MT collet.
This collet requires a drawbar – I use a long 3/8-NC bolt. The complete setup looks like this:
I turned the wooden knob to use with the lathe where this gets put on and taken off quite often. The other lathe where I use this set-up is almost permanently set up. I use a bolt with nuts and washers for spacers and there is no knob on the hand wheel end of the headstock (below).
I also use the MT2 collet to drive my three-wheel buffing setup, as well as my mandrel for bottle stoppers.
A few notes about the MT2 mandrels:
- you do need to tap them out with a hammer – I loosen the drawbar a few turns and tap it with a brass hammer.
- They don’t fit the mandrel “exactly” – the 1/4 inch fits the 0.246 (“7 MM”) mandrel pretty closely, but to fit the “B” mandrel (same size as an L drill bit), the 5/16 mandrel collapses considerably past its nominal size.
I also use a “mandrel saver” from PSI for the standard size mandrel.
The complete set-up looks like this:
Turning pens with barrel ID larger than the 0.246 mandrel:
I use a MT2 60-degree dead center in the headstock to drive the barrel and a 60-degree live center in the tailstock. These fit into the bushings for the pen barrel and center it better than a mandrel.
(The bushings don’t match the finished barrel in the picture above – the bushings are for the Sierra Vista while the barrel is for a standard Sierra).
Then, to finish the barrel, I remove the bushings and drive the barrel directly with the 60-degree dead center. This eliminates bringing the gray sanding dust (iron) from the bushing onto the barrel.
You will get a little slop-over of CA onto the end of the barrel – this can be sanded off, or even cut off with a sharp knife if the CA is not set up too hard. (I use a knock-out punch mounted in a Jacobs chuck in my tailstock and a purpose-built sanding disk that screws onto the 1×8 thread on the headstock.)
People, even some “experienced” penturners forget that the bushing needs some maintenance from time-to time. Things to look for in order of descending importance:
1: CA (or other crud) build-up on the step of the bushing. This is the area indicated by the point of the knife blade in the picture below.
2: CA (or other crud) build-up on the back of the bushing. This is the endof the bushing facing the camera in the photo below:
If this area is not clean, and you are running the bushings back-to-back (like on a Cigar pen), the bushing can cock slightly and throw BOTH barrels out of round.
3: Condition of the hole in the center of the bushing. The bushing should slip easily over the mandrel if a mandrel is used. Use a letter D drill but to clean and re-size the hole.
If a mandrel is not used, the end of the bushing that fits over the 60-degree center must be round and perhaps have a slight chamfer. Clean it up with a countersink mounted in a wooden handle.
4: Buildup of CA on the bushing. This can fool the woodturner into thinking the pen barrel is turned to size, when in fact it is still too large.