Help me design an electric log splitter

[cstamm81]

If I want to stick to one of these 22GPM pumps:
Surplus Center - 22 GPM 2 STAGE HYD PUMP S31004-5278
Surplus Center - 22 GPM DYNAMIC 2-STAGE PUMP
(other than brand not sure of the difference between the two)

Could I get away with a 5HP motor or should I jump to 7.5HP (assuming I have the capacity in my electrical panel). The motors I have been looking at now are:

Leeson 132044.00 AC Electric Motor M01750 - 1 Phase, 7.5 HP, 184T Frame, ODP, 3600 RPM, 208-230 Volts, 60 Hz, General Purpose
Leeson 131616.00 AC Electric Motor M01746 - 1 Phase, 5 HP, 184T Frame, ODP, 3600 RPM, 208-230 Volts, 60 Hz, General Purpose

I have access to a lot of Leeson motors, so if anyone has a better recommendation on another Leeson motor let me know.

 

[blades]

ODP= open drip proof. Personally I would want a TEFC unit. ( Totally Enclosed Fan Cooled)
Couple reasons, if a hose or fitting lets go and sprays hydro fluid, dust and dirt and wood chips. None of this is kind to the internals of an electric motor. I have a small machine shop every motor in here is tefc. I have replaced 2 motors and 2 rebuilt in 20 years, the replacements were do to over voltage ( way over) thanks to a screw up by the electric power company ( by the way that also welded most of my circuit breakers into a non-functional state) That whole scenario is another story. The rebuilds because the mounting ( frames) were unique and no longer available in an off the shelf supply ( any time a mfg says its SPECIAL, hold on to your wallet very very tightly cause its going to hurt big time).

Also I would go with a known US mfg on the pump, then you know repair is possible, same with your valves. That way it only hurts the first time. ( 45 years of repair experience speaking) Chris

 

[triptester]

When looking for an electric motor consider a C-face type this will for a direct pump mount the same as used with a horizontal shaft gas engine.

http://www.electricmotorwarehouse.com/single_phs_cface_wbase_TEFC.htm

http://www.vescor.com/pma_df125.htm

 

[cstamm81]

I agree with the TEFC motor recommendation, and will try to find that type. Of course it is quite a bit mor expensive than the ODP's. I too had thought C-face would give me more options to mount, so I would want c-face and also base mount. Going to that style of motor also cranks up the price again. So, my dream of getting a motor in the 400 dollar range new is out the window if I want TEFC and C-face.

 

[pdhowell]

Here again, everybody on this thread is way ahead of me, but having an electric splitter for several years, and not going back to a gas one, let me share some thoughts.

I have discovered that it is worthwhile siting your motor where wayward splits or even rounds do not fall on it. I have a very dented starting capacitor cover.

You will need a TEFC motor because splitting seems to produce a lot of small trash that gets into the motor frame. You will want the capacitor start motor because you are always starting the motor against the drag of a hydraulic pump and the oil. Automatic transmission oil worked for me, when hydraulic oil was too heavy in the colder weather. Look for an overheat cutout since these motors can run hot under load.

When you compare engines, look at torque, not just amp draw. What drove me to a 1750 rpm motor was that the torque was twice that of the 3450 rpm motor. Unless you are running some huge stuff with four way wedges, I can't see the value of 5 horse, 3450 rpm motor, although I can see the argument of using a larger pump.

Compare the torque of gas engines of gas splitters that do what you want to do, to see how much you need. An electric motor sucks up more amps to create the torque you need to turn the pump under heavier load. It does not slow down, until it stalls and overheats. The pump relief/bypass valve should cut in way before the motor hits the stall. If the motor stalls the overheating is damaging.

Maybe helpful, Dave

 

[WV Mountaineer]

Hats off to attempt to make such a product on your own. A solid working final result would make me feel good about myself.

I have a degree in EE and was watching this thread hoping to keep that to myself, but I wanted to point out a few factors that I haven't seen anyone mention. Please take this with a grain of salt as I don't want to provide any direct advice. For me to do that it would require spending considerable time doing the math to make sure it was engineered correctly.

There is a big difference in Horsepower for gas engines and Horsepower for electrical motors. For instance, in electrical power, 1 hp = 746 watts. Please note we are talking about output there and not input. Motor efficiency will affect your electric bill considerably. 5 hp would be 3730 watts and would need to run on 220v to keep the current draw low. Just make sure to account for the efficiency of the motor before calculating the breaker size.

The general MECHANICAL formula is HP = (Torque x RPM)/5252. So for a 5hp 3450RPM motor, you will get about 7.6 ft lbs of torque. A 5hp 1740RPM motor will result in 15.1 ft lbs of torque. Torque is the actual twisting force and what you should be using to calculate the proper motor size for the pump, not hp.


Electrical motors are much higher in torque than gas engines of relative hp. A 5hp motor is massive, usually about 100lbs. I think it is going to be much more than what you will need but again, take that with a grain of salt because I'm not doing the numbers and don't want you to be upset with me if your end product doesn't split like you wanted it to.

I would copy a gas powered design that you like and simply calculate the torque the gas engine makes and substitute it with a comparable low RPM motor.

EDIT: Of course pdhowell chimes in right before I submit my post. I think we are saying the same thing in different ways.

 

[blades]

Good notes Dave, 1750 vs 3450, But that also depends on the windings. I have a 1.5hp motor about 6" dia od. I also have a 1.5hp motor about 14" od both are 3450 rpm, torque on the 14" is around 3 times the 6". Pumps are generally rated at the higher rpm for max flow. His original statement was quick cycle times, cutting the rpm cuts the flow rate so now 22gpm pump is closer to 13gpm. Cycle time is a function of flow rate, possible to over come that by using all 1" lines and ports or larger. Reality is what is ready made off the shelf vs custom ( see my note a few post back about custom/special).
I would say get specs together you are trying to achieve, then talk to Haldex or Barnes ( pump mfg) and get their take on electric motor sizing. Heck all we are doing here is conjecturing anyway and for them it is bread and butter. My $0.02 of highly devalued currency worth. Chris

 

[cstamm81]

I thought I had decided upon the motor RPM, but you both bring up interesting points on torque output using a lesser RPM motor. I had located and was really leaning towards this motor, but now I have to rethink it again. WEG 00736ES1E213T AC Electric Motor M00267 - Single Phase, 7.5 HP, 213T Frame, 3600 RPM, TEFC, 208-230/460 Volts, 60 Hz, General Purpose
So what I am gathering is the 1725RPM motor would allow me to use a smaller HP rating than a 3600RPM motor, as it has increased torque. But, I will never get the GPM flow as advertised if I step down to a 1725RPM motor.

 

[cstamm81]

Oh, and I am considering installing a variable frequency drive as well. If I do that I will be able to slow down the motor that way, set accel and decel rates, and use it as an overload vs my breaker. Really trying to nail down the motor I want to go with soon so I can get that ordered. The other components will have to wait. I will try to call some pump mfg's today.

 

[blades]

With using a properly sized VFD you could now use a 220v 3 phase motor. The vfd can take 220v single phase input and output 3 phase with very little loss. Advantage 3 ph motors cost quite a bit less for the desired hp/ torque range and amperage requirements are about 1/2 that of a comparable single phase motor. you will still have to account for line loss in your amperage needs calculation as well as sizing the the power leads appropriately for the distance intended.

This done quite a bit( single -VFD-3 phase) in shops where 3 ph is not available, much cheaper option than the $2-5K the power co wants to run a 3 ph line if available in the immediate vicinity.

 

[cstamm81]

Very good point on using a vfd as a phase converter. Question, do most vfd's have this ability or will it specify 230v single phase input to 230v 3 phase output ?

 

[pdhowell]

Thanks to all the people here, because I love the discussion of electric motors on splitters. The one item not yet discussed is the value of using higher pressure related components, on a smaller ram to produce the same splitting force as a manufactured splitter.


Ie, you are building a high pressure, lower volume splitter as opposed to a low pressure, high volume splitter.

To explain, without insulting hopefully, it seemed easier to build a high pressure splitter using components,( valve, pump, hoses), all rated 3000 psi or above, so that the ram diameter could be less, and the volume of the pump was less a factor. Less flow should be less friction, which is less heating of the oil.

You rarely need all the splitting power, and when you do, the squealing valve causes you to back off the high pressure immediately.

It appears to me that the manufactured splitters are now using a valve set to bypass at 2000 psi, as opposed to the 2250 psi of a couple of years ago. A valve which handles 3000 psi allowed me to use a 3.5 inch ram, instead of a four inch ram and get the same (actually a little higher) splitting force as a four inch ram with a 2000 psi valve.

Using an 18 inch ram, instead of a 24 inch long ram, (I only can use 18 long inch wood), further decreased the cycle time.

This entire package, running 3000 psi with a smaller ram, on a 10 gauge 30 amp circuit, on a reinforced box beam, can run in my shed or garage. It is much smaller than an I (or H) beam with four inches, 24 inch ram. The smaller size, no gas, no oil, less noise, being able to run off a generator set in the back of a pickup when out in the woods, and having equivalent or slightly greater splitting force, works better than a bigger electric or a gas splitter for my purposes.

Others will have different circumstances and come to different conclusions.

Enjoying this discussion, Dave

 

[blades]

They have been setting the reliefs lower to get less complaints about bending and twisting components. Let's face facts in that no one ever ( tongue in cheek) puts a 20" round of twisted up elm, or your choice, in a commercially made vertical/horizontal hydro splitter that clearly states in its manual 8" is max diameter round. Come on now everybody fess up.

So here I go: 30t HF splitter v/h , before rebuild bent foot plate, and beam, trashed stripper,
had the rear cylinder mount disengage itself from beam & last but not least bent the beam flanges. pretty much covers just about everything, never bent the ram though. 12 years later and rebuild. Same pump same cylinder same briggs motor new valve ( plumb wore out the chi com one)

 

[cstamm81]

ouch, a VFD for a 5HP or 7.5HP motor is going to be some $$$!

 

[cstamm81]

I actually snagged a 7.5HP 3 phase 3600RPM about 20 FLA TEFC Dayton motor today at the industrial salvage yard for a little over 100 bucks. If it has issues I get my money back. Need to wire it at work and amp out all the legs, make sure it seems healthy. If I wind up using this motor I will either need a phase converter or more preferably a single phase to 3 phase VFD. Quite spendy new though! Also found a 10HP 3 phase for like 50 bucks, not sure on the RPM though.

Big question is, can this 7.5HP motor run the 22GPM MTE pump properly? I never got a chance to call the pump company.

 

[cstamm81]

so it looks like if I use a phase converting VFD, I would actually need one rated for 15 output HP as the output gets cut in half when there is a single phase input. Does that sound right? Lol, I may have been hasty in this three phase motor buy, the cost of the VFD may have gone way up again if I need a 15HP rated one.

 

[nathon918]

i was wondering if you had even looked at VFD's before, when you mentioned you wanted one, but you didnt want to spend more than 400 for a motor...your project isnt going to be cheap..
i dont know if you have a motor repair shop around, but id check if you do, they might have a rebuilt motor for less than a new one

 

[cstamm81]

Yes the vfd price was a shocker. As for the motor, that's a good idea and there are a few rebuild shops near me. As long as the 7.5hp motor I got today tests well, I will move on to sourcing a pump, trying to source an affordable vfd, and start collecting metal for the build.

 

[cstamm81]

cheapest phase converting 15hp VFD I have found thus far:
MA7200-2015-N1

 

[Hddnis]

The output doesn't get cut in half for all VFDs when going single to three phase. Some are rated for single phase input and then it will translate watt for watt to the three phase side. Drives vary, so finding the right one will be key, getting the cheapest may not be the best way.


Here is a link to a thread, have a look at post #4 for some basic guidelines.

VFD question(s)




Mr. HE