Jim4929
Roanoke, VA
Senior Member
Joined: 04/29/2007
View Profile
Good Sam RV Club Member
|
When we started out on a 6 week trip, the last thing I thought I would have trouble with was the leg blocks I made. I cut a 4x6x8ft pressure treated pine into 9 inch sections. I then glued them together and put a 1/2,8 inch lag bolt in them to hold them together. The hole for the lag bolt was predrilled with a 3/8 drill bit the entire length of the bolt plus one inch. The top of the bolt is offset 1 inch down. The problem is that the wood is splitting in the same spot on all four blocks on both sides with the grain. Question. Did I did a bad piece of pressure treated pine or is this just the wrong kind of wood to use? Fifth Wheel is rated 13k. Any sugestions?
* This post was
last
edited 05/25/12 05:50pm by Jim4929 *
View edit history
2011 GMC 3500 Sierra Diesel SRW
B&W Patriot Hitch
5th Airborne Pin Box
Laredo 321BH
"Have Trailer, Will Travel"
|
CRAMD
Saskatchewan,Canada
Senior Member
Joined: 11/21/2006
View Profile
 Offline
|
Jim4929 wrote:When we started out on a 6 week trip, the last thing I thought I would have trouble with was the leg blocks I made. I cut a 4x6 block in to 9 inch sections. I then glued them together and put a 1/2,8 inch lag bolt in them to hold them together. The hole for the lag bolt was predrilled with a 3/8 drill bit the entire length of the bolt plus one inch. The top of the bolt is offset 1 inch down. The problem is that the wood is splitting in the same spot on all four blocks on both sides with the grain. Question. Did I did a bad piece of pressure treated pine or is this just the wrong kind of wood to use? Fifth Wheel is rated 13k. Any sugestions?
I'm beginning to think that pressure treated wood in general may be more prone to cracking. I have some pieces of 2x8 pressure treated to use for blocking under the wheels, and most of them are starting to split lengthwise. The equivalent size pieces of untreated fir are still doing fine.
|
Francesca Knowles
Port Hadlock, Washington
Senior Member
Joined: 02/23/2011
View Profile
Offline
|
I'm not getting the picture- you "cut a 4x6 block into nine inch sections"????
Take a pic and post it, if possible...
" Not every mind that wanders is lost. " With apologies to J.R.R. Tolkien
|
bpounds
Whittier CA
Senior Member
Joined: 12/12/2010
View Profile
Good Sam RV Club Member
Offline
|
Pressure treated wood is often very wet. It isn't going to be stable. It may have been destined to split there eventually, and eventually is now. Or you might have hastened that day by bolting and glueing wet lumber. Can't say without knowing more about the blocks. Also, the grain orientation is important.
You really didn't need blocks under the legs at all, so it isn't a big deal.
Edit: Just noticed your pics. Unfortunately that timber has the pith right down the center. It was going to split on you, no matter what you did. For the same reason that log "rounds" split. Differential of shrinkage. You want to look for quartersawn or riftsawn, but not centercut.
Edit again: You can save those. Take the bolts out, and saw them lengthwise right down the center of the pith. Then reverse each block so the rings oppose each other, and glue them back together again and reinstall the bolts. Your sawcuts will relieve the tension in the growth rings. Be careful sawing them if they haven't split yet. They will be under tension. If you can let it all dry a couple of months before doing that you will end up with a more stable block.
2006 F250 Diesel
2011 Keystone Cougar 278RKSWE Fiver
|
mobilefleet
on the road
Senior Member
Joined: 10/09/2005
View Profile
Offline
|
I made my blocks from pvc fencing that I had left over, from deck railing. Screwed several pieces together for different heights and made several sizes. It will never rot, crack, or warp, and the best part is it came from short pieces that would have been going to the trash can anyway. Lynx levelers are great as well
|
|
|
Acampingwewillgo
USA
Senior Member
Joined: 11/15/2002
View Profile
Good Sam RV Club Member
Offline
|
I made my blocks for the MH out of a section of 2x8 lumber sandwiched between like size pieces of 1" plywood cross grained. Ive used them for support under my jacks and tires for the past 8 years....they still look as good as new.
* This post was
edited 05/25/12 06:48pm by Acampingwewillgo *
96 Vogue Prima Vista 37' CAT 3176B
Our Babies: Mollie, Rubie, Cassie and Maggie, all rescued Cavalier King Charles Spaniels
Rainbow Bridge: Laddie, Scoutie, Katie, Cooper, Kodie
Rally's and get togethers.....Lots
|
n7bsn
Yes
Senior Member
Joined: 04/11/2004
View Profile
Offline
|
bpounds wrote:....
Edit: Just noticed your pics. Unfortunately that timber has the pith right down the center. It was going to split on you, no matter what you did. For the same reason that log "rounds" split. Differential of shrinkage. You want to look for quartersawn or riftsawn, but not centercut.....
This man knows what he is talking about. Unfortunately a lot of 4x6's (and 4x4) are cut this with.
The pith is the center
(ps, I recall pbounds is also a wood-worker and turner)
2008 F350SD V10 with an 2012 Arctic Fox 29-5E
When someone tells you to buy the same rig they own, listen, they might be right. When they tell you to buy a different rig then they own, really pay attention, they probably know something you don't.
|
stubblejumper
Saskatchewan
Senior Member
Joined: 11/28/2010
View Profile
Offline
|
A lot of 4x4 and landscape timbers are actually made from the center of logs that have rotary "peeled" for plywood. Just means that the left over center doesn't end up in the scrap pile.
I use 12x12x2 cut from planks with a hole in the corner and a piece of rope with a dowel handle knotted through the hole. Ropes just make it easier to pull out once the jacks are up.
1999 Winnebego Chieftain
Wayne & Leila and Teddi (the Kid in the brown fuzzy pyjamas)
We are not 2 people that own a dog, we are 2 people that are owned by a dog ..
|
Pete_k
Stantonville Tn
Senior Member
Joined: 03/18/2004
View Profile
Offline
|
Thats normal with fresh treated yellow pine. Now let it dry out for a few months before cutting it. Then it does not crack as bad. But hard wood is best for this .
If it were me, cut pieces of plywood to fit these. Screw it down both both sides. This will lock it all in place for a while.
Pete
2004 Duramax/allison Trans C/C 4x4
2012 Landmark Key Largo
2008 Lund 1825 Pro Guide Tiller, With a Evinrude 90 HP E-Tec
Live near Pickwick Dam and the Tn river
|
sirdrakejr
Las Vegas, Nevada
Senior Member
Joined: 11/18/2001
View Profile
Good Sam RV Club Member
Offline
|
I would suggest using 3/4" plywood that already has the grains crossed. A long time ago I also saw a tip of using tire tread thrown from truck tires and cut them into squares. They are going to outlast anything we could make up.
Frank
2011 Palomino Maverick 1000SLLB on a 2004 Dodge Quadcab CTD Ram3500 SRW long bed equipped with Timbren springs, Stable Load bump stops, Rickson 19.5" wheels/"G" range tires and a Helwig "Big Wig" rear anti sway bar.
|
|
|
