Ive been making cues for about 15 years and still have problems with a joint movement. I know its critical to get the tendon, hole and pin concentric and I try to do that. I use a steady rest and do all my machining and facing with that so I know the parts fit straight. I make tiny holes in the forearm for the epoxy so there is no pressure and everything is filled with no gaps. Sometimes when im assembling it notice that after the pin starts to take the butt and forearm are not quite true and when they tighten and face up they are true. So theres gotta be some pressure there. Im thinking the pilot hole for the screw might be off a hair. Some advise would be appreciated. Thanks. Mark
A joint headaches
- Thread starter kiinstructor
- Start date
solved by CH
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Do you glue the pin in first or do you put the whole thing together all at once?
I found that everything was much more sound and likely to stay straight if I glue the pin in first and adjust it to get it turning just as true as my joint pins do. Then let it dry and reface everything the next day and assemble it. If that pin is causing sideways pressure when assembled, my experience is that eventually the wood gives into that pressure and warps.
I found that everything was much more sound and likely to stay straight if I glue the pin in first and adjust it to get it turning just as true as my joint pins do. Then let it dry and reface everything the next day and assemble it. If that pin is causing sideways pressure when assembled, my experience is that eventually the wood gives into that pressure and warps.
What Chris said about gluing and truing up the connecting pin. But how are you tapping the internal threads? Tapping tool ? Plus if your tailstock isnt dead center with the chuck you tap slightly off center, and that can cause what you're describing too.
Do you dry fit the cue & spin between centers before gluing? That will show you if your machining was accurate or not. If it spins true, but doesn't after you glued it, then you cranked it together too tightly & tweaked/compressed something. The glue will act as a lubricant & allow the pieces to be threaded together further than when dry. Threads are very strong and can easily pull the pieces together with more force than the host materials are able to withstand without distorting. It's especially bad if you have rings.
I'd suggest dry fitting before gluing, and taking care to notice the alignment of each component so that you do not go past that point when glue is used. Even the glue itself can weep into end grain & cause distortion in the face, which obviously causes a misaligned fit.
I'd suggest dry fitting before gluing, and taking care to notice the alignment of each component so that you do not go past that point when glue is used. Even the glue itself can weep into end grain & cause distortion in the face, which obviously causes a misaligned fit.
Ok guys thanks for the input. Heres my proceedure. Feel free to critique it in any way that might help. I always screw the handle into the forearm. Hold the forearm between centers and use a steady rest. Drill and bore out at .750 hole in the forearm at a depth of 1.5". Then I drill and ream a .315 hole to tap for my pin with a long 3/8 x 16 tap. ususally I go in another 2 inches with that hole. Then I drill 1/32 holes in both areas the pin area and the tendon area for epoxy pressure displacement. I usually put inlays over these areas. On the butt I hold the piece between centers again and use the steady rest. and make a tendon that is just slightly less than 1.5". Drill that and tap for the pin allowing about 1 7/8" of pin exposed. I have a 60 degree center on my pins to that I can make sure they are true. I glue with 5 minute epoxy and allow to set. Then I make notches on the tendon. I make sure this is all faces true with the tendon. I then practice fit the 2 sections and its usually very close if not perfect. Then I glue with 60 miinute epoxy and tighten. I agree with the post that the epxy does lubricate the pieces and allow for another turn but both faces were true. I allow to dry for about 2 days before making passes and at time I can usually see some movement already. So I take it out with the pass and let it hang to acclimate. Next pass runs true so I think Ive got it licked but not all but some still move. What really pisses me off is when Ive cut the pockets out and installed the inlays and the dam thing moves.
Bore the .750 after you create the threads. That way you start the threads straight and the tap is at it's strongest.
Way too far to start at 1.5" out.
Way too far to start at 1.5" out.
There is a number of different ways to pull a forearm and a handle together.
When I abandoned using a bolt to draw the two halves together my end result became far better.
[check]...IF you dry fit the two halves and it sits for 6 to 12 months [min] with no movement chances are you'll have a higher end success rate.
IMO...the number one reason for A joint failure is over tightening once the glue is applied.
Figure out a way to dry fit the two halves together with a minimal [.002 or less] run out at the A when put between centers. After the glue is applied, if you're doing things correctly, this run out should not change. If it does, you're introducing potential side pressures that will undoubtedly show up in the future as a mistake you have made in your assembly process.
You should experience far less movement once you've figured this out.
[checkmate]
When I abandoned using a bolt to draw the two halves together my end result became far better.
[check]...IF you dry fit the two halves and it sits for 6 to 12 months [min] with no movement chances are you'll have a higher end success rate.
IMO...the number one reason for A joint failure is over tightening once the glue is applied.
Figure out a way to dry fit the two halves together with a minimal [.002 or less] run out at the A when put between centers. After the glue is applied, if you're doing things correctly, this run out should not change. If it does, you're introducing potential side pressures that will undoubtedly show up in the future as a mistake you have made in your assembly process.
You should experience far less movement once you've figured this out.
[checkmate]
Others have said it but this is the problem.
You are over tightening the connection and creating internal stress.
Your faces are true when dry-fit but under additional compression they are distorting.
Next time you make a connection that runs true on dry-fit, put a 'witness-mark' on ea. pc.
When you assemble with epoxy, match up the witness marks and don't go further.
I'll leave a cue glued and btwn center & chuck in my lathe overnight. Not many move.
HTHs, KJ
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As mentioned there are all kinds of ways to make an A joint. I quit using a long tenon like you are doing many years ago, not for warping issues, but for buzzing sound issues. You would be having to use almost a 4 inch pin to make that joint system solid in my opinion with that long of a tenon. I want about 3/4" tenon with about an inch of pin sticking out. That puts a little over an inch of screw back into the solid part of the forearm and handle.
Witness-marks are wonderful things. 5 minute epoxy for an A-joint pin...not so much. Indicate on the end of your pin when you install it. See if it get the same reading after the 5 minute epoxy has set. You may be surprised to see that it has moved.
Alan
Alan
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I think witness mark is the trick. I agree also about drilling and tapping the pin thread hold first, thus eliminating the off center fit. I really want to thank you guys for your imput. Many heads are always better than one. Sincerely, thanks. Mark
Mark,
If your equipment is tuned in, try a putting a 2 inch long precision tapered collet matched to your forearm contour, not one of those split ones. Place the forearm between centers and skim the OD of the collet to make sure the OD is running true on your tapered piece.
Now chuck it up about an inch from the A Joint at an oversized OD about .025. Indicate the OD and if it is off a little, shim the jaw(s) to indicate zero. Do the same with your handle. If you can't shim it to zero you will not get a concentric A Joint with repeatability.
If both faces indicate zero, your bolt indicates true and you have a bump in the blank when you dry fit and spin it........... Your equipment is at fault or your settling for less that zero and getting cumulative error. Make sure your tenon does not hit the bottom of the hole in the forearm.
Zero takes time to shim out but it makes all the difference. You mating parts must be concentric with the spindle's bore.
JMO,
Rick
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