Glass cutting techniques; Dimpled reflectors

Doug S

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In my search for dimpled reflectors to play with, I am eyeing some MR-11 lamps I have laying around. These are the glass reflector lamp modules with an aluminized coating. To use them I would need to cut off the rear glass extention. Is there a feasible way to do this or should I skip this step and just cut all of my fingers with a sharp razorblade? My only idea so far is to use an abrasive cutoff disc but would like to hear other ideas before using up my supply of bandaids.
 

sunspot

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How large of a hole do you need? I have some diamond drills that are hollow in the center. An abrasive disc may work.
 

Doug S

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Originally posted by sunspot:
How large of a hole do you need? I have some diamond drills that are hollow in the center. An abrasive disc may work.
<font size="2" face="Verdana, Arial">The part I want to remove has a rectangular cross section of about 0.4 X 0.6".
 

sunspot

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Well, I can't cut a rectangular hole. I can cut a 5/8" circle. Whatcha gonna put in it?
 

Doug S

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Originally posted by sunspot:
Whatcha gonna put in it?
<font size="2" face="Verdana, Arial">I intend to play around a bit with Luxeon HDs and side emitters. I don't have a stand alone finished light in mind, I just want to see the range of beam patterns that can be attained.
 

woodbender

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Doug S...interesting that you bring this up. I've been following the dimpled reflector thread and I realized I have an old non-working mr-11 lying around. I'm not sure looking at it how to modify it either. If you can find a custom glass shop, they can probably grind it off for you. Good luck.
 

B@rt

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How about using a "rod saw"?
rodsaws3.jpg

They are only a couple of bucks, and great for cutting glass. To minimize the risk of the reflector cracking, try sawing underwater.It dampens the vibration, and there is no dust.
winkie.GIF


(Do not use powertools for this...
Eyecrazy.gif
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)
 

B@rt

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Hi Dana,
here is a larger pic of a rod saw.
sawsj4.jpg

Usually made of a Tungsten Carbide coated mild steel wire. It's very easy for cutting through a varyity(sp?) of materials . It also cuts omnidirectional, so if you have a hole to feed the saw through, it's easy to cut out complex shapes.

Hope this helped,
 

CNC Dan

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Originally posted by Doug S:
In my search for dimpled reflectors to play with, I am eyeing some MR-11 lamps I have laying around. These are the glass reflector lamp modules with an aluminized coating. To use them I would need to cut off the rear glass extention. Is there a feasible way to do this or should I skip this step and just cut all of my fingers with a sharp razorblade? My only idea so far is to use an abrasive cutoff disc but would like to hear other ideas before using up my supply of bandaids.
<font size="2" face="Verdana, Arial">Look into stained glass supplys. They make a small table top bandsaw that has dimond grit on it that is used to cut glass in intricut shapes.

If you can find a place that has stained glass classes, I bet they would have one.
 

sunspot

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Thanks Bart. I was making a glass lantern but had to use a section of aluminium to mount the switch. This may work for my needs.
 

McGizmo

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Hi guys,

Think diamonds! A good diamond burr will grind glass away, no problem. Add a flow of water for cooling and keeping the glast dust from flying and you are in there! There are many diamond abrasive devices on the market now and they Rock! The harder the material, the bettter they work. If any of you have the Fein triangle sander of any of the knockoffs, you can get a carbide grit circular saw or dimond grit circular saw and it will cut glass again with no problem. The type sander I am talking about works just like a cast cutter. It has a tight circular orbit as oposed to spinning on axis. If any of you are do-it-yourselfers, the Fein triangle sander is another fantastic tool!!!

Sorry, got excited there..................

- Don
 

whiskypapa3

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If your going to try a Dremel tool and cutoff disks, glue two disks together (epoxy or silicone rubber) and run at the lowest speed on the tool and take light cuts. Two disks are quite a bit stronger and cut just as fast.A little light oil (olive? canola?)helps keep the dust down. This works for me with opals.
 

sunspot

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I have diamond drills that are really tubes that have a rough diamond burr coating. As you say Don, keep a flow of water on the work for dust but more for cooling. Tell me more about Fein. EDIT. Bart knew what I was going to ask.

whiskypapa3. Thanks for the tip on the Dremel.

Damn if I don't learn stuff here everyday.
My thanks to all the members!!!!
 

McGizmo

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Fein makes some great and unfortunately expensive tools. They have some vacuums that really SUCK!
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The triangle sander will get in areas nothing else will. You can put a toothed saw on it and trim moulding and make cuts in areas you never could have before. They make a putty/scrapper blade that will lift and break off linoleum and tile. For cutting fiberglass and carbon fivber laminates, I have found the saw blade with water flow is awesome. Since the blade isn't spinning, you aren't throwing coolant all over the place. They make a sanding pad with holes and a vacuum attachment for the sander. If you have some sheet rock repair and don't want to fill the room with fine dust, the sander and vacuum work great. Most shop vacs like to send the dust right back out the rear end. The Fein vacuum has tight enough filters that this isn't a problem. They even have a HEPPA (sp?) filter that won't let tiny critters pass through.

Another great tool company for air driven tools is dynabrade. They make some grinders and belt sanders with built in water feed. Couple these with diamond abrasives and you can have at it with glass, ceramic, marble or any other hard materials. Want to sculpt some granite? have at it.

I really like tools and going where you aren't normally supposed to go
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Bet you couldn't tell...........

- Don
 

Doug S

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Thanks guys for the input and especially to Don for the reminder on the importance of considering dust control. Don, don't tempt me with those expensive tools, I'm generally fiscally responsible but tools are a weakness of mine. This job I needed to do on the cheap. The job is done and I kept it under $3, none of that for bandaids. I went with the fiber disk approach. Spent $2.50 for a 10 pack of the cheap 3" ones from Harbor Freight. Spent another $0.30 for a 3/8X1 1/4" bolt with nut and 2 washers. I used the later to make a 3/8" arbor to hold the disk so I could chuck it in my drill press. Duct tape to hold shop vac nozzle to catch dust. I took it slow, about 1/2 hour of grinding time to complete. The resulting hole was a bit ragged looking but did not affect performance. It turns out that my initial cut resulted in the reflector being about 0.060" too long for tightest spot focus with a 1W HD. I spent another hour taking about 0.010" off at a time, checking performance after each pass. Initial performance looks good, I will post further after I have a bit more time to evaluate it. For those considering modding with MR style reflectors, this was a bit of a PITA. Their attraction, however, is that they come in a variety of optical shapes, Flood, Narrow Flood, Spot, Narrow Spot. This affords some flexibility depending on your objective. If I had it to do over, I would try to find a diamond disk if available in 3".
 
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