# How to drill a reflector?



## cd-card-biz (Nov 15, 2006)

Is there a recommended way to increase the hole size of an aluminum reflector? At $20 - $30 a pop, I would rather not damage them.

OK to do it in a drill press? High or low speed? From reflective side or from back side?

Thanks for any info,

Bill


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## highorder (Nov 16, 2006)

if you are drilling an Aluminum reflector, do it in a drill press between 1000 and 1600 RPM with a HSS bit, start from the back. 

with plastic, you can increase both the speed and feed.


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## MikeHunt79 (Nov 16, 2006)

Hmm, I need to do mine aswell, as my IRC bulb is very wide. 

I would go with a drill press, on a medium to low speed, and probably go from the backside. I'd be interested to hear from someone who has already done it, as I don't want to get it wrong either.


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## DonShock (Nov 16, 2006)

I've drilled a couple out. I used a handheld power drill. I drilled from the back so any burrs would be on the back. I only used the weight of the drill to put force on the bit to prevent deforming the inside of the reflector as it punched through. The final precaution I took was to work my way up one bit size at a time so I wasn't trying to remove too much material at once. It takes longer, but I ended up with a nice smooth hole.


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## havand (Nov 16, 2006)

I think you need to use something highspeed and take very little at a time...at least that is what my gut is telling me.


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## Trashman (Nov 16, 2006)

Using a hand drill and drilling from the back it's pretty easy to do.


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## highorder (Nov 16, 2006)

if you can, use a drill press. use an RPM between 800 and 1600. 

I'm not pulling these numbers from the air. we machinists actually have formulas, and beyond that, experience.

aluminum can be cut without coolant at high speeds, with moderate to fast feeds. higher surface finish is a function of faster RPM.


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## will (Nov 16, 2006)

Make sure that the work is held securely - this prevents 'chatter' Generally speaking, the larger the drill size, the slower the speed. To clean the item after it is drilled, if it is necessary, warm soapy water. Swish it around, do NOT rub it clean. Rinse with clear water, then just blow it dry. 

Note - any burrs that might be left, will be on the bottom of the work, If you drill from the backside, the resulting burr will be on the inside. That is better than drilling from the inside, any slips and the reflective side will get damaged.


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## highorder (Nov 16, 2006)

+1 for Will.


he speaks the truth.


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## havand (Nov 16, 2006)

will said:


> Make sure that the work is held securely - this prevents 'chatter' Generally speaking, the larger the drill size, the slower the speed. To clean the item after it is drilled, if it is necessary, warm soapy water. Swish it around, do NOT rub it clean. Rinse with clear water, then just blow it dry.
> 
> Note - any burrs that might be left, will be on the bottom of the work, If you drill from the backside, the resulting burr will be on the inside. That is better than drilling from the inside, any slips and the reflective side will get damaged.



Plus metal shavings hanging off the bit could get spun around on the reflective surface.


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## MoonRise (Nov 16, 2006)

Note,

Drilling the aluminum or plastic reflector is not all that hard to do. Plastic and aluminum are not all that hard physically.

The 'tricky' part IMO is not buggering up the relective coating(s).

Basically, to do a good job you need to do a good job. Do a good job with the locating of the workpiece, the holding/clamping of the workpiece, the selection of the drilling speed, the selection of the bit(s), and so forth.

Can you just take a handheld drill and make the hole bigger? Sure. But it will usually be better (and safer!) to use a drill press (or mill, or lathe) and clamp/hold the work properly (not using your hands!) and drill/mill/bore the hole out to the desired size.

I'd recommend doing the 'cutting' from the reflector side and going toward the back, for the reason that the existing material will support the reflective coating as you start the cutting. If you go from the back side towards the front reflective side, I feel there is more of a chance of lifting the reflective coating as you finish off the cut because there is nothing but air to support the coating. Yes, I did that.  Of course you have to watch out for scratching the reflective coating with the chips/swarf as you make the cut.

Yes use a drill press. At typical hole sizes for a flashlight, use a pretty high speed (high speed means smaller, finer chips/swarf at moderate feed rates and usually a smoother surface finish) and a SHARP bit. Clamp/hold the workpiece properly and securely, handholding the reflector on the drill press table is neither. If you can't remove the chips/swarf via a vac as you are drilling, then drill from the back side towards the reflective side and beware as you are 'punching through'. If you can use a chamfer/countersink to start the operation from the reflective side to 'ease' the edge of the reflective coating first and then flip the workpiece over and do the drilling from the backside, that would be good too.

As stated above by Will, do NOT try and rub a reflector clean. Rinse clean and gently blow dry. Reflective coatings are often not all that durable to touching and such.


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## scott.cr (Nov 17, 2006)

Personally I'd pay someone (or beg someone haha) to bore it on a lathe.

Trouble with drilling is that it's hard to get the drill bit parallel and centered with the existing hole. Plus like others have said, the ribbons of aluminum chips will be spinning and scratching the heck outta your reflector's finish.

Maybe I'm anal but when boring a reflector I've spent over an hour with the setup and like 50 seconds doing the actual boring.


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## will (Nov 17, 2006)

MoonRise said:


> I'd recommend doing the 'cutting' from the reflector side and going toward the back, for the reason that the existing material will support the reflective coating as you start the cutting. If you go from the back side towards the front reflective side, I feel there is more of a chance of lifting the reflective coating as you finish off the cut because there is nothing but air to support the coating. Yes, I did that.  Of course you have to watch out for scratching the reflective coating with the chips/swarf as you make the cut.



question - on the aluminum reflectors - is the finish a coating? or is it just highly polished?


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## Ganp (Nov 17, 2006)

Last night I modified a McR 27L to use with the Cree XR-E. It was set it up in the lathe and - from the back - carefully drilled out to 7.0 mm so it would fit over the metal ring of the LED. Then I used an end mill in the chuck and reduced the back some more.
The overall reduction was 0.8mm but this enabled this reflector to sit back by about 1.2 mm, and be centered by the metal ring. The focus is pretty good IMHO.  
As the back of the reflector now sits behind the LED lens any minor damage to the reflective surface should not be a problem. If you'r real carefull and do as everyone else suggests... set up well - high speed - take your time...etc... there should be very little damage.

Colin.


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## PEU (Nov 17, 2006)

Its a vacuum deposited coating. 

I also drilled a McR reflector from the inner side and Im happy with the results 


Pablo


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## MoonRise (Nov 17, 2006)

"question - on the aluminum reflectors - is the finish a coating? or is it just highly polished?"

Almost all aluminum reflectors have a coating on the aluminum to make the reflector shiny and reflective. The same with most plastic reflectors.

It is the thin, shiny, reflective, and fragile coating that makes the typical reflector reflective. Take a look at a blue plastic Mag reflector, the blue plastic sure isn't reflective. It's the reflective coating that makes it reflective. The typical coating on a metal reflector is a similar type of coating, just applied to metal instead of plastic.

Yup, doing precision or picky work is often/usually about 95+% set-up time and the actual operation takes just a fraction of that time to do.


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## jch79 (Nov 17, 2006)

It seems like drilling makes it easier to damage the reflector, whereas sanding can be more controlled... if I have a hand drill, a Dremel, and sandpaper, what's the best bet of getting the desired results?
john


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## tron3 (Nov 17, 2006)

highorder said:


> if you are drilling an Aluminum reflector, do it in a drill press between 1000 and 1600 RPM with a HSS bit, start from the back.
> 
> with plastic, you can increase both the speed and feed.


 
I've built models and mistakenly put a dremel tool to some of the plastic parts for sanding. You can QUICKLY melt the plastic this way. 

Keeping in mind that plastic reflectors are a stiffer grade of plastic, I'd still proceed with caution and try a lower speed. You may only be drilling a hole, but the rapid build up of friction may melt it a little larger than you expected.


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## will (Nov 17, 2006)

jch79 said:


> It seems like drilling makes it easier to damage the reflector, whereas sanding can be more controlled... if I have a hand drill, a Dremel, and sandpaper, what's the best bet of getting the desired results?
> john



the infamous dremel - great for a lot of things, not this. 

If you were sanding to make it shorter, that is easily controlled, sandpaper on a flat surface, draw the piece back and forth, eventually it will be shorter, leaving ton of small aluminum bits on the inside. 

To use a dremel to enlarge a hole, it can be done, but you will still be left with the pesky little sanding bits on the inside, and a hole that is probably not as round or straight as you would like. Been there - done that..

best bet is a drill, just be careful.


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## jch79 (Nov 17, 2006)

Thanks Will!


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## greenLED (Nov 17, 2006)

Since I lack certain fancy tools, I enlarge reflector openings "by hand". I use increasingly larger dril bits, and turn slowly them with my fingers, or with a pair of pliers. So far, so good.


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## will (Nov 17, 2006)

greenLED said:


> Since I lack certain fancy tools, I enlarge reflector openings "by hand". I use increasingly larger dril bits, and turn slowly them with my fingers, or with a pair of pliers. So far, so good.



that is actually like hand reaming - it works.


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## TranquillityBase (Nov 18, 2006)

Has anyone tried a step drill bit? McMaster has 4 mm to 12 mm x 1 mm increments...It's $23.20 just to get the 7mm step, but these type of bits are hard to beat for drilling concentric holes in thin material.

PN 89275A31


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## cmacclel (Nov 18, 2006)

I use the lathe with a boring bar. All my reflectors are opened up in 1 single pass with a vacuum cleaner positioned right at the boring bar.


Mac


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## TranquillityBase (Nov 18, 2006)

cmacclel said:


> I use the lathe with a boring bar. All my reflectors are opened up in 1 single pass with a vacuum cleaner positioned right at the boring bar.
> 
> 
> Mac


Did you reduce the length of the McR20's for your Tri-Cree, or just bore them to 7mm?

TB

BTW Chris, the two Cree XR-E's you sold to me, have a nice tint...I bench tested both of them last night, they're perfect to my eyes.


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## cmacclel (Nov 18, 2006)

TranquillityBase said:


> Did you reduce the length of the McR20's for your Tri-Cree, or just bore them to 7mm?
> 
> TB




I took 0.025 off the back them opened them up to fit outside the metal ring on the Cree's.

Mac


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## TranquillityBase (Nov 18, 2006)

I just destroyed my last McR20...Oops

I did have some McR18's, so I cut one of those down and drilled it to 7mm...I don't have a tiny boring bar. Anyway...I faced *.015"* off the length, and then I drilled for the Cree collar to fit...A letter 'I' drill bit is just a few thou smaller than 7mm, and it worked perfect...I first drilled with a 6mm drill (largest metric drill I have) then followed up with the 'I' drill.

*I just did some comparative measuring, and .015" is all that was removed to the overall length...the scotch tape that reflector is sitting on, is only .001" in thickness. I have 4 more new McR18's to take measurements from, and .015" was the average. I don't think the beam will focus tighter if more length is removed, but I haven't tried it, so I'm not sure. The .015" replicates the Lux III pattern perfectly, so I'm very pleased with the results.*

I've since tested this with one of Mac's XR-E's, I isolated the electrical contacts with scotch tape, set the McR18 directly over the ceramic pad and powered-err-up...the beam is excellent, to my eyes it looks nearly identical in pattern to my Lux III McR18 light...just a whole lot brighter.

I have both the Lux III McR18 light, and the Cree XR-E/modded McR18 pointed straight up at the ceiling, and they look very similar in beam profile, actually they look identical to me.

TB


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## cmacclel (Nov 18, 2006)

I don't have a small enough boring bar either.....thats where the HSS blank and the grinder came in 

Mac


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## TranquillityBase (Nov 18, 2006)

cmacclel said:


> I don't have a small enough boring bar either.....thats where the HSS blank and the grinder came in
> 
> Mac


 About the only thing I grind in my shop are coffee beans, and my parting-off tool. 

I think the benefits of grinding your own tools are immeasurable, I'm just too lazy, and I'm always in a rush...

The drill worked really nicely, and I imagine the one-shot pass with the boring bar is excellent too.

TB


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## PhotonFanatic (Nov 18, 2006)

Hey, if you guys want some small boring bars, send me a PM--I have a ton of Micro 100 boring bars in solid carbide in various sizes.


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## TranquillityBase (Nov 18, 2006)

Sorry for getting off track here, but I'm excited...I just assembled one of my 18mm heads with the cut down McR18, and one of my XR-E LE's, so this is the real deal...The beam pattern is absolutely fantastic, it has a really nice concentrated hot spot, and a nice wide spill...silky smooth transition from hot to spill, no rings...

TB


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## will (Nov 18, 2006)

TranquillityBase said:


> I don't have a tiny boring bar. TB



In the world of things that can be used for something else - I needed a tiny boring bar for something, Didn't have one, couldn't get one. Most of my work is with aluminum or wood. I had an old hex key that was just about right size. I sharpened the end to make a cutting tool. worked great, It was a pain to put in the tool holder, but for a one shot deal it was fine. Now the hexkey is harder than wood or aluminum, this would not work with steel.


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## PhotonFanatic (Nov 18, 2006)

The right tool can make all the difference:










I've got a bunch of these boring bars that I picked up from a retiring machinist, all solid carbide from Micro 100. Various min bore sizes available. $10 each, if you need one.


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## Northern Lights (Dec 9, 2006)

How do you enlarge a Mag Charger OEM reflector hole? I was going to start a thread to ask this but found this one. Hope to hear today, as I am heading for it in 5 hours.

The MagCharger reflector is spun steel, is uniform in thickness, a parabolic reflector. So cutting the end off is one solution but I think I need one regarding drilling or reaming. I have a drill press but not milling machine or lathe. 
The reflector is supported in a plastic frame that is held in place with brown automotive high-temp silicone sealer that does not stick to the plastic so the metal reflector can be out and free. I need to get it over a Phillips 5761. I have a .377 bored Mag D, camless reflector that will fit so I need to get the hole up to around the .377 .
I was thinking of placing the reflector front down and drilling from behind. I am leary of chatter on the thin edge of the spun sheet metal.
Would a grinding stone bit be a better choice than a reamer or champfer or drill bit?

The fact that the reflector can be freed from the frame allows some possibility of heat syncing it. 

The 5761 I learned from CPF research can get wa1185 sized lumens or more from smaller capacity lights as 2D on lithium or NiMh or 2C on lithium, 7.2 volt systems.


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## Northern Lights (Dec 9, 2006)

"How do you enlarge a Mag Charger OEM reflector hole?"
I ANSWERED MY OWN QUESTION THE HARDWAY; I WENT FORTH:
MC reflectors are spun steel in a plastic housing. I popped the reflector out of the plastic frame, it is held in with brown high temp automotive silicone gasket sealer that does not stick to the plastic, and I placed 4 pads of fiberglass, the type used in auto-body repair, felt as insulators that are place around the plastic frame with super glue thus creating an air space when I reassembled it. The reflector needs to be opened up to accommodate .377 diameter bulbs, the 5761. I did this by dressing a conical or round Dremel grinding bit to .378 and putting it into a drill press and hand holding the reflector now out of the frame face down. The stone run at 700 rmp centers the hole and ground in without chattering. Blown air, water and alcohol cleaned the reflector for use again. Getting the old silicone off the steel was the most difficult part as care must be taken to protect the optical surface.


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## schill (Dec 11, 2006)

will said:


> that is actually like hand reaming - it works.



I use a hand reamer for stuff like this. If the material that you're removing is relatively thin, it works quickly and cleanly. You get a very slight taper to the hole but I've never encountered a problem because of this.

I use one like this (but not necessarily this one): Reamer at www.micromark.com


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## Northern Lights (Dec 11, 2006)

schill said:


> I use a hand reamer for stuff like this. If the material that you're removing is relatively thin, it works quickly and cleanly. You get a very slight taper to the hole but I've never encountered a problem because of this.
> 
> I use one like this (but not necessarily this one): Reamer at www.micromark.com


Thanks, Schill,
I have a cross handle reamer and I considered it, putting it in the press. But then I looked at it, can't figure why it is so dull, I just got it, June, 1968, I think. So I went to the stone. I always have practiced the philosophy, if you need a tool, buy it don't rent it. Got that from my Grandfather and Father, both gone now and I have tools going back to the early 1900s but the family shop is 1400 miles down the road at the moment. I hate to buy duplicates and I am surprised, having used many of those tools for all my life I can remember what is in inventory. I usually ask family to mail what I need to me. But I was impatient, a month ago I found a draw full of the reamers but did not help myself.  
Merry Christmas and thank you, 
NL
:santa:


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