Coring, tolerances?

Kim Bye · Dec 14, 2016

How many thou clearance do you guys prefer?
I`m gonna order a new gun drill from Sterling, but I`m debating with myself as to how tight a fit I should go for.
I have tried different glues now and I find that I prefer West epoxy over gorilla glue, so I`m leaning towards a fairly tight fit. .750" cores and .755" gun drill is what I`m thinking.
Any thoughts?

MVPCues · Dec 14, 2016

Why constrain the cores to .750? My gun drills are .650, 11/16, .775, 13/16.

By the gun drill and then turn your cores to match the tolerance you want with the particular glue you ultimately use. When ready to install ringwork, butt caps, etc, turn the tenons down to fit the mating component.

PRED · Dec 14, 2016

Coring 12" and holding a .005 tolerance looks good on paper. Drill a core and measure the ID and see if it holds that number. Tight fit might benefit from a couple of glue relief grooves. A pilot hole will help tremendously and a slightly smaller exit hole will minimize tear out.

whammo57 · Dec 14, 2016

I do a .010 undersize for the dowel and then sand for a slip fit.... I use gorilla glue.

I am afraid if West System soaks in it will leave voids.............

you will have to hammer in the dowel with a .005 clearance..........

don't over think it

Kim

CuesDirectly · Dec 14, 2016

Kim Bye said:
How many thou clearance do you guys prefer?
I`m gonna order a new gun drill from Sterling, but I`m debating with myself as to how tight a fit I should go for.
I have tried different glues now and I find that I prefer West epoxy over gorilla glue, so I`m leaning towards a fairly tight fit. .750" cores and .755" gun drill is what I`m thinking.
Any thoughts?

I hope you have not ordered yet, I hope I can help. First, I am assuming you mixed up the numbers, you can't drill .755" and then bore .750" Either way, it's way to close.

The thing you must consider is how much will your drill bit wobble, I promise you every drill bit will wobble more than five thousands of an inch in wood.

How far will you be drilling? Some gun drills are 12" or longer, look at the other end and see how far off center it becomes, double it and you should be about right.

Another guy recommended with a centering bit, awesome advice, it helps. I use a turret on my lathe, it starts with that centering bit, then a medium size bit before the final size, if I want a finish of .750", I will drill 45/64" bit and the bore will clean it perfectly every time.

I make my own boring bars, did my first one 30 years ago. It works better than the ones you buy with the inserts.

I hope this helps and it sounds like you're on the right track, Thanks, Dave.

JoeyInCali · Dec 14, 2016

Are you going to use stock metal or fiber rings?
Do you have a long boting bar?
On a good setup, .008" clearance is plenty.
For forearms, I use a. 700" drill these days. I bore the bottom to fit..825" by 6".
For handles, I go over 7/8.

stevel · Dec 14, 2016

I use a .760 gun drill. And my cores are .753 give or take .001 to clean up for rings.

JC · Dec 14, 2016

MVPCues said:
Why constrain the cores to .750? My gun drills are .650, 11/16, .775, 13/16.

By the gun drill and then turn your cores to match the tolerance you want with the particular glue you ultimately use. When ready to install ringwork, butt caps, etc, turn the tenons down to fit the mating component.

What if you use a full length core and want to use any kind of pre made rings at the A joint? Too big of dowel size throws a monkey wrench into these plans I learned.

The gun drills I settled on for how I want to build my cues were .631 and .756. .006 clearance and gorilla glue seems not to be a problem if you move quickly.

JC

Kim Bye · Dec 14, 2016

I`m using stock rings and rods, they are all .750" Id.
@Dave I meant .750" core and ordering the gun drill in .755"
I need to be able to drill atleast 12"
Maybe I should go for about .758" that gives me a bit more room.
As for the buttpiece, I`ll just bore that out with a long boring bar for now.
Thanks for the advice guys :thumbup:

Renegade_56 · Dec 14, 2016

with stock rings I'd core at .750 and turn the core to fit.

MVPCues · Dec 14, 2016

JC said:
What if you use a full length core and want to use any kind of pre made rings at the A joint? Too big of dowel size throws a monkey wrench into these plans I learned.

The gun drills I settled on for how I want to build my cues were .631 and .756. .006 clearance and gorilla glue seems not to be a problem if you move quickly.

JC

Add steps in the core and Counterbore the rear of the forearm to .750, the rest of the forearm being .650 or 11/16. Nothing says a full length core has to be the same diameter the entire length.

I also made a ring expanding jig.
http://dzcues.com/trim_ring_jig.html
Works perfectly for increasing the inside diameter of already cut/purchased rings. With that, the entire core can be the same diameter and you can increase the inside diameter of prefab metal rings with zero problem.

Kim Bye · Dec 14, 2016

MVPCues said:
Add steps in the core and Counterbore the rear of the forearm to .750, the rest of the forearm being .650 or 11/16. Nothing says a full length core has to be the same diameter the entire length.

I also made a ring expanding jig.
http://dzcues.com/trim_ring_jig.html
Works perfectly for increasing the inside diameter of already cut/purchased rings. With that, the entire core can be the same diameter and you can increase the inside diameter of prefab metal rings with zero problem.

That`s a nice tip, I need to make me a few of those stat!

JoeyInCali · Dec 14, 2016

JC said:
What if you use a full length core and want to use any kind of pre made rings at the A joint? Too big of dowel size throws a monkey wrench into these plans I learned.

The gun drills I settled on for how I want to build my cues were .631 and .756. .006 clearance and gorilla glue seems not to be a problem if you move quickly.

JC

You don"t thread your collars and butt plates?

I too made that ring boring jig like DZ's.
I bore the stock fiber .015" stock fiber rings with 5/8 ID.
I like my collar tenons at .675. I thread the 5/8 ID'd phenolics . I bore them to .530.

I like my handle core at 7/8 at least.
Why turn down the coring dowel down to 3/4 when 7/8 to .900" are just fine?

QMAKER · Dec 14, 2016

Boring bar

Kim Bye said:
I`m using stock rings and rods, they are all .750" Id.
@Dave I meant .750" core and ordering the gun drill in .755"
I need to be able to drill atleast 12"
Maybe I should go for about .758" that gives me a bit more room.
As for the buttpiece, I`ll just bore that out with a long boring bar for now.
Thanks for the advice guys :thumbup:

.758" should do the job nicely.

cueman · Dec 15, 2016

I use a .775 coring drill and a .765 core dowel. This gives plenty to cut to match .750 to .755 ring work.

JoeyInCali · Dec 15, 2016

cueman said:
I use a .775 coring drill and a .765 core dowel. This gives plenty to cut to match .750 to .755 ring work.

Less than .050" wall on top of the forearm sleeve worries me just a bit.

QMAKER .758" should do the job nicely

Plenty. .005" and some sanding ( if needed ) lengthwise with a 120 grit is plenty for a good setup.
It doesn't hurt to make a sanding dowel for the sleeve too, to scratch the inside of the sleeve.
A 120 grit paper rolled around a smaller plunger going up and down the sleeve to scratch the inside doesn't hurt imo.

cueman · Dec 15, 2016

JoeyInCali said:
Less than .050" wall on top of the forearm sleeve worries me just a bit.

Plenty. .005" and some sanding ( if needed ) lengthwise with a 120 grit is plenty for a good setup.
It doesn't hurt to make a sanding dowel for the sleeve too, to scratch the inside of the sleeve.
A 120 grit paper rolled around a smaller plunger going up and down the sleeve to scratch the inside doesn't hurt imo.

.775" Handles. .650" Forearms.

JoeyInCali · Dec 15, 2016

cueman said:
.775" Handles. .650" Forearms.

Ah!
My bad.

qbilder · Dec 16, 2016

Doesn't matter how you do it, so long as the end result is something you are happy with. I turn the core to fit smoothly in the bore, so that it slides in easily but enough grab that gravity cannot make it fall out. That fit means a whole lot more to me than the measurement number. If you ever core with woods other than maple, you understand what I mean.

Kim Bye · Dec 16, 2016

qbilder said:
Doesn't matter how you do it, so long as the end result is something you are happy with. I turn the core to fit smoothly in the bore, so that it slides in easily but enough grab that gravity cannot make it fall out. That fit means a whole lot more to me than the measurement number. If you ever core with woods other than maple, you understand what I mean.

Thanks. I`m experimenting with different core materials now.
I made a bunch of of samples today I simply could not measure or think my way through this.
It seems that a difference of 0.008" is just about right to get that fit you are talking about.
I have tried with maple, purpleheart, oak, jatoba and bubinga cores but only on short 8" pieces, and with different types of glue and epoxy.
Even on short pieces like that, I see what you mean about each piece needs to be tweaked to fit just right, I can only imagine that will be even more important on longer 12" - 16" pieces.
I got a quote from Sterling now, I must say the prices are very reasonable.
Is it any point in ordering the gun dril longer than 18" or will longer drills just flex too much and give less accuracy?

Coring, tolerances?

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