DIY Genturi Shopping List

[sajohnson]

I finally got around to designing a homemade Genturi system. It is not installed yet, but will be in the next few days. Here is a partial shopping list:


1) 8' x 3.5" O.D. / 3.25" I.D. 6063 T52 Aluminum Tube:

http://www.onlinemetals.com/merchant.cfm?pid=18122&step=4&showunits=inches&id=278&top_cat=60

$61.61 Minus 10% with coupon code "Save10" = $55.45, plus shipping (our shipping cost was $17.40). Total was ~$73.


2) 1-3/8'' Galvanized Flat "Brace Band" - Round -- for chain link fence.

3-1/2'' Galvanized Beveled Brace Band - Round (flat would be fine, but beveled was all they stock in the 3-1/2" size).

carriage bolt/hex. nut 5/16'' x 1-1/4''

http://www.hooverfence.com/catalog/cpage2.htm

3 @ $0.42 each

3 @ $1.25 each

3 @ $0.18 each

~~~~~

There are of course numerous sources for the above materials. I picked OnlineMetals and HooverFence after looking at several sites, but there may be (and probably are) better sources. I've never purchased from either company before, so no warranty expressed or implied.

I've already ordered the 3-1/2" tube, but may try to find the chain link fence hardware locally, because while the prices are fine, the shipping is a little pricey at ~$16. I'll make a couple calls and if I can't quickly find the bands close to home I'll go ahead and order from Hoover Fence.

I checked into the potential for corrosion from dissimilar metals (aluminum and zinc) and the consensus seems to be that the anodic index of each is close enough that it should not be an issue. I will have to place rubber splicing tape (or similar) around the vertical ladder tubing anyway, because it is only 1" diameter and the bands are 1-3/8". I may be able to find similar bands in a 1" size, but they will almost certainly not be as stout as the chain link fence hardware. Also, they may not be galvanized.

This method of attachment has a few advantages:

1) No damage to the coach or ladder -- no holes to drill, etc. The pipe/tube can be removed and leave no trace (although we plan to leave it in place).

2) Secure mounting. It is possible to mount the pipe to the wall, but it would have to be on standoffs to clear the upper and lower trim (where the tail/brake lights are) and to be secure would require locating the metal framework underneath, and drilling/screwing into that. The ladder is rated to support 225 lbs.

3) The bands can be rotated on the ladder to adjust the position of the exhaust tube relative to the ladder and coach before tightening them.

4) Chain link fence hardware is inexpensive and strong. I found some aluminum fence hardware, but not 3-1/2" (only 3" and 4") and since galvanic corrosion is not much of a concern, I'm going with the galvanized stuff. Aluminum bolts and bands would look better, but they are not as strong. The last thing I want is to see my shiny aluminum pipe rolling down an embankment behind us...

5) Installing the bands on the ladder immediately above the rungs will prevent them from sliding downward, even if they get loose. Of course, there's nothing to prevent the tube itself from slipping if the 3-1/2" bands get loose, but it can only drop a few inches before hitting the 90* bend of the generator exhaust pipe, which will be supported with exhaust hangers.

I chose the tube I purchased because 6063 T52 aluminum has a nicer finish than 6061 and is more corrosion resistant. 6063 is not as strong as 6061, but in this application strength of the tube/pipe is not a concern -- weight and cost are. That's why I went with the thinner wall (1/8") tubing, which equates to schedule 10 pipe, rather than schedule 40 or 80. The latter 2 are overkill, weigh more, and cost more (about $95 for schedule 40, not incl. shipping). 6063 is known as "architectural aluminum" due to it's more finished appearance

The 8' length is the longest section they offer. It is plenty long enough to extend well above the roofline and still drop down below the ladder so that the generator exhaust will not have to be extended up very far. I really wanted to keep it one piece. If possible I might have gotten it a few inches longer, but 8' will be fine.

Total cost should be less than the Camco Gen-turi system, and it will be (semi) permanent and much more durable. No setup and teardown.

Hopefully this will help others save some time and brain cells.

There are probably other methods that are as good or better -- I just figured I'd share what we came up with, FWIW.

 

[sajohnson]

Quick Update:

Local fence company has the brace bands and bolts in galvanized steel in stock and they are willing to sell by the piece (same as Hoover Fence).

Price is decent -- ~20 cents each for the bolts (w/nut); 54 cents for the smaller 1-3/8" bands, and 95 cents for 3" bands.

Unfortunately, they do not have 3-1/2" brace bands in galvanized, but suggested that the 3" might work better in this application because they would be more snug. No doubt about that, but the tabs/ears of the band would be quite far apart, and not parallel to each other. After all, 'pi' times an extra 0.5" diameter = over a 1-1/2" difference in circumference (between 3" vs 3.5") -- so I'm not sure about that plan. A 1.5" gap is a lot.

I think it's best to get the proper 3-1/2" size bands. If they are not tight enough I can probably find something heat resistant to place between the tube and the bands. Another option, but one that I'm not crazy about, would be to run a screw(s) through one or more bands and through the wall of the tube.

The woman at the local fence company is checking with her supplier (Merchant's Metals) to see if she can get aluminum bands and hardware. I'm still considering going that route, but only if the aluminum parts seem strong enough.

 

[Geriakt]

Are you making this for a diesel generator or propane?

 

[sajohnson]

Are you making this for a diesel generator or propane?

Diesel -- the QD3200.

It runs fine and doesn't smoke once it warms up (which doesn't take long) but we've found we can still smell the exhaust if the breeze is blowing from the rear and we have the door or window open with the vent fan on.

 

[Old Crows]

Photos????????????

 

[TJLee089]

Yet another reason to go with LP.

 

[sajohnson]

Yet another reason to go with LP.

I'll be the first to agree that LP burns a lot cleaner than diesel fuel, but please -- let's not turn this into yet another:

"Sunday, Sunday, SUNDAY!! It's Diesel vs Propane!" thread.

Both have their pros and cons, both are good choices depending upon intended use.

I'd like to stay on the topic of the DIY Genturi.

By the way, many people with LP gensets also use a Camco Gen-turi or a homemade one genturi. I'm not sure why, the LP generators' exhaust barely has any odor at all. Maybe there are still concerns about CO poisoning.

Also, some genturi users claim that they reduce the exhaust noise somewhat. I can't imagine it lowers the db level by very much, but I plan to take before & after readings just out of curiosity.

 

[sajohnson]

Photos????????????

Patience grasshopper!

As I mentioned in the OP I have not installed the tube yet. I don't even have all of the supplies (but I will soon).

In the meantime imagine using 3 pair of brace bands -- 3 small, 3 large -- pictured here:
http://www.hooverfence.com/catalog/cpage2.htm

the 3 smaller ones go on the vertical ladder tube closest to the passenger side, and the 3 larger ones go around the 3.5" genturi tube. Then attach the bands together using one bolt through all 4 tabs/ears.

In effect, I'm making a closed 'saddle clamp' using the brace bands. See the saddle clamp here:
http://www.hooverfence.com/catalog/cpage52.htm

If they were made in a 1" x 3.5" size, saddle clamps might be an option but as far as I can tell they are typically symmetrical. Even if they were made in the correct size, they would probably not be as secure because if the bolt loosened up enough, that might allow the 2 halves to separate to the point where the pipe/tube could slip out. In any case, I don't think they are made in odd sizes like that -- but looking at them led to the idea of using 2 brace bands bolted together.

 

[rollerbearing]

Just throwing this out. I think these were mentioned here on the forum somewhere some time ago. I used them on my ladder tubes and they worked very well. They don't have much tendency to crush or scar the tube and hold tightly.

DX Engineering Resin Support Blocks

https://www.dxengineering.com/search/product-line/dx-engineering-resin-support-block-clamps

I could see passing the block clamping bolt through the ear of the larger tube clamp. Or use a long bolt & nut to clamp the block, followed by the ear on the same long bolt and a final nut. I would buy two metal reinforcement plates for each block set you use.

They also have some "Heavy Duty" Saddle Clamp Blocks made out of aluminum instead of resin.

 

[sajohnson]

Just throwing this out. I think these were mentioned here on the forum somewhere some time ago. I used them on my ladder tubes and they worked very well. They don't have much tendency to crush or scar the tube and hold tightly.

DX Engineering Resin Support Blocks

https://www.dxengineering.com/search/product-line/dx-engineering-resin-support-block-clamps

I could see passing the block clamping bolt through the ear of the larger tube clamp. Or use a long bolt & nut to clamp the block, followed by the ear on the same long bolt and a final nut.

Interesting idea. I wasn't aware of these, thank you for the tip.

I have to admit, without any photos (at least that I could see) on the DX website, I'm not sure how these blocks are supposed to be used. I can see how they clamp around pipe or tubing, but then what?

How are these used to mount an antenna?

I think I follow what you're saying. That would probably work, but I'd be concerned about the bolts being threaded into the plastic blocks. Maybe they'd be fine, I don't know.

 

[rollerbearing]

Agree, the website really doesn't show their application very well. The bolt actually passes all the way through the block and then is secured by passing a bolt through the holes and adding a nut. The bolt doesn't actually thread into the plastic, so it is really pretty solid.

They also have a metal version:

https://www.dxengineering.com/searc...e&sortby=BestKeywordMatch&sortorder=Ascending

 

[sajohnson]

Agree, the website really doesn't show their application very well. The bolt actually passes all the way through the block and then is secured by passing a bolt through the holes and adding a nut. The bolt doesn't actually thread into the plastic, so it is really pretty solid.

They also have a metal version:

https://www.dxengineering.com/searc...e&sortby=BestKeywordMatch&sortorder=Ascending

Thanks, that makes it more clear. This is one of those 'picture is worth 1,000 words" situations. My guess is that because the people at DX know how their products are used they assume that anyone looking at their website does too. It would be helpful for anyone who doesn't install and/or maintain antennas for a living to see some examples of ways that the saddle clamps are used.

The aluminum ones you linked to look very nice! Unfortunately, the smallest fits a 2" tube/pipe. They call them "super duty". The 2" size costs ~$40 each.

The text does say this:

"Our tradition of innovation continues with the addition of narrower solid saddle clamps, our DX Engineering Heavy Duty Saddle Clamps, available to fit tubing with Outside Diameter (OD) inch-sizes of 0.75, 1.00, 1.25, 1.50, 1.75, and 2.00."

I searched for "Heavy Duty Saddle Clamps" on their website and found this page:

https://www.dxengineering.com/search/product-line/dx-engineering-heavy-duty-saddle-clamps

I think they might do nicely! They appear to be sort of their mid-range clamps -- aluminum rather than resin, but not as serious (or expensive) as their "super duty" clamps.

The price is actually less than the resin clamps (when you include the cost of the stainless steel plates), but obviously the HD clamps won't work for applications where electrical isolation is required. In this case, since the ladder is aluminum, I'm thinking they should work well:

https://www.dxengineering.com/parts/dxe-hds-100ap

I'm very tempted to use them instead of the brace bands -- especially since they are the correct size (1"). I really appreciate you pointing me toward this site.

Before ordering them I have to re-engage my brain and determine:

1) If I am going to still use the 3-1/2" brace bands.

a) If so, which material (aluminum or galvanized) would be best. My only reservation with aluminum is strength. The tube is only about 12 lbs, but there will be a lot of vibration.

b) How to attach the brace bands to the HD saddle clamps. The face of reinforcing plate on the clamps will of course be vertical. The tabs on the brace bands will also be vertical, but perpendicular to the plates. Like this:

So the question is, how to best secure the brace bands to the saddle clamps. Offhand I'm thinking a piece of angle might do the trick.

Your thoughts?

 

[rollerbearing]

Glad you found those heavy duty saddle clamps. I saw them in the printed catalog and mentioned them in my orginal post, but when I tried to search for a link to "heavy duty saddle clamps" nothing came up - closest I could get was the Super Duties. Anyway, glad you found them somehow.

 

[sajohnson]

Glad you found those heavy duty saddle clamps. I saw them in the printed catalog and mentioned them in my orginal post, but when I tried to search for a link to "heavy duty saddle clamps" nothing came up - closest I could get was the Super Duties. Anyway, glad you found them somehow.

Sure enough -- you did mention them. I must have overlooked that.

I only found them because I noticed that the the heavy duty clamps were mentioned in the text on the "super duty" clamp page. I didn't recall the resin clamps being referred to as 'heavy duty', so that's why I did a search.

I can see why you had trouble finding them. Just now I searched for "saddle clamps" and the resin ones didn't come up at all.

I'm hoping to come up with a clean way to attach the 3.5" brace bands to the saddle clamps. I have some 2" aluminum angle left over from installing solar panels on the roof of the View that might work, but I'm open to other ideas.

 

[rollerbearing]

I was visualizing just using a longer bolt in the saddle clamp block and using the same bolt through the fencing clamp ears. Something like bolt, block, tube, block, nut, ear, nut.

But that may not fit with what you had in mind. For me this is the kind of thing that it helps if I have most of the major parts in my hand in order nail down those last details.

Please post a picture when you get it all finished up!

 

[sajohnson]

I was visualizing just using a longer bolt in the saddle clamp block and using the same bolt through the fencing clamp ears. Something like bolt, block, tube, block, nut, ear, nut.

But that may not fit with what you had in mind. For me this is the kind of thing that it helps if I have most of the major parts in my hand in order nail down those last details.

Please post a picture when you get it all finished up!

I get what you're saying. That would be simpler, and therefore better -- more secure.

When you mentioned it before my concern was that there would not be enough distance/offset between the tube and the ladder. After looking at it I think it may work!

I'm going to go ahead and order a couple of the heavy duty aluminum 1" saddle clamps.

The 3.5" tube is supposed to be here next Tuesday.

It should go together quickly -- especially if I can just bolt the brace bands directly to the saddle clamps. I will definitely post photos when it's complete.

 

[sajohnson]

Re: EDIT/CHANGE DIY Genturi Shopping List

It's too late to edit the OP, so I thought I would post here that the three (3) 1-3/8" chain link fence "brace bands" have been replaced with 2 of these saddle clamps:

https://www.dxengineering.com/parts/dxe-hds-100ap

This change was made due to the suggestion made by 'rollerbearing', above.

The 1-3/8 brace bands (the smallest readily available) would have worked, but these are even more secure and they are the correct size (1"). The brace bands would have required that the ladder tube be padded out -- wrapped with rubber splicing tape or similar. These saddle clamps should fit perfectly without any modification.

Otherwise the parts list remains the same.

 

[sajohnson]

Quick post for update:

The DX Engineering clamps arrived and they should be perfect. They are solid aluminum with stainless steel plates. The aluminum has a textured surface for more grip and resistance to movement.

Now just waiting on the 3.5" tube and brace bands.

Photos soon.

 

[sajohnson]

Photos for Old Crows

The aluminum tube was delayed. Supposed to be here tomorrow.

I did get the brace bands and hardware today. I went ahead and installed one clamp and band to see what it looks like.

The tan plastic pipe will probably be removed. It is a sewer hose holder that was installed by the previous owner. We've never used it.

 

[rollerbearing]

Looking good!

Think about adding one more nut to double nut the last nut (did that make sense or was it just nutty?)

That way you can get and keep it real tight without crushing your alum tube.