# Log boom grapple build



## dave_dj1 (Dec 13, 2013)

Since my boom grapple build is underway I decided to start a new thread instead of adding to my other thread. I figure this thread may get more traffic than the one titled "grapple boom help".
I had the bright idea to build this thing after using the truck to pull some logs off a pile then having to bend over to cut them to firewood lengths. I have a dump trailer I built a couple of years back and I'm going to put this on the tongue. I will do away with the electric over hydraulic unit on the dump trailer and power the grapple and dump with a gas powered motor hooked to a hydraulic pump. I have most of what I need here, I have a bunch of 2"x2"X1/4" angle iron I picked up cheap at the scrapyard this summer, the main lift cylinder which was given to me, the pump came in a hydraulic tank I used for my log splitter, a piece of 6" well casing that was given to me, 3/8" x 6" flat stock was left over from a previous project, I bought the 2 1/2" square tube for the boom, I had the jeep axle and the bearings were in a drawer that I had bought for a project that never happened.
Anyway, the plan is to get a HF 6.5 hp motor for 99 bucks, a backhoe control valve either used or new. I will need to buy a crowd arm cylinder and sabilizer cylinders, an adapter for the pump to motor and hoses etc. etc.
Here are a few pics of what is completed so far, I will get some more pics of the bearing set up for the base of the turret.
Here's how most of my projects start, a doodle. I doodle when I have my morning coffee! LOL






jeep axle cut down pass side






the 6" casing fit almost perfectly over the axle end where the brake drum would go







Plan is to weld the spiders, put a large chain sprocket on the yoke and drive it with a hydraulic motor, I'm trying to figure out the gear ratio and how fast the turret will spin. Given a 6:1 chain drive and a 3.73:1 axle drive I'm guessing somewhere around 24:1, I hope this will be slow enough. (I could use some help here)
I'm searching for the drive motor.
I will keep you updated as this thing progresses.
thoughts on stabilizer legs, folding or sliding, I'm thinking folding will be less weight?

dave


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## Hddnis (Dec 13, 2013)

This'll be a fun thread to watch.



Mr. HE


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## jthornton (Dec 14, 2013)

Good Start!


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## Milkman31 (Dec 14, 2013)

Nice!!


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## lapeer20m (Dec 15, 2013)

Subscribed!

I want to build a grapple for the hoe end of my backhoe.


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## dave_dj1 (Dec 16, 2013)

Part of the "plan" is to take the actual grapple off and put on a post hole digger so the motor will have to be rated for that.
I wish I had the time and money to just do this thing all at once, right now I'm just piecing things together. I'm making it modular for ease of storage and working on different pieces when time and funds are available.
@lapeer20m , keep us posted on your build. I'm just starting to draw out the grapple part, getting both sides to have power and move together is challenging. I "think" I have it figured out 
dave


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## lapeer20m (Dec 16, 2013)

Here is the basic concept I want to copy as far as the actual grapple:



You can buy special flow control devices that meter equal amounts of fluid to both cylinders, but I'm not convinced that is necessary. Does it really matter if one side closes faster than the other?

I really like how the grapple dangles from a chain in the video below. Much simpler and cheaper than many of the other systems I've seen.



I think a grapple on the end of the hoe will really increase my firewood gathering efficiency. I live on 60 mostly wooded acres. Plus we are building a processor in the spring and a grapple would be handy to load logs onto the feed deck.


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## Jim Timber (Dec 16, 2013)

I could see that second one on the boom really handy if you had a sawmill too.


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## muddstopper (Dec 16, 2013)

I am still trying to figure out how your going to put a support bearing at the bottom of that 6in pipe.


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## Jim Timber (Dec 16, 2013)

Turn a bushing to fit, or shop-made needle bearings would work good too.


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## dave_dj1 (Dec 16, 2013)

muddstopper said:


> I am still trying to figure out how your going to put a support bearing at the bottom of that 6in pipe.


Not a problem! LOL
I have them all set to weld in.



don't forget there is an axle inside the pipe that has an upper (outer on a car) bearing and it sits in a bearing in the center section. These bearings are more or less just to help take some stress off the axle shaft.
If you look at my sketch you'll see how they are going to go in. 






The base is making some progress. I'll take more pics as it progresses. 
dave


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## dave_dj1 (Dec 16, 2013)

Jim Timber said:


> Turn a bushing to fit, or shop-made needle bearings would work good too.



Problem with that is there is no way to get it on without cutting the outer (upper) end of the tube off, there is a flange where the backing plate was bolted and it holds the wheel bearing. It would have to be two pieces and bolt together, I guess that would be an option for someone more talented and better equipped shop than myself.


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## Jim Timber (Dec 16, 2013)

You'd capture both halves by the pipe when installed. No need to bolt them together.


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## dave_dj1 (Dec 16, 2013)

true enough!
dave


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## muddstopper (Dec 17, 2013)

Neat solution. I supposed those bearing are going to be mounted on the axle housing and not the pipe?
While the axle is supported inside the tube with bearing at top and bottom in carrier, those by themselfs wont support a crane boom. Most likely the weight and leverage of an extened crane would bend the axle tube, possibly breaking it off at the carrier housing. Your ideal to provide additional support at the bottom of the tube should make for a pretty strong boom. 

To attach a gear and hydraulic pump to pinion, I propose machining the yoke down so that it will fit inside of a weldon sprocket. Slip on, true up and then weld. Make a mount for the hydraulic motor and use a smaller sprocket to get your gearing. I suggest using a #100 size roller chain, thats what we used to use on our old Kennemer wood loader. Been know to break a few so we always kept plenty of master links on hand. With your ring and pinion gear set, I dont think your loader will see the stress we used to apply to the Kennemer, but I have seen #60 roller chains sprocket setups and it appears to be very hard to keep them under proper tension so that the chain doesnt jump the sprocket teeth.


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## dave_dj1 (Dec 17, 2013)

" I supposed those bearing are going to be mounted on the axle housing and not the pipe?"
I hadn't even considered welding them to the axle itself, I was going to weld them to the pipe. Do you think it will make any difference? 
I thought by welding them to the pipe I could just hold them tight against the axle, if I weld them to the axle I will have to do some fancy measuring. LOL
dave


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## muddstopper (Dec 18, 2013)

If you weld them to the pipe, will they slip over the axle tube? It just looks to me if welded in the pipe to fit the axle tube, then it wont slip over the top of the axle. Also , mounted in the pipe would mean the same bearing is carrying the load which ever direction the boom is turned. Welded to the axle, bearing should roll inside the pipe and distribute the load better as the boom is turned. Am I looking at it wrong?


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## dave_dj1 (Dec 18, 2013)

Good points which I hadn't considered. You are looking at it correctly. I don't care about it slipping over the axle, I was going to weld them on in place. I may take your advice and weld them to the axle, that way 1) like you said, the same bearings won't always be under load and 2) if I do brake the axle shaft I can still slide it up out and replace it and salvage the bearings.
thanks,
dave


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## Hddnis (Jan 12, 2014)

Hey, One with the Offensive Avitar, any progress on your build here? 



Mr. HE


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## ttyR2 (Jan 12, 2014)

You can also put an inline orifice in the hydraulic line going to the hydraulic motor to slow it down instead of doing a bunch of stuff with gearing. Being as how the motor won't be running continuously, the orifice shouldn't heat the fluid too much.


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## Jim Timber (Jan 12, 2014)

The downside to flow control is the lack of additional torque from gear reduction.


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## dave_dj1 (Jan 13, 2014)

Hddnis said:


> Hey, One with the Offensive Avitar, any progress on your build here?
> 
> 
> 
> Mr. HE



I've made very little progress, I'm still trying to figure out my landing gear. I did get the jib bored and bushed and cut on the angle. I think I just figured out how I'm going to make the joint at the main boom and jib. It all boils down to money which I don't have any extra right now. It's been so cold that I haven't felt like starting the stove in the garage only to have it take all day to warm up in there. I may start it today though, just to dry things out a bit. Even though I haven't made any physical progress I have been making mental progress. I constantly doodle different pieces getting my head wrapped around what what's going to look like. LOL I'll keep you all posted. I could have used this thing last week!
dave


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## dave_dj1 (Jan 13, 2014)

dave_dj1 said:


> Good points which I hadn't considered. You are looking at it correctly. I don't care about it slipping over the axle, I was going to weld them on in place. I may take your advice and weld them to the axle, that way 1) like you said, the same bearings won't always be under load and 2) if I do brake the axle shaft I can still slide it up out and replace it and salvage the bearings.
> thanks,
> dave



I have discovered that the pipe isn't perfectly aligned over the axle tube so I think I will have to weld the bearings to the pipe instead of the axle. It's off by like an 1/8" run out.
dave


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