Automated Fixtures Mac 700 gobos-glass or aluminum

[kensmithld]

I have heard conflicting reports on the use of glass or aluminum gobos in the mac 700. The gobos I am planning to use are rather simple design and seem to be stable enough. Should I go for the glass gobos or will the aluminum gobos last me 30 performances. And is there really any difference between stainless steel gobos and aluminum? Martin recommends only aluminum and not really sure why.

Ken

 

[derekleffew]

Huh. I'd never heard of an aluminum gobo before.

From the MAC 700 Profile manual:

CUSTOM GOBOS
Martin can provide many additional gobos for the MAC 700 Profile. Gobos are interchangeable between
MAC 500, MAC 550 and MAC 700 fixtures. For more information, please visit the Martin web site at
Martin Entertainment.
For optimum performance and gobo life, custom glass gobos should be made with the artwork reversed on
the coated side and used with the coated side facing away from the lamp.
While glass gobos are generally the most durable, satisfactory results can be obtained at less expense with
aluminum gobos. Custom stainless steel gobos can also be used, however they can warp, losing
sharpness, in a matter of hours. The useful life will depend on the gobo pattern and the projection cycle.
Consult your gobo supplier for more information.

Now generally I've only used glass gobos when custom, but that's because corporate clients demand the highest resolution possible. If you're not projecting text or a logo, I suspect stainless will be fine, particularly the thicker material available from one manufacturer.

 

[Kelite]

Huh. I'd never heard of an aluminum gobo before.

From the MAC 700 Profile manual:


Now generally I've only used glass gobos when custom, but that's because corporate clients demand the highest resolution possible. If you're not projecting text or a logo, I suspect stainless will be fine, particularly the thicker material available from one manufacturer.

Having provided custom aluminum gobos for a rather large and ongoing Bose project, Apollo regularly provides 8 mil stainless steel for durability. Most stainless steel custom gobos in the market are 5 or 6 mil tops.

If the show is 30 performances, I personally think the additional cost per run is somewhat insignificant when averaging metal vs glass.

When you refer to 'rather simple design', are there a number of bridges involved or are we talking about a star/square/circle/simple shape?

 

[kensmithld]

Here is info I received directly from Martin.

The aluminum gobos are tested and approved for the fixture so there is no problem with durability as long as you keep to the design specs for the gobos (ei. Alu thickness, image size etc.). Keep in mind that the smaller you make the image and the less material you remove from the gobo the hotter the gobo gets so if you make a gobo with a tiny hole in the center you might start seeing problems.

Stainless steel has the problem that it gets very hot during use and it takes a long time to cool down again after use compared to aluminum. Using stainless steel gobos might damage the rotating bearings in the gobo holders and the gobo itself might bend and discolor due to heat. I do not recommend using stainless steel gobos in products with more than 100W lamp.

Glass gobos are great except for the price. They are normally much more expensive compared to metal gobos. If you need a gobo without colors and just an image an aluminum gobo does the job just as well for a lower price.


Best regards,

Asbjørn Winther
Technical Product Supporter - Moving Heads

Having provided custom aluminum gobos for a rather large and ongoing Bose project, Apollo regularly provides 8 mil stainless steel for durability. Most stainless steel custom gobos in the market are 5 or 6 mil tops.

If the show is 30 performances, I personally think the additional cost per run is somewhat insignificant when averaging metal vs glass.

When you refer to 'rather simple design', are there a number of bridges involved or are we talking about a star/square/circle/simple shape?

 

[derekleffew]

Now am just I as confused as before I read the thread. Kelite, let's say I wanted to buy six #3573 "Jungle Mania" gobos (as that's my favorite pattern) in 27.9 mm with 23 mm image size for SteveB's six MAC 700s.

Would you recommend glass, aluminum, 8 mil stainless steel, or my choice of any of the three? If the latter, what is the MSRP of each for an "off the rack" template?

 

[soundlight]

The MAC700 is the only fixture that I've seen what I think are "aluminum" gobos in. The non-glass stock gobos for that thing have a really weird sheen and finish and they're rather thick for metal gobos. Makes me think that they are, in fact, aluminum.

 

[Kelite]

Now am just I as confused as before I read the thread. Kelite, let's say I wanted to buy six #3573 "Jungle Mania" gobos (as that's my favorite pattern) in 27.9 mm with 23 mm image size for SteveB's six MAC 700s.

Would you recommend glass, aluminum, 8 mil stainless steel, or my choice of any of the three? If the latter, what is the MSRP of each for an "off the rack" template?

Sure, Derek-
I would suggest B/W glass, as the image absolutely WILL NOT bend or deform from heat within the Mac700 fixture.
MSRPs are as follows:

Apollo Std Steel $12.75
Apollo Std Alum $ per run basis depending upon qty. Laser settings are much different than SSteel.
Apollo BW Std $69.00

We replaced just this week a few glass gobos sold as OEM patterns because the university wanted to change them out for a fresh look. These 1500W fixtures are a number of years old and used regularly.

 

[SteveB]

Apollo Std Steel $12.75
Apollo Std Alum $ per run basis depending upon qty. Laser settings are much different than SSteel.
Apollo BW Std $69.00

.

Having never heard prior to this thread of aluminum gobo's, the question in my mind is, is Martin blowing smoke ?, or do steel gobo's really cause issues down the road.

My Studio Spots are convection cooled and I use stainless when I don't need color. Didn't even know aluminum was available. I have as yet not had any issues with stainless in a 575w unit with no cooling fans.

I do believe the extra gobo's Martin provides with a new fixture are indeed aluminum.

Curious.

 

[derekleffew]

... the question in my mind is, is Martin blowing smoke ?, or do steel gobo's really cause issues down the road. ...

I can't answer that, but was reminded of this, by a V/L spokesperson, posted to another forum in 2006:

I'd like to add one last clarification - all of the imaging Vari-Lite fixtures only support glass gobos. Our thought here is that the glass gobos provide a better quality image and that they withstand heat better than metal gobos do. The glass also helps to insulate the other mechanics of the various wheels from heat much better than metal - which quickly transfers it right to them.

 

[SteveB]

" Our thought here is that the glass gobos provide a better quality image and that they withstand heat better than metal gobos do. The glass also helps to insulate the other mechanics of the various wheels from heat much better than metal - which quickly transfers it right to them."

Am I the only one here that questions the science behind a statement that says glass withstands heat better then metal ?. Seems a bit counter intuitive to me. I do understand that metal can transmit heat better (to surrounding fixture parts) then glass, but isn't that all a heat managment design issue ?.

I always thought that the VL use of glass exclusively was a way to make money on the gobo's, given that they were only available for many years from VL .

Certainly the argument can be made that glass is not required for simple images that do not have color.

As to aluminum vs. steel ?. I'm curious if a fan cooled MAC700 generates more heat at the gobo then a convection cooled Source 4 ?, which can readily accept glass and which has little effect on a stainless steel gobo.

 

[derekleffew]

...I'm curious if a fan cooled MAC700 generates more heat at the gobo then a convection cooled Source 4 ?, which can readily accept glass and which has little effect on a stainless steel gobo.

Interesting question. Both use a cold-metal reflector. The MAC700 produces more light in a smaller image area, and the Source Four doesn't have plastic, rubber, glue, and other non-metal moving parts in close proximity.

 

[SteveB]

To expand the question, the ETC S4 Revolution allows glass or "metal" gobo's. No comment about aluminum. Fan cooled unit with a 750 watt lamp

The similar VariLite VL1100 doesn't actually state in the .pdf literature except to say "Additional gobo's are available from Vari-Lite" so the assumption is going to be that glass is the only thing that'll fit. Also a fan cooled unit with a 1000w lamp.

I'd ask this question over on the LightNework, but seeing as how the manufacturers directly support that site and have manufacturers forums, I'm not sure I'd get an answer.

To me, it seems that aluminum is a lot of BS.

 

[Kelite]

" Our thought here is that the glass gobos provide a better quality image and that they withstand heat better than metal gobos do. The glass also helps to insulate the other mechanics of the various wheels from heat much better than metal - which quickly transfers it right to them."

Am I the only one here that questions the science behind a statement that says glass withstands heat better then metal ?. Seems a bit counter intuitive to me. I do understand that metal can transmit heat better (to surrounding fixture parts) then glass, but isn't that all a heat managment design issue ?.

I always thought that the VL use of glass exclusively was a way to make money on the gobo's, given that they were only available for many years from VL .

Certainly the argument can be made that glass is not required for simple images that do not have color.

We have had dealers contact us regarding their own personal VL units which were rented out, only to have custom metal gobos inserted into them by the user. The VL fixture's mechanical rotation components were damaged and not covered by the VL warranty, as per the owner's manual, much to the dealer's dismay. This had become enough of a problem that VL Product Manager George Masek himself spoke with Milad (our OEM and International sales rep) and me regarding this ongoing problem.
When a steel gobo order came in for a VL fixture, we would ask the dealer to expect b/w glass, as we would not manufacture steel gobos for the VL fixtures, as per requested by VL. While we would not make steel gobos for these VL fixtures other companies would produce them, presumably because the end-user saved a few bucks at the expense of the VL owners, who then dealt with non-warranty failures.

The transfer of heat is very different between metal gobos and glass gobos. Glass reflects more heat energy while metal (stainless or aluminum) passes it along to the ring holding the pattern within the light.

Once upon a time, when Apollo acid-etched gobos (a dirty and hazardous process), aluminum was offered for large OEM and permanent installation use. Aluminum hasn't been available to the general public due to the multiple changes needed within speed and energy settings of the laser equipment.

 

[kensmithld]

Interesting discussion on this. I have found that Rosco and InLight also produce aluminum gobos for this unit. After sending specific gobo requests to Martin they recommended glass for only 2 of the 10 designs I was going to use. It all depended upon how much open space the gobo had and the fine detail of the cuts.
Rosco MSRP is $13.50 and turnaround is one day.

We have had dealers contact us regarding their own personal VL units which were rented out, only to have custom metal gobos inserted into them by the user. The VL fixture's mechanical rotation components were damaged and not covered by the VL warranty, as per the owner's manual, much to the dealer's dismay. This had become enough of a problem that VL Product Manager George Masek himself spoke with Milad (our OEM and International sales rep) and me regarding this ongoing problem.
When a steel gobo order came in for a VL fixture, we would ask the dealer to expect b/w glass, as we would not manufacture steel gobos for the VL fixtures, as per requested by VL. While we would not make steel gobos for these VL fixtures other companies would produce them, presumably because the end-user saved a few bucks at the expense of the VL owners, who then dealt with non-warranty failures.

The transfer of heat is very different between metal gobos and glass gobos. Glass reflects more heat energy while metal (stainless or aluminum) passes it along to the ring holding the pattern within the light.

Once upon a time, when Apollo acid-etched gobos (a dirty and hazardous process), aluminum was offered for large OEM and permanent installation use. Aluminum hasn't been available to the general public due to the multiple changes needed within speed and energy settings of the laser equipment.

 

[chausman]

Thought I might mention this, since someone brought up Vari*lite. When I ordered some gobos for two VL1ks, I just told the local shop I wanted x and y gobos for two VLs, and he got them. When they came, they were two (very small) gobos, and little pieces of glass to match the gobos. I asked him about that, and he said thats what they always have done. That he'd never had problems with it. It worked just fine for our use.

 

[Kelite]

The VL fixture line up over the years has used various wattage lamps, some producing less heat than others. Many moving light fixtures (in addition to VL) also use a variety of cooling methods, each chosen for that specific family of fixtures. I'll close by saying that if the owner's manual states glass only- there is a reason for it.

 

[Kelite]

Interesting discussion on this. I have found that Rosco and InLight also produce aluminum gobos for this unit. After sending specific gobo requests to Martin they recommended glass for only 2 of the 10 designs I was going to use. It all depended upon how much open space the gobo had and the fine detail of the cuts.
Rosco MSRP is $13.50 and turnaround is one day.

No mention of this product within the website search-
Rosco Search Results

And I don't believe Inlight produces stainless steel or aluminum gobos-


We did not advertise our either aluminum gobos either, as it was a solution for specific large installation projects.

 

[SteveB]

Since Derek offered to buy me some gobo's for my new MAC700's I'll then ask for either aluminum or glass, as using stainless might void the warranty.

Which I guess is the final answer if the fixtures are still under that warranty.

 

[derekleffew]

Nope. [The next time I do a show on your stage], You're getting six stainless steel Jungle Leaf gobos and you'd better use them and like them. Martin's literature doesn't say anything about voiding the warranty:

Custom stainless steel gobos can also be used, but...

IF they warp (and how could you really tell?), I'll replace them.

And together we'll figure out how to do color donuts for the MAC 700s.

 

[rochem]

And together we'll figure out how to do color donuts for the MAC 700s.

Now that would be cool! Kelite, have you ever had an order to make a custom color chip that wasn't a solid color all the way through? Would you guys even be able to make a glass color filter with a lighter color on the inside of the circle? Hypothetically speaking, of course.