rcaerobat
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Post by rcaerobat on Sept 28, 2020 16:50:13 GMT -8
Hey Folks,
So, what is the best method to protect the bare wood on the bottom of the camper? I have seen that you can buy corrugated plastic. I have seen people use a thick truck bed liner to coat the bottom. I have seen some paint the bottom and I have heard others say to use a layer of roofing felt.
So, what have you used and what has worked or not worked over the years. If you liked specific products, please let me know what they are. I am getting ready to start to build up my frame on my 68 Scotty Hilander and want to do it right.
Thanks!
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Post by vikx on Sept 28, 2020 22:13:52 GMT -8
The floor underside should be painted or coated. I use Black Beauty fence paint; it's goopy and dries rubbery. Any thick goopy coating is fine.
Corrugated plastic (Coreplast) is OK but hard to seal on the edges. Tarpaper works well but must be installed before the floor is laid.
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rcaerobat
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Post by rcaerobat on Sept 29, 2020 6:09:55 GMT -8
Is there any specific prep for the wood before putting it on? Does it seem to last a long time?
One other question, are galvanized bolts good enough on the floor or should I use stainless steel?
Thanks.
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John Palmer
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Post by John Palmer on Sept 29, 2020 9:00:43 GMT -8
Is there any specific prep for the wood before putting it on? Does it seem to last a long time? One other question, are galvanized bolts good enough on the floor or should I use stainless steel? Thanks. Galvanized carriage bolts are about the lowest grade bolt you can buy. They are used for chain link fencing, they have no place on a moving trailer. The next carriage bolt grade up, will be zinc or cad plated and they are acceptable to attach the plywood flooring to the steel frame. These are still a low grade bolt, but better than Galvanized. Use normal plated nuts and lock washers, not nylox nuts on this application. 5/16 to 3/8 is the best diameter, nothing smaller. Stainless bolts are easy to twist off, if you do not coat with anti seize grease which is very messy. Stainless carriage bolts are pricy, and just over kill IMO. Flat head elevator bolts are pricy, and also over kill. Since you will need to fill all of your bolt head holes, screw head holes, and all of the plywood seams in order to place your Marmoleum sheet flooring, there really is no need to use exotic carriage bolts. John |
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Post by vikx on Sept 29, 2020 10:37:49 GMT -8
I agree with John on bolt type.
Black Beauty seems to last well and is easy to touch up.
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sawset
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Post by sawset on Sept 29, 2020 11:24:07 GMT -8
Why the preference for zincplated?
Galvanized hot dip bolts have a thick zinc coating.
Barrel rolled electro zinc plating would have a much thinner zinc coating.
Corrosion resistance is related to coating thickness?
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ekimnamniets
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Post by ekimnamniets on Sept 29, 2020 13:06:36 GMT -8
J.P. is speaking material hardness, not one coating being better than another. There are multiple grades (hardness) of any hardware. The typical chain link fence variety is about the weakest. They have almost no tensile strength. Very easy to shear off.
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John Palmer
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Post by John Palmer on Sept 29, 2020 16:00:21 GMT -8
J.P. is speaking material hardness, not one coating being better than another. There are multiple grades (hardness) of any hardware. The typical chain link fence variety is about the weakest. They have almost no tensile strength. Very easy to shear off. Thank you, Exactly correct. Galvanizing is a cheap coating process. It's used on very low quality hardware, so it does not increase the cost to manufacture the part. Galvanized bolts/nuts are manufactured with a very loose thread fit so the thick hot dip coating can fill up the threads. Try to spin a nut on a galvanized bolt, then try the same test on a higher quality zink or cad plated bolt, there's no comparison. Save the galvanized hardware for the fence repairs. John |
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sawset
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Post by sawset on Sept 29, 2020 18:53:25 GMT -8
Have you seen bolts shear.
Just questioning is all.
Why 5/16 to 3/8 then.
Just going by what I've seen, and that is bolts in low tensile situations like what we're dealing with don't generally fail from tensile stress, but from a corrosive atmosphere. Or is it both.
I just see zinc plate bolts around here starting to corrode after a short time and wonder if there would be better. Hot dip is recommended (actually irc code requirement) for treated decks, which isn't too far from a trailer subject to salt spray.
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John Palmer
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Post by John Palmer on Sept 29, 2020 19:36:56 GMT -8
Have you seen bolts shear. Just questioning is all. Why 5/16 to 3/8 then. Just going by what I've seen, and that is bolts in low tensile situations like what we're dealing with don't generally fail from tensile stress, but from a corrosive atmosphere. Or is it both. I just see zinc plate bolts around here starting to corrode after a short time and wonder if there would be better. Hot dip is recommended (actually irc code requirement) for treated decks, which isn't too far from a trailer subject to salt spray. Yes, we have seen many "body to frame" bolts completely failed when deconstructing these 60 to 70 years old campers. Most trailers were built originally with 5/16" carriage bolts. I use 3/8" which is not much of a upgrade. The bolts that I have seen personally, have failed from rust. I'm not talking about surface rust, but bolts that have rusted into two pieces. After the body to frame bolts are gone, "Nothing holds the trailer body to the frame". IMO, upgrading from 1/4" or 5/16" bolts to a preferred 3/8" diameter is a safety improvement for only maybe $5 bucks. At the very least, your buying extra time before the new bolts have rusted to cause a safety issue. We never recommend pressure treated wood to be used during the trailer rebuild. The reason is corrosion. You might be able to avoid some of the corrosion problem by using stainless bolts, but then you have the same problem with the treated wood against the mill finish aluminum skin. Who wants to sleep inches away from chemically treated wood. They used to use arsenic to manufacture the treated deck wood. Thanks for asking for my views. By the way, I have lived most of my life in the dry desert areas of the southwest where rust is mostly non-existent. My views might be different in the PNW, or if I lived along the gulf coast. John |
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sawset
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Post by sawset on Sept 30, 2020 4:42:16 GMT -8
Just thought I would put this out there since I'm curious and looking into this anyway for the near future.
For reference from Fastenal website:
ASTM A Similar in strength to Grade 2
ASTM A325 Similar in strength to Grade 5
ASTM A490 Similar in strength to Grade 8
Grade 2 Low strength.
Grade 5 Medium strength.
Grade 8 High strength.
Electro plating thickness (.0001"), (zinc plate, zinc coating)
Hot dip plating thickness ( .002"), (hot dip, zinc coating)
Fastenal bolts available for our purposes from the above recommendations:
3/8-16 x 4", grade 2, zinc plate, $.59
3/8-16 x 4", grade A, zinc plate, $.88
3/8-16 x 4", grade A, hot dip, $1.36
It looks like they group grade 2 and grade A together as a category, the next up is grade 5, with several finishes available for each.
Zinc Plate (their description):
This finish, also know as zinc plating, zinc chromate or dichromate provides good corrosion resistance and is the standard for many hardware fasteners. It is an electroplated zinc layer covered with a chromate post-treatment. The zinc protects the steel from corrosion and the chromate layer protects the zinc from degrading. It is a popular finish because of its protection, cheapness, and ease of coating. Slightly less corrosion resistant than yellow zinc, it is a versatile finish that is best used indoors. This finish should not be used in marine or high salt spray environments.
I also looked up to see if there were any strength changes involved with various coatings. It ended up that regardless of finish, the tensile strength, and torque to failure were mostly the same for all of the finishes tested. (zinc plate, hot dip, plain finish, dichromate, and iron zinc). So there didn't appear to be any annealing or softening going on during the plating process.
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John Palmer
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Post by John Palmer on Sept 30, 2020 8:21:14 GMT -8
We call that "Paralysis of Analysis".
My recommendation was to use a normal 3/8" diameter cad. plated carriage bolt, right off the shelf of any hardware store. If you analyze every item on your trailer, it will never get rebuilt. The goal is to rebuild the trailer, using safe materials and methods, and then go camping.
John
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sawset
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Post by sawset on Sept 30, 2020 9:19:37 GMT -8
Sorry about the excessive details. I do this every day so I get a little carried away sometimes. But stuff gets built here, so I think I'll be ok. I just find some of the above to be nonsense is all. I wouldn't call it low quality to be dismissed, but more like purpose built materials. It's trivial though, so it's best not worry about it. I'm sure the hardware they used 70yrs ago in the rv industry was off the shelf cheapest they could get. There are other things to analyze though, and folks are doing that every day by the questions that I'm seeing. Great source of info here.
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Post by vikx on Sept 30, 2020 11:21:44 GMT -8
A question was asked and answered in detail. We prefer to keep the threads debate free. All are welcome to post an opinion while not going overboard.
Thank you for not posting excessive details. We are all capable of looking things up online, in fact I often check facts that way. We are here to discuss rebuilding our vintage trailers and worrying about bolt types is a little over the top. If you are worried about bolt strength, go with grade 8.
VTT does not allow links if they are commercial in nature.
I am locking this thread because it no longer is following the original poster's question.
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