winch - my project - and where next


Hi everyone
Want to ask you all about my recent project and how I could develop
it.
I've been making a winch. Kept project webpage diary. As you'll see
it's a totally simple experimental device for learning about the
characteristics of winches.
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Where could I develop my projects from here?
Where I've been already:
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[any comments analysing myself not the projects - I've probably heard
them all already!]
So where to next - any ideas?
I've got a worm-drive gearbox (still with 3ph electric motor) which I
salvaged in storage - which I was hoping to use to make a capstan.
Same idea as for "winch" - find out its characteristics as a stepping
stone to other things. Any ideas how to make the capstan drum? How
to get the slimming-down "waisted" shape for a capstan barrel?
Other project I want to try is a "Pole derrick".
One is shown here:
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That's why I started with the winch, by the way - I had in mind making
one of these.
Any suggestions on good designs for a pole derrick? Any experience
of...? I was thinking of something genuinely useful - maybe with pole
about 5m long, able to lift more than a tonne and hopefully carryable
by a person.
Have plasma cutter, welding machines (mainly stick - all three rod
types 6010, 7018, 6013) and access to machine tools.
Richard Smith
Reply to
Richard Smith
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HI Richard,
I couldn't help thinking about fishing when looking at your project. When I used to go fishing like on a small river out out of a small boat at a fresh water lake or pond there were two kinds of reels. The bait caster type and the open face type. The bait caster type was quite similar to the aspect ratio of what you have. It has a moving "slot" which goes back and forth to stack the line. On shrimp boats of the type which drag in the gulf of Mexico which also have an aspect ratio of about what you have selected there is a slot device which is manually operated (well things may well have been modified since I was involved). This slot thing wasn't usually needed however if you didn't get the cable (wire rope of about 3/4 inches on the boats I was on) started right or didn't watch it towards the end you could have a real problem.
You probably should make the aspect ratio narrower, not use nylon rope preferably something which doesn't stretch so much wire rope, Dacron ?sp. I think you are doomed to having anything but wire rope or cable cutting into the layers below with any real load. of course the lower layers will resist being cut into much more if they are wrapped while under tension.
They have these things I call quads or atv which generally have a single cylinder engine and handlebars. There are electric winches for them which you might wander around the internet and look at.
I use what we call a come a long which uses a cable and has an arm you crank. There are much more expensive ones which use chain.
What you have created looks wonderful for winding up something perhaps coaxial cable or wires for a timing system for a drag race but heavier than necessary. It also kind of looks like a large version without the one way device of what you might attach to a boat trailer to winch the boat out of the water.
Fran
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Reply to
fran...123
Not sure what you plan to move with that winch, but with a 1 to 1 gear ratio (direct drive) and a fairly large diameter drum you are going to probably find it won't be much more if any than you could just pick up and carry. There are some circumstances where that might be beneficial though. Recently I had to move a bunch of tree trimmings. The branches have spines as large as rooster spurs so I threw a grappling hook on each one and just dragged it with my tractor rather than try and get through the stems and branches to grab the main branch with my hands. None of them were heavier than I could have just grabbed, but the spines made it a big pain.
Take a look at the winches on boat trailers. They many use a gear reduction drive, and still have a handle as long as is practical.
As to your question about rope. I have one boat trailer winch that has rope on it and it experiences the same problem you mentioned about rope binding. My larger boat trailer winches all have a wide flat nylon strap that lays flat on itself in one layer.
For short distances you could use a boat trailer inch with a wide nylon strap (20 feet (6 meters) maybe) for a lot less money than your time is worth for what you are trying to build. I have used short pull devices to pull from a lot further away than that with some ingenuity though. I have used a farm jack in a pinch with a combination of straps and chains to move a truck more than 200 feet. It only had a working length of 4 feet.
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If you are trying to come up with some kind of universal winch to save time in the field like to mount on the front bumper of a truck then a big electric Warn winch is the way to go. I have one for my 4x4 and it will drag that truck right out of axle deep muck. It is however not cheap. It would be even much less cheap to build it as a one off project.
In any case you will need additional leverage or gear reduction or both. Fiber rope is not a good option except on some form of rigging where steel would not last. Steel (wire rope) cable will self align to some degree if you guide it at the turnover and you give it some side pull as you go. For a quick and dirt straight pull application nylon strap would still be far superior to fiber rope.
I would also suggest you add a ratcheting anti reverse mechanism or your winch will wind up hurting you or somebody else sooner or later.
Bob La Londe
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Reply to
Bob La Londe
Any pole 5 meters long that will lift a ton will be all any one would want to carry. Harbor Freight has a 2000 pound 12 volt winch on special for $40 regular price $80. I plan on buying two. I need two poles to lift the walls on a garage I am building. I probably will use 2" square tubing for the pole. Since I am lifting a wall fastened at the bottom no need for guy wires or bracing. I do need about 8 meters long for a 14 foot high wall. When I am done lifting the walls I will convert the poles into a sheet rock lift. Probably sell the winches when I am done.
Reply to
Pat
Hi Pat, anyone
What do we know about poles for this task? You reckon 2inch (50mm) sq. tube. What other options - lightest and stiffest? All cranes use lattice masts if they can - understand triangulated lattice frame gives best performance for weight. Anyone know whether that is doable - and design?
Richard S
Reply to
Richard Smith
Of course it's doable. The question is for smaller scale projects like this, is there any point to further modifying an existing material when it is reasonably servicable as-is?
The first, simplest way to remove a bunch of weight and approach a lattice beam form would be to simply drill/burn a bunch of large holes down the web (for 2" tube, I would guess about 1-1/4" to 1-1/2, or about 30-40mm) might be a servicable compromise. If you're burning (torch or plasma) anyway, it's not that big a jump from there to use a template for a rounded triangular opening that you flip as you work along the beam. If using a drill or holesaw, you could add further holes in the thick triangular areas between holes, for the 1-1/4" holes, 3/16 might work, and for the 1-1/2", 3/8. Holes have an advantage when dealing with stress as they produce much less of a stress concentration that a sharp cornered figure, so even if you cut out triangle shapes, you should at least round the corners.
Another way to do this is to simply vary your material thickness. Use a thinner 2" tube, then add maybe 10mm angle to all the corners.
As to should you, and will it work with your 1-ton (tonne?) design load, perhaps you'd feel the most confident if you ran the numbers yourself(*). This looks like a good intro:
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google "column buckling". Note that your lattice shape will make calculating the sectional inertia, and from that, the buckling load quite a bit more complicated.
(*) Liability being what it is, no way in heck will I run the numbers for you or post them in a public forum. Then there's that whole engineering licensing and areas of practice thing. Oh, and speaking of licensing, in my jurisdiction, any machine capable of hoisting more than 500# technically requires a license to operate. I don't know if that includes man-powered devices or not (like engine hoists).
To get your loading, google "Free body diagram", and play with your geometry for your expected range of lifting angles to get the component of force acting axially on your column. Bonus points if you double check the loading in your guy wires and that your attachment points at both ends of the beam and guy wires will hold up.
With all of that said, there is also this little bit of wisdom: for any man-portable structure, you can never know if the design loading is the only one it will be subjected to.
You could have the perfectly designed and made column, which meets all the best safety practices of at least 4x safety factors, etc., etc. when loaded as intended--a direct axial compression load. And then some idjit could come along and say "Hey, that looks like just the thing to help me lever my rover out of the mud" and the next thing you know, it's being subjected to twice the design weight, in bending, over a rock. If it were the simple box shape, there's a chance it could hold up. That lightenned latice structure? A lot less likely. And more often than not, the idjit needing to get his rover out of the mud, or whatever, and with the best access to all your stuff is, well, you. I suspect we've all done something like it, at one point or another. So sometimes the best way to protect yourself from yourself is to actually not overthink it and just grab the 2" box section off the rack. --Glenn Lyford
Reply to
Glenn Lyford
I suspect we've all done something like it, at one point or another. So sometimes the best way to protect yourself from yourself is to actually not overthink it and just grab the 2" box section off the rack. --Glenn Lyford
2" tubing is very useful stuff to have left over when you are done hoisting.
Reply to
Pat
Thanks Pat, Glenn - you are right - I can easily borrow some 50mm/2inch SHS to start with and see how everything behaves. Then I'll know where to next. There's a balance between knowing where you are going and gtting out there and opening up experience.
Other thing is - gets me where I want to go with winch more easily than winch project itself - fairlead becomes lead block, winch mounts to tube and load / tension is weight you are lifting vertically.
Have some 6mm wire rope already - overhead crane cobbled its cable so grabbed it from scrap - so can do fibre rope and steel cable for initial trials - plenty of experimenting ahead. Thinking at least 2:1 velocity ratio with single-sheave hook-block - so not a "whip line" which will tend to spin?
Someone commented my "winch" looks rather heavily built. Well - had in mind that forces may go way up when using steel cable - both external to the load and upon the winch barrel and flanges.
And noted comments that should have a ratchet mechanism so won't self-unwind uncontrolled. Reckon will plasma out another circular piece from steel sheet which has the ratchet-teeth.
Rich S
Reply to
Richard Smith
Pat, Glenn, everyone
Thanks for previous contributions.
I calculated the numbers for 50mm / 2inch, 3mm (1/8th-inch) wall thickness SHS.
Anyone check them?
Assuming is 275MPa yield - S275 structural steel! - then the crush load (= tensile yield load) would be about 15.5Tonnes-force.
Found that given length of column, you would be left with 1.65Tonnes-force of load-bearing capacity.
For a 5m length and calculated radius of gyration of 19.5mm., the slenderness ratio is about 256.
Which puts you clear into the domain of the Euler equation for columns.
F = Pi^2 E I / L_e
Where F = critical max compressive load which can be supported Pi is the well-known constant E is the elastic modulus = 2 x 10^11 Pa for steel I is 2.1 x 10^-7 m^4 for 50mm, 3mm wall-thk SHS (I calculate) L_e = the effective length, which is the actual length in this case
Found typing out all the equations is very time-consuming - have scanned my on-paper calculations and put them at
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Anyone able to comment?
If this were true, this derrick would have potential! Everyone rooting for the project now - have gardens to landscape, sheds to build, etc, etc.
Rich S
Reply to
Richard Smith
I built a swinging davit lift for my cabin out of two inch hitch stock. It was serious overkill, and I had all kinds of forecasts from it will handle it to yer going to put yer eye out. It works great, and even the wife finally complimented me on the job after seeing how much difference it is to lift two stories with an electric winch and a wire basket rather than schlep everything up the stairs.
Wish I had more of it left over. It's spendy stuff.
Steve
Reply to
Steve B
I would want a large safety factor on a hoist.
Reply to
Pat
Hi again everyone
Break for Christmas
Anyway - calculations - 5m long pole of pole derrick
Using Blodgett's "Design of Welded Structures" for the "Moment of Inertia" or "Second Moment of Area" and Euler equation for critical force for instability in a long slender strut, get for SHS (Structural Hollow Square) with 3mm wall thickness:
50mm sq - F-crit = 1.7Tonnes force
75mm sq - F-crit = 6.0Tonnes force
As some off-centre loading and hoping for at least 1 Tonne lift, looks like 75mm SHS is the way to go.
Hopefully have some I can "loan" for a while!
Thanks all
Richard Smith
Reply to
Richard Smith

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