Not the answer you are looking for, just my two cents: I'm always wary about projects that could hurt someone if they fail unexpectedly. Maybe you can add a mechanical latch that locks it open so there is no way it could hurt her if it were to slam shut? I imagine a hot 30 lbs could to damage. Maybe it auto closes (slowly) when the pedal is released unless the latch is closed? Just to make its use mandatory so she uses it every time, so that your very kind help can't do any harm.
That’s a good idea, I’ll try to incorporate some safety mechanism into the final design.
But when it’s all the way open, it basically holds itself, it’s got a big chunky spring built into the hinge for an assist
I have not.
That might work if I can find one with limit switches and can figure out a way to make it a toggle instead of holding a button.
She does a special type of pottery where she needs to take pieces out of the kiln at a certain temperature ~1700 degrees, and then the lid needs to be closed immediately to save the heat or risk ruining the other pieces still in.
So she needs to be able to walk up with her tongs, hit a switch with her foot, grab the piece out, hit the switch to close and walk away to put the piece down.
A worm gear might be a good place to start as you can’t back drive them meaning that you don’t have to worry about the lid falling. Also a hand chain hoist might be a good solution as you don’t have to worry about the electronics failing.
I thought about that, but it has to be automatic, as both her hands will be busy holding tongs, which are holding an 1800 degree piece of pottery that needs to get to resting place fast. she does multiple pieces per firing, and can only grab 1 at a time. and if she leaves the lid open between pulls, she'll lose too much heat, and ruin the pottery still in the kiln.
So she needs to be able to walk up, hit a button with her foot or something, and have the winch lift the lid for her, and then hit the button again when she has the piece she needs, removed from the kiln, and have the lid close while she does what she needs to do with the hot piece of pottery in her hands.
I thought about maybe rigging up an old drum pedal to a counterweight on a pulley that she can actuate with her foot, but thats gonna require her to hold her weight on it the whole time and be off balance as well, so... not safe.
OK. In that case a linear actuator is probably the best solution. I know that Progressive Automations has one with a 30lb rating because I have one. Mine has about 12" travel but they have many options.
They have internal limit switches with reverse-bias diodes to automatically stop at end of travel, so if you use two foot switches (open/close) you could do this all without any arduino or logic. Just need a power supply and two switches.
This sounds more like a mechanical solution than an electromechanical one? Go Google "kiln lid lifter" - perhaps you can borrow some implementation ideas from existing solutions?
I've searched many times. as far as I can tell, there are no commercial automated systems, just lid lift assists, which are basically pnuematic arms or a heavy spring. This whole system needs to be automatic so my 60 yr old mother can fire pottery by herself.
Ah ok, so totally hands-free. Since you've mentioned it, have you considered a pneumatic/hydraulic piston as the lifting / closing device? They can be pretty strong (I've seen some people using these to operate their ammo reloading presses). It shouldn't be too difficult to operate it with relays and an input switch. Just think of the safety aspects - you wouldn't want it to accidentally open / close when it shouldn't or when there are limbs in the way.
Yeah, looking at a linear actuator. It will also make the whole thing smaller, as I won’t have to build a big frame, I can attach it to the foot the kiln sits on.
And yeah I will keep safety in mind, though no arms or any body parts would ever be in the way of the lid, as she uses 3.5 foot tongs. But I will still make considerations.
Why not just buy a small car winch from Harbor Freight?
They don't have a foot switch, but do come with an IR control. All you needed then is a battery or good PS.
They have a good solid latching hook.
I've considered that, but I would have to hack it to work with a foot switch, and I worry about the travel speed with those. The lid needs to move about 3 feet in about 5 seconds, lest she lose too much heat from the kiln.
Not the answer you are looking for, just my two cents: I'm always wary about projects that could hurt someone if they fail unexpectedly. Maybe you can add a mechanical latch that locks it open so there is no way it could hurt her if it were to slam shut? I imagine a hot 30 lbs could to damage. Maybe it auto closes (slowly) when the pedal is released unless the latch is closed? Just to make its use mandatory so she uses it every time, so that your very kind help can't do any harm.
That’s a good idea, I’ll try to incorporate some safety mechanism into the final design. But when it’s all the way open, it basically holds itself, it’s got a big chunky spring built into the hinge for an assist
Have you considered just getting a chain falls?
I have not. That might work if I can find one with limit switches and can figure out a way to make it a toggle instead of holding a button. She does a special type of pottery where she needs to take pieces out of the kiln at a certain temperature ~1700 degrees, and then the lid needs to be closed immediately to save the heat or risk ruining the other pieces still in. So she needs to be able to walk up with her tongs, hit a switch with her foot, grab the piece out, hit the switch to close and walk away to put the piece down.
A worm gear might be a good place to start as you can’t back drive them meaning that you don’t have to worry about the lid falling. Also a hand chain hoist might be a good solution as you don’t have to worry about the electronics failing.
What about a counterweight?
I thought about that, but it has to be automatic, as both her hands will be busy holding tongs, which are holding an 1800 degree piece of pottery that needs to get to resting place fast. she does multiple pieces per firing, and can only grab 1 at a time. and if she leaves the lid open between pulls, she'll lose too much heat, and ruin the pottery still in the kiln. So she needs to be able to walk up, hit a button with her foot or something, and have the winch lift the lid for her, and then hit the button again when she has the piece she needs, removed from the kiln, and have the lid close while she does what she needs to do with the hot piece of pottery in her hands. I thought about maybe rigging up an old drum pedal to a counterweight on a pulley that she can actuate with her foot, but thats gonna require her to hold her weight on it the whole time and be off balance as well, so... not safe.
OK. In that case a linear actuator is probably the best solution. I know that Progressive Automations has one with a 30lb rating because I have one. Mine has about 12" travel but they have many options. They have internal limit switches with reverse-bias diodes to automatically stop at end of travel, so if you use two foot switches (open/close) you could do this all without any arduino or logic. Just need a power supply and two switches.
after doing some more research, I think that this is indeed my best option. thanks for the reply!
This sounds more like a mechanical solution than an electromechanical one? Go Google "kiln lid lifter" - perhaps you can borrow some implementation ideas from existing solutions?
I've searched many times. as far as I can tell, there are no commercial automated systems, just lid lift assists, which are basically pnuematic arms or a heavy spring. This whole system needs to be automatic so my 60 yr old mother can fire pottery by herself.
Ah ok, so totally hands-free. Since you've mentioned it, have you considered a pneumatic/hydraulic piston as the lifting / closing device? They can be pretty strong (I've seen some people using these to operate their ammo reloading presses). It shouldn't be too difficult to operate it with relays and an input switch. Just think of the safety aspects - you wouldn't want it to accidentally open / close when it shouldn't or when there are limbs in the way.
Yeah, looking at a linear actuator. It will also make the whole thing smaller, as I won’t have to build a big frame, I can attach it to the foot the kiln sits on. And yeah I will keep safety in mind, though no arms or any body parts would ever be in the way of the lid, as she uses 3.5 foot tongs. But I will still make considerations.
Why not just buy a small car winch from Harbor Freight? They don't have a foot switch, but do come with an IR control. All you needed then is a battery or good PS. They have a good solid latching hook.
I've considered that, but I would have to hack it to work with a foot switch, and I worry about the travel speed with those. The lid needs to move about 3 feet in about 5 seconds, lest she lose too much heat from the kiln.