"Richard Smith" wrote in message ...
"Jim Wilkins" writes:
"Richard Smith" wrote in message
...
...
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The samples in your tester are similar to my centrally spliced gantry
hoist track problem. I'm trying to determine where to best locate
splice plate bolts so their holes minimally weaken the four 4" x 5.4
channels that comprise the track. Maybe along the web's neutral axis,
if the web has sufficient bearing strength or I weld on
reinforcements?
Another possibility is welding loose-pin hinge leaves under the lower
flanges to take the tension.
https://en.wikipedia.org/wiki/Knuckle_joint_(mechanical)
I'd like to help you with this, if I can.
Sorry - been preoccupied getting the "testing" thing going
I'll see if can find past articles where you describe the issue.
Do you have a webpage you post pictures and articles to - like I do?
So I can see what you mean?
Regards,
Rich Smith
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So far what I have is four 8' sections of 4" x 5.4 lbs/ft channel iron,
which are former pallet rack shelf supports, and a Harbor Freight gantry
hoist trolley to run on them when bolted back-to-back like an I beam.
https://www.harborfreight.com/1-ton-...ley-97392.html
I built a lighter version from four 8' sections of 3" channel, with two hung
back-to-back from the front and rear roof beams of a storage shed and two
more making a temporary track extension out over the path past the shed,
where I set up the sawmill and load logs and beams to/from a narrow trailer.
The moving overhead hoist is very useful to move logs onto the sawmill bed
and adjust the partly sawn cants, by suspending them in a loop of nylon rope
hung on a pulley so I can easily turn and level them. The rolling bandsaw
mill head needs nearly 8' of clearance between the shed and the track's
outer end support post
That part works quite well for 8' oak logs and 6" square beams for shed
columns. I have to set up the overhead extension track by my self and one
channel's weight is near the max that I can maneuver with one hand while
inserting bolts with the other. Safe handling and a shortage of covered
storage space are why I don't use a single 16' beam (~240 lbs) for the
track.
The problem is 12' logs for roof beams, which could overload the 3" channel
and won't fit the 10' deep shed. I have another shed 19' long by 4' wide
that can hold 12' beams if I hang a crosswise travelling hoist from its roof
to move them in. It contains some already, which I moved by an
unsatisfactory temporary arrangement of the 3" extension channels. I'd like
to run the 4" channels out 8' over the sawmill to a braced post beyond it
and in through the shed plus 4' out the far side to another post, for
lifting logs off the trailer. In that case the track will be centrally
supported from above at the joint between its 8' sections, no problem.
The extreme case is joining the four sections to make one 16' gantry track
hung from tripods at the ends, perhaps to load a bulky appliance onto a
truck. I may never need it but I'd like to find a center splice joint design
that doesn't exclude or conflict with the central mounting from the shed
roof beam. Hopefully one design will work for both centrally and end
supported cases. That knuckle joint under the tension flanges looks good
because I could raise the ground-assembled track by it and then lift and
level the two outer ends separately, and it won't transfer sag on one side
into lift on the other, and shift a shed column off its footing. I don't
quite know how to design one to weld onto the channel flanges, for instance
how much to taper the leaves to distribute the elongation and weld shear
stress.
Specifically I'd like to know if bolts in tapped holes in the upper flange
can be considered part of the compression area and the accepted way to
reinforce the holes for splicing plate bolts through the channel web. Does
the reinforcement need to be diamond shaped to avoid vertical welds?
Since I'm not on the clock I can customize bolts on the lathe and hand-fit
them with minimal clearance. They are all Grade 8, fine thread, 150KSI.