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Head saw

Started by JBS 181, March 23, 2009, 01:51:25 PM

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JBS 181

                     Trying to cut some costs at my sawmill. I have a 48" head saw that I make everythig into cants and then run them through a band mill. The head saw has a 60 hp electric hooked to it. Will it run on say a 40 hp. Would like some input on what others run on their head saws even if it is diesel or such. Thank you

Chico

It may work if you back off on the feed and don't mind losing the prod. I'd think it's a trade off .If  you're using 3ph the extra amperage (demand) you use may cost as much according to when you use it . If you're on 3PH you might find out when peak demand hrs are and don't start and run your mill then and keep it running as much as poss Starting a motor cost a good bit more than running it. Also if you run a chipper debarker etc stagger the times you start them this will also decrease demand. Also if you run a debarker and are able to run it in sat.  and peel as many logs as you can and only crank it if you need more but do it after peak hrs in the evening or before in the morning JMO
Chico
My Daughter My sailor MY HERO God Bless all the men and Women fighting for us today If you see one stop and thank them

Jeff

I can't imagine that trade off from 60 to 40 electric would save you anything if you relate the lost power to lost production and higher work load. You might actually save more by going to a higher horsepower.
Just call me the midget doctor.
Forestry Forum Founder and Chief Cook and Bottle Washer.

Commercial circle sawmill sawyer in a past life for 25yrs.
Ezekiel 22:30

Chico

I agree Jeff I think a 100 is about the smallest I ever ran on a circle mill mostly 150 though A lot of folks don't realize that loading the saw therefore increasing the amps (demand) is what costs
Chico
My Daughter My sailor MY HERO God Bless all the men and Women fighting for us today If you see one stop and thank them

Ron Wenrich

Rule of thumb on motor for circle saws is 5 hp/1" of stock.  You're underpowered with the 60 hp motor.  If you're cutting 8" log, you will be OK.  I'm running a 125 hp motor with a 54" saw. 

If you're looking to decrease your cost, than you actually should be increasing your production.  I've always used the following equation for everything in the business:

Profit = sales price - resource price - production costs.

All figures should be in a per Mbf form.  Since your sales and resource prices are the same in comparing both scenarios, you have to figure out your savings in production costs.  But, they have to be in a per Mbf format. 

So, your hourly costs have to be divided by your hourly production to compare the costs.

Cost/Mbf = (Cost/Hr)/(Mbf/Hr)

I think you're jumping over dollars to save dimes. 
Never under estimate the power of stupid people in large groups.

MaddiesDad

That can't be a good idea.  The smallest I've seen was a 75 HP on a friends mill.  It worked oddly.  Most of the mills I've seen are 125-150 HP. 
There's also some school of thought that you'd pull more current and have more draw since you're pulling harder. 
Oddly I did see a friends mill over in Northern MO with a 300 HP motor on a 60" saw.  I've got no clue why.

JBS 181

               I guess I should have explained myself better. It looks like most of my responses have come from people in hardwood country. I live in Wyoming and cutting strictly pine there is no hardwood here. Also have to remember I am just making cants so I am just taking the edge off the log. The sixty has no problem. Just thought someone out there maybe doing something similar. The reason I am trying to downsize a bit is because I have a huge transformer setting outside my building and my rural electric supplier says I need to down size some motors in order to get to a smaller transformer and to get into a different price bracket. Maybe my supplier is feeding me a line. the two largest motors I have are the 60 and a 40 then drops down to a 15 and so forth. the only motors running at the same time are the 60 and the 15 along with a 5hp. This transformer I am told is probably a 150 or 175 kva transformer. I think some of these outfits realize when they have a customer that doesnt know anything about electricity.

Jeff

Could be thats what he was able to scrounge when putting things together, or he was runnig his Hydraulics with it as well.  The cmc I ran had a 150 for the headsaw. We ran 56" saw primarily. The Forestall and Morbark before that had 100s as did the Renco.  The Renco's motor also turned the Hydraulics which was not a good situation. I like a dedicated motor for the head rig. Use a separate motor for running Hydraulics.   The CMC had the 150 for the headsaw, 75 on the vertical edger and 75 on Hydraulics for a total of 300.
Just call me the midget doctor.
Forestry Forum Founder and Chief Cook and Bottle Washer.

Commercial circle sawmill sawyer in a past life for 25yrs.
Ezekiel 22:30

JBS 181

    Let me ask you this? How much are your electric bills running per month on some of your setups. Iam green to this and my efficency will probably come with time. Maybe I just think I am using alot. My bill runs $1000 plus per month. Big motors are running 4to5 hrs per day if that.

bandmiller2

JBS,you have a 40 hp motor try it, pine logs that aren't too large just slabbing it might be ok.Possibly droping to a smaller headsaw, narrow kerf.But as the big dogs say you will loose some production.Frank C.
A man armed with common sense is packing a big piece

Ron Wenrich

Some electric companies have a minimum.  You pay $1000/month whether you use it or not.  Then, there are charges above and beyond that.

When we went over to electric, we had the electric company run some costs for us.  We figured it to be cheaper to put in a genset.  In a couple of years, they're going to take off deregulation, and those electric bills will get even more expensive in out state.  They're talking about a 35-50% increase.  Even when diesel went up in price, our costs were competitive.

I'm in hardwood country, but I cut a bunch of tulip poplar, which is pretty soft.  Jeff was a sawyer in Michigan and did a lot of aspen.  Are you doing much of the bug killed stuff?  That's probably harder than some of our soft hardwoods.

The problems I am hearing is that you have a limited amount of expansion that you can do.  Electricity is too expensive for your operations.  Unfortunately, efficiency usually increases with more energy input.  Hydraulics are a big boost if you don't have it. 

We're running 125 hp on the head saw, 75 hp on the chipper, 75 hp on the hydraulics, 60 hp on the vertical edger, 50 hp on the horizontal edger, 20 hp on the shaker table, 10 hp on the blower, and 10 hp on the green chain.  We also run a few lights.  The debarker has a diesel power unit.  We're running a 300 kw genset, and we're maxed out.  Fuel consumption is in the 8 gal/hr range when we're producing.  Production is about 1.3-1.5 mbf/hr.  I've been higher, but a lot depends on the logs.

For all you're running, a small genset may be a better investment than a smaller motor. 
Never under estimate the power of stupid people in large groups.

JBS 181

   Who makes a good genset?

Meadows Miller

Gday

And Welcome to the forum JBS pull up a pack anytime Mate  ;) ;D ;D 8) 8)

The other Blokes have Said it how i would have mate  ;) with the horse power just stick with the 60hp motor if it doing a good job for you  ;) My grand fathers mill had a 100hp on the carriage and a 75 hp on the 6 saw 4x36 edger  and they where working hard sometimes  ;) :D  Cummings Onan gensetts are a good choise i know of afew blokes running their mills overhere with them  but they arnt cheap here  ;) :D

Reguards Chris
4TH Generation Timbergetter

Ron Wenrich

I would guess that any genset that is large enough to suit your purposes is a good genset.  They run different types of diesels, and some run on natural gas.  Look for used ones.  Much cheaper than new.
Never under estimate the power of stupid people in large groups.

sparky

The question was raised of switching from a 60 HP motor to a 40 HP motor to save on your electric bill. I am a retired electrical engineer and served on our company's energy committee for many years. I did a lot of analysis of electric motor applications. I found that a 60 HP motor doing the work of a 40 HP will use almost the same energy as a 40 HP motor. There would be little, if any, savings in a typical application. I have some reference books that I could quote from, but they are buried in my old files.

The efficiency of a typical electric motor is quite flat from full load down to about 1/2 load. Below that, the efficeincy falls off and the power factor drops off as well. You will need to know what amperage the 60 HP motor is drawing in typical sawing operations. Full load amps for a 60 HP at 230 volts is about 146 amps as I recall. A 40 HP motor will draw about 90 amps at full load. I would suggest taking a reading with an Amprobe to determine what your motor is drawing in normal use. I would also like to see a copy of your utility bill to see what billing structure you have. You may be paying demand charges and possibly paying a power factor penalty.

Is your 60 HP motor reasonably new? The newer motors have much better efficiencies than the old "U-frame" motors that were built when electricity was "penny cheap". The purchase price of a new replacement motor would be hard to justify if you are only running 4-5 hours a day. I bought a used, energy efficient, 50 HP motor at an auction last year for $54 with an adjustable motor base. A replacement might be justified if the price is right!

Someone suggested looking at your electric utility's rate structure options and consider shifting high energy demand work to an off-peak time to work under a cheaper rate, if available. That is a very desirable way to reduce costs if it is practical for your operation. Do you have a dedicated power meter for you mill? If so, you could experiment with different production rates to see what you kilowatt hour consumption might be under different situations.

Will (Sparky)
I'tnl 2050 with Prentrice 110, Custom built 48" left-hand circular and 52" Bellsaw right-hand circular mills, Jonsered 2171, Stihl 084, and too many other chainsaws. John Deere 3020 and Oliver 1800 with FELs. 20" 4-sided planer and misc.

JBS 181

                 Thanks for the input. Sparky, The 60 is an older model, I dont know how old but older. Someone suggested maybe putting in a Variable frequency drive. Looking on the internet I see they are pricey but what isnt nowadays. Have you messed with theses much?

Meadows Miller

Gday

Jbs ive used older style VFD's in the past and they make a difference i reckon  ;) just kick er in the guts then winderup it uses a lot less power to get the motor up to speed and ifn you have a saw thats playing up you can just tune it in till it stands up for you  ;) ;D 8) 8)

Chris
4TH Generation Timbergetter

StorminN

Like Sparky and others said, the first step is figuring out how you are billed... at our factory, we're billed for kWh + a power factor penalty, + a peak demand usage, 15 minute period. On the demand usage, that means if someone comes in and switches on all the big loads... three 40hp motors, a couple of 20's, a slew of 10's and the resistive loads... a 200A 480V oven, and about 30 5kW heat blankets... if they switch these all on within the same 15 minute period, our demand rate is high and we are penalized (billed accordingly). If, however... they came in and staggered out the start times... like one big motor every 16 minutes, our demand would be low and our bill would be much lower.

You also mentioned something about your transformer size... does your utility charge a different rate per kWh based on the kVA size of your transformer, or is it a flat monthly rate for the transformer, or how is it structured? Talk to someone at the utility (if it's a PUD, they might have a "conservation" person on staff now, it's cheaper for them to teach conservation than to run new high power lines). It could be that if you really only run the 60hp, 15hp and 5hp at the same time, you could get away with a smaller transformer, but I'd doubt the utility would knowingly let you downsize the transformer and keep the same motors, in the event that someone accidentally turned everything on at once...

-Norm.
Happiness... is a sharp saw.

sparky

JBS,

Could you PM me a copy of a recent electric bill? I could give you a quick review of possible options if I saw what rate structure you are operating under. I have installed a lot of VFDs over the years. They were generally used more for speed control than for other reasons. They allow a "soft start" which means a much lower inrush current when firing up a large motor. They also hold a constant speed independent of the load on the motor. I intend to install one on my sawmill when I find one at a reasonable cost. (My 48" circular mill will be powered by a 50 HP motor.)

There is another feature of VFDs that I have used a number of times. Most VFDs can be used to operate a 3-phase motor from a single phase source. A VFD can operate from a single phase source if it is derated to 50% of it's rating. A friend ran a machine shop in his garage with 3-phase machine tools from a VFD that I loaned him.

Sparky
I'tnl 2050 with Prentrice 110, Custom built 48" left-hand circular and 52" Bellsaw right-hand circular mills, Jonsered 2171, Stihl 084, and too many other chainsaws. John Deere 3020 and Oliver 1800 with FELs. 20" 4-sided planer and misc.

JBS 181

      Sparky,
                Thanks for the information. I should be getting an electric bill the first of the month. I am not very computer savy. How do you want to look at it? It will be interesting to know how your Vfd works on your 50hp.

bandmiller2

Sparky,when you say VFD do you mean the system where a motor drives a generator with a reeves drive so you can vary the gen. RPM thus its frequency??JBS you could hook up an engine to the headsaw for intermitant use and leave everything else the same.Frank C.
A man armed with common sense is packing a big piece

sparky

Frank C.,

When I speak of a VFD, I am referring to a solid-state device that converts the normal 60 cycle (in the USA, and 50 cycle elsewhere) power to an adjustable frequency. These units have a rectifier section that converts AC to DC. That is followed by an inverter section, which converts the DC to an adjustable frequency AC. They are extremely reliable due to the development of advanced power semiconductors.

The typical VFD can provide an output with a frequency range of from 10 cycle to 90 cycle power. A VFD should not be operated below 20 cycles as the motor may overheat if operated for extended periods. The speed of an electrical motor is directly locked to the supply frequency. A typical 1750 RPM motor (in the USA) can be made to operate at speeds from 200 RPMs to a theoretical maximum of 2700. You MUST be very cautious when driving a motor beyond its nameplate RPM rating and consult with the motor manufacturer before doing so. Overdriving would be used at values close to the normal speed of the motor to provide better equipment performance, or to synchronize conveyors, etc.

I am very familiar with some of the motor/generator types of frequency changers, but they are quite inefficient and cumbersome. A typical VFD has an efficiency of 92%. A motor/generator's efficiency could be as low as 60% when considering the combined losses in the motor, generator, and drive. This would not be desireable when attampting to reduce electrical energy costs.

That is VFD 101 in a nutshell,
Sparky
I'tnl 2050 with Prentrice 110, Custom built 48" left-hand circular and 52" Bellsaw right-hand circular mills, Jonsered 2171, Stihl 084, and too many other chainsaws. John Deere 3020 and Oliver 1800 with FELs. 20" 4-sided planer and misc.

D._Frederick

Ron W,

You mention in reply 10 that your genset is maxed out. Does this mean that genset can not hold voltage or  does the electrical frequency fall?  How does sawing with a genset compare to sawing with direct diesel power?  If you did not have a cost factor, which type of power would you rather saw with?

Ron Wenrich

Maxed out means we shouldn't put on any more motors or we will have problems.  Right now, we can get into some problems when a big chunk goes through the chipper while I'm in the cut.  It all depends on how soon the genset recovers. 

We had some problems with a mechanical governor.  We now have an electric governor and that works a lot quicker.  So, we don't have any drawdown.  With the mechanical type, it wouldn't be uncommon to lose some RPMs when you started a cut in real hard wood.  I could work around that if I had to.

I don't notice too much of a difference between our electric and the diesel we had.  But, the diesel was dedicated solely to the head saw and it was a 6 cylinder.  I've sawed with some 4 cylinder diesels, and they just didn't seem to have the oomph.  Usually they were run at a lower RPM.

I've also watched guys saw that just love to stick the log into the saw at a high rate of speed.  Its not good technique, and it can get you into a bind.  I've also heard guys gnaw their way through a log instead of sawing it.  The saw continues to lose speed as they saw.

The electric is a lot more convenient, and we can run bigger hydraulics and other things that wouldn't be as convenient as with a diesel.  Our hydraulics are running about 125 gpm, and that takes a lot of power.  Those types of hydraulics can make sawing a whole lot easier.  I'm also running a much higher RPM on the saw. 

So, I guess it really depends on your set up and your sawing technique.  For what we're doing now, electric works better.
Never under estimate the power of stupid people in large groups.

bandmiller2

Sparky thanks never knew that existed.One more would it be practical if you needed 20 hp of motor to use two identical 10 hp motors start one then when up to speed switch on the outher to reduce starting amps??Never knew a man with boath right and left hand circular mill must be confusing.Frank C.
A man armed with common sense is packing a big piece

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