BODY BORING

[MCFLYFYTER]

I can not find much info on boring bodys for 18650's. Any help would be greatly appreciated. I do not have the correct size reamer. My choices would be a drill or boring bar, both in a 17x33. Which one is capable of the best results in a 6P? Also, most people like to leave a lip to retain the batteries. Any idea how much lip to leave? I am guessing about 1,000 rpm for both drilling and boring?

Thanks,
Russ

 

[precisionworks]

An 18650 can run as large as 18.50 mm (.728"). A 47/64 drill bit is .734" and would be close to the correct size.

I am guessing about 1,000 rpm for both drilling and boring?

Most aluminum alloys drill well at 250 to 300 sfpm. 1000 rpm equals 191 sfpm, a little slow but should work fine.

A boring bar, because is uses a single point cutting tip & has tons of chip clearance, can run lots faster ... 800 sfpm is a good place to start (if your spindle will run that fast) - 4200 rpm is the calculated speed. Most lathes (not counting high speed CNC machines) top out at less than that, so use the highest speed setting you have.

Which one is capable of the best results in a 6P?

A boring bar allows sneaking up on the final dimension. Take a light cut, measure, cut, measure, etc.

A drill, perfectly sharpened, can do a nice job. Or it can grab, dig in, go off center, or mess up the work in every imaginable way.

 

[MCFLYFYTER]

Thanks for the info. I ran a little test, and I think the boring bar will work just fine. I will just have to mess with the feed speed, and hopefuly by the final pass I will have it figured out. I will have to wait until tomorrow to get a dial, and to have more time to set it back up like I found it. Those machinists get mad if you monkey with their stuff and don't put it back EXACTLY like it was. Heaven forbid their lube brush is leaning the wrong direction.

 

[wquiles]

... A boring bar allows sneaking up on the final dimension. Take a light cut, measure, cut, measure, etc...

The only thing to add is that depending on the material (steel or carbide) and the overhang (multiples of the bar's dia) you might have to take a "spring cut" - meaning that you leave the boring bar at the same setting and take 1 or 2 cuts at zero again. I was quite surprised the first time I took a spring cut - still cutting even at zero!

 

[gadget_lover]

I will have to wait until tomorrow to get a dial, and to have more time to set it back up like I found it. Those machinists get mad if you monkey with their stuff and don't put it back EXACTLY like it was. Heaven forbid their lube brush is leaning the wrong direction.

I imagine they get even madder if it LOOKS like it was as they left it, but is really a touch off in one axis or more.

The nice thing about battery tubes is that the tolerances are not as demanding as some other parts. If you bore it a little large, or if bore 1 is slightly different than bore 2, it will usually cause no problems.

Daniel

 

[wquiles]

I just finished one today:

First used the boring bar to verify a centered body - just taking a very light cut:

Then I did a pass with a 23/32's (46/64") S&D drill and then a second pass with a 47/64" S&D drill (If I recall correctly done at 550RPM) using AccuLube LB2000 cutting fluid:

Fit is very nice, and not tight at all:

My notes and measurements (they do make sense in my head!):

EDIT: By the way guys, I am now using a smaller file size for the 800x600 images. Can you guys tell a difference in loading speed?

Will

 

[gadget_lover]

Nice post Will. The pictures seemto be loading fast, but I'm on a different computer than normal, so I don't know.

You raise an interesting point about centering the work. You can center on the existing bore, which may be off center. But you can also center on the external surface of the light, but it occurred to me that it might also work best if you indicate off the part that will interfere with the boring, and that's the o-ring groove or the thread run-out groove.

Centering on the outside can make things interesting if the original bore is significantly off center.

Daniel

 

[65535]

In the future I would recommend keeping the boring bar as retarded in the holder as possible. I mean that it should have the lowest overhang possible. Not hugely critical here, especially seeing as you had a rigid setup for drill with the large S&D bits.

 

[737mech]

I just finished one today
Will

Hey I recognize that light....

 

[wquiles]

Nice post Will. The pictures seemto be loading fast, but I'm on a different computer than normal, so I don't know.

Good to know. The pics are about a 1/3 of the size as before, but they still look good quality-wise, so I will keep this smaller size for how.

You raise an interesting point about centering the work. You can center on the existing bore, which may be off center. But you can also center on the external surface of the light, but it occurred to me that it might also work best if you indicate off the part that will interfere with the boring, and that's the o-ring groove or the thread run-out groove.

Centering on the outside can make things interesting if the original bore is significantly off center.

Yup. It worked out well this time as everything was fairly well centered, but I still took the two steps (with the two S&D drills) so I would not be pushing things too hard.

In the future I would recommend keeping the boring bar as retarded in the holder as possible. I mean that it should have the lowest overhang possible. Not hugely critical here, especially seeing as you had a rigid setup for drill with the large S&D bits.

Absolutely. In fact anything more than the very light cut would have been fairly futile here as the this Circle carbide boring bar was starting to "sing" as it was :devil:

Hey I recognize that light....

You are right. It should look vaguely familiar

 

[sardo_67]

i have a 6P and an 18650 i want to put in it. my brother works in a machine shop and took the body on the lathe, we did not finish because we were concerned with the end thickness near the tail cap where the O-ring groves are. is this just something that happens and is normal or are we doing something wrong?

 

[cmacclel]

Will I'd be careful using drill bits for boring work. The only time I have had things *slip* in the chuck is when drilling. This to me would have been a 100% boring bar job

Mac

 

[StrikerDown]

Will I'd be careful using drill bits for boring work. The only time I have had things *slip* in the chuck is when drilling. This to me would have been a 100% boring bar job

Mac

And look at the long chips he is getting! I am certain if I tried drilling this thin walled body this with a drill this big it would grab the whole enchilada and rip it right out of the chuck in a mess of aluminum scrap! Of course I don't have the advantage of a 6 jaw either!:twothumbs

 

[wquiles]

Will I'd be careful using drill bits for boring work. The only time I have had things *slip* in the chuck is when drilling. This to me would have been a 100% boring bar job

Mac

Point taken Mac. That is why I decided to do peck drilling (cut, back-out, clean chips, re-lube, cut some more, repeat), and why I decided to do the boring in two steps, first with the 46/64", and then with the 47/64" drill, again with lots of lubrication - I certainly did not wanted to push my luck.

And look at the long chips he is getting! I am certain if I tried drilling this thin walled body this with a drill this big it would grab the whole enchilada and rip it right out of the chuck in a mess of aluminum scrap! Of course I don't have the advantage of a 6 jaw either!:twothumbs

Yes, the gripping power spread over 6 contact surfaces is awesome. I can't say enough of how much the 6-jaw makes things so much easier.

 

[sardo_67]

but as far as the thin part near the end that's just normal?

 

[will]

When you are boring for a larger battery, centering is not all that important. The work should at least look like it is centered in the chuck.

I always check the diameter of any external grooves before I bore something out. That is one thing you learn the first time you make a mistake.

I rarely use a drill to open up an existing bore in a lathe. Too easy for the drill to grab. And, a drill will follow an existing hole, a boring tool will cut a hole that is centered in the chuck.

 

[precisionworks]

I ordered the SureFire 6PX Pro, thinking it will be a nice utility light. Of course, it makes sense to run the same 18650 (2900mAh AW protected cell) that is used in the Catapult V2. Which got me thinking about boring, as did the recent thread by Shao.

I agree with all those who recommended against using a twist drill. Drills often make an oversized hole, that hole is rarely straight, and the surface finish is ... not so good. As Will Q pointed out, a .500" boring bar, or even a .625" boring bar, will be hanging out into the next time zone to go all the way through a two cell body. But, it's the best place to start.

My plan (when the 6PX arrives) is to bore the hole to 95% of callout, then ream the last 5% with a straight shank chucking reamer. I need to measure the AW18650's, but say that they mic a little under 18.5mm (.728"). That means boring to about .690"-.695" (nothing smaller) and reaming the last bit. It should work well.

May buy a BRM FlexHone for final finishing, but that's more for appearance than anything else. Plan to do this in the 4-jaw using some type of shop made soft jaws.

More to follow ...

 

[metalbutcher]

You guys have peaked my curiosity. Do you make these flashlights totally from scratch or do you buy kits and finish them? Sorry for the rather ignorant question but I joined the forum for the excellent tool and machining advise I see on here.

Ed

 

[gadget_lover]

We do both.

Some have specialized in modifying existing lights. Look at some of Wquiles posts for some really great looking MagLites that have been sculpteds.

Others build their own. A small light (1 or 2 cells) is easy to do on a home lathe. It just takes time. Lots and lots of time.

Dan

 

[precisionworks]

I need to measure the AW18650's, but say that they mic a little under 18.5mm (.728"). That means boring to about .690"-.695" (nothing smaller) and reaming the last bit

As expected, the AW18650's are not perfectly round - they mic about 18.48 at the fattest part. Reaming to 18.5mm is not going to be large enough.

Checked my Catapult V2 and the ID is 18.75mm. Also checked a 5Mega tube (fits Surefire 9P) and it measured 19mm. The 18.75mm size is what I'm going with for now. MSC offers one in exactly that decimal size, .738".

FWIW, the 5Mega tube is pretty thin at the rear O-ring ... .751 ID, .779 OD at the O-ring. That leaves a wall thickness of only .014". Aluminum is stronger than I thought, as that tube has seen some hard use and it's still in one piece

If the Surefire tube measures the same .779 at the O-ring, and the ID is reamed to .738, the walls will be .020" thick. That sounds a lot better than .014"