jcm71
Member
You can probably subtitle this as "Floating mandrel-neat idea, or death wish at 3500RPM?"
Ever since I started turning between centers I have been mulling about how to turn a Slimline TBC using the bushings. I know the more advanced turners out there dispense with bushings and mount your tubes directly between your centers. This is for the rest of us, who do not necessarily have the patience, temperament, and/or skill to turn without bushings.
The solution I came up with, for lack of a better term, is a floating mandrel, which is not affixed to either center. The basic setup is shown here.
I cut a spare mandrel to six inches in length. MAKE SURE IT IS STRAIGHT!! The two end bushings are worn out double bushings. These ones are from old Cigar and Tycoon bushing sets, not that that makes a difference. The important thing is that they are double bushings. That is in case the mandrel floats to either center, there is at least ½ inch of mandrel in the opposite bushing. The other bushings are standard .330 inch bushings. Here is a picture of the basic setup mounted on my Shopsmith.
The tube, from a Tablet Stylus kit, is 3 and 3/16 inches long. Notice that I removed one of the spacer bushings to allow further mandrel penetration into the end bushings.
This next picture shows the whole assembly spinning at 3500RPM.
CAUTION HERE
Should you choose to try this, bring your speed up incrementally to check for vibration. There should be none. Do this before gluing your tube in your blank. Probable causes of vibration are: bent mandrel (however slight), out of center or dirty bushings, over tightened head stock. Once satisfied that your setup is vibration free at turning speed, go ahead and glue your tube in the blank.
Here I'm set up to turn a piece of unstablilized Maple Burl.
Here's the blank spinning at turning speed.
Since I can't figure out how to attach more than 5 pictures to this post, see Part Two for the finished product.
Ever since I started turning between centers I have been mulling about how to turn a Slimline TBC using the bushings. I know the more advanced turners out there dispense with bushings and mount your tubes directly between your centers. This is for the rest of us, who do not necessarily have the patience, temperament, and/or skill to turn without bushings.
The solution I came up with, for lack of a better term, is a floating mandrel, which is not affixed to either center. The basic setup is shown here.
I cut a spare mandrel to six inches in length. MAKE SURE IT IS STRAIGHT!! The two end bushings are worn out double bushings. These ones are from old Cigar and Tycoon bushing sets, not that that makes a difference. The important thing is that they are double bushings. That is in case the mandrel floats to either center, there is at least ½ inch of mandrel in the opposite bushing. The other bushings are standard .330 inch bushings. Here is a picture of the basic setup mounted on my Shopsmith.
The tube, from a Tablet Stylus kit, is 3 and 3/16 inches long. Notice that I removed one of the spacer bushings to allow further mandrel penetration into the end bushings.
This next picture shows the whole assembly spinning at 3500RPM.
CAUTION HERE
Should you choose to try this, bring your speed up incrementally to check for vibration. There should be none. Do this before gluing your tube in your blank. Probable causes of vibration are: bent mandrel (however slight), out of center or dirty bushings, over tightened head stock. Once satisfied that your setup is vibration free at turning speed, go ahead and glue your tube in the blank.
Here I'm set up to turn a piece of unstablilized Maple Burl.
Here's the blank spinning at turning speed.
Since I can't figure out how to attach more than 5 pictures to this post, see Part Two for the finished product.