Jib Crane for Lathe: Ideas

Machine Shop
#1

Doing a little more research for a jib crane for the lathe;

Here design I’d advocate:

  • Stable, not just a single column merely bolted to floor
  • Easy to construct: Tube, small iece of plate, I-Beam, Angle
  • Electric trolly for I-beam, 1 Ton Capacity

Just a real quick look for parts:

Electric Hoist, 550# capacity.

image.png988×490 117 KB

The hoist would connect to a trolly:
image.png1040×312 81.8 KB

on a frame similar to this jib crane:

Looking at this style for the structural form of the legs.

In speaking with @frank_lima the mast/jib would be easier to fabricate if this style. Concur with his advcie.

This would give us at least 3X+ safety factor on the load limits but it will allow easy movement of the chucks. Just need to get a few of us together brain some more, submit a budget to Nick & Committee.

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#2

I have been think about this since Thursday evening. 2" & 2.5" sched 40 pipe. The 2" will slide in the 2.5". We can then heat it with a rosebud & hit it with a ball peen hammer. You would have two pieces of plate to mate the faces with a little added grease. This is how we do our davit arms for work. They are incredibly strong for what we need. We can then top it with an I beam & put on triangulated gussets. It can then be anchored to the floor. I’ll see it I can find a picture or take one next week.

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#3

Concrete is strong, just have to calculate pullout strength of the anchors with a given load cantilevered a given distance. I would trust something bolted to the slab more than something that can slide around. See auto lift where everyones life depends on those concrete anchors.

What is advantage of building it vs buying something that you know will be safe?

http://www.northerntool.com/shop/tools/product_200651951_200651951

#4

in compression

:blankspace:

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#5

in our case the crane will be a one trick pony - needed only for the lathe so it doesn’t have to be as robust as the commercial one. We’ve got some pretty good fabricators so I don’t have any fear about safety. I was concerned about fitting the square hoist on the round bar but if I understand Tim’s proposed design with the square plates on it, I think it will work.

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#6

If we were lifting something very heavy, I’d agree. However, the weight of the objects being lifted, the heaviest item is at maximum a 13" 4 jaw chuck that weighs just under 100 pounds. We’re not lifting “really heavy” objects, so our safety factor will be well up there. We’d test load it with 500# which is the limit of the winch without cable doubling, which may be done to reduce speed, which would be ~ 5X without testing to failure or ultimate strength.

Size: The jib you cited has a 80" arm with a 70" usable length or approximately 13’ 4", We only need an arm that goes from center-line of chuck mounting face to the shelf at end of lathe where we store chucks, I’d guess 48" arm would give maximum arm swing range of about 8’ 0". This is a greatly reduced moment arm and would not be swinging out over the blue work table This would extend only about 16" past edge of lathe vs 48".

The cost of the jib you show is ~$1,000 + $250 shipping and that’s without the trolly or the electric hoist, so call it $1,550 total.

We can fabricate, we are a Markerspace, we have more than a few engineers or engineering students that could do a statics moment arm calculation on a 4" I-beam, 150# load at 48". Or at the very least point out we’re doing something very wrong. Using Tim’s suggestion which is conceptually close to what Frank Lima and I discussed, for less $500 plus shipping: Trolly $20, Hoist $30 = $550 total or saving about $1000, but say there’s about 50% error in that SWAG (which would all being the metal cost, other components know cost) and it costs $750, still saving $750 (that’s would also by $500 of steel) enough savings for a new collet chuck and collets,

The advantage of this type of base, IMO, is it is easily moveable if we in the future need to move the machine, it will not interfere with machine. Not against bolting to the floor if we know for certain that’s where it will stay. The engine hoist is smaller dimensional metal than we are looking at and with the same arm length it’s rated at 1,500# or more 15X what we’re lifting.

Anyway, it will be @nicksilva’s (new Chair - well nominated) and the machine shop committee decision which way to go. I’m throwing out suggestions. As is Tim and and yourself. At the next Machine Shop meeting please attend a express your concerns and alternatives. That’s how the Machine Shop committee operates.

#7

I started drawing a prototype last night for it. I’m wanting to do a stress test on the file once I am done in inventor.

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#8

From a usability standpoint, the deflections are critical in this application. Fully loaded, all the way out, the jib arm can’t deflect so much a person can’t control the load trying to push it uphill. The arm will want to rotate in reaction to pushing uphill.

Does that make sense?

#9

Yes, I don’t expect much deflection on a 4" I-Beam 48" out with a 100# load.

The main goal of the jib is to support it “close enough” that it can be maneuvered into position without the person having to “hold it” at arms length. I just measured from the lathe chuck mounting point to the furthest edge of the cart is 80" total. allowing room for trolly, 48" span will cover everything and the boom will only stick out about 10" past the edge of lathe when swinging by but the item being lifted would be inboard of that.

Top of the jib should be about 7’ high in my opinion so no heads get hit.

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#10

Yes it does and good point. We may be able to incorporate a spring loaded detent pin that locks it in place since it will always be locating in the same position over the chuck mounting location. A lanyard can be hooked to the hoist pendent to unlock and stows out of the way.

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#11

I know we plan to use it for a 100-pound item, but what would its lifting capacity be? If there is any way it can be moved and used somewhere else, then we should probably clearly mark the lifting capacity on it.

#12

Contrary to belief it not difficult to push a few hundo uphill while suspended. 5-6k can even be done relatively easily with a couple people.

#13

The trolley 1000#, Hoist 550#/1100# if cable doubled - which we will probably do as is cuts speed in half.

We’ll have to have someone do a calculation as to ultimate load, but I’d plan to load it to at least 300#~500# test loads. My guess structurally it should be well over 1000#, a 4" I-Beam that is only 48" long should easily hold 100#. But when we test it we’ll know for sure.