segments
Either way is a matter of personal choice, but slipping and gluing them over an elongated tenon will give a much stronger joint. I actually prefer to make a double tenon for the end piece, when possible, so that no joint is visible at the tenon.
Regards,
Frank.
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Grouch Happens!
People usually get the gods they deserve - Terry Pratchett
Frank.
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Grouch Happens!
People usually get the gods they deserve - Terry Pratchett
Detailed instructions of the Kurt method: http://pipedia.org/index.php?title=Using_Delrin_Tenons
Regards,
Frank.
------------------
Grouch Happens!
People usually get the gods they deserve - Terry Pratchett
Frank.
------------------
Grouch Happens!
People usually get the gods they deserve - Terry Pratchett
In order to get an even taper to the outside of the stem, you need to taper the inside airway, especially if you make a saddle stem.android wrote:I've another question, what is the exact purpose of the tapered bit for the airhole? and is it ok to just use a normal 5/32?
Also, you need a gradual change in airway diameter. If you use a straight bit, you will have a sudden change in airway diameter from 5/32" to approx 1/16" about 1" from the button.
Also, at the point of diameter change, you will create a very weak area in the stem, since it will be closest to the surface, plus have a very sharp inside angle.
Hard to put into words, but you should get the gist of it. My advice: use a tapered bit, not a straight bit.
Regards,
Frank.
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Grouch Happens!
People usually get the gods they deserve - Terry Pratchett
Frank.
------------------
Grouch Happens!
People usually get the gods they deserve - Terry Pratchett
2 things, it makes the wall thinner at that point (bite through).Frank wrote:... If you use a straight bit, you will have a sudden change in airway diameter from 5/32" to approx 1/16" about 1" from the button.
Also, at the point of diameter change, you will create a very weak area in the stem, since it will be closest to the surface, plus have a very sharp inside angle.
Plus it creates a 'stress riser'... that means it's a weak point that adds and potential for failure (break/crack) right at the point where the diameter drops down to the smaller diameter.
Stresses along a gradual taper distributes loads across the entire cross section. When that cross section has a sharp change in direction, those stresses pile up at that point (stress riser).
That is also why it is kind of important to have a small radius at the base of the tenon. This obviously doesn't apply when using delrin tenon, but when you cut the tenon from the stem material itself, a radius at the base of the tenon helps to reduce the stress riser at that point.
I cannot for the life of me etch-a-sketch one of these things on a stem when I'm cutting a tenon. I've ruined more blanks doing this than I did trying to learn how to handcut a stem. Any thoughts?? Or is it just something you have to get used to doing?kkendall wrote:
That is also why it is kind of important to have a small radius at the base of the tenon. This obviously doesn't apply when using delrin tenon, but when you cut the tenon from the stem material itself, a radius at the base of the tenon helps to reduce the stress riser at that point.
Last edited by hazmat on Fri May 30, 2008 2:04 pm, edited 2 times in total.