Mathematics Time!

[Dave Shepard]

What is the GVW of the trailer?

Triaxle is almost always 9 ton. It may be the first legal load picture on the forum. :D

[Josef]

Wow, interesting to see trailers loaded like we load out here in the sticks, but gotta say that would get us a mighty interesting citation. After loading and running like that for years we found out that our itty bitty F-350's needed a "GCVW" rating on the truck registration to tow a trailer registered over 10k, and now the state of PA doesn't let you "buy" a rating over the recommended GCVW of the tow vehicle as stated on the vin tag by the manufacturer. Don't ask how expensive a lesson that was to learn (or how I know how expensive it was). We have a local DOT officer that has a pet peeve for pick-ups, amazing how many citations he has written on big horse trailers rigs in the last few years.

Would love to find a deal like that for pine logs around here but I'd have to hire out the hauling.

Joe

[schmism]

The reason I ask is because I went to draw a load of pine today, need to saw out 100 8-foot 2x4s for a customer. 

pardon my ignorance on this point....but....

If they are not the customers logs... how on earth can you possibly buy logs,  and saw out 8' 2x4's for anywere close to what the customer could go buy them from lowes for?

I mean granted special sizes, or species maybe... but pine 2x4's?!?!?

ps it seemed like a pointed question on a thread labeled "math time"

[Dave Shepard]

Wow, interesting to see trailers loaded like we load out here in the sticks, but gotta say that would get us a mighty interesting citation. After loading and running like that for years we found out that our itty bitty F-350's needed a "GCVW" rating on the truck registration to tow a trailer registered over 10k, and now the state of PA doesn't let you "buy" a rating over the recommended GCVW of the tow vehicle as stated on the vin tag by the manufacturer. Don't ask how expensive a lesson that was to learn (or how I know how expensive it was). We have a local DOT officer that has a pet peeve for pick-ups, amazing how many citations he has written on big horse trailers rigs in the last few years.

Would love to find a deal like that for pine logs around here but I'd have to hire out the hauling.

Joe

How does that work when the GCVW is not posted on the VIN? I found it listed in my owner's manual for my pickup. That load is probably legal, as I doubt the trailer is anywhere near maxed out with a 1,000 feet of pine on there. It may be close on the recommended GCVW, however.

[drobertson]

The reason I ask is because I went to draw a load of pine today, need to saw out 100 8-foot 2x4s for a customer. 

pardon my ignorance on this point....but....

If they are not the customers logs... how on earth can you possibly buy logs,  and saw out 8' 2x4's for anywere close to what the customer could go buy them from lowes for?

I mean granted special sizes, or species maybe... but pine 2x4's?!?!?

ps it seemed like a pointed question on a thread labeled "math time"

If they are to be full 2x4's then there's the reason.  Plus, I find that many folks just don't like the big box stores' selection, for whatever reason they may have, I saw out plenty of dimensional 2x's as well as full size 2x's.  If someone, anyone in fact asks, I will do my best to deliver. 

[Josef]

"How does that work when the GCVW is not posted on the VIN? I found it listed in my owner's manual for my pickup. That load is probably legal, as I doubt the trailer is anywhere near maxed out with a 1,000 feet of pine on there. It may be close on the recommended GCVW, however."

DOT gets the GCVW (or GCWR) from the vin number on the title using their manufacturers database, but mine are listed on the door column sticker. Several years ago, after paying for the DOT education, we retagged all our trucks and trailers, but not as expected. The rule sent down by PA DOT was, 99 F-350 dualie with 7.3 diesel and 4.10 gears as per FMC has a designed GCWR of 20,000 lbs and a max trailer weight of 12,700 lbs. What we found was that the GWR of the same truck was 11,200 lbs per FMC and by tagging our trailers down to 10k we were under the legal requirement for a listed GVWR on the truck and could legally motor at 21,200 lbs (truck and trailer) so long as no individual axle exceeded the designed max weight rating, takes judicious loading if you get close to knowing the actual weight and distribution of the load.

Lets say 9 logs 21' long 16" small end, eastern white pine, at 1055 lbs each stacked 4 over 5, would be 9,500 lbs, with the trailer empty weight of 3,750 lbs and an empty truck weight of 8,600 lbs I'd gross at 21,850 lbs, 650 lbs over weight at minimum, but still less than 1k over so I'd chance it but only with good brakes. Doesn't matter what you can haul, if you can't stop it's all academic. And at best these conditions do exceed the manufacturers listed maximums so in a court of law you'd still be up that creek at anything over 20k, doesn't matter how technically legal you were on paper, they'd still find you were negligent in civil court.

I love math. Oh yeah, just to further muddy the pot, you can modify your tow or towed vehicle and get a licensed inspection officer to sign off on higher limits if you can convince them it's safe. By now this probably should have been a different topic, sorry.

[Brucer]

Back to the original question. Arky taught me the "half-again" formula for calculating how big a log you would need to cut a square timber of a certain size. Take the width of the timber and add half again. For example, for a wane-free 8x8 take the width, 8", and add half of that. "4", to get a 12" diameter log. This is slightly bigger than the theoretical minimum diameter but the reality is that logs are rarely perfect and you have a little room for imperfections, errors in centering, etc. It's also very easy to calculate -- even in your head.

I adapted this rule to handle rectangular timbers. Take the average of the width and thickness and then apply the "half-again" rule. This will work up to about a ratio of 1:2 (thickness:width). The further away you get from a square timber, the less safety factor you will have. Once you go beyond 1:2 your log will be undersized.

If you want to go the other way, take 2/3 of the diameter to figure out what size wane-free square timber you can cut. If you want a rectangular timber, start with the square dimension. Reduce it by whatever amount you need to in order to get your desired thickness -- then add that same amount to the square dimension to get your width.
Example: 15" diameter log.
2/3 x 15" = 10" square timber.
If you want an 8" thick timber, subtract 2" from 10 to get your 8" thickness. Then add the same 2" to 10 and you will end up with a 12" wide timber.

Do this in your head for a while and before long you'll automatically know what size square timber you can get out of a certain diameter log. From there it's easy to figure what size rectangular timber you can get.

[Alligator]

If the logs have sufficient taper across the 8' mark you might have less
waste if you buck them to 8' first

Just a thought,

DGDrls

Same thought here. Only buck them as you go if you want 16' lumber for the barn. You can't glue the back together.

[4x4American]

What is the GVW of the trailer?

I registered it for 10 ton.  There are 3- 10,000# dexter oil bath axles riding on 10 ply tires. 

[4x4American]

What species of pine is this? White pine is way lighter than red pine. Red pine (green) is nearly as heavy as red oak. The stuff is all water.

Eastern White Pine

[4x4American]

Wow, interesting to see trailers loaded like we load out here in the sticks, but gotta say that would get us a mighty interesting citation. After loading and running like that for years we found out that our itty bitty F-350's needed a "GCVW" rating on the truck registration to tow a trailer registered over 10k, and now the state of PA doesn't let you "buy" a rating over the recommended GCVW of the tow vehicle as stated on the vin tag by the manufacturer. Don't ask how expensive a lesson that was to learn (or how I know how expensive it was). We have a local DOT officer that has a pet peeve for pick-ups, amazing how many citations he has written on big horse trailers rigs in the last few years.

Would love to find a deal like that for pine logs around here but I'd have to hire out the hauling.

Joe

I got passed by a DOT officer on the way back when I ended up on the highway, and a few troopers.  Must be they didn't give a turkey.  If a DOT officer pulls anyone over, they will always at least find something wrong.  If they can't, they will make up some bull dinkle like "low washer fluid" or "looked at me wrong way"

[4x4American]

The reason I ask is because I went to draw a load of pine today, need to saw out 100 8-foot 2x4s for a customer. 

pardon my ignorance on this point....but....

If they are not the customers logs... how on earth can you possibly buy logs,  and saw out 8' 2x4's for anywere close to what the customer could go buy them from lowes for?

I mean granted special sizes, or species maybe... but pine 2x4's?!?!?

ps it seemed like a pointed question on a thread labeled "math time"

well ya see, we're buried under a lot of DanG snow, business has been slow, and I'm not turning away any work.  All of my portable jobs have been postponed until better weather.  I have kept the sawmill cleared with every snowfall.  It might not be an order chock full of $300 boards, but I'm still profiting  enough to make it worth it.  There's around 533 bdft in 100 2x4's full size.  I got 1080 bdft in logs according to the international scale for $180.  I'm getting $2.50 per piece.  He also wants a bartop and I have another guy who wants a bartop, so if I can get them somewhere out of this load, I'll be happy happy happy...


ps.  my threads/conversations in real life almost never stay on topic, and I wouldn't have it any other way  ;)

[4x4American]

Back to the original question. Arky taught me the "half-again" formula for calculating how big a log you would need to cut a square timber of a certain size. Take the width of the timber and add half again. For example, for a wane-free 8x8 take the width, 8", and add half of that. "4", to get a 12" diameter log. This is slightly bigger than the theoretical minimum diameter but the reality is that logs are rarely perfect and you have a little room for imperfections, errors in centering, etc. It's also very easy to calculate -- even in your head.

I adapted this rule to handle rectangular timbers. Take the average of the width and thickness and then apply the "half-again" rule. This will work up to about a ratio of 1:2 (thickness:width). The further away you get from a square timber, the less safety factor you will have. Once you go beyond 1:2 your log will be undersized.

If you want to go the other way, take 2/3 of the diameter to figure out what size wane-free square timber you can cut. If you want a rectangular timber, start with the square dimension. Reduce it by whatever amount you need to in order to get your desired thickness -- then add that same amount to the square dimension to get your width.
Example: 15" diameter log.
2/3 x 15" = 10" square timber.
If you want an 8" thick timber, subtract 2" from 10 to get your 8" thickness. Then add the same 2" to 10 and you will end up with a 12" wide timber.

Do this in your head for a while and before long you'll automatically know what size square timber you can get out of a certain diameter log. From there it's easy to figure what size rectangular timber you can get.

I like this method, thanks for sharing!