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Thread: New Mitsu P73 quad build

  1. #1
    Join Date
    Feb 2008
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    Northern Indiana
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    Default New Mitsu P73 quad build

    New 4 banger P73 red i am working on. This will be 4 diodes knifed with no PBS. Everyone that has worked with these diodes know how much of a pain it is to align multiples with a high power telescope. In the past the diode had to be centered and rotated in the same place on the mount by loosening screws and manually moving it around. Both centering and rotating are fairly easy alone. Its when trying to do them at the same time the hair pulling frustration sets in. Just the slightest rotation can throw the spot off going through the tele. Second the distance from the collimation lens to the first correction lens has to be very precise. Moving the mount back and forth to accomplish this can be very trying to say the least. Trying some new ideas... I ended up using a round barrel lens holder mount. The diode block attaches to the rear of the barrel and can be moved x and y for centering. After this is done the diode block shouldn't have to be unscrewed. Next the barrel will be mounted in a stanchion style clamp. This will allow for rotation and easy adjustment back and forth. Most of the parts are machined. Hopefully everything works as planned (wish me luck ). I will post progress pics as I go.
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  2. #2
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    Had a little more time to work on this project today. Separating the different alignments help tremendously. The correction lens in the firs pic is a 300mm fl cylinder. looks like around 6mm at aperture and calculates to about .2 X .6 mrad. Seems a little lower than expected. I only measured the spot at 30 feet. Need to doulble check that at around 100 feet or so.

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  3. #3
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    Good design and the short thermal path not to mention the mechanical stiffness is top notch. So far so good.

  4. #4
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    I put the module in my test projector. It has turned out to be a very stable platform that is very easy to adjust. If you have the space in your projector I recommend the use of a single cylinder for correction. It makes life so much easier. If you are going to build a big red and have access to machine tools the large diameter barrels are great to set rotation of the diodes with out much fuss and aggravation.

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  5. #5
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    . If you are going to build a big red and have access to machine tools the large diameter barrels are great to set rotation of the diodes with out much fuss and aggravation.
    Do your barrels allow for a little X/Y shift of the diodes vs the collimator lens?

  6. #6
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    Northern Indiana
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    Quote Originally Posted by planters View Post
    Do your barrels allow for a little X/Y shift of the diodes vs the collimator lens?
    Yes. The holes that hold the diode holder to the barrel are oversized. This is allows the diode to be centered quickly and easily. In my previous designs, when the lens holder was fixed, I would use the oversized holes to allow for rotation of the diode as well. This did work but was really finicky to adjust. Also, in previous designs the diode was pressed in. Now I have the diode holder slotted with a screw to clamp it. This works awesome. I believe that the outer rim of the diode has the most surface area and is therefore the best place to transfer heat out.

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  7. #7
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    Nice saw cuts. How do you do them? I built a couple of tip/tilt flex mounts for a pair of mirrors that could have benefited from thinner cuts. The same project needed a full custom diode holder and it works, although I like your design better, I overhung the back plate substantially and that sure gets your adjustment hand out of the way of the screw driver.

  8. #8
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    Northern Indiana
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    I use a slitting saw in my mill. Similar to this:
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  9. #9
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    I thought so. I just never looked into very thin saws. Do you have a recommendation for a good thickness? Stiff enough, doesn't gall up etc.? What did you use, for example?.

  10. #10
    Join Date
    Apr 2010
    Location
    Grand Rapids, Mi
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    So jealous of you all with the tools and the skills. Nice builds n ideas
    leading in trailing technology

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