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Make your own overhead projector

Discussion in 'General Airbrush Tutorials' started by Malky, Mar 18, 2012.


  1. Malky

    Malky Guest

    Projector4.JPG Projector5.JPG




    As promised, here a more in depth description of how to make the home made overhead projector, which will help immensely with the geography of your compositions and also save you lots of money.

    Firstly, I will use this thread to describe the process in as much detail as I can, so there is no need to post replies here, however, if you see anything here that you think can be done easier or quicker, then feel free to post, all input is welcome, also if you have questions or something isn't clear, post your question here.

    Note that I will use my own projector as an example, and will state all measurements and dimensions from there, but these are by no means compulsory, the measurements of your own will be dependant on the parts you use, this will become clear later in this thread.

    Also note that the projector here was purposely made to project onto standard A2 paper at approximately 1.2 metres from the work surface, if you want to make a full size projector you will find that the Fresnel lens mentioned below will be difficult to find and also be very expensive, with this format you will stay comfortably under $40.

    A list of all the things you will need and where necessary a description of their purpose

    Projector1.jpg


    1. A photo frame 13.5cm X 18cm, you can make this yourself but they cost almost nothing, this will act as the bed for your transparencies.

    2. A lamp, your light source, I recommend an led lamp like the one in the photo because they do not get hot, if you use any other type of lamp you will need to install a cooling fan and since some your parts are plastic this could be dangerous, the lamp in the photo is 10cm X 14cm app and you can find these at any D.I.Y. store, this will constitute the bulk of your cost, but because the lamp is loose it can be used as extra light source for your work, take note that these lamps are usually supplied without the power cable as this one was, if that is the case you will need that too.

    3. A fresnel lens named after it's inventor, Augustin Fresnel a French physicist, this lens was first used in light houses, although you can see them all around your car, it simply distributes the light over the whole area of your transparencies, the one in the photo or similar is available at most book shops, because it is made as an aid to book reading for sight impaired people, the lens in the photo is 12cm X 18cm and will be detached from it's frame later.

    4. A standard magnifying glass, used to magnify and project your image, the one in photo is 7.5 cm in diameter, you can use something a little larger, but preferably not smaller, you can find these also at book stores or hardware stores.

    5. A mirror, all this does is project your image at 90 degrees form the horizontal, not absolutely necessary if you can draw on the ceiling or lie your projector on it's side. the mirror I used is 7.5 cm X 11 cm, a little bigger is no problem, but not smaller.

    6. Aluminium L profile approximately 1 metre X 1cm, available at all D.I.Y. stores, this will provide you with a rail for your projector head and allow you to focus your image at different distances.

    7. Some 3mm plywood to make the box/casing, about 0.5 square metres should be sufficient, to bring your box together some wood triangle profile is also handy, my box is 21cm high, 18cm wide and 13.5cm deep.

    In the next post, I will proceed further with the build process, this will give you time to pop out now and get all the parts, lol.
    Last edited by a moderator: Mar 26, 2012
    Diegojavbau likes this.
  2. Malky

    Malky Guest

    Projector6.jpg Projector7.jpg Projector8.jpg

    A note on projector transparencies;
    You can make these yourself using transparency printer paper from your nearest office suppliers shop (if you like to drive you can also use the furthest) using your own printer, the reason I mention this this now is because you will need to have one image ready to perform a test before your projector is completed, doesn't matter what it is, it can be a photo of your cat, if you don't have a cat steel your neighbours cat, your transparencies should small enough to lie on your photo frame with one centimetre space all around, if it's right you can 8 or 9 images on one sheet, so if your planning a lot of projects you can print them all at once.


    Now we can begin with the step by step build process, first of all, there three photos here above, if you open each of these photos, right click with your mouse you can select "save as" then save these to your desktop, print them out and keep them at hand while you read the rest of the text here below (the two drawing or plan photos are more important).

    Using the first photo we will split the project into 4 easy steps;

    1. Making the transparency bed (your photo frame and Fresnel lens)
    2. Making the projector head, mirror and magnifying glass.
    3. Making the box, and positioning your lamp, and
    4. Making the projector head adjustable arm.

    Transparency bed
    First take your photo frame and remove all cardboard and stuff, including the stupid picture of a dog that usually comes with it, when done you will be left with only the frame, glass and the parts that secure the cardboard to the frame, put this aside for the moment, now take your Fresnel lens, carefully remove any frame or plastic parts so that you are left only with the plastic lens.

    Cut your lens with heavy scissors so that it fits snugly in the photo frame (third photo 7.) behind the glass, important!!! you will notice that your Fresnel lens is slightly concave, it must remain so, if you try to flatten it, it will do nothing (third photo 8.). you should be able to secure the glass and lens with the parts that came with your frame, if not secure first the glass and then using epoxy 2 part glue on all four corners of the Fresnel lens insuring that it still hangs concave as in the third photo at 8.

    leave this aside your transparency bed is ready for the time being.

    Making the projector head
    First prepare the magnifying glass, your magnifying should have a solid plastic handle, place the magnifying glass over the photo frame so the handle points to one of the longest sides of the frame and the lens is in the middle of the frame, the amount of handle hanging outside the frame needs to be cut away, do this with a small hacksaw while keeping your cut as straight as possible.

    Once this is done, carefully drill a hole suitable for an M4 screw into the remaining handle about two thirds of the way, try to keep this the parallel to the sides of the handle, you can see why this important at third photo 3. and 4., once you have done this insert something long and thin into the hole to measure the length of the hole, the length of this hole plus one centimetre is the length of screw you will need, e.g. if the hole is 22mm you total length of screw is 32mm, for this you need an M4 self-tapping or machine screw 32mm long.

    For the rest of the head you need 1 piece of plywood 9cm X 9cm, 1 piece of plywood 9cm X 12cm and a small piece of wooden triangle profile 9cm long, see this drawing;

    Projector9.jpg

    When you have these items, before assembly you need to cut a perfectly round hole 2mm less in diameter than your magnifying glass rim e.g. rim diameter = 7.3mm, hole = 7.1mm, i did this with a hole saw then used sand paper till it was the right size, once done, sit your 9cm X 9cm with hole over the rim of your magnifying glass centred and glue this with super glue keep the handle at 90 degrees, allow this to dry.

    Once dry place and glue 9cm piece of triangle profile parallel to handle then place and glue remaining 9cm X 12cm plywood as in the drawing directly above, now using super glue place your mirror under this last piece ensuring the centre of the mirror is in line with the centre of the magnifying glass.

    Your projector head is now ready.

    Making the box and projector head arm in next post
    Last edited by a moderator: Mar 26, 2012
  3. Malky

    Malky Guest

    Projector10.jpg



    Making the box/casing

    The box is extremely simple, look at the diagram above, the inside measurements of the box must match the outside measurements of your photo frame, the height of the the box is approximately 21cm high, you will need to make a base, 2 side panels, a front panel and a panel for the back, the back panel should come about half way from the top to around the middle, how big this opening is at the back, is dependant on the dimensions of your lamp.

    On the inside of the box, in the diagram you can see the wooden triangle profile strips in all four corners (you must make these also for the base), allow 1cm between the top of the profile and the top of the box, later your photo frame/transparency bed will sit comfortably in here, which means you can remove it periodically for cleaning, make sure that the profile is precise enough that your frame does not wobble.

    In the first real photo of my own model, you will see in the opening a small block of wood, the purpose of this is to position the lamp such that it is steady and completely parallel to the glass in the transparency bed, the size and shape of this will depend on the dimensions of your own lamp, your lamp should be situated roughly about 12cm form the frame above it.

    This info and all the photos so far should be sufficient to help you complete the box, if not just ask.

    the adjustable projector head arm

    Projector11.jpg

    Your aluminium profile will look like 1. in the diagram here and should be 1 metre long and both sides should be 1cm, in the middle of your profile with a small hacksaw cut away a small piece about 1cm in length as in the diagram at 2. carefully and slowly start to bend where you removed the small piece, place something a little thicker than your projector head screw at the bend to insure that stays wide enough to allow your screw to move freely up and down, once you've done this it should look like 3. in the diagram.

    you will need to drill four small holes at the bottom of the profile to attach it to the box, you can see this clearly in the first real photo, make sure that the top 2 screws are under the bottom of your transparency bed, also make sure that the opening stays parallel from top to bottom.

    once you have completed this remove all sharp edges with sandpaper or a small file.


    Now we are ready to assemble all of the main parts

    This is almost self explanatory, simply attach the projector arm to the back of the box making sure it remains at right angle to the horizontal, with your machine screw and 2 washers (one back and front of the arm) attach your projector head and then place your transparency bed into the box/casing.

    place your lamp into the opening at the back, you can secure the lamp by placing a small screw at each side of the box near to the back and fastening an elastic between them.

    Your projector is now ready for use.

    If all your materials are similar in size to those mentioned here, your projector should work fine, you can loosen the machine screw slightly on the head and move it up and down to adjust focus, to fill your paper/canvas with your image simply move your projector closer or further away.

    you may copy all photos and diagrams to help with your build, you may also copy and paste all text so that you can print it out if it helps

    I think I have supplied enough info here to help you complete your projector, however if something is not clear post all your questions here.

    Lastly good luck with the project and please post photos of your completed model here.


    Regards Malky
    Last edited by a moderator: Mar 26, 2012
  4. Malky

    Malky Guest

    I almost forgot, as I stated at the start of these instructions that you will need to have a transparency ready, the reason for this is if all your materials differ largely in size from those above ( a few millimetres make no difference) you can perform a test to insure that all your distances are good, to do this you need only your lamp, completed transparency bed and completed projector head, lay the lamp flat, hold the bed about 12cm over this and hold the head about 25cm over the bed, when you get a good image projection, measure the distances, these are then the measurements you will work from, use these to decide the dimensions of your other parts.
    Last edited by a moderator: Mar 19, 2012
  5. DreadfulEpiphany

    DreadfulEpiphany Young Tutorling

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    Ohmyshit. I just got back from my hardware store and absolutely NONE of the workers had any idea how long a meter was. Such a frustrating experience, I was standing around for twenty minutes while the workers were asking each other who should help me. I forgot my phone at home so I couldn't check online, but I remembered that one meter is about three feet (not exactly though) so I did the best I could with that. I got plywood and I grabbed the LED light but they didn't have ANY magnifying lens' so when I went home to check online I ended up finding a $35 Sunsplash projector on ebay (which was the same amount as the LED light anyway). So I returned the LED light now I just have to wait for the end of the week for that Sunsplash. I kept the plywood to paint on, though.

    This tutorial really is brilliant. I wish it worked out.
    :[

    *big sigh*
  6. Malky

    Malky Guest

  7. RobW

    RobW Young Tutorling

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    LOL, Its used just about all over the world. I guess just not in america. Didnt they learn about this at primary school?? We were taught both imperial and metric in all departments, distance, weight etc.
  8. Madbrush

    Madbrush As daft as it gets and then some!!! Elite Member!

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    Your absolutely right Rob, but your a little younger thane me I think.

    While living in England 20 years ago, when everything was turning metric, I went to a builders supplier to to buy some dado rail for my living room.

    I asked the man behind the counter, "what does it cost for 28 yards of dado rail?" he replied "Everything is metric now, we only have metres" I said "O.K. then what does it cost for 27 metres of dado rail" and he said "37 pence per foot" lol
  9. Mary Yzah

    Mary Yzah Young Tutorling

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    I'm just wondering... I'M VERY VERY CONFUSE.. are all REALLY IN CENTIMETERS??? it is very very small.. and it's not accurate.. I'M SORRY.. can you please explain it.. THANK YOU
  10. Mary Yzah

    Mary Yzah Young Tutorling

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    I'm just wondering... I'M VERY VERY CONFUSE.. are all REALLY IN CENTIMETERS??? it is very very small.. and it's not accurate.. I'M SORRY.. can you please explain it.. THANK YOU
  11. JackEb

    JackEb Elite Member! Elite Member!

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    Why isn't it accurate. ? And it doesn't have to be huge and bulky. By my quick calculation it stands about 110cm tall which is roughly 3 1/2ft tall not exactly tiny ! It's only designed to throw images onto an A2 piece of paper, not onto a 30ft auditorium wall !
    Seeing as you did such a good job on this one how about showing us how to do an image projector (like the EZ tracer) they are hard to find here in Oz, and the few I have found are a ridiculous price for what they are!
    You know I'm gonna print this out Malky and give it a go :) just as soon as I get all the projects done and out of the hen den I'm going into air brush overload!
    Last edited: Jan 10, 2013
  12. Madbrush

    Madbrush As daft as it gets and then some!!! Elite Member!

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    I'm not sure what it is you need explained, or even if actually you have built one, but if you are referring to the accuracy of the measurements, the reason for this is that it depends on the sizes of the items you use to build it, if you are referring to the clarity of the image projection, this is optimised by moving the projector head up or down exactly like the full size model in order to focus.

    The projector was actually 21" high and the transparency surface was 9" x 5.5", I worked in centimetres because that is what is accepted in the part of the world where I live, I didn't bother to convert the sizes because there are more than 1000 free conversion apps on google to download, but to be honest it's easier to say "one millimetre" than it is to say "one twenty fifth of an inch" it's also easier to say "one kilometre" than to say "three quarters" of a mile.

    The projector as Jackie stated was intended simply for accurate outlining on maximal 30" high portrait paper at a distance of around 2 metres (7 feet) and it served it's purpose well for me, I only stopped using it because I got mini beamer which allows me to beam images directly from my computer at any size at all, therefore no need for transparencies.

    The main purpose of the whole exercise was to allow people who like me love challenge to build something they could use and be proud of, and with the exception of the Fresnel lens and magnifying glass, it was built entirely form stuff I had in house.

    My advice is if you don't like a challenge or you don't like the machine, Don't build it, I'm into model building and totally love a challenge and that is the only reason I built it.

    @Jackie, unless you want to push yourself and do it for the fun factor, I wouldn't bother building this, there are many other low cost ways to project your images, I even found a Samsung phone with a built in projector, but to be honest I don't even use my beamer now since I found this http://www.airbrushforum.org/digital-airbrush-tutorials/1656-posterazor-poster-software.html , with this you can print on cardboard and make one great big stencil, ideal for portraits.
  13. JackEb

    JackEb Elite Member! Elite Member!

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    LOL i dont knowo about 'fun factor' but i have been accused of being a touch insane every now and then !
  14. TattooGabby

    TattooGabby Double Actioner

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    Very cool idea. Thanks for sharing
  15. Jar

    Jar Young Tutorling

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    Wow that is in depth I have switched to digital a while back. I know some guys that refuse to switch to digital and they still pull off great work, so its not the tools its the craftsmen. Good luck.

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