Thread: Major engineering challenge

Oops, apparently my verbiage was easy to mistake. What I meant was, if he wanted to hire someone to create the device for him or his company. I do something unrelated now, but in the past I designed machinery and robotics. So, no Lou, you're not chopper liver.... or


whatever...

-John

Originally Posted by scarface

so...what am I.....chopped liver???

Ilija....pass me the Grey Poupon!

-whatever

-Lou

I see some of my questions are partially answered while I was writing my post.

I'd bet that regardless of what the cable/wire weighs, it will have lots of friction once there is 1500 feet of it laid in the tunnel. It's hard to imagine how a 2" motorized anything could get enough traction to pull the kinds of forces involved here.

Lou's idea is a good one... I was thinking along similar lines... the reason I asked about pumping a high volume of water is because it would create turbulence which would reduce the friction of the wire against the tunnel walls and could be used to force a ball or parachute shaped plug through the tunnel pulling the wire. Lou's method was to seal around the plug, my idea was to flush the plug through the tunnel with a very high volume of fluid... sorta like how a toilet flushing moves things through a pipe.

Originally Posted by FiReSTaRT

Actually that's a very good idea.. If we can wedge the vehicle in and pull the line through, using it to send the cabling all the way in, that would solve the problem.
Your other point is a detail that I'm fairly uncertain about is because at the beginning of the line, there's a modular probe with 8 different terminals (1 per data channel) How that's supposed to work is still beyond me, but I'll have alex write a paragraph about it tomorrow.
By the way, is there a fishing line that can pull about 250lbs of weight?

Actually, that's what I meant in my earlier post #11. Electricians do this all the time. What I was suggesting is a very very light poly type line, maybe even polyester thread. Once it's through, you use the end to pull through a larger line of the same type. Repeat a few times until you can get something though with enough tensile strength and durability to haul your data cabling through. And, as for the width, that's why I drew my sketch with the motor dragging behind the crawlers. This way, you could keep the overall minimum diameter of the crawler small. You could pull extra batteries for this trailing behind, so that you can get the distance you're looking for on the crawl. They could have rollers or wheels to lessen their friction. I mention drills because the small motors used in modern DC hand tools are the state of the art in specific power, and can be had cheaply. They also are in the 1 1/4-1 1/2" OD range.

Originally Posted by Namdnas

Actually, that's what I meant in my earlier post #11. Electricians do this all the time. etc etc.

You're exactly right... I've done this on long underground cable pulls through PVC pipe. The little tank we used wasn't remote control, just battery powered and the tracks spin whenever the battery is turned on.

The times i have used this method it took a couple of goes and wasnt 2000ft more like 500 - 750ft but it did work... you're right.

Greg Frazer

I am not sure how smooth a water-bored tunnel would be. That's why a tracked vehicle would be the best option if we're taking that route. Another engineering challenge would be for us to make it an anchor point for the line/probe we'll be pulling through after the light-weight line.

Mate

I dont know if I am quite picturing this hole properly... is it vertical or horizontal? Can people access both ends of the whole? I mean could you look into either end?

Greg Frazer

Originally Posted by FiReSTaRT

By the way, is there a fishing line that can pull about 250lbs of weight?

Yes there is. here is a link: http://www.powerpro.com/purchase/sto...PRODUCT_ID=126

So I gather we're talking about a blind hole. You're just looking to put the probe in the end and test for minerals? Looking to save the expense of digging a mine for possibly nothing?

I like Lou's idea. I was going to say and this is a big, IF, if you can get the hole to seal airtight. A plug with a hole in the center that is attached with tubing to a vacuum pump would enable you to put the plug down as far as you like. You shouldn't even need to pressurize behind the plug to enable it to move.

Another concept I thought about was basically like a spear gun. A small dart (I'm thinking like a badmitton shuttlecock) with trailing line shot through the hole. I'm thinking pneumatically would be the way to go, ie more PSI = farther distance.

That's the only things I can come up with ....

Ray

Also is there a way to drill a small relief hole at the blind end of the hole? I may have another idea if that is possible.

The hole is horizontal (so no help from grav). There's a curvature to the hole, so it can't be a straight shot. I don't think a relief hole can be drilled. Here are several other influencing factors...
1) If the rock is soft, errosion may impede the vehicle
2) I'm not sure how water in the tunnel will affect electrical equipment, especially for delicate measurements.
3) If the vehicle is an anchor point for the cable, how do we anchor it in there so it won't move and how do we get it un-anchored once the job is done?

Mate

Another electricians trick... use 16mm pvc conduit (pipe)... tape the cable to the leading end and push it into the hole... as you come to the end of the conduit you glue another length on and keep pushing.

I have only used this on runs of a couple of hundred feet... so how it would go at 2000 feet is anyones guess.

You can use the cable or the conduit to pull it back out of the hole.

You have to use electrical tape to make the leading edge rounded otherwise it will catch on any square edge it encounters along the way.

hmmm... maybe 2000ft is longer than my imagination... dunno

Greg Frazer

That would be a good solution if there weren't enough space constraints to scrap the idea (already been discussed at work)...
1) Too much material for tight quarters (the tunnel is leading from a mine shaft)
2) Too much weight
3) Even with lubrication, 2000' of piping would generate too much friction