I could use some help. I purchased a block of Bocote, and thought I would use it on this short pipe. After making the tenon and inserting the extension in the stummel, this is what I saw:
What did I do wrong? How do I fix it? I'm really puzzled at how careful I was, then proceded to bugger it so badly...
my guess is that you faced both ends (right?) but did it with a fostner bit... which is fine but then the sections that were not faced, i.e. outside the fostner bit's circumference, butted up against each other.
I'm not sure what equipment you have, but i would turn down the extension to the size of your facing. You could also turn down the shank too, but i don't think you would have too. Then chamfer the mortise using a countersink bit.
Whenever I've had extensions that don't match it usually stems from a highpoint around the tenon. When you chamfer the mortise it makes for a real tight fit.
KurtHuhn wrote:First things first: How did you face the briar and shank extension and attempt to make the ends square?
I squared the Bocote all up and used the Pimo Tenon tool. The tool is squared up also. Maybe it's not up to the job? I did this before with Loquat wood, which is a whole lot harder...
Is there another way, other than a lathe, to make a good tenon on an extension?
bscofield wrote:my guess is that you faced both ends (right?) but did it with a fostner bit... which is fine but then the sections that were not faced, i.e. outside the fostner bit's circumference, butted up against each other.
No, didn't use a Forstner. I used a sander and made double sure it was square...
JSPipes wrote:It doesn't look like the bocote is square. Not only that, it looks curved in the picture. Are you sure you faced off the side that contacts the briar?
Yes, the Bocote is square, but I wil check again tomorrow. Thanks!
custom300 wrote:I'm not sure what equipment you have, but i would turn down the extension to the size of your facing. You could also turn down the shank too, but i don't think you would have too. Then chamfer the mortise using a countersink bit.
Whenever I've had extensions that don't match it usually stems from a highpoint around the tenon. When you chamfer the mortise it makes for a real tight fit.
Good luck.
The mortise has been countersunk. Maybe it hasn't been countersunk enough? I'll check that again.
BTW, didn't use a lathe. No turning except with the Pimo tool.
No, didn't use a Forstner. I used a sander and made double sure it was square...
Hi Michael,
Using a sander to face surfaces that need to be perfectly flat and square is virtually impossible.
You can do an acceptable job on a drill press with a forstner bit or an aircraft counter bore, but then turning a tenon that's perfectly square to the area that you've faced gets a bit tricky. I'm not sure how you'd go about that without a lathe.
Shank extensions and drilling stems were primary of the reasons I sprung for a lathe a few years ago. As Rad said, it's nigh impossible to properly square something using a sander.
If you're using a drill press, I would find one of those self centering vises (if you don't already have one) and invest in a precision-ground Forstner bit. Face the shank and drill the holes right after each other. This way you'll be confident that the hole is perfectly perpendicular to the face. Do not move the wood AT ALL until the entire operation is complete. If it moves, it will be out of alignment. I suggest facing first, since the bit will tend to vibrate and you'll have grain tear-out if you try to face after the mortis is drilled. The one piece missing is getting a tenon on either the briar or the shank extension to be sure the joint is robust and secure. You could, however, use a piece of delrin for this.
KurtHuhn wrote:Shank extensions and drilling stems were primary of the reasons I sprung for a lathe a few years ago. As Rad said, it's nigh impossible to properly square something using a sander.
If you're using a drill press, I would find one of those self centering vises (if you don't already have one) and invest in a precision-ground Forstner bit. Face the shank and drill the holes right after each other. This way you'll be confident that the hole is perfectly perpendicular to the face. Do not move the wood AT ALL until the entire operation is complete. If it moves, it will be out of alignment. I suggest facing first, since the bit will tend to vibrate and you'll have grain tear-out if you try to face after the mortis is drilled. The one piece missing is getting a tenon on either the briar or the shank extension to be sure the joint is robust and secure. You could, however, use a piece of delrin for this.
Thanks for the tips, Kurt.
I don't have a precision Forstner. I do have a Freud bit that hasn't been ground to precision. Do you have anyone that can do it on my existing tool? Or, do I need to get one already ground?
The delrin tenon sure sounds tempting at this point, that Pimo Tenon tool is out of its' league...
A precision ground forstner bit isn't all that expensive. Perhaps on the order of $15 or so, I honestly forget. But, once the bit has been initially ground, it would be a serious PITA to re-grind the cutting edges. You *might*, if you're careful, be able to get in there with a diamond hone and clean up the edge a little. When mine go dull and develop small imperfections, though, I just relegate them to the toolbox and go get a new one.
Thanks guys, it worked. I used that Freud forstner to face off the mortice and was able to get very flat. However, that caused some shredding of the surface. It was fairly easily sanded off and the parts mated pretty darn well. I've got it glued up and clamped now. It worked so well that I took one of my old shop-franken-pipes apart and put a Bocote extension on it as well (why not, the setup was fresh in my mind) and it also worked out well.
Now I think I'll get one of them thar fancy precision grounded up Forstner bits !
If you care to spring for a bit more cost than a Forstner or Freud, this little Wagner Safe-T-Planer does a great job on facing a flat surface using a Milling Machine or a Drill Press with cross slide: http://www.frets.com/FRETSPages/Luthier ... laner.html
I had almost forgotton I had the thing, but remembered it when I needed to laminate a few hardwood blocks together. I achieved perfect mating of the surfaces after planing with this item.
After planing the surface, if you remove the planer & replace it with the appropriate size drill bit, you will drill/bore your hole at a perfect 90° to the planed surface.
Regards,
Frank.
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Frank wrote:If you care to spring for a bit more cost than a Forstner or Freud, this little Wagner Safe-T-Planer does a great job on facing a flat surface using a Milling Machine or a Drill Press with cross slide: http://www.frets.com/FRETSPages/Luthier ... laner.html
I had almost forgotton I had the thing, but remembered it when I needed to laminate a few hardwood blocks together. I achieved perfect mating of the surfaces after planing with this item.
After planing the surface, if you remove the planer & replace it with the appropriate size drill bit, you will drill/bore your hole at a perfect 90° to the planed surface.
That is a slick tool. You could also use it to surface two sides of a block of briar to ensure they are flat and parallel to each other.
