dai sensei
11th October 2011, 10:39 AM
Not a pen, but the mandrel would work for closed end pens too if the appropriate diameters were used, so I have put it here.
I previously used a homemade jig from a dynabolt, but it only took a minor out of square end or knock during turning and the ends were not turned central to the tube. So I discussed the problem with my helpful fitter & turner Gawdelpus (John) and we came up with the following chuck/mandrel. I'm down in Melbourne at the moment and have access to my father's metal lathe.
Basically it is a brass round turned down to suit a collet chuck at one end, and the inside dia of the o-ring at the other. I could have turned a M2 taper, but straight is easier and I have a full collet set. The o-rings have an outside diameter to suit the brass tubes to be held. I used a 1/4" bolt, but for pen mandrel, you should consider 3/16" threaded rod. You could also use steel instead of brass, it's just what I had access to.
I then used Delron rod, as it doesn't stick with CA, turned down to the bush size at one end, and the inside dia of the brass tubes for the remainding sleeves. The last Delron sleeve needs to be long enough to ensure assembly is longer than the brass (by 2x o-ring thickness). The washers are turned down to be less than the Delron, and the bolt heads are also turned down to minimise length.
The whole assembly fits neatly into the brass sleeve, and by tightening the bolt via a slot cut to suit a screwdriver and spanner on the nut, it holds the sleeve by the o'rings at each end of the brass tube. I also made another for the shorter tube, it was easier than mucking around with sleeve sizes on the longer chuck.
Works a treat, just need to get back to Gold Coast to try it.
Cheers
I previously used a homemade jig from a dynabolt, but it only took a minor out of square end or knock during turning and the ends were not turned central to the tube. So I discussed the problem with my helpful fitter & turner Gawdelpus (John) and we came up with the following chuck/mandrel. I'm down in Melbourne at the moment and have access to my father's metal lathe.
Basically it is a brass round turned down to suit a collet chuck at one end, and the inside dia of the o-ring at the other. I could have turned a M2 taper, but straight is easier and I have a full collet set. The o-rings have an outside diameter to suit the brass tubes to be held. I used a 1/4" bolt, but for pen mandrel, you should consider 3/16" threaded rod. You could also use steel instead of brass, it's just what I had access to.
I then used Delron rod, as it doesn't stick with CA, turned down to the bush size at one end, and the inside dia of the brass tubes for the remainding sleeves. The last Delron sleeve needs to be long enough to ensure assembly is longer than the brass (by 2x o-ring thickness). The washers are turned down to be less than the Delron, and the bolt heads are also turned down to minimise length.
The whole assembly fits neatly into the brass sleeve, and by tightening the bolt via a slot cut to suit a screwdriver and spanner on the nut, it holds the sleeve by the o'rings at each end of the brass tube. I also made another for the shorter tube, it was easier than mucking around with sleeve sizes on the longer chuck.
Works a treat, just need to get back to Gold Coast to try it.
Cheers