# Question about building a gantry to lift a spreader



## ss502gmc (Sep 12, 2008)

I'm gonna build a gantry to lift my 8ft stainless Vbox spreader. Would using pressure treated 4x4s suffice? Or would I need to go with 6x6 lumber? I plan on making it 10ft tall and 8ft wide and will be bracing it at the bottom of the posts and at the top. Any input would be appreciated as I'm sure some of you out there have done this. I just want to make it moveable so if 4x4s will work id like to use them but if it's not safe then I'll go bigger.


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## Builder630 (Dec 23, 2011)

I'm a carpenter since 1990... 4 by 4 should work however a 6 by 6 would be much sturdier and more wood to fasten into. I'd make sure it was cross braced. Not sure what kind of wheels you would use but you would have to be on level ground.


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## Citytow (Sep 21, 2014)

i used scaffolding before to work on them . (2) 7' tier high .use the braces . be careful , mine were lite plastic .


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## AccuCon (Jan 31, 2013)

You are supporting over 1,000 lbs and moving it around...

I'm just thinking:

(4) 6x6 10' Posts
(2) 6x6 10' horzinotal beams place atop and secured with simpson strong tie plate or angles set to give you the 8' length
(2) 6x6 10' cut down to size to sit atop the 8' length giving you the necessary width to clear the truck
Using remainder scrap for knee braces (no matter what even if you use 4x4 I would still put in knee braces)
I would also on the 8' Length put a bottom plate to help keep it square and from spreading

And for casters:
http://www.harborfreight.com/materi...-x-2-inch-heavy-duty-swivel-caster-41565.html

I would use something with a minimum of 600 lbs rating which would give you a total capacity of around 2400lbs

Just thoughts, you could probably get away with 4x4 construction and timberlocks...But 6x6 with strong tie plates is going to last a very very very long time

~edit

After looking at some tables you could probably build it with 4x4 post and double 2x8 beams (still using knee braces) 4x4 beams will be cutting it close on an 8' span and that loading since typical #2-4x4PT at 8'0" span has an approx. capacity of 600lbs

#2 6x6 PT beams have more than enough capacity (overkill)


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## Citytow (Sep 21, 2014)

looks like scaffolding is more economic with the same results


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## ss502gmc (Sep 12, 2008)

Thanks for the input, I won't be moving the gantry with the spreader hanging from it, just wanted to be able to move it in the spring out back so it's not a lawn ornament. I have the spreader sitting on a trailer right now that I move around with my atv when I'm working on it. So when I wanna clean out the truck bed I can just set it on the trailer and move it wherever. I'm not a carpenter by any means but I was planning on using braces at top and bottom with all 4x4s. So maybe using 2 6x6s for the posts and double up some 2x10s for the cross member and some good bracing should do the trick?


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## JohnRoscoe (Sep 27, 2010)

I'd watch Craigslist for a used steel gantry. Much sturdier, much safer, more uses, and you can sell again if you no longer need it someday.


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## AccuCon (Jan 31, 2013)

I think I had some slight confusion of what you wanted to build....

4x4 post can handle around 4,000lbs vertical 10-0" height

6x6 Beam can handle around 2,500lbs horizontal at an 8-0" span

Single 2x8 can handle around 1,200lbs a beam made up of (2) 2x8 would be about 2,400lbs capacity at an 8'0" span

If that helps

You could use the 4x4 posts and secure them to 4x4 bases as beams with a span of 5'-0" (950lb capacity) then run your beam out of a double 2x8 and secure to the top of post....get (4) casters rated for 250lbs each and should be good to go

I have rounded these numbers and I used #2 PT lumber in beam loading tables the above rig if fasten together properly should be able to safely handle 1,800lbs - Do not quote me on this and only use this as advice....For CYA purposes

~edit

You could use some flat stock steal for bracing on the uprights and the beam to uprights


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## ss502gmc (Sep 12, 2008)

Thanks, that's the info ive been trying to find, trying to figure out the strength of different size lumber vertical and horizontal. My initial thought was to build it with just 2 posts like a car lift with all necessary braces, then I was thinking of building it like a swing set, like 2 triangles on each end with the top beam connecting them. Ill figure it out now that I have an idea on the strength of the lumber. Thank you


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## Nozzleman (Feb 6, 2003)

Probably not as cheap as building it yourself but Harbor Freight has one on sale for $699
http://www.harborfreight.com/http-w...-ton-telescoping-gantry-crane-41188-html.html


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## AccuCon (Jan 31, 2013)

ss502gmc;1852088 said:


> Thanks, that's the info ive been trying to find, trying to figure out the strength of different size lumber vertical and horizontal. My initial thought was to build it with just 2 posts like a car lift with all necessary braces, then I was thinking of building it like a swing set, like 2 triangles on each end with the top beam connecting them. Ill figure it out now that I have an idea on the strength of the lumber. Thank you


I see an error in my post in regards to the casters those would technically only give you 1000lb capacity with that set up but if you're not moving it should be ok...But the casters would be your weak point you could always put 4 per side and be fine at 1800lbs max for the system

You could use 4x4 knee braces that would go from top beam to post (inside angle) or flat stock steel on the outside... And use 4x4 knee braces on the bottom from the post to the base beam at like a 45 degree angle to per side you could cut them from 8' 4x4s meaning you would only need 3 for all six knee braces...Or you could just use flat stock, angle iron what have you...

If you need to know capacity of any other dimensional lumber and span post it it I will try to be of assistance, I subscribed to the thread


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## rcnease (Nov 3, 2013)

I am making something similar. I just had a new driveway put in and I sank 3" pipe 4ft into the ground. I will use 2 1/2" pipe coming out of those with a 3" pipe as my cross pipe and then use a chain fall to pull my spreaders enough to put them on barrels. I had this designed by an engineer. The only concern is if there is any sway since those support poles will be 8' out of the ground. I won't have a lot of bracing for them. I suspect it will be interesting to see what happens. I was glad to see this thread to see that someone else is doing something similar.


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