Hi, I'm new to OpenBuilds, trying to build a device that would move a painting up and down to cover a flat screen TV. 1. The system would need to lift 12 lbs, and travel 32.5" or ~825mm. 2. I'm thinking the gantry plate would attach to a custom stand-off bracket, which would itself attach to the wall. The lift mechanism would mount vertically inside a square edge frame and be hidden from view by the canvas painting. 3. What parts would be required for such a mechanism including motor controls? ANSWER from experienced member: For lifting and holding anything I would use a screw, the 8mm acme openbuilds has would work great for this (as long as it's less than 1000mm); for the motor, I would not use a stepper, just a simple geared dc motor on a limit switch setup for up-down limits. Any additional thoughts and suggestions would be much appreciated. Thanks. Dennis EDITED 7-2-19: My conceptual idea for this mechanism is depicted in the attached drawing. It would use either a sub-frame onto which the actuator is mounted (as shown), with the actual canvas painting on its own independent frame sitting over the sub-structure or, if the gantry-to-rail attachment is sufficiently rigid, I would attach a cross rail at the top of the track onto which a singular canvas frame would mount. The benefits of the latter idea would be reduced weight/ load. In either case it seems important the mechanism is easily accessible for adjustments/maintenance, etc.
You might also need a catch to hold it in the raised position - I would research how push-to-catch/push-to-release catches work (as often used on glass doors). Alex.
Hi Alex, With a stepper powered off maybe you would need a catch but a low RPM geared brushed motor would have a bunch of drag, and the screw will not turn under 12lbs load (probably ) I'm trying to wrap my head around how you could mount this to a wall with one actuator and not need one on both sides of the TV with the art moving in front of it, and not have the actuator in front of the TV too. Cheers Gary
How much space do you have between the TV and the wall as you approach the vertical outside edges of the TV?
I'm on my phone at the moment so can't draw this, but anyone who has assembled /disassembled a drawing board with a parallel motion will recognise this - wires/strings in a horizontal figure of eight. Up on the right, round a pulley, diagonally down to bottom left, round a pulley, up on left, round a pulley, diagonally down to bottom right. Left and right go up and down in unison and have a fitting clamped to them which is attached to the item to be raised / lowered. If you can get the diagonal wires/strings behind the TV this could work - they don't have to go in a straight diagonal line if you put a couple of extra pulleys in the system. Sorry - that would have been much clearer with a drawing. Alex. Further thought - with two extra pulleys the "diagonal" wires could run vertically at the sides and across at the bottom. Actuator could be attached to a wire running across the bottom and everything mounted/hidden in a frame around the outside.
Even further thought - to eliminate slippage you could use a toothed belt and a toothed driving pulley (I think Openbuilds could supply the parts for that) Alex.
Assuming the painting is taller than the TV setup: One of these: https://smile.amazon.com/uxcell-Reversible-Turbine-Electric-Gearbox/dp/B072B83JY4/ A couple limit switches, a pair of linear rails attached to the back of the painting (or even black anodized V-Slot) with the bearings/wheels mounted to the wall, four stabilising sprung wheels at the corners that roll on the drywall itself, some GT2 parts and an Arduino and you're set. The entire setup could be hidden on a wall-mounted plate directly above the TV where the mechanism for the painting's movement is completely invisible at all times (with some side-skirts)
As it will be at least 12 hours before I can get to some cad software I've had to resort to using a carbon isomer encased in a ligneous sheath and some pulverised vegetable matter spread into a thin sheet. I hope this innovative technological technique will work. Alex. EDIT - wrong word - not isomer - should have said allotrope.
I would like to embed here my conceptual drawing for this mechanism, but can't figure out how. I attached it as an edit to my original post, but would people see it? Any help would be appreciated. Is there a section of this website that explains how to use the website?
I had no problem opening the pdf. If you want it to be visible in the body of the message upload it as a jpg. Alex.
Thanks to all for your input - much appreciated. My conceptual idea for this mechanism is depicted in the drawing below, and I welcome any thoughts. It would use either a sub-frame onto which the actuator is mounted (as shown), with the actual canvas painting on its own independent frame sitting over the sub-structure or, if the gantry-to-rail attachment is sufficiently rigid, I would attach a cross rail at the top of the track onto which a singular canvas frame would mount. The benefits of the latter idea would be reduced weight/ load. In either case it seems important the mechanism is easily accessible for adjustments/maintenance, etc. View attachment 40920
Comment received from Mark Carew in separate thread: 1. Please see the actuator test specs here for the various style systems. 2. Yes they OpenBuilds limit Switches will work in the track of the V-Slot 3. I would suggest using an arduino with a simple stepper motor driver. I've inserted my drawing here, since it shows as just an attachment in my original post. - DJM
