log splitter plans

[ByronMill]

One book that I had ( I cant find it now) actually listed that formula for the sizing of an ELECTRIC motor. And not just HP requirements. Those #'s that you listed do seem a bit small to me. An example of where I work, we have a denison 29GPM pump and it is driven by a 15HP 3phase motor. And we have several of them units where I work and they are all sized the same.

As an other example, when we hooked our 11gpm pump up to an electric motor, the current draw was 19-21 AMPS @ 3000psi. Current draw is the most important factor to look at.

As for the link to your "motor of choice", is not a good motor at all. First it is an Air comp motor, which are built much lighter, usually not designed for contunious duty, only have a SF of 1.0, and it is an open motor and not a TEFC. That motor is also rated @ ~20 amps, which would barley be adequite on the 11gpm pump, based on the current draw that we have tested. If you go to TSC and compare their "farm duty" motors to the Air comp motors, you'll see what I mean. The Farm duty is twice the size and usually a "true" 5HP motor is rated between 25 and 30 amps.

This is close to what you need, although I still wouldn't use it on bigger than a 16gpm and I would also try to find a TEFC motor, otherwise the benifit of electric motors lasting a long time goes right out the window.
Leeson Reversible Electric Motor 5 HP, 3450 RPM, Model# 131616 | Electric Motors | Northern Tool + Equipment

LD1,

You mentioned that you connected the 11GPM pump to an electric motor. You did not state what RPM the motor was or voltage you were running at. 3600 or 1800 RPM motor? Voltage? 11 GPM would only be the case if using a 3600 RPM motor and amps alone do not tell about load. I assume probably 230V. 3PH or single?

 

[LD1]

The electric motor was 3450rpm motor off an old craftsman air compressor. It was nameplate rated @ 5HP SPL and 13.5 Amps @ 230v/240v. It drew the 19-20 amps while in the split and didn't drop back below the 13.5 amp max until the split was done. That motor wouldn't last long with only a SF of 1.0.

Also it is a open motor. AS I mentioned, most air comp motors are and this also makes them not a good choice. Given the environment, you really want a TEFC.

 

[ByronMill]

Your information confirms what I was saying previously. That air compressor motor is not really 5 HP. 1 HP equals 750 watts, so 5 HP would be 3750 watts. Watts divided by voltage equals amps, so 3750 divided by 230 V equals 16.3 amps. Small motors like that are typically only about 80% efficient, in other words only about 80% of the electrical energy is converted into rotational torque. Therefore to get actual 5 HP at the shaft you need to input a 20% surplus. So 16.3 amps divided by .8 (to give the 20% surplus) = 20.4 amps. Therefore if you had a motor with a true output rating of 5 HP you would be fine, even with a 1.0 SF rating. The air compressor motor is in reality an "uprated" 3 HP. A true rated 5 HP motor with a typical nameplate efficiency of 78-82% would draw about 20 full load amps at 230 V. Best way to tell what a motor really is rated at is by looking at FLA and motor efficiency. If efficiency is not stated on the tag assume about 80%. Motor ratings on some motors are like Tons rating on splitters. How does anyone rate a splitter with a 4" cylinder at 27 tons of force? Same deal with the motors. How can a motor that only draws 13 FLA be rated at 5 HP? Fuzzy math?

General rule of thumb: (these are approximate values)

Every 1 HP @ 120VAC will draw 8 amps
Every 1 HP @ 230VAC will draw 4 amps
Every 1 HP @ 460VAC will draw 2 amps

I am not sure that the issue of an open motor versus TEFC/TENV is that big of an issue unless you are using it in a really dusty or dirty environment. If you keep it covered or out of the weather when stored there should be no real issues. If open motors hold up in woodworking applications they will surely provide acceptable service in a hydraulic drive. Heat is the biggest enemy of motors and open motors actually cool better than TE motors, unless of course they get packed full of dust.

I'm not challenging you or saying you are wrong. You are actually quite correct and on the right track, once you understand that air compressor motors and some "special duty" motors are actually over-rated.

 

[skidsteer.ca]

Will a 3in cylinder work? Have one(3 by18) and scrap steel enough, want to add it to my small tractor 15 hp?
Have a set of plans from Mother Earth News from years ago, all will need is a valve and hose, maybe wheels and tires as well
thnx
didnt mean to hijack the thread
thnx

Think you better check what your max pressure is first. Ifyou have 2500fine, if its 1500
Ken

 

[gould37]

Sorry for not getting back to you all sooner with an update. I had to split a tractor and fix a stump grinder and a chipper. I have not yet been able to locate all the goodies I need for my log splitter. Still looking for a reasonably priced motor and cylinder. If I can find the stuff in a reasonable amount of time, I will let you know how it turns out.

THANKS AGAIN FOR ALL THE HELP. THE INFORMATION IS GREAT.....

 

[chainsawnut]

hey guys pete here from down under I have been following your thread with much interest and enjoying it very much.I have been accumulating gear to build a splitter,I have a bunch of hoses,an 18inch by 41/2 inch ram a heap of steel and two smoky honda engines,1 at 6.8 hp and 1 at 10hp.
I have given up here in oz on the priceof 2 stage logsplitter pumps close to400 bucks,but have been viewing american prices even with the exchange rate they seem viable .
Because the detente valves can be bought and freighted in the same parcel.I have emailed a few suppliers so far no one has bothered to reply
.Can someone tell me I see haldex barnes pumps around the 170 180 range are they better quality than many that show no brand name.
I was thinking of the 16gpm pump but if an 11 will do the same job and let me use te smaller motor I would prefer that.
Illness is slowly robbing me of strength but I love my old saws I burn wood and I want to stay self sufficient for as long as I can .Being only 51, I want to hang around for as long as I can.
I have some pumps but they are rather large edbro pto units are these a hydraulic pump or not.
They have gear drive but I felt I could cut away the body and fit pulley drive,there ondition is unknown as they along with most of the other bits were in my late fathers shed.Thanks for any replies and does anyone have an email adress for surplus center that will get to them,they show some great prices cheers

 

[Oliver1655]

The Haldex 2 stage pumps are proven performers for log splitters. With a 4 1/2 in dia cylinder you can get by with the 11 gpm pump but you will be at the slow side of splitting. I am still using a 4 in dia cylinder with a 16 gpm Haldex 2 stage pump and find it to be a good match. I am using an 11 hp Greyhound engine I purchased through Harbor Freight and only have to run it at a little above an idle. This keeps the noise level way down and saves a lot on fuel. The engine is electric start but will start with only 1 or 2 pulls.

 

[richmatz]

Interesting reading, I made a log spliter in high school, my first lesson was that there is a right and left hand hydraulic pumps.

So now I am going to build a splitter that will attach to my skidsteer. I know thats an expensive hydraulic pump... So i put an extra 10 hours a year on the motor.

The machine is a bobcat s300 with hi-flow (37gpm) at 81hp or something like that. The machines pressure relief is at 3300PSI
Suggestion on a ram?
Suggestion on a valve?
pressure hose diameter?
PHOTOS?

there are a few manufactures of these attachemnts out there. They all want around $2500 Here is a link to the best unit that I could find I would buy this if i didnt have the capabilities to build one. The only problem with this unit is the shape of the wedge when splitting hard woods.
Log Splitter for Skidsteer / Skid Steer / Loader / Compact Tractor - Quick Split - fits Bobcat and most other brands

I figure for $1500, not including my time I can build one.
Your ideas and comments are appricated!

 

[J_J]

If you have 37 GPM, why do you want another pump? Do you have QD's on the front of the machine? If the SS is only running slightly above idle, you should have enough hyd to get the job done.

 

[richmatz]

JJ
Thanks for the comment back, I was going to use the bobcat as the source of hydraulic pressure...Yes there are quick disconnects on the front of the machine, I have everything except the ram, valve and hoses.