Hydraulic limb saw project.

[Smokeydog]

Working on saw arm bar clamp. Up sizing bar bolts and increasing bar slot width. Also tightly fitting the bar outer cover to the 8” channel motor mount to support the bar bolt attachment. While finesse and careful manipulation are going to be required, trees and extended loader work are unpredictable.

Going to tack pieces together then gang drill. 10 holes needed to line up closely.

 

[workinonit]

I'm following this. I want to build one as well.

 

[workinonit]

I'm thinking I will get a 2.5" or 3" receiver so that I can eliminate the step up and strong back. I think spending the money for that will trump the extra weight.

 

[Smokeydog]

I'm thinking I will get a 2.5" or 3" receiver so that I can eliminate the step up and strong back. I think spending the money for that will trump the extra weight.

Great! Hope you can learn and improve from this experience. Please share your results.

Some of the design is material on hand. Mine is heavier given the wall thickness. May or may not be beneficial. Don’t have to worry about structural material cost or shipping. Without direct comparison with manufacturers versions may never know.

2” receivers already mounted on several attachments on different tractor platforms. The transition from 3”-2” gave an extra 1’2” boom length but also -25#s and more fabrication effort. Not the way to go into production. Only want one.

Would recommend a 3” tubing for strength.

Don’t see the heavier boom having issues. With the saw arm, it’s hinged weight is the force that pushes the saw thru the cut. My heavy, extra armor, robust construction may be a problem. Hoping the torque of the hydraulic motor to pull thru.

At some point want to experiment cutting vertically small limbs while driving slow down my 1/2 mile green tunnel driveway. Saw head supported with coil spring over shocks both ways to control dynamic loads. Don’t know if that will work but another reason for robust construction and boom bracket design.

 

[workinonit]

Yea, mine will be with materials on hand as well. I'm still curious what you are going to use as the saw. I have a hydraulic motor that I think will work. Just have to figure out the motor to chain configuration.

 

[Smokeydog]

The motor is Parker, 5,000rpm, xx25 from Surplus center. Think this motor gives about 17hp at 12gpm, 2500 psi? Hopefully might work on the smaller 7gpm tractor too. Looks like LimbSaw uses a Parker motor from same motor family. IDK which one.

Ordered a chain drive gear from LimbSaw that fits the 9/16” keyed shaft of the motor. IDK which pitch chain they use. Have a few combinations of saw chain drivers to yet explore.

A used 20” bar and especially sharpened 3/8” chisel chain will be first test.

Spring is rolling in fast and R&D department employee is the first to get cut.

 

[airbiscuit]

You may wnd up experimenting with drive sprocket size to achieve optimal chain speed.

 

[Smokeydog]

12 saw bar bolt holes drilled and bar plates welded. Stores stock are scarce on specialty hardware and paint. Ordered online the type of sems grade 8 bolts.
Tack welding the bolt flanges to make one side stud fasteners.

Saw bar.
Was going to use my >40 years collection of 3/8” chains and 20” bars. May develop this option latter. LimbSaw uses I believe .325 chain? I’ve been blissfully ignorant for a long time only needing one type of chain and bar. Researching the difference may have found a reason. Many types of chains with different attributes. There are over a dozen chainsaw bar mounting options. D025 style has a 0.475” slot. This has a small drilled bar that bridges the two 3/8” mounting bolts. This creates a tab to fit the bar slot and better support the bar under heavy load. Common with some large .325 saws. Ordered .325, 063”, 81 drive links, full chisel chain and 20” D025 bar.

Automotive bump stop to cushion the saw arm when in folded transport position. Cushion the blow if the angle strap ever broke too.

Saw chain cover made it to the paint shop. While bending a flange, the 7.5” wide plate in the press, it cracked. Another surprise the salvaged plate material was cold rolled 1/4” steel. While twice as strong as hot rolled steel doesn’t bend well. Nothing a little extra welding couldn’t cure. Making the saw motor box cover amour from the same material.

Saw cover will have 4 bolts to pinch the saw bar.

Saw boom mounted on right side grapple. Saw blade mounted on left side of boom to maybe give better line of sight from operator seat?

 

[Smokeydog]

Thinking the saw bar on the left would give a better line of sight from the operator’s seat. Chainsaws are made with bar on the right. If switched to the left, the bar oil hole is at the bottom of the blade. Could cause lubrication issue? Making the mount with both top and bottom oil ports. 1/4” pipe plug in one not used. If using the top would have to drill extra oil holes in the bar. Extra holes are blocked when clamped. Design changes have consequences.

 

[Gordon Gould]

Just catching up here. I'm finding this very interesting Smokey. It is amazing how involved things get when you stop and think them through like you are doing. Glad you are posting your work !!

gg

 

[Smokeydog]

Just catching up here. I'm finding this very interesting Smokey. It is amazing how involved things get when you stop and think them through like you are doing. Glad you are posting your work !!

gg

Thanks for the feedback. Sure hope this works.

Just picked up the last of hydraulic fittings and got the experience of the local hydraulic shop to bless the motor and metering valve plumbing.

Last pieces are cut. About 4’ of welding left to do so getting to the short rows.

 

[Smokeydog]

Motor side.

Saw side. 9 tooth drive sprocket.

 

[Gordon Gould]

Looking good !!

It looks like you are bleeding off some hydraulic fluid on the pressure side to use as bar and chain oil .... am I seeing that right ??

gg

 

[Smokeydog]

Looking good !!

It looks like you are bleeding off some hydraulic fluid on the pressure side to use as bar and chain oil .... am I seeing that right ??

gg

Yes. Sees pressure when cutting. Built in check valve when not. Reversible motor to help back out of a pinch.

Will need to adjust to get the right amount of oil. This will run approximately 2340’/minute, a little less than half the typical chainsaw speed. But instant torque. Guesstimating starting at a drop every 4 seconds at no-load speed. 60/4=15 drops per minute. 15x60= 900drops per hour. 900/20=45ml/hr. 45/30=1.5 oz of oil per hour when the saw is running at no load. Guess a little more volume under load. Lower chain speed, less heat and oil throw off and seconds per cut are advantageous. A week of cutting may use 1-2 cups of oil? It’s going to be feature to monitor and adjust when using.

Did drill the chainsaw bar to have top oiling while mounted on the left.

Few short sided set backs.
The 15’ hydraulic hoses are too short. Boom and saw arm are longer than first planned. Ordered 5’ pair of extensions.

Typical 81 drive link saw chain too short. I started out modeling like my Husky 3/8” saw mount then switched to .325. Stud spacing and distance to drive sprocket all a little different. Need 83 drive links. They do make that loop size just not typical. Saw shop could custom make too.

Few features.
Using SS tethered ball release pins for saw arm adjustment anchors. Less to come apart or lose when using.

Saw arm motor mount 15*
off straight. Mimicking a manual polesaw curve to cut from the top down to help prevent pinching. Also improved max height geometry.

Not much left to complete and anxious to get to use.

 

[mike0000]

Very interesting project. I recently bought my first pole saw, I’m amazed at how much work I get done with it (also how quickly it makes a large brush pile).
Thanks for posting.

Mike

 

[BackRoad]

Mr. Smokeydog, does your design permit for an initial cut to the underside of a limb?

 

[jmc]

Is that a common thing, using hydraulic oil for chain oil? The chain oil I've used seemed stringy or sticky when you pour it, like lathe way oil, which has paraffin in it to keep it from wiping off the ways.

Really enjoying your workmanship.

 

[Smokeydog]

Mr. Smokeydog, does your design permit for an initial cut to the underside of a limb?

Short answer no. Can’t use the loader hydraulics to move the saw thru the cut. Not a good way to feel saw pressure. The saw arm is hinged so the weight is what carries saw thru the cut. Best to make several section cuts back to the trunk to reduce bark stripping. Time of year and some judicial use of manual polesaw could improve arborist results.

Could some coil over shock springs on the saw arm give a controlled force on the saw to also give an upward cut? Idea needs some clever development.

 

[Smokeydog]

Is that a common thing, using hydraulic oil for chain oil? The chain oil I've used seemed stringy or sticky when you pour it, like lathe way oil, which has paraffin in it to keep it from wiping off the ways.

Really enjoying your workmanship.

Common and convenient for hydraulic saws. There are other options too.

 

[newbury]

Have you thought of mounting some sort of camera to view live video to help you to maneuver the sawhead in tight places? Like a backup cam?