Engineering advice needed

[638]

I have picked up a scrap LP gas tank (500 gal) to build a lawn roller. It is 3 1\2 ft in dia and will be about 6 1\2 ft wide. What size axle shaft would you recommend putting in this thing. My sod looks like a plowed field due to the moles.

Ron

 

[Egon]

Has the tank been well purged?

Rolling may only inconvienience the moles.

Egon

 

[ccsial]

3" large gauge(.25 wall).
For gophers I use road flares and a garden hose.

WMD's for Gophers, Chemical warfare. I love it. Gonna try it soon.

 

[638]

Ran a vacuum pump on it for about 8 hours and then filled it with CO2. Should be safe to cut on!!! Had planed on a solid shaft with pillow block bearings, but the 3" pipe through the middle and stub shafts on each end would be cheaper. Welding around a solid shaft to make it watertight would cause a lot of stress at the weld area and I was afraid that too small of a shaft might not hold up as well as it should.

Ron

 

[RonMar]

Your gonna fill this thing with water? A spherical ended 500Gal Propane tank alone weighs around 1000#. 500 Gal of water is going to add another 4000# to that. I am guessing that this LP tank skin is probably not more than 5/16" thick. No matter what you weld it to, that skin thickness is always going to be the weakest link. You are correct that larger end connections would spread the stresses over a larger portion of the tank skin. The specs on a 500 gallon tank I have seen show it at just under 10' long and 37" in diameter. That leaves about 7' of sidewall and with only a portion of this in contact with the ground, at 5000# that is well in excess of 1000# PSF on the ground. That is a lot! That is also a lot of stress for cast pillow block bearings, particularly when turning, unless you are using really massive ones. If you are not going to be using it every day, you might consider makeing up a bushing affair on either end. This would allow for a good strong connection and save a considerable ammount of money.

If I was building it here is how I would do it:
Put a piece of pipe all the way thru the tank end to end. After looking at the weights more, I would up my initial reccomendation from 3" to 4" heavy wall pipe. This pipe would stick out the end of the tank about a foot on each side. This would be the Axle. Over this pipe I would slip a plate with a hole in the middle and weld it to the pipe/tank to act as an inner thrust bearing. Over the pipe axel I would slip a slightly larger pipe with a fairly close tollerance fit that is just shorter than the length of pipe comming out of the tank. Into this piece of pipe I would drill and tap 1 or 2 zerk fittings near the middle of it's length to fill the small gap between the two pipes with grease. To this pipe I would weld the structure that will connect the tank axel to the tractor towbar. Into the end of the axle I would weld a plate that is drilled/tapped. To this axle endplate I would bolt an outer end plate about the same size as the inner plate. This is not strictly necessary as the towbar structure would hold the bushings in place. Please see the attached .BMP which is a top view of one end.

This is of course steel on steel, but with occasional grease applications, should work fine for a low-speed application such as this. I certainly wouldn't want to get a 5000# roller up to any real speed What are you going to tow this thing with anyway?

 

[Neophyte]

I have always heard that dumping a container of black pepper down a ground hog hole will force it to abandon the tunnel. Is this true? Would it work for gophers?

 

[RonMar]

I have always heard that dumping a container of black pepper down a ground hog hole will force it to abandon the tunnel. Is this true? Would it work for gophers?

I have heard that one also, along with chewing gum and human hair. Supposedly they eat it and their digestive system won't pass it so they eventually die. Don't know if this works, havn't tried any of them.

 

[Soundguy]

I've hear of peanut butter mixed with mortar mix... I hear it gives the offender bad case of constipation.. ( can't verify.. )

Soyundguy

 

[turnkey4099]

I saw a blurp on TV about a "rodentvator" that the bleeding heart liberals are protesting. It pumps a gas mixture down the hole then ignites it. The demonstration was I believe in a ground squirrel patch in Texas. Fascinating picture of blasts coming out of holes all around the operator. The Animal rights figure it is cruel. Oh? An just how is that crueler than the poison that is currently being used which also affects animals that are not targeted?

Then there is the ammonia pipe that was popular here not too long ago. Don't know if it is still in use. You stuck a hose down the hole and let the gas fill the burrows.

Harry K

 

[HomeBrew2]

For pocket gophers, I use all the tricks. (Except rodentvator ... $1800 is too steep for my 5 ac.) Flares, traps, poison (sparingly), .22 occasionally, shallow runs I can flood them out then stomp them (most fun). As to the amonia: My most used method is to put 1 or 2 tbs of spa chlorine granules into the hole then pour in ~ 1 cup of liquid amonia (pure, no suds or anything) ... creates a pretty toxic gas that seems to be heavier than air ... seems to be the cheapest solution but isnt effective on very large runs or when the soil has deep cracks in the summer.

 

[Neophyte]

Wow! Bill Murray's character in Caddy Shack doesn't have anything on you guys!

 

[638]

The plan is to cut most of the sperical end off of the tank and weld flat plate in its place. No, I don't think that my little BX 23 would be able to handle it completely full of water. Probably about half full would be enough. I just wanted something wider than the little ones at the box stores. By the way, I think the ends will make a good fire pit. $50 for the tank was just to good to pass up.

Thanks for the suggestions,

Ron

 

[SPYDERLK]

Ran a vacuum pump on it for about 8 hours and then filled it with CO2. Should be safe to cut on!!! Had planed on a solid shaft with pillow block bearings, but the 3" pipe through the middle and stub shafts on each end would be cheaper. Welding around a solid shaft to make it watertight would cause a lot of stress at the weld area and I was afraid that too small of a shaft might not hold up as well as it should.

Ron

Dont cut into the tank. Fabricate about 10" dia "cups" for each end and weld on. Weld stub shaft To center of "cup" bottom. Cup bottom should be at least 1/2" thick. A shaft going thru the tank is a waste as well as less sound because the connection to the tank is relatively small and therefore highly stressed.
Larry

 

[patrick_g]

Commercial gopher getters can be lit and placed in the hole. Wherever smoke comes out of the ground cover that hole, (repeat as needed.) You can make your own gopher getters out of salt peter (potassium nitrate) and powdered sulphur. I add a little confectioners sugar to increase the burn rate and make more smoke so other outlets are easily found. Mix the stuff and roll it up in a sheet of paper and tape it together. Light the end and when it starts buring put in the hole. Makes large volumes of sulphur dioxide which will displace the O2 and is itself toxic. After it burns out the fumes dissipate with no ongoing environmental negatives. You want to avoid breathing large quantities of the fumes.

About the tank... I think there will be so much weight that the thin tank skin will deform and work harden near the pivots and self destruct. Also the thin walls of the tank will dent in if you run over a "mole hill" or gopher pile. One solution to both problems is to fill the tank with concrete. NO flex! Better operating parameters. Smoother lawn.

I'd be looking for a smaller tank to fill with concrete or a heavier gauge tank if you insist on water. The big tank can be converted to one heck of a smoker or BBQ!!!

Pat
Pat

 

[hazmat]

I think the compaction you will cause with said roller will do more damage to the lawn than the gopher/moles. Besides, the other methods sound like a heck of a lot more fun.

Seriously though, compaction of the soil is bad for the grass roots - that's why you want to aerate, not roll.

 

[RonMar]

The plan is to cut most of the sperical end off of the tank and weld flat plate in its place. No, I don't think that my little BX 23 would be able to handle it completely full of water. Probably about half full would be enough. I just wanted something wider than the little ones at the box stores. By the way, I think the ends will make a good fire pit. $50 for the tank was just to good to pass up.

Thanks for the suggestions,

Ron

Well if you are going to cut off the domes and put on flat end plates, then you can increase the thickness of those plates which will help with the stress issues you will encunter with the original tank wall thickness. I disagree that a continous axle would be a waste. With a stub axle ALL the bending stress would be borne by the tank skin and the point where the stub axle is attached. With a solid axle, a good portion of the bending stresses encountered with starting and stopping the tank would be borne by the axle itself. Also a 10" diameter cup out of 1/2" steel, while a good idea to re-enforce that portion of the tank skin, would be a pretty hard thing to fabricate, at least for me it would. It would require tools and time that I would guess most of us don't have readily available. With changing to flat sidewalls, it is easy to add a doubler plate around the axle to re-enforce it. You should be carefull with a partially filled tank, particularly when stopping. You will stop the roller, but the water inside will want to continue to move(free flow effect) and can lead to some unpredictible movements as the water sloshes to a stop.

I personally don't think that a roller is going to do all that much for your gopher issues. As mentioned, I think the resulting soil compaction will actually do more harm to your grass by restricting water being absorbed and air/gas exchange at the roots. I think you might find a dethatching rake pulled behind your CUT more effictive at collapsing tunnel runs and re-distributing the soil from the mounds.

 

[SPYDERLK]

Well if you are going to cut off the domes and put on flat end plates, then you can increase the thickness of those plates which will help with the stress issues you will encunter with the original tank wall thickness. I disagree that a continous axle would be a waste. With a stub axle ALL the bending stress would be borne by the tank skin and the point where the stub axle is attached. With a solid axle, a good portion of the bending stresses encountered with starting and stopping the tank would be borne by the axle itself. Also a 10" diameter cup out of 1/2" steel, while a good idea to re-enforce that portion of the tank skin, would be a pretty hard thing to fabricate, at least for me it would. It would require tools and time that I would guess most of us don't have readily available. With changing to flat sidewalls, it is easy to add a doubler plate around the axle to re-enforce it. You should be carefull with a partially filled tank, particularly when stopping. You will stop the roller, but the water inside will want to continue to move(free flow effect) and can lead to some unpredictible movements as the water sloshes to a stop.

I personally don't think that a roller is going to do all that much for your gopher issues. As mentioned, I think the resulting soil compaction will actually do more harm to your grass by restricting water being absorbed and air/gas exchange at the roots. I think you might find a dethatching rake pulled behind your CUT more effictive at collapsing tunnel runs and re-distributing the soil from the mounds.

A thru shaft that long will flex more than the stubs bearing on large diameter cups. With the "cups" which dont have to be fancy, the connection to the tank is spread out to prevent force from being concentrated in a small portion of the tank by the axle which is much smaller than the cup. The tank is plenty rigid in itself. You just need to make connections out nearer to its circumference rather than in its center. Only the bottom of the cup needs to be thick.
Larry

 

[ovrszd]

WMD's for Gophers, Chemical warfare. I love it. Gonna try it soon.

This is great!!! Reminds me of the movie Caddyshack!!!! Hahahahahahaha!!!!!

 

[ovrszd]

Ran a vacuum pump on it for about 8 hours and then filled it with CO2. Should be safe to cut on!!! Had planed on a solid shaft with pillow block bearings, but the 3" pipe through the middle and stub shafts on each end would be cheaper. Welding around a solid shaft to make it watertight would cause a lot of stress at the weld area and I was afraid that too small of a shaft might not hold up as well as it should.

Ron

I saw one built out of fuel barrel and the guy just welded a 3/16" square plate on the end, then welded a stub shaft to that with a bearing for the tongue to pull on, never breached the tank.