Coring question

Stop drilling is not necessary as long as you have a machine powerful enough to handle.

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The drill should be at least. 630 for a 5/8 core dowel.
The exit end sometime blows out from the gun drill.
A short undersized hole would do.
Bore the entrance hole to size so the gun drill doesn't wander off line.

I did what Joey has said above and have had good results. This might be really obvious, I did check my tailstock with the gun drill bit in place and did have to do some slight tweaking to get it to run completely true with my headstock on that far of a drill. I was using the hightower style lathes, maybe you have to do this on a larger one, maybe not.

Just make sure you drill and bore a starter hole, 1" deep is enough, just enough to get the head of the gun drill to fit snugly in your blank.

If you machine has a steady rest with interchangeable collets, make one the diameter of your coring drill and put it in front of the piece to be cored and put the end of your coring drill in it and you will not need to bore a starter hole.

Kim Bye said:

Just make sure you drill and bore a starter hole, 1" deep is enough, just enough to get the head of the gun drill to fit snugly in your blank.

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It's a good Idea to rub bar soap or bees wax on the outside of the tip of the gun drill when you start drilling. Seems to prevent chatter that can get you off line from the jump.

I drill and bore a starter hole and my drill does wander. Could this be caused by feed and speed? If is so could someone give me a good starting feed and speed? I’m using an older Logan lathe with a quick change gearbox.


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waynewrc said:

I drill and bore a starter hole and my drill does wander. Could this be caused by feed and speed? If is so could someone give me a good starting feed and speed? I’m using an older Logan lathe with a quick change gearbox.


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I start out very slow until the drill starts cutting the hole past your starter hole. The bottom of your starter hole will not have the same contour as the gun drill and this is where the trouble starts. Slow and easy with speed and feed so the gun drill doesn't have the chance to hog out your starter hole before it find's it's groove. 500 rpm seems good. Then I speed up the speed to about 1200 and the feed rate. I would say it takes me 5 minutes to drill 12 inches depending on the wood. Some like BEM is a struggle other like cocobolo cut like butter. You have to feel of it while you're going so you can feel knots and such and slow down. I broke one of my gun drills on a knot once.

waynewrc said:

I drill and bore a starter hole and my drill does wander. Could this be caused by feed and speed? If is so could someone give me a good starting feed and speed? I’m using an older Logan lathe with a quick change gearbox.


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I think your compound rest is off.
Indicate the drill behind the carbide bit and down to the boring holder.

What kind of lengths are you guys drilling?

Just forearms? or longer?
I know gun drills will drill almost silly lengths in metal, I've never used one.

Thanks
smt

Ssonerai said:

What kind of lengths are you guys drilling?

Just forearms? or longer?
I know gun drills will drill almost silly lengths in metal, I've never used one.

Thanks
smt

Click to expand...

Usually 12" to 15"

Mario

What I've learned....

when coring for cues.
Unless you're doing full length cores on a 29" cue a 15" gundrill will suffice. If you can get one a few inches longer the better so you have room for a dust collection set up.
(unless you want to blow wood chips all over the place and have a mess to clean up after)
Make sure your drill is sharp.....yes, they need to be sharpened occasionally.
Especially after coring ebony and other like woods. I don't care if it is carbide...still gets dull much faster than most believe. (dull cutter and/or incorrect cutting edge angle = chatter)
Bostitch makes a spray that works well on the head and won't effect the glue bond.
Unless you using the drill for a punch hole and boring to size afterwords I would not use wax or such for fear of the glue not bonding and a possible dreaded buzz down the road.
If you are not boring after the gundrill I would also suggest scoring the inside of the host wood with some scratching paper and take the shine off the wood left over from the drill burnishing the ID of the wood. You'll get a much better glue bond between the host wood and the core.

You need air........and lots of it or you're going to over heat the wood. Turn the air on full enough to evac the chips and help cool the wood. Most probably do not have an air compressor large enough to handle the volume needed so if you're doing more than a few cores at a time, take a break and let your compressor rest up. It's going to run constantly to try and keep up.

You have to play with speeds and feeds for your particular setup. Different woods...chances are different speed/feed will perform better. Ebony is going to cut differently than BE and cocobolo is going to cut differently than both of those.
Learn how to set the drill up so you're going straight in.
I prefer mounting the drill on the tool post and let the lathe do the work.
Some prefer working harder at it and mounting the drill in the tailstock.
That much info should get you started enough to mess up a few pieces of wood.

I really appreciate OP asking the question. Trying not to hijack: thanks for the answers on depth for gun drilling. I was thinking whether to core some of the fronts up through the joint on some FS blanks, but will probably just continue solid for these. If i make more, will consider coring fronts before splicing. The ones with maple fronts. Slight BE & slight curly; but still cross grained materials.

Photo, last photo post #12
https://forums.azbilliards.com/showthread.php?t=506641


Will watch for gun drill(s) on the popular auction site & eventually make a snap decision. I use a planer for most cue work that is usually done on a lathe; so if a gun drill is acquired, will probably set it up in the tool slide, and the rotary parts on the bed, like my profile rig. All my lathes are small SB + Hardinges.

smt