Hoist lifting mechanism?

M. Moore · Dec 11, 2014

Looking for a way to flip products using an overhead hoist.
Slab of wood up to 5' wide and 14' long, 2.5 to 3.5" thick, max weight in the 500 to 600 lb range.
I have been brainstorming to come up with a workable solution and wondered if something already exists.
One idea was to grab from both ends and rotate 180° then set down. Clamping the product securely is an issue no matter how it is flipped, currently we have endless slings and rotate the large wood slabs in the slings and then set down, this works but is very slow and cumbersome. Having to set the slings each time is a pita.
Ideally the flipper can grab a slab from the top of the pile and move it into position and or flip if needed.
Is there a 180° capable heavy duty powered knuckle joint? The grabber could be hydraulic or mechanical and I have a few ideas on how to make that work. With the knuckle joint setup the slab would be grabbed from one edge and flipped, the movement of the slabs' position is not a problem as they don't have to be flipped in place, just flipped and the overhead hoist can easily reposition onto the table.
Thoughts?

Michael

Orange Vise · Dec 11, 2014

How about a forklift rotator and clamp?

snowman · Dec 11, 2014

Why not just put the endless sling in choker so that it chokes one edge to pick up vertical, then ease it back over. You maintain full control.

Forrest Addy · Dec 11, 2014

Roll 500 lb glue-lams? C-clamp a 2 x 4 on the end and lever them over. I've used that gimmick on 1600 lb 15 x 50# I beams but you got to have the item blocked up on 4 x 4's.

Chip Chester · Dec 11, 2014

How nice to the workpiece to you need to be? Can you stab it in the end-grain with some spikes? Is it consistently smooth enough for vacuum cups? Are you looking for absolute speed, in seconds? Or can it take two minutes without pissing anyone off?

I would think some slings sliding on a bar with strategically-placed snubbers would allow a quick and drama-free flip with minimal human intervention... especially if landing on risers instead of flat on the target surface. The risers would allow straps and snubbers to remain under the landed workpiece.

In a thread about a month ago, there was a link to a Hobbit-inspired hydraulic machine... one ring to roll them all. (Sorry.) It was a assembly-line quality flipper where the work rode in a rotating cage that was 6-8 feet in diameter, and probably quite pricey.

There's another machine in that thread that resides in a horizontal table-like platform, and two pivoted arms rise up, flipping the piece in a controlled manner, as two opposite arms rise to catch it and provide a controlled descent. Pretty slick and quick. Bad news if the pitcher does but the catcher doesn't.

Chip

matt_isserstedt · Dec 11, 2014

So, a couple of heavy duty saw horses faced with clean sawhorses would seem to be the best support system. Four guys working together should be able to flip the face over fairly easily. Not sure if you are trying to flip with one man?

If you want an end effector, the simplest idea I can think of involves two "C" sections, long and narrow, heavy duty, capture the board. Pneumatic clamp by soft faces. Flip via hinged joints via other air cylinders. Set back on saw horses, unclamp, disengage, reflip. Hard for me to put into words. Just think of capturing the board between your thumb and fingers on its flat faces, then rolling your wrists back 180 degrees towards your body. A sketch would be best if I have time.

All you need is an air compressor and some controls.

M. Moore · Dec 11, 2014

Wow, some quick feedback, isn't anyone working??LOL

I will try to answer all and provide more info.

The forklift flippers are excellent devices, but no room to use the f-lift and flipping the long way probably not the best. Also those rotators are super heavy duty and need to be for what they do, our lifts are a bit lighter and I was hoping to hang the flipping device off of the hoist cable.

To answer a lot of repies in one go, we need to flip a lot of slabs and they are too heavy ,usually, for one person. All methods have been tried, four people is unworkable. These slabs are being worked on and after one side is done then the other needs to be done. Typical day would see 10 to 15 slabs done, with the current slow flip, speeding up the flip process will probably result in double the work done in a day.
Also sometimes the slabs need to be laid out first before cutting etc, so if slab flipper could quickly grab slabs from pile and place (without flipping) that would be a real time saver. The pile can be 8 to 10 feet high so not easy to put slings on or otherwise grab the slab, so if the slab flipper was able to mechanically grab an go then that is ideal.

Keep up with the ideas,
Thanks,
Michael

M. Moore · Dec 11, 2014

Matt,
I just reread your post and that is close to what I was thinking in the OP.
I am having trouble with the 180° flip with air cylinders, can't visualize how that could work? I can easily see how it could be done to 90° but not 180.

My first idea was to have two end clamps, (with sharp pins to secure the board) and mount them on a spreader bar so they could be pnuematically clamped or screw driven etc, then rotate the clamps with a chain drive or whatever. The issue with that is to keep the clamps timed and have enough adjustment. The timing is important as I thought at first to drive only on end for the flip, but what happens to the other end? Brake of some sort so it stays in place when not loaded? That might be best as sometimes the slabs are a bit twisted so each end would be out of alignment slightly. Not sure how the clamps would be realigned to parallel if they got out of time.
Keep in mind the clamps will be 10 to 14' apart and sometimes up in the air so positioning this rig is a key factor in making it work.

Michael

snowman · Dec 11, 2014

Big I beam held horizontal, parallel to long surface of board.

Vertical member attached to I beam via four V rollers (or just traditional I beam trolly).

Screw that allows independent adjustment of location relative to center of I beam.

Other end of vertical member has "spindle" assembly, that carries "arms". The overall length of the arms are the width of the board to be lifted. End of each arm has a clamp.

So, lower with overhead crane, screw vertical member to wood length so that clamps can be clamped. Once clamped, lift and flip. If it's even close to balanced you'll be able to flip it easily. If you want a more "sure thing", then put a 10:1 worm drive gear box on one end with a handwheel. Five turns of the handle and it's flipped. Now set it back down, unclamp and lift assembly out of the way.

M. Moore · Dec 11, 2014

Snowman,
I like the sound of what you describe but I can't quite picture how it works exactly.

Your suggestion has helped me come up with another possibility. Fairly simple really, I beam as you suggest but hanging below that is a complete channel frame. The long channels are longer than the longest slab, the long channels move in or out from the center line as needed for different widths of slabs. The channel captures the slab and it can then be flipped safely by hand or power. The difficult part is powering the long channel movement, perhaps air cylinders would be the best bet.
I like the worm drive gearbox idea, automatic brake and sturdy.
The only flaw in this plan is the irregularity of the long sides of the slabs, think "natural edge of a tree" kind of thing, definitely not as straight as channel. Back to the drawing board.

Keep em coming!

Michael

matt_isserstedt · Dec 12, 2014

M. Moore said:
Matt,
I just reread your post and that is close to what I was thinking in the OP.
I am having trouble with the 180° flip with air cylinders, can't visualize how that could work? I can easily see how it could be done to 90° but not 180.

You raise a good point. I think it might have to be a rack and pinion drive at the pivot, the benefit of which could be a cross-shaft to keep the pinions timed the same. Probably some stout air cylinders, armed with flow controls. As the thing rotates the center of mass obviously shifts around, not good to try to do that fast without a lot of structure.

doug8cat · Dec 12, 2014

Should have bought it in Australia, that way it would have arrived side up

Limy Sami · Dec 12, 2014

What about a simple spreader beam the length of the part + a bit, and two clamp on pintles - think deep steel channels to fit over end of part with built in screw clamps to grip on thickness?? Short eyed strop either end lift and turn over by hand, any out of balance parts can be easily gauged by eye and adjusted accordingly.

JP Machining · Dec 15, 2014

Properly applied choker hitch.

JP Machining · Dec 15, 2014

Spreader with powered roller

JP Machining · Dec 15, 2014

2 crane hooks

cvairwerks · Dec 30, 2014

Michael: You need to build yourself a version of this tool: Spreader Bar (M1) I have a friend that owns a monument company and he can flip a rock weighing up to nearly a half ton by himself with this style of a spreader bar.

M. Moore · Dec 30, 2014

Cvair,
I posted earlier that we already have one of those flippers and they are too slow and cumbersome.
Slipping the slings onto the slab is what we are trying to eliminate.

The slab flipper needs to be able to grab a slab from the top of a pile, maybe 8' up, with no assistance from the crane operator ( if possible). The slab flipper needs to do two jobs, grab onto slabs quickly from the pile, enabling them to be moved to the planing machine, (not a thickness planer), and also flip said slab when required.
Grabbing onto, moving and letting go of the slab needs to be fast and easy for the one operator.
I know it is asking a lot but I think it can be done and after some deliberation I have come back around to the original idea of grabbing the slabs from the ends. I will try and get a sketch done and post it here for some critical input.

Michael

gbent · Dec 31, 2014

Are you actually looking at two different problems at one time? The first to pick a heavy plank of variable dimensions from the top of a pile where there is no underside access, and the second to turn over the plank?

I didn't see where you mentioned how much damage, if any, was allowable.

For pulling off the stack, an end grab with a powered spreader bar may be best. If the grab arms are mounted on trunions with 1/2 of the slab width for clearance to the spreader bar it could be used to turn the slab over as well. This method may require more under hook height than you have available.

A stand alone table to flip the slabs may be a solution if you have enough room available in the shop.

M. Moore · Dec 31, 2014

Ghent, yes you nailed it.
Two problems at once. I was trying to describe an end grab powered spreader that can also roll the slabs.
Usually the ends of the slabs are trimmed so sharp dogs that go into the end grain would be the best way of securing the slab.
We have enough ceiling height, we don't need to flip the slabs until they are down at working height.

Michael

Hoist lifting mechanism?

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