# WARNING: pictures not for the faint of heart!



## shao.fu.tzer (Sep 10, 2011)

An early run C2-HA body that was blown to pieces during boring due to an improper calibration:












Eeeeek... I want to throw it away but I can't bring myself to do it... I think I'm going to stick it in under glass with a brass plaque that reads: Leave Boring to the Professionals..


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## gadget_lover (Sep 10, 2011)

That's not too bad. I expected flecks of red from where it hit you as it flew from the chuck. 

Boring is not hard, and does not require extreme skill. It does require that you follow a few simple rules. One of those rules is to turn the chuck by hand after changing the setup to check clearances. 

The skill comes in when you decide what fixture is needed to hold it securely. Chucks and collets soft-jaws and mandrils and steadys... The possibilities are endless. 

So don't give up.

Daniel


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## HotWire (Sep 10, 2011)

We are both lucky.... You are lucky you are not injured, and I am lucky that I've done a few home-boring jobs without incident. Glad you are okay!


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## shao.fu.tzer (Sep 10, 2011)

Thanks for your concern, but this was actually bored by my ex-business partner... I was no where near it when it happened... He sent it back to me and I just found it the other day and thought I'd share... I can't afford the machinery to do in-house boring right now, unfortunately, so I'm outsourcing...

Shao


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## Acid87 (Sep 10, 2011)

This looks pretty brutal. Looks like an alien burst from the inside.


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## indadark (Sep 10, 2011)

Can't buff that out.


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## ICUDoc (Sep 11, 2011)

Ouch. That hurts just to look at!


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## PEU (Sep 11, 2011)

That scratch HA3 withstand cannot <yoda> 


Pablo


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## gadget_lover (Sep 11, 2011)

I was looking at the picture, and trying to imagine the forces that ripped that apart. The long gouge (or is that a crack??) on the tailcap end for instance, was that from the jaws as it was ripped free? Was it from the boring bar biting into it as the light whipped around off center? Was it cracked because a big boring bar got hung inside the bore but the machine had enough power/inertia to keep turning?

Which makes me wonder. Is bigger always better? I have a clutch on my hand held drill/driver to keep from breaking screws as I drive them in. I have an overload on my 7x12 lathe that stops everything if the tool jams. Do they do that for the bigger lathes?

I guess in some cases smaller is better. My lathe would still have marred the finish on the light, but it probably would not have been destroyed. 

Daniel
Dan


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## Morelite (Sep 11, 2011)

That gouge looks more like it is from a grinder or cut-off disk than from a boring bar. He should have had the head end in a chuck or collect as the boring needs to be done from the tailend on those bodies. It also looks like he may have been using inserts that were not designed for aluminum if you look at the finish on the exposed section.

Here is a little mishap I had with a C2 body while boring. Not near as bad as I can and do still use it.


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## precisionworks (Sep 11, 2011)

> Was it cracked because a big boring bar got hung inside the bore ...


Probably not since the largest bar normally used is .500" diameter & the bore (from the factory) is just over .690". Boring any of the SF lights using a solid carbide bar and an aluminum specific insert generates miniscule cutting forces. 






The finish inside the tube might suggest that the tip of the insert was far above center which caused extreme chattering because the insert is approaching the tube wall at a very small angle. The finish might also suggest that the insert tip was far below center and the lower edge of the insert was dragging against the tube wall.

Best guess is that the boring tip was not at center height & the tube was not well supported.


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## gadget_lover (Sep 11, 2011)

precisionworks said:


> Probably not since the largest bar normally used is .500" diameter & the bore (from the factory) is just over .690". Boring any of the SF lights using a solid carbide bar and an aluminum specific insert generates miniscule cutting forces.
> 
> 
> The finish inside the tube might suggest that the tip of the insert was far above center which caused extreme chattering because the insert is approaching the tube wall at a very small angle. The finish might also suggest that the insert tip was far below center and the lower edge of the insert was dragging against the tube wall.
> ...


 

Actually, I was thinking that they might have used a bar that was big enough that the trailing or bottom edge of the bar was scraping the bottom of the bore. This does two things; 
1) tears up the aluminum and 
2) pushes it off center, eventually breaking it free if you are agressive enough.


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## Lightfoot98 (Sep 16, 2011)

Morelite said:


> That gouge looks more like it is from a grinder or cut-off disk than from a boring bar. He should have had the head end in a chuck or collect as the boring needs to be done from the tailend on those bodies. It also looks like he may have been using inserts that were not designed for aluminum if you look at the finish on the exposed section.
> 
> Here is a little mishap I had with a C2 body while boring. Not near as bad as I can and do still use it.




A little bit of Bondo should fix that right up!!


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## shao.fu.tzer (Sep 16, 2011)

Lightfoot98 said:


> A little bit of Bondo should fix that right up!!



Yep... Bondo or JB Weld... then sand and cerakote and you're in business!


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## Boltgun (Sep 16, 2011)

wow...in terms of boring, can one use a drill bit instead of boring bar on a lathe? newb machinist here

Boltgun


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## StrikerDown (Sep 16, 2011)

Yes but that would be drilling not boring! 

Drill bits have a few problems. They don't drill perfectly round. They often don't drill the correct size, usually too large, never smaller, unless worn or ground smaller. If drilling large delicate items they can bite just a tad too hard and shred the part. 

Will Quills has pulled off some very nice drilling jobs and posted pics here... He also has a great 6 jaw chuck to help hold delicate parts securely by distributing the holding pressure more evenly around the parts.


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## precisionworks (Sep 16, 2011)

> can one use a drill bit instead of boring bar on a lathe?


I've seen people use Dremel grinding discs instead of a boring bar which proves that almost anything is possible. 

Enlarging a thin walled tube by any method is not an easy job. Here's one that came in for a redo:






No idea what tool was used for that but metal eating termites certainly comes to mind  There was just barely enough metal left to clean up the tube & bring it out to the right diameter for 18650:

http://i12.photobucket.com/albums/a206/barrymilton/8a7cbdd7.jpg





I wouldn't even think about trying to enlarge a flashlight bore with a twist drill as replacing a damaged light can cost more than buying the correct tool.


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## shao.fu.tzer (Sep 16, 2011)

Wow Barry, I can't even begin to imagine what was used on that L5 body to get that texture! Maybe they did it with Drain-O or something...


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## PCC (Sep 23, 2011)

I had PM'd shao about that C2 in the original post. I received it just today. I cut it off and bored it to 18.65mm, which, coincidentally, is what others bore Surefire hosts to. Looking at this picture you'll see that the walls at the wider flats is quite thin on three out of four sides. If you don't put the host into the lathe right even a small bit of runout will mean that you're going through the wall. It's not enough to ensure that the host is centered on the lathe at one point, usually the tail cap end, but, you need to enure that it's centered at the other end, too.


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## PCC (Oct 26, 2011)

Here's the reason that I wanted to buy this broken C2 to begin with. I cut windows into it so that I can see how close I am getting when making a heatsink for a Surefire host for optimal contact between the copper heatsink and the aluminum host.






This aluminum slug was made way back when as a proof of concept to see if I could even do it (it was done on a mill if you can believe it). You can see that there's contact being made only at the end of the heatsink right at the throat of the lamp assembly pocket. The rest of the heatsink is making almost no contact with the host at all.


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## precisionworks (Oct 26, 2011)

> so that I can see how close I am getting when making a heatsink for a Surefire host for optimal contact between the copper heatsink and the aluminum host.


You may want to make a cast using Cerrosafe. Super low melting point & easy to use. Available from Brownells.


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## jh333233 (Oct 27, 2011)

PCC said:


> I had PM'd shao about that C2 in the original post. I received it just today. I cut it off and bored it to 18.65mm, which, coincidentally, is what others bore Surefire hosts to. Looking at this picture you'll see that the walls at the wider flats is quite thin on three out of four sides. If you don't put the host into the lathe right even a small bit of runout will mean that you're going through the wall. It's not enough to ensure that the host is centered on the lathe at one point, usually the tail cap end, but, you need to enure that it's centered at the other end, too.



Didnt realise my C2 has such a thick body :S, its still so thick even it was bored!
the thinnest part of the body is still thicker than common lights...


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## gadget_lover (Oct 27, 2011)

> Didnt realise my C2 has such a thick body :S, its still so thick even it was bored!
> the thinnest part of the body is still thicker than common lights...



What we do not know is if the original bore was off as much as the rebore was. My first instinct would have been to align the light by indicating the inside of the factory bore. That makes you concentric with Surefire's work BUT it also means that you will repeat any mis-alignment. 

One reason to make a thick bodied light is to allow for 'manufacturing variances'.... in other words to compensate for worn or inaccurate tools and tooling. Add an extra .020 thickness to the walls and you only have to position the drill within +- .010 to meet the same minimum wall thickness.  Of course, another reason is to provide a VERY sturdy light. 

We see this a lot more often in cheap parts where the tolerances are very forgiving. For example, over-sized attachment holes are common so that they will line up easily. 

Daniel


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## precisionworks (Oct 27, 2011)

> My first instinct would have been to align the light by indicating the inside of the factory bore.


I indicate each light by using the bottom of the O-ring groove since that's going to be the thinnest area. Once the O-ring groove is running true the bore will at least be concentric in that area. 



> Didn't realize my C2 has such a thick body ... its still so thick even it was bored!
> the thinnest part of the body is still thicker than common lights...


Actually not 

I've measured a number of C2's prior to boring & they average .775" across the closest flats & .850" across the widest flats. The C2 & 6P both measure .775" at the O-ring groove BUT the 6P measures 1.000" for the remainder of the tube. 

The thickest Surefire (at the O-ring groove) is the U2 which measures .800" or a bit more. Combine that with a very thick tube & that light is a tank.


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## precisionworks (Oct 27, 2011)

> My first instinct would have been to align the light by indicating the inside of the factory bore.


I indicate each light by using the bottom of the O-ring groove since that's going to be the thinnest area. Once the O-ring groove is running true the bore will at least be concentric in that area. 



> Didn't realize my C2 has such a thick body ... its still so thick even it was bored!
> the thinnest part of the body is still thicker than common lights...


Actually not 

I've measured a number of C2's prior to boring & they average .775" across the closest flats & .850" across the widest flats. The C2 & 6P both measure .775" at the O-ring groove BUT the 6P measures 1.000" for the remainder of the tube. 

The thickest Surefire (at the O-ring groove) is the U2 which measures .800" or a bit more. Combine that with a very thick tube & that light is a tank.


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## brandocommando (Oct 27, 2011)

I have done 3 like this and have never had any problems.


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## csshih (Oct 27, 2011)

hahaha - get some finer grits and polish those insides up! 

Craig


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## gadget_lover (Oct 27, 2011)

The pictures always make it look rougher than it really is. 

The use of the long drill as an arbor for the sand paper was pretty good.

Daniel


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## PCC (Oct 28, 2011)

precisionworks said:


> You may want to make a cast using Cerrosafe. Super low melting point & easy to use. Available from Brownells.



The point of the exercise is that I can verify that the copper slug is making contact and this will also allow me to see why a heatsink is not fully seating in a Surefire host. Having a cast made will give me dimensions to shoot for, but, it doesn't tell me if it's making good contact with the host and it doesn't tell me why it's not fully seating.



gadget_lover said:


> What we do not know is if the original bore was off as much as the rebore was. My first instinct would have been to align the light by indicating the inside of the factory bore. That makes you concentric with Surefire's work BUT it also means that you will repeat any mis-alignment.


I indicated this piece on the flat section just forward of the widest part of it. It's the flat area that is covered by the hex of a Z44 bezel. How it was indicated by the previous machinist who caused the initial damage is beyond me.


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## precisionworks (Oct 28, 2011)

> Having a cast made will give me dimensions to shoot for, but, it doesn't tell me if it's making good contact with the host and it doesn't tell me why it's not fully seating.


If your heat sink is identical in every dimension to the casting there will be 100% contact. If the heat sink varies in any way from the casting there will be less than 100% contact. The casting provides a dead accurate model to copy when making your drop in.

Or you can follow the Elzetta approach & use the Malkoff drop in as the model and build the light around the drop in.


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## mikesantor (Oct 28, 2011)

Thats not too bad Shao, nothing a little cerakote wont fix


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## jh333233 (Oct 29, 2011)

Btw... how would it be early-run?
My C2 with previous surefire logo(Now one is the UB3T one) was already A90591 and the op's is A97019


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## LE6920 (Dec 30, 2011)

jh333233 said:


> Btw... how would it be early-run?
> My C2 with previous surefire logo(Now one is the UB3T one) was already A90591 and the op's is A97019



Maybe he means an early boring run. Not an early Surefire.


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## precisionworks (Dec 30, 2011)

A boring bar will always travel in a direction exactly parallel with the center line of the of the lathe - imagine a laser shining through the headstock bore (from the left end) and the laser spot will exactly touch the center in the tailstock. Because of that any part that is perfectly centered will have uniform wall thickness from end to end.

Because a boring bar always travels in a straight line it can bore through a thin walled part if that part isn't perfectly centered. The center line of any part has to be concentric with the center line of the lathe.

The OP didn't say how the body was being held (3-jaw, 4-jaw, 6-jaw, 5C collet, faceplate, etc.) A worn out chuck could push a part off center enough to bore through the side.


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