Hey guys I ave a bit of a problem and need some advise the way I machine my threads for my shafts is with live tooling drill bore and cut threads with router and thread mill . That parts ok but what I'm finding is the threads are still crooked . When I thread the shaft on the butt it is not true until I make a face to face contact with the butt I want the cue to roll straight with the shaft slightly unthreaded I want my threads to be straight start to finishthe cue shaft is indicated In both front and back in the lathe but could it still be at an angle slightly pre thread cutting I don't know what I'm doing wrong or a proper way to hold the shaft so I can make perfect threads help will be appreciated thanks a bunch
Aligning threads in shaft
- Thread starter kiinstructor
- Start date
I agree it's probably a pre-cutting alignment problem. Just because you have both ends indicated true doesn't mean there isn't a bend between the two chucks.
An easy way to check if your front chuck is holding the shaft true is to leave the back end of the shaft free and turn on your spindle at a slow speed. If you're chucked correctly, the back will run true. If it doesn't run true & you simply chuck up on it & indicate it - all you've done is bent the shaft into submission. And it will unbend itself once unchucked.
The front collet does all the work. It should hold & align your shaft perfectly. The rear chuck is used only to support the free end of the shaft.
In my video on cutting shaft threads, I show a split collet being used to support the back of the shaft but in real life, the rear chuck is tightened on a scrap of tubing with a 1" bore - purely to prevent the jaws from loosening due to the rotation. The shaft hangs free & is supported only by the front collet. All it takes is a glance to my left & I can see if the shaft is running true before threading. The rpm is slow enough that shaft "whip" isn't a problem.
Keep in mind that this is a completely different situation than chucking on a butt. The butt is large & stiff enough to resist bending. A shaft isn't.
Another option is to use a steady rest. The same "rules" apply...it's just easier to see if you're forcing something the wrong way.
An easy way to check if your front chuck is holding the shaft true is to leave the back end of the shaft free and turn on your spindle at a slow speed. If you're chucked correctly, the back will run true. If it doesn't run true & you simply chuck up on it & indicate it - all you've done is bent the shaft into submission. And it will unbend itself once unchucked.
The front collet does all the work. It should hold & align your shaft perfectly. The rear chuck is used only to support the free end of the shaft.
In my video on cutting shaft threads, I show a split collet being used to support the back of the shaft but in real life, the rear chuck is tightened on a scrap of tubing with a 1" bore - purely to prevent the jaws from loosening due to the rotation. The shaft hangs free & is supported only by the front collet. All it takes is a glance to my left & I can see if the shaft is running true before threading. The rpm is slow enough that shaft "whip" isn't a problem.
Keep in mind that this is a completely different situation than chucking on a butt. The butt is large & stiff enough to resist bending. A shaft isn't.
Another option is to use a steady rest. The same "rules" apply...it's just easier to see if you're forcing something the wrong way.
Indicate the thread mill.
Indicate the front then go in to see if it's not angled.
Indicate the front then go in to see if it's not angled.
Hi,
You could always cut your threads first and turn your tapered shafts around the X Axis by driving on a centered pin tool.
No, just kidding. That will never work for perfect concentricity. :scratchhead:
Seriously and kidding aside, if you are misaligned on your threads, could your pin be canted also? Might explain the deal on rolling straight only when faced.
One side could be off a little and the other is off a little and that may amplify on one cue and then again the stars may line up now and then and give you a good result on another.
Use a high resolution indicator and verify your chuck TRO with a precision dowel pin. If thats OK you have a procedure problem.
Good Luck,
Rick
You could always cut your threads first and turn your tapered shafts around the X Axis by driving on a centered pin tool.
No, just kidding. That will never work for perfect concentricity. :scratchhead:
Seriously and kidding aside, if you are misaligned on your threads, could your pin be canted also? Might explain the deal on rolling straight only when faced.
One side could be off a little and the other is off a little and that may amplify on one cue and then again the stars may line up now and then and give you a good result on another.
Use a high resolution indicator and verify your chuck TRO with a precision dowel pin. If thats OK you have a procedure problem.
Good Luck,
Rick
Shouldn't a chucked-up sanding mandrel show that ?
First thing I do after threading a shaft is to chuck up the sanding mandrel then spin the shaft at high speed unsupported at the tip end.
First thing that comes to my mind is that you are using v-groove 3/8-10 pins. With v-groove pins, if the major of the milled threads in the shaft is larger than the OD of the pins, then a v-groove pin will settle to one side of the hole, causing it to be cocked a little. The threads must be ground to fit the pin's threads. If you are using flat bottom thread pins then you hole must fit the minor diameter of your pins. Point being, if the hole & threads are not cut to fit the pin's diameters, then there's nothing to regulate & prevent the pin from cocking to one side of the hole while it's being screwed in. No different with installing the pin into the butt. There's more to it than cutting a hole & threading it. Using live tooling is pointless if you aren't using it to cut the right dimensions.
And don't make the fit exacting. If you OD is .372", then mill the threads to .373 or .374. If your minor is .308 like the Atlas flat thread pins, then make your hole .309 or .310. You want the hole and the threads to be cut just barely over the size of the pin so that it fits but is a smooth fit & cannot have more than a couple thou. slop. .002" slop will be a TIGHT fit that feels like you are cross threading, & requires some type of lube to smooth out the feel. Simple linseed oil inside the shaft hole is great for this. You get a smooth but no slop fit.
And don't make the fit exacting. If you OD is .372", then mill the threads to .373 or .374. If your minor is .308 like the Atlas flat thread pins, then make your hole .309 or .310. You want the hole and the threads to be cut just barely over the size of the pin so that it fits but is a smooth fit & cannot have more than a couple thou. slop. .002" slop will be a TIGHT fit that feels like you are cross threading, & requires some type of lube to smooth out the feel. Simple linseed oil inside the shaft hole is great for this. You get a smooth but no slop fit.
Funny, I was just thinking that if you can't things right, pre-finish sanding arbors will straighten it up & make things concentric to the pin & shaft bore LOL Cheating & unrelated to what you are saying, but would work.
If ti's what I'm thinking, you'll wake up in the middle of night haunted by the thought of the center hole at the small end was moved 1/128th away from the true center of the wood to compensate for that early bored hole .
:grin:
Hi,
I never chuck a sanding mandrel. Only use it between centers to bring in the epoxy substrate & clear coat dimensional coating aberrations back into concentricity. Why would you not want the tip supported if the shaft is straight? I like my tip supported in the live center because I know my X axis has been totally concentric with my taper geometry and the center of my threads for the last 8 or 9 taper passes with the face 90 degrees to the X. Faced they roll perfect on the table and also rolls with no bumps when the face is not engaged.
Rick
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Your sanding mandrels have center holes and you use a lathe dog ?
I don't install the tip and turn with the tip.
I spin at high speed to check how good that shaft is with the ferrule unsupported so the tailstock does not guide that shaft back to center.
Shafts are soft enough that the live center can guide it back to center but if the threads or face are off, the shaft will wobble about 6 inches past the chuck.
Spinning unsupported at the small end shows straightness to me.
But, it just might be me.
As to why anyone would care how the cue rolls - esp when almost
together, I'll leave to you and only repeat my oft repeated advice.
Stop rolling cues.
The real problem is you are trying to accomplish double-perfect alignment
of mating parts through threading. Basic machinging concept defines this
approach as a serious no-no.
If you want good alignment - use a shoulder on something.
Dale<who is properly aligned with shoulder to the wheel>
Damn!!!!!!!!
i'd like to see bob put a .001 or .002 shim on there to demonstrate to the laymen, just how important the facing is
just 1 or 2 1000ths at the joint = big wobble at the tip
I want to thank everyone for their help and opinions. I look so forward to viewing and learning from this forum daily. My appreciation to bob and Chris especially as they have been key in me cue building adventures. I believe I have an alignment problem I'm bending the shaft slightly pre threading operation. Bob suggests just chucking Accurately onthe joint end but the Shaft is slightly tapered there and my Collet is not tapered. Also is the split collar just a convenience issue? If your collar is tapered it would definitely hold the shaft snugged but I have no clue how to make one. I may try the steady rest operation as I will be able to see the entire shaft to ensure straightness. I lie your method bob and the result is evident when you spin the shaft on that. Motor. Thats amazing and I will aspire to make my shafts similar. Any further opinions will be appreciated and if you feel ambitious bob maybe you could make me a split collar which I will be happy to pay for and at least I'll get started in the right direction . Happiness. Mark
A tapered collar is useless unless the taper matches your shaft taper and diameter. I encourage all budding cuemakers to make their own collets. It's a pretty basic operation. If you can cut the taper on a shaft or a butt, you have the tools to make perfect collets. Practice on scrap wood if you're not sure of yourself & when you have it right, use your material of choice.
i'd like to see bob put a .001 or .002 shim on there to demonstrate to the laymen, just how important the facing is just 1 or 2 1000ths at the joint = big wobble at the tip
Brent, adding a shim is a great idea! If I get an hour to kill later today, maybe I'll make a new video.
Bob,
I agree 100% about the tapered collets. I made my set using my taper bar set up on my metal lathe and put my roller bearing on the backside and reversed the springs the other way. I don't split them and there is absolutely no gap on either side of the collet.
I make 5 point full core cues most of the time but I do make a 4 pointers using the A-Joint. After mate up I see only a couple thou at the a joint at most where before using my split collets it was always an adventure.
Since doing so my pin and shaft threading is perfect and so is the facing.
Your videos on You Tube are awesome.
Rick