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Hi all and welcome to TheWoodHaven2 brought into the 21st Century, kicking and screaming! We all have Alasdair to thank for the vast bulk of the heavy lifting to get us here, no more so than me because he's taken away a huge burden of responsibility from my shoulders and brought us to this new shiny home, with all your previous content (hopefully) still intact! Please peruse and feed back. There is still plenty to do, like changing the colour scheme, adding the banner graphic, tweaking the odd setting here and there so I have added a new thread in the 'Technical Issues, Bugs and Feature Requests' forum for you to add any issues you find, any missing settings or just anything you'd like to see added/removed from the feature set that Xenforo offers. We will get to everything over the coming weeks so please be patient, but add anything at all to the thread I mention above and we promise to get to them over the next few days/weeks/months. In the meantime, please enjoy!
Oak TV cabinet (TV lifter video)
- Thread starter Mike G
- Start date
Mike G
Petrified Pine
I am going to quickly go over some ground covered in other threads which have focused on the electrics/ switching, so apologies if you have seen that before. I'll then move on to new stuff.
This is the kit of parts with which I will be making the lifting mechanism for the TV:
That's a power unit which converts 240V AC into 12V DC, an old 14V drill, and various 2 way switches. Here is the drill taken apart:
I had hoped to use the reversing switch from the drill, but it is puny:
I hooked the drill up to the power unit, and it worked perfectly:
As did the 2 way microswitches:
I ordered some 12V reversing 2 way switches to use in place of the drill's reverse switch, and when they arrived without a wiring diagram, I sacrificed one of the 5 so that I could see inside and work out how they worked:
I then threw the entire weight of my electrical experience into producing a world class wiring diagram to include the new switch:
I then made up that circuit:
I started the mechanism:
I was bothered by the potential instability of this, and went down a few different design paths, including raiding my old Meccano box:
None of that seemed any better than the original plan, so having wasted a few hours I got on with the woodwork:
I needed an axle which would rotate as the mechanism moved, and which would capture the nut which would turn on the threaded rod which runs the whole thing. I have quite a lot of plastic stock left from an invention of mine from a few years ago, and with an eye to the friction, I made the axle out of that:
All done with woodworking handtools. In many ways this plastic works more easily than wood. It planes beautifully, cuts well with a saw, and pares nicely with a chisel.
You can see it at bottom left between the legs of the mechanism in the following photo:
I ran this many times with a cordless drill, and realised that I need to design in a fail-safe mechanism. Collapses in the workshop when bearing no load have an altogether different scale of consequences compared with collapsing when loaded with a TV.
Here is the mechanism for the switch hidden behind the Tudor rose carving:
The thing in the middle is a push-to-open cabinet catch, which means that pushing the rose will leave it 15-ish mm in to the cabinet when the TV is up, then you push it again to return the carving to flush, and the TV to the down position.
Finally, I rigged up the actual drill and the jerry-rigged electrics, and it all worked beautifully. I've got a bit of soldering to do, but the key to this whole enterprise is the mechanism which tells the platform to stop at the end of each run, and which reverses the position of the reversing switch. That will be tomorrow's fun (I've now finished architectural work for christmas). Here's what it looked like as I shut up the workshop a few minutes ago:
By the way, the pivots are all just bolts at the moment, but once this is finished and adjusted and working well, I'll buy some appropriate bearings and let them into the wood, to help reduce the friction in the system.
This is the kit of parts with which I will be making the lifting mechanism for the TV:
That's a power unit which converts 240V AC into 12V DC, an old 14V drill, and various 2 way switches. Here is the drill taken apart:
I had hoped to use the reversing switch from the drill, but it is puny:
I hooked the drill up to the power unit, and it worked perfectly:
As did the 2 way microswitches:
I ordered some 12V reversing 2 way switches to use in place of the drill's reverse switch, and when they arrived without a wiring diagram, I sacrificed one of the 5 so that I could see inside and work out how they worked:
I then threw the entire weight of my electrical experience into producing a world class wiring diagram to include the new switch:
I then made up that circuit:
I started the mechanism:
I was bothered by the potential instability of this, and went down a few different design paths, including raiding my old Meccano box:
None of that seemed any better than the original plan, so having wasted a few hours I got on with the woodwork:
I needed an axle which would rotate as the mechanism moved, and which would capture the nut which would turn on the threaded rod which runs the whole thing. I have quite a lot of plastic stock left from an invention of mine from a few years ago, and with an eye to the friction, I made the axle out of that:
All done with woodworking handtools. In many ways this plastic works more easily than wood. It planes beautifully, cuts well with a saw, and pares nicely with a chisel.
You can see it at bottom left between the legs of the mechanism in the following photo:
I ran this many times with a cordless drill, and realised that I need to design in a fail-safe mechanism. Collapses in the workshop when bearing no load have an altogether different scale of consequences compared with collapsing when loaded with a TV.
Here is the mechanism for the switch hidden behind the Tudor rose carving:
The thing in the middle is a push-to-open cabinet catch, which means that pushing the rose will leave it 15-ish mm in to the cabinet when the TV is up, then you push it again to return the carving to flush, and the TV to the down position.
Finally, I rigged up the actual drill and the jerry-rigged electrics, and it all worked beautifully. I've got a bit of soldering to do, but the key to this whole enterprise is the mechanism which tells the platform to stop at the end of each run, and which reverses the position of the reversing switch. That will be tomorrow's fun (I've now finished architectural work for christmas). Here's what it looked like as I shut up the workshop a few minutes ago:
By the way, the pivots are all just bolts at the moment, but once this is finished and adjusted and working well, I'll buy some appropriate bearings and let them into the wood, to help reduce the friction in the system.
Nico Adie
New Shoots
The cabinet looks great and I love the A-Team/Macgyver style tv lifter.
Mike you will be able to video this wont you?
Mike, the cabinet looks great and now it's getting really interesting with the lift!
Used to have my TV in a cabinet on a lift, I made the cabinet but not the lift. It was supposedly a premium lift and cost about £450. It failed in under a year so they replaced it and the new one failed just the same. They went up fine but started juddering when coming down to the point I thought it would damage the TV, I just gave up on them. Seems like it is harder to support the weight coming down then going up :eusa-think:
Looking forwards to seeing yours in action.
Used to have my TV in a cabinet on a lift, I made the cabinet but not the lift. It was supposedly a premium lift and cost about £450. It failed in under a year so they replaced it and the new one failed just the same. They went up fine but started juddering when coming down to the point I thought it would damage the TV, I just gave up on them. Seems like it is harder to support the weight coming down then going up :eusa-think:
Looking forwards to seeing yours in action.
MattS
Nordic Pine
Can’t wait to see this working!
Mike G
Petrified Pine
[youtube]4GstLDTR2jA[/youtube]
It works, as you can see. :eusa-dance: :eusa-dance: However, I'm not completely confident enough to mount the TV on it. I want to sort the cable runs out, the motor mounting, and fit an over-run kill switch before I fit it in the cabinet.
It works, as you can see. :eusa-dance: :eusa-dance: However, I'm not completely confident enough to mount the TV on it. I want to sort the cable runs out, the motor mounting, and fit an over-run kill switch before I fit it in the cabinet.
Nico Adie
New Shoots
Mike G":12s8ra5a said:
Outstanding! Top work, Mike :eusa-clap: :text-bravo:
Cabinetman
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Terrific bit of work that Mike, funnily enough I’ve just come back from my workshop having fitted some captive nuts like that in a rocking deckchair design of mine.
I do love messing about with things like that, I also have been a bit of an inventor in my time, wonderful prototype’s but once I’ve proved it works I lose all interest in it so never made any money at it.
Mike I use a lot of nylon bushes/tubes 25 mil long 10 mm outside diameter takes a six mil bolt as an axle, I have 1 million, well quite a few, PM me if you would like me to pop some in the post to you. Ian
I do love messing about with things like that, I also have been a bit of an inventor in my time, wonderful prototype’s but once I’ve proved it works I lose all interest in it so never made any money at it.
Mike I use a lot of nylon bushes/tubes 25 mil long 10 mm outside diameter takes a six mil bolt as an axle, I have 1 million, well quite a few, PM me if you would like me to pop some in the post to you. Ian
Mike G
Petrified Pine
Random bits of the mechanism explained. Firstly, the over-centre device for stopping at the end of a run, and for setting a change of direction for the start of the next run:
It fits in this gap:
Because of the tight space, I had to make a complex new tool to turn a screw eye into place:
You can see the principle here, with a spring to flick it up or down:
The over-centre device has to trigger two switches. The first is a simple microswitch to turn the power off. The critical point is that this has to happen BEFORE the reverse switch (the other switch) is triggered. Mocking up the microswitch against a cam on the over-centre device:
That was very straightforward. It triggers within about 5mm either side of dead centre. Triggering the reverse switch at the right time was a bit more involved. I mocked up a pivoting arm which would push the switch through all 3 of its positions as it swung, just to work out the geometry:
Translating that to the machine itself:
That's the top platform removed and held vertically in the vice, with the reverse switch mounted in the end. This is the bit that pushes the switch:
Now, that arm which controls the pushing of the switch needs to be triggered by the over-centre mechanism (O-CM), but not until it has nearly finished it's movement. The piece of plastic (white, below), mounted to the side of the O-CM, pulls the lever at the last moment, which in turn moves the reverse switch through "off" to "reverse", in each direction:
You can see here that the O-CM has nearly reached the end of it's run, but the lever is still in the centre position:
....and then finally moves and trips the switch:
Going the other way:
So, that's the guts of the machine. The lag between turning the motor off and setting the electrics to run it the opposite way next time it comes on is done entirely mechanically. I've now run it up and down at least 200 hundred times, and I've had 4 or 5 failures. Each of those has been mechanical rather than electrical, and all of them easily sorted. Formalising the pivot points will help, as will finding a way to locate the motor properly rather than just clamp it around the plastic body. The O-CM has worked faultlessly, but was over-tensioned to start with.
Fun as all this has been, it's taken rather too long. I've more important things to be getting on with.
It fits in this gap:
Because of the tight space, I had to make a complex new tool to turn a screw eye into place:
You can see the principle here, with a spring to flick it up or down:
The over-centre device has to trigger two switches. The first is a simple microswitch to turn the power off. The critical point is that this has to happen BEFORE the reverse switch (the other switch) is triggered. Mocking up the microswitch against a cam on the over-centre device:
That was very straightforward. It triggers within about 5mm either side of dead centre. Triggering the reverse switch at the right time was a bit more involved. I mocked up a pivoting arm which would push the switch through all 3 of its positions as it swung, just to work out the geometry:
Translating that to the machine itself:
That's the top platform removed and held vertically in the vice, with the reverse switch mounted in the end. This is the bit that pushes the switch:
Now, that arm which controls the pushing of the switch needs to be triggered by the over-centre mechanism (O-CM), but not until it has nearly finished it's movement. The piece of plastic (white, below), mounted to the side of the O-CM, pulls the lever at the last moment, which in turn moves the reverse switch through "off" to "reverse", in each direction:
You can see here that the O-CM has nearly reached the end of it's run, but the lever is still in the centre position:
....and then finally moves and trips the switch:
Going the other way:
So, that's the guts of the machine. The lag between turning the motor off and setting the electrics to run it the opposite way next time it comes on is done entirely mechanically. I've now run it up and down at least 200 hundred times, and I've had 4 or 5 failures. Each of those has been mechanical rather than electrical, and all of them easily sorted. Formalising the pivot points will help, as will finding a way to locate the motor properly rather than just clamp it around the plastic body. The O-CM has worked faultlessly, but was over-tensioned to start with.
Fun as all this has been, it's taken rather too long. I've more important things to be getting on with.
Mike G
Petrified Pine
Cabinetman":zv5utr5m said:
That's really kind of you Ian. I might just take you up on that offer.......but I want to think it all through first. I had planned to have bearings for all the principle pivot points, but the mock-up has shown that friction isn't a big issue here.
Mike G
Petrified Pine
Thanks Roger. I know the electrics have been painful for everybody, and I've not done it the way anyone else would.......but working with my limited knowledge and abilities has been a stiff challenge.
AJB Temple
Sequoia
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Very relieved that it works. :eusa-clap:
You could make another one wired to a burglar alarm and make a skeleton bearing a gun pop up.
I showed it to my friend. She's female (hence the she) and Irish. She said, it's all very well, but what if he has a power cut? He won't be able to get it up. :lol:
You can never be entirely sure when she's joking and whether double meanings are intended. So I just keep quiet.
She also remarked that soft start and finish would be nice. I said that is the normal state of affairs, but Mike likes to finish with a jolt.
You could make another one wired to a burglar alarm and make a skeleton bearing a gun pop up.
I showed it to my friend. She's female (hence the she) and Irish. She said, it's all very well, but what if he has a power cut? He won't be able to get it up. :lol:
You can never be entirely sure when she's joking and whether double meanings are intended. So I just keep quiet.
She also remarked that soft start and finish would be nice. I said that is the normal state of affairs, but Mike likes to finish with a jolt.
Cncpaul
New Shoots
Great job Mike, l bet you enjoyed building the lifter
Mike G
Petrified Pine
Cncpaul":fipkc6lw said:
I enjoyed thinking about it more than building it, frankly. The way it's built as a trial-and-error prototype also means I am going to have to re-build it fairly soon.
DaveL
Old Oak
Well done Mike that works a treat.
I would recommend you fit some sort of bearings as the wood will soon wear and the holes will become oval.
I would recommend you fit some sort of bearings as the wood will soon wear and the holes will become oval.
MattS
Nordic Pine
Brilliant. Don’t know why given it’s a drill running it by expected it to run slower. Very impressive!
Cabinetman
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AJB Temple":37q8ioy6 said:
Wonderful, almost too much double entendre and innuendo for a sleepy Ian at this time of night.
Re-the gun bearing skeleton, Halloween before last I was in America and they were selling full-size plastic skeletons – far too realistic. I was imagining what would happen to them all, how to dispose of a very lifelike skeleton, and just how many police callouts there would be when people started to dig up their patios in the future haha. Ian
DaveL
Old Oak
Another thought, how about U bolts to hold the motor? Or maybe big hose clips?
Thanks for sorting the video Mike. Makes it a whole easier for me to understand the workings.
Mike G
Petrified Pine
Thanks Sam.
And a huge thanks to Michael (MY63) for the cordless drill which runs the mechanism, and to DaveL for the switches and power unit (they work, Dave, so we must talk.......).
It's now semi-permanently fitted in the TV cabinet, properly triggered by the rose carving, and all working albeit without having the TV on it yet. There are a few niggles, particularly to do with some sockets and outlets which are in the way when they have something plugged in to them, but I'll sort those on Boxing Day. I also need to make some new feet for the TV, which again will have to wait for Boxing Day. It will all come out again when I upgrade the pivots. That shouldn't be a complex job.
And a huge thanks to Michael (MY63) for the cordless drill which runs the mechanism, and to DaveL for the switches and power unit (they work, Dave, so we must talk.......).
It's now semi-permanently fitted in the TV cabinet, properly triggered by the rose carving, and all working albeit without having the TV on it yet. There are a few niggles, particularly to do with some sockets and outlets which are in the way when they have something plugged in to them, but I'll sort those on Boxing Day. I also need to make some new feet for the TV, which again will have to wait for Boxing Day. It will all come out again when I upgrade the pivots. That shouldn't be a complex job.
Rod
Old Oak
Fascinating work. For some reason none of your photos show up here but the video does.
Rod
Rod
Phil
Old Oak
Impressive! :eusa-clap:
Impressive Mike, noisy as all hell though.
Rod
Old Oak
Perhaps you could project a man playing an organ as it rises and falls like in the olden days [emoji3]
Rod
Rod
Nico Adie
New Shoots
Tremendous work!
Mike G
Petrified Pine
Sadly, it looks as though the drill wasn't quite up to the task. It has suffered a gearbox/ clutch failure. It's in bits in my workshop at the moment whilst I try to work out how everything works. There are 4 layers of planetary gears to try to understand. If I have to swap to a more powerful drill, I'll need to get an 18V power supply, and have a look at the rating of all the switches.
MikeG, I haven't read the whole thread, and I know you'd rather do a improvised fix (and spend no money), but how about a linear motor/actuator?
I looked into them for a self lifting top for a roof tent for a Landy (a project that got overwhelmed by... life, I suppose...), and they looked pretty natty, and could be used with your existing hinged frame arangement. It might end up being smoother and less like a 70s Dr Who special effect.
If you have considered this and discarded the idea, my apologies.
I looked into them for a self lifting top for a roof tent for a Landy (a project that got overwhelmed by... life, I suppose...), and they looked pretty natty, and could be used with your existing hinged frame arangement. It might end up being smoother and less like a 70s Dr Who special effect.
If you have considered this and discarded the idea, my apologies.
Mike G
Petrified Pine
A roof tent? I held a patent for a rooftent for a while. You can see the prototype I made on the Youtube channel were I've posted the TV lifter video. And I drove the length of Africa in the 90s using a homemade 4 man rooftent every night.
As for the linear actuator......well, the thing is I know there are loads of better ways of doing this thing. I mean, fabricating it from steel would be a start. But I've set out my stall now, and the damned thing is going to work.
As for the linear actuator......well, the thing is I know there are loads of better ways of doing this thing. I mean, fabricating it from steel would be a start. But I've set out my stall now, and the damned thing is going to work.
Rod
Old Oak
My daughter a few years ago bought a house with a TV that came down from the ceiling where it was suspended over a bed.
What made it even more horrid was the TV was an enormous Sony Trinitron
Rod
What made it even more horrid was the TV was an enormous Sony Trinitron
Rod
Mike G":wdwvr6yp said:
Ok, I more than understand.
Er, I don't know whether I 've mentioned this, but I was brought up in Africa (Zambia and Egypt). I've been to most of the southern and eastern bits. Mind you my partner has now been to more African countries than I have. Malaria research. Ghana, Nigeria, Upper Volta (ok, Burkina). Mali, Sudan, Ethiopia and others I can't remember off hand.
All delightful in their way.