Escher ductwork

It's metal! I need to revamp some of the dust collector ductwork and one of the technicians came to me and said: "You've GOT to see this!" In a 36' length of 6" round duct made of 4' pieces and bolted together with three #12 machine screws with square nuts. The nuts are on the outside! We can't figure out how they did this! How do we get it apart? The screws just turn with the nuts. I guess we just grind them off. WTF!!!

Reply to
Tom Gardner
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Use a Mobeus Inverter. The 1999 model seems to work the best. and its safer. The interlock against use on small mammals actually works , which is handy as your crew wont be puking every 10 minutes as they encounter inverted mice etc.

Gunner

The two highest achievements of the human mind are the twin concepts of "loyalty" and "duty." Whenever these twin concepts fall into disrepute -- get out of there fast! You may possibly save yourself, but it is too late to save that society. It is doomed. " Lazarus Long

Reply to
Gunner

Gunner, you're too much! That was actually funny!

Lane

Reply to
lane

I have heard of cases where the ductwork enters a cyclone separator in such a way as to form a Klein bottle. You can tell this if your system has been picking up dust and returning it to the room for no apparent reason.

Reply to
Leo Lichtman

The "easy" way to assemble this would be to take a 5' stick, and glue on a socket that fits the bolt. Add a little bit of blue-tack. Now, line the pipes up, and poke the stick down, until it's lined up, and poke the bolt through. Have a buddy to fix the nut on.

You can do it single handed. First line the pipes up. Now, take some thread/string. Tie a tiny nut onto the end of the string. Poke the string down the hole. Fish it out of the pipe using a magnet. Now, tie a bolt onto the string. You want to end up with a bolt tied on at the base, and with a couple of strings going up the sides to a point where they join a bit after the end of the bolt. Now, tape over this so you get a point, and the string is held in place. The bolt will now pull through the hole. (if it's not too small) (to really puzzle someone, you can epoxy the string to the end, and then it will do this with no clearance.) Hold the bolt in place using locking pliers, and remove the tape and string. Start the nut, remove pliers when it hits them, and grab the end, before completing.

Reply to
Ian Stirling

The big question is why do it that way? It lowers the efficiency of the unit by creating turbulance and air drag.

Reply to
Gears

You can tell this if your system has been

And I was wondering all these years...

Reply to
Tom Gardner

The only problem that I see is getting it all together. Putting the screws into the holes will be the problem. My suspicion is that the ducting is the kind where the seam can be opened and the whole length was put together flat and then the seam was closed. As to getting it apart, the forcing of the joint so that the bolts won't turn (each in turn) and the removal of the nuts will do nicely.

-- Bob May Losing weight is easy! If you ever want to lose weight, eat and drink less. Works every time it is tried!

Reply to
Bob May

Wrong.

The heads only are on the inside. No nut and screw length to create turbulance. And if these are round head screws, even better from an air flow standpoint.

Howard Garner > The big question is why do it that way? It lowers the efficiency of the unit

Reply to
Howard R Garner

"> My suspicion is that the ducting is the kind where the seam can be opened

By Jove! I think you're right! But why? It had to be a bear to put together. I still am just shaking my head.

My Ancestors! "So many graves, so little urine!"

Reply to
Tom Gardner

My misunderstanding... I was thinking there was a flange in the inside.

Reply to
Gears

I'm sure you want the nuts on the outside for dust collector ductwork. Or else they may start to collect a clog.

You are describing 9 pieces of 4' long ductwork, each joint attatcehd with three screws, with the nuts on the outside. It could have been assembled, with duct tape holding the screws in place until the nuts were tightened. With age the duct tape may not be holding the screws from turning. An impact wrench set on high might loosen them.

Having a smooth surface on the inside might be more desirable than with regular furnace ductwork, for example.

Just speculaton... Pete

Reply to
Pete Logghe

Howard R Garner wrote: (clip) And if these are round head screws, even better from an air flow standpoint. ^^^^^^^^^^ It's pretty important to line up the screwdriver slots in the screw heads with the air flow. I recommend scribing a line on the end of each screw, so you can tell from the outside whether it is properly aligned. Better yet, make a small saw cut, so the position can be adjusted from the outside.

Reply to
Leo Lichtman

How would you join the ends with the screws sticking out of the holes? I'd bet on a guy with 5 foot arms before I believe the duct tape theory. :)

Reply to
Pete Bergstrom

How did they start the screws in the holes...think about it...I'm baffled!

Reply to
Tom Gardner

Most likely it was assembled with the duct flat and then the seam was hooked. The seam on the pipe is likely a lock joint like is used in many ducting applications. It's easier to hook than to unhook but you may be able to get it apart if you can get that length of pipe laying on the floor.

Wayne Cook Shamrock, TX

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Reply to
Wayne Cook

Tom: You must not be a boat person -- if you were, you would know it was put together by some refugee from a boat manufacturer. On a boat, the thing you want to unfasten is always at least 6 inches out of reach of your longest tool, once you are hanging upside down in some restricted space, unable to move. The only rational expanation is that there is a tribe of boat assemblers who are all 7 feet tall, 110 pounds dripping wet, and have arms long enough to walk on their knuckles. Then, one of these guys uses a four foot wrench to set the fastener in question....

I more than once have found bolted fastenings where I couldn't even SEE the nuts, much less reach 'em. I can only guess they built the boat around those parts.

Regards,

Bob

Reply to
Bob Edwards

Gunner The two highest achievements of the human mind are the twin concepts of "loyalty" and "duty." Whenever these twin concepts fall into disrepute -- get out of there fast! You may possibly save yourself, but it is too late to save that society. It is doomed. " Lazarus Long

Reply to
Gunner

Yes, probably. In the case where I've got some bolt which I can reach, but cannot see, I find myself automatically closing my eyes to concentrate on my hands. Anyone else doing the same when working by feel alone?

Ole-Hj. Kristensen.

Reply to
Ole-Hjalmar Kristensen

Use carriage bolts. Self holding, and no "cuts" in the head.

Reply to
Brian Lawson

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