[Karthalin]

I could use some brainstorming ideas to get started on my DIY projector lift.


I would love to use this:

But with the dimension constraints I cant get a linear actuator big enough to fit in there and get the total movement I need. So on to the specifics:


Projector: Epson 6500UB

Dimensions of Projector: (W x D x H) 17.7" x 15.5" x 5.4"

Weight: 16.5

Estimate weight of projecter+enclosure: 40 lbs


Dimensions of space in ceiling: (W x D x H) ANY x 17" x 10"

The depth is 10" from the top of the cut-out in the ceiling down to the bottom of the drywall, so anything I make has to account for 1/2" to 3/4" of drywall that would have to be installed on the bottom of the enclosure.


I need the projector to move up/down approximately 15". There is a $100 linear actuator that can handle 400lbs and move 18" and I was looking at that as my starting point ( http://www.firgelliauto.com/product_...products_id=56 )


Due to the 17" depth dimension and 10" height dimension constraint I am thinking of doing a cable/pulley system, a linear actuator and an enclosure on rails or with round alignment pipes to keep it from spinning. Something like this:

But with the actuator mounted sideways:

And thats kind of where I am at now. I would love to do a simple scissor lift, but I am having a hard time envisioning it. I have looked at the 80/20 website and again, having a hard time really seeing how I could use the 80/20 parts. They look simple and easy, but with my constraints I dont think I can really utilize the 80/20 method. Any help is greatly appreciated!

 

[Brad Horstkotte]

Check out Rich Harkness' build thread for another approach to PJ lift (starting post #11):

http://www.avsforum.com/avs-vb/showthread.php?t=1254505

 

[Karthalin]

I'll check that link out.


In the meantime here is my latest MS paint idea, using the above example

 

[Karthalin]

I checked that thread out in the link above. I dont have nearly as much money or time as that guy. Plus he did a projector lift from behind a sofa, he wasnt worried about space restrictions. I, on the other hand, have a much smaller spce to shove a lift into and a much smaller budget to stay within.

 

[Bsims2719]

No offense but I don't think that it will work very well. The main problem will be coming back to the same position every time. If you are trying to hit a border or a fixed screen especially if your throw is long. Just an eight of an inch would be visible to the projected image.


Also is this recessed into an attic? If so heat will be an issue. Heat exposure to the projector and heat escaping when projector is in the down position.

 

[Karthalin]

Not recessed into an attic, recessed into the ceiling of the first floor in a two story house.


As far as coming down to the right position everytime I would love to have a more accurate system, but I dont know what would be more accurate. I could add some bump stops to the collapsable piping/rods on each corner so regardless of how far the actuator goes the bump stops prevent the projector from going more than X inches down everytime.

 

[jrwhite]

Hi Karthalin,


I've built a couple of projector lift type projects using linear actuators and sliders. Here's what I see looking at your plan.


I think the scale of your drawings are way off .. the height of the projector appears to be about 2" by that scale, instead of the nearly 6" of the Epson.


If you were to use a pulley drop system, the main problem you will have is the racking on the slides .. where the projector platform will tilt right / left and bind the sliders. In order for this type of system to work you will need a minimum of 3 slides .. the two that you've pictured on the left/right, as well as at least 1 on either the front or the back to control the pitch and roll as the platform moves up and down. It would be better if you had 2 sliders on each side, and 2 sliders on the back.


It would be much better if both the top and bottom platforms of your projector cassette were affixed to the moving element of the sliders.


Consumer drawer type full extension sliders will only extend the slider height, so, your maximum extension in a 9.5" space is only 9.5". I think the smallest readily available full extension sliders are 12". You might be able to cut the non-extending ends of them off.


The transverse mounting of the linear actuator in your later diagram is the only thing that is workable in that space. The size of the linear actuator is it's extension plus the extra space for the motor and gearing. You'll have to see if fergelli offers a 9.5" extension actuator, if not, you'll have to move up to the next highest size and then rig a microswitch to stop in the up position.


All this means is that if you have a 9.5" cavity, the maximum drop you can achieve is 9.5". Assuming your lower platform is an inch or so thick, then this would allow the projector lens to be fully exposed when dropped.


I wouldn't worry about the drop accuracy. I've used the fergelli LA's before, and their end limit is accurate to a couple of millimeters.


Re-draw all your plans to scale. I think it could work if you could cut the sliders down to your cavity height.


Good Luck on your project,


Jonathan

 

[Karthalin]

Thanks a TON Jr. I was hoping to get a response like that. The 18" drop I was planning on was based on the location of the projector prior to the project. The bottom of the projector was 11" from the ceiling using the universal mount I got 2 years ago. Now the projector would be about 6" up in the ceiling and would require ~17" of movement to come back down to its original location.


Looking at the Epson projector specs I can easily do what you mentioned and just have the projector far enough down so its poking out of the ceiling. I am going to start looking at the 12" actuator now.


And yes the drawing is definetely not to scale. I will start drafting your ideas into a proper drawing here in the next two days.

 

[Karthalin]

Here is an idea I though of last night. Dont know how paractical it would be though.


I would use two linear actuators, 9" stroke on each side. Both rated at 400lbs. Total vertical linear travel would be 11.5" inches (down from the original idea for 18"). Take look at the attached drawings.

 

[Karthalin]

Looking at it, that might be too much linear force being turned into vertical motion with that setup. Could attempt to attach the moment arms to the bottom of the projector cage. Think I found the weakness in that above posted design...

 

[Karthalin]



Quote:
Originally Posted by jrwhite /forum/post/20790312


Hi Karthalin,


I've built a couple of projector lift type projects using linear actuators and sliders. Here's what I see looking at your plan.


Consumer drawer type full extension sliders will only extend the slider height, so, your maximum extension in a 9.5" space is only 9.5". I think the smallest readily available full extension sliders are 12". You might be able to cut the non-extending ends of them off.


Jonathan

Well, I am looking into a slider type siystem, very similiar to the original drawing. I could use some help findind the right drawer slider. I plan on getting 6 total, 2 pairs for the sides and 1 pair for the back. So far I have found these that I think will do the job and are 10" in closed length.

http://www.drawerslides.com/p/kv-8407-ano-10

Catalog: http://www.drawerslides.com/_media/s...efcd6216ac.pdf


And these ones, cheaper but much beefier:
http://www.drawerslides.com/p/ry2250.10-qd

Catalog: http://www.drawerslides.com/_media/s...2f9608711a.pdf


Next is to throw it all back into AutoCad and see what comes up

 

[jrwhite]

Hi Karthalin,


Mechanically, I think your original pulley design is better and easier to fabricate / implement.


In this design you're using the mechanical properties of a lever to your disadvantage. To illustrate the point, try putting a 5 pound weight at the end of a 15 inch rod, and then try to lift the weight by pivoting the end of the rod. Pretty heavy eh? Now, increase that to 20 pounds. That's what the levers in your design will be carrying. On top of that, there will be a lot of wasted energy and stress on the lever joints, the track the levers rides in on the top frame, and the frame of the cassette trying to convert the transverse energy into vertical movement. This means that most of the energy used is trying to pull your cassette frame apart, and the small by-product is that it lifts up.


On top of this, fabricating the parts for the frame, leavers, and cassette would probably be more complex than building a scissor lift from aluminum bars or 80/20 components .. like the original photo you posted.


Jonathan

 

[jrwhite]

I missed your last post while I was posting. The slides don't have to be overly beefy, as there will be very little transverse load on them. They are only being used to stabilize the pitch/roll of the cassette while it's moving.


Jonathan

 

[Karthalin]



Quote:
Originally Posted by jrwhite /forum/post/20793335


Hi Karthalin,


In this design you're using the mechanical properties of a lever to your disadvantage. To illustrate the point, try putting a 5 pound weight at the end of a 15 inch rod, and then try to lift the weight by pivoting the end of the rod. Pretty heavy eh? Now, increase that to 20 pounds. That's what the levers in your design will be carrying. On top of that, there will be a lot of wasted energy and stress on the lever joints, the track the levers rides in on the top frame, and the frame of the cassette trying to convert the transverse energy into vertical movement. This means that most of the energy used is trying to pull your cassette frame apart, and the small by-product is that it lifts up.


Jonathan

I am too visual of a person. Staring at the 2 linear actuator idea finally made me realize what you were saying. I've almost got the slider idea from the original post mocked up in AutoCAD now, I just need to find an appropriate pulley online to model.

 

[GlenH]

Check out this projector lift ...


Here's the lift in action .

 

[Verge2]

Murphy's law, as soon as you have a bunch of people over, your lift is going to break.


Eliminate the possibility IMO.