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Greg Faber
Greg Faber's picture
Band and travel speeds?

Question of the month: How many of you have measured your SFM of your blade and how many of you have measured your travel speed of your mill? Do you know what they are supposed to be? Do you have a way of telling when you are sawing?

JP
JP's picture

I purchased a rpm meter to see what was going on when the blade was slowing down// found the blade speed was in range as stated in the book/ I cant remember but think about 4300 fpm- I have timed the feed rate several times--by timing the cut in a 12' log--with sharp blade in a 8\" cut in nice Pine 55-65 fpm\n in a 10\" oak cut--about 20-25 fpm \n if anybody wants to use the rpm meter ill send it --email me JP

LM2000,23hp: NewHolland 30hp tractor/igland 3000winch: log arch. JP setcut dial.

whitey
whitey's picture

Nah if it sounds right I just wind it up and follow it when it get to the end I start over until I have a pile of lumber. :D :D Whitey

Greg Faber
Greg Faber's picture

Whitey, You may be doing better than JP. 4300 sfpm is too slow for most 1-1/4 band blades and his fpm through the log are astronomical!! You guys need to go to the Suffolk Machinery site and look at the engineering facts about blades. I follow them religiously and have since saved blades, sharpenings, money, time, and extra board feet, with minimum wear on my mill. Just do a search of Suffolk Machinery and you will find Timber Wolf stuff for sale but also a lot of great technical data. This technical data actually works! I don't work for them and I don't sell their stuff (I buy their blades) and I believe what they say.

Gregory Faber

Greg Faber
Greg Faber's picture

Maybe I am a assuming something here. Do you run a circular saw blade or a band mill JP?

Gregory Faber

JP
JP's picture

Someone ck my math but the 23hp Briggs runs I beleave at 3900rpm driving a 4.5\" clutch pully\n 3900x 3.14x4.5/12= 4592ft per min\n \n pushing throu a 12' long Pine making 2x6s takes 10-12 sec for the cut-- that = 60+ ft per min more or less/ JP

LM2000,23hp: NewHolland 30hp tractor/igland 3000winch: log arch. JP setcut dial.

JP
JP's picture

Robert corrected me on the clutch dia as being 4.25\" not 4.5 so the calc. fpm would be 4337 at 3900rpm --tomorow ill retime it if I can/ JP

LM2000,23hp: NewHolland 30hp tractor/igland 3000winch: log arch. JP setcut dial.

Greg Faber
Greg Faber's picture

I would really be interested in that jp. I am running a 16 hp and hope to run at 18 ft/min through an 8\" cant. If I can do that I will be very happy. I thought I read somewhere that a 23 hp Norwood can run around 22 ft/min with a 23 hp engine. Am I wrong? Good discussion this is. It takes the myth out of sawing toothpicks!!

Gregory Faber

JP
JP's picture

I tested the mill this afternoon with the following results:\n 23 hp Briggs engine rpm with throt. wired down ave = 3520 rpm\n \n clutch pulley dia. 5 1/4\" (not as stated before/ )\n \n rpm of 18 1/2\" driven pulley wheel 960 rpm\n \n ( 3.14 x 18.5\"/12 ) x 960 rpm=4640 ft per min on the blade\n \n calc. using the 5 1/4\" dia clutch pulley\n \n (3.14 x 5.25\"/12) x 3520 = 4835 ft per min.\n \n I do not know why these two dont agree more closely JP

LM2000,23hp: NewHolland 30hp tractor/igland 3000winch: log arch. JP setcut dial.

Bill
Bill's picture

JP using your speeds and diameters with my formula i came up with 4838.06 so you must be pretty close. btw i'm not to sure what my formula is :o )\n \n Bill

aquacanis
aquacanis's picture

Your pretty close to the exact formula my friend. I have 1-1/4\" band blades with a 7/8 pitch which are designed to run at 5400 sfpm. Run your unit so you get the sfpm that your blade calls for and you will have a very efficient machine. I like the Timberwolf formulas and data for what speed to run what blade. They seem to know what they are talking about.

aquacanis
aquacanis's picture

Look at things this way. At 18 feet per minute feed through the log (which Norwood recommends for a 16 hp motor) it will take you 30 seconds to make a pass through a nine foot log. I bet most of us are \"pushing\" our blades faster than that. If so is it a problem with blade life and blade breakage? I think it is. I am trying to run according to the advise of the experts.

JP
JP's picture

Here are a few more feed rates:\n \n 8' red Oak cut 2 yrs.\n \n 16\" wide cut 3 pc ave. 11.2 feet per min.\n \n 10\"-12\" cut 6 pc ave. 24.2 fpm\n \n 8\" cut 6 pc ave. 32 fpm\n \n frozen Hemlock 10' log\n \n 8\"-10\" cut 4 pc ave. 24 fpm\n \n 6\" cut 10 pc ave. 32 fpm\n \n These are stopwatch times trying to push at my normal pace. Some head shake on the Oak 16\" cuts. One cut time discarded when I stalled the blade/ JP

LM2000,23hp: NewHolland 30hp tractor/igland 3000winch: log arch. JP setcut dial.

whitey
whitey's picture

I don't see that in my operation that cutting speed makes much diffrence . the quality of the lumber is what I go by. If the band is sharp and motor running good it will cut good lumber some times you have to slow down for knots or turn the log . I go for the Quality rather than Quanity. Since I quit pushing hard i haven't broke a band ( 2yrs) some are on the 6th sharpening so it works for me \n \n happy holidays Whitey

JP
JP's picture

Note that the speeds shown are listed only for referance and are my \"normal\" speeds giving top quality product. the blade used in this has been sharpened more than 4 times and I have never broken a blade. JP :)

LM2000,23hp: NewHolland 30hp tractor/igland 3000winch: log arch. JP setcut dial.

aquacanis
aquacanis's picture

Hey JP, interesting stuff you are doing. I am shut down for the winter but will be doing some of the same tests and timing when I start up in May. Looking at your figures, i suspect you are really pushing your mill sometimes. The fastest feed rate I have seen printed for a 23 hp is 23 ft/min. As long as you are not breaking stuff I guess the 32 ft/min must be ok too. If you stalled the motor going that fast however, it tells you you are getting at your limits would you think?

aquacanis
aquacanis's picture

JP I see your calculations and I think you are doing the math correctly but I think you may be running your 7/8 pitch blade about 1000sfm\n too slow. Timber wolf recommends 5700sfm for their 1-1/4' -7/8p blade. Can you get to 5700 easily and try it? I have bought a new motor sheave and double belt for mine and will speed it up next spring and let you know what happens.

JP
JP's picture

wELL i HAVE ALWAYS FELT THAT THE bRIGGS SHOULD BE RUNNING FASTER // BUT i WOULD NEED TO GET FROM 3500 UP TO 4100RPM TO GET CLOSE TO 5700SFM --I DONT KNOW HOW TO DO THAT??\n \n YESTERDAY I WAS SPLITTING 200 YR OLD OAK BEAMS-DEAD DRY-RUNNING NO WATER-AFTER CUTTING 3-4 1/4\" NAILS PUSHING HARD AS H--L TO GET OUT SO TO CHANGE THE BLADE I COULD ACTULLY LUG DOWN THE MOTOR// NO SLIPPAGE AT ALL/// FIRST TIME FOR THAT// :eek: :eek:

LM2000,23hp: NewHolland 30hp tractor/igland 3000winch: log arch. JP setcut dial.

Dail
Dail's picture

I borrowed the local small engine guy's electronic tach back in the summer,my 23 Briggs was turning about 3250,he said that was the rated speed for that engine. Seems slow to me,but what do I know?

Robert in W. Mi.
Robert in W. Mi.'s picture

Dail\n \n Well, B&S says it's 23 @ 3,600!!\n \n Vanguard 23hp \n \n Robert

LM2000 with bed extensions, Vanguard 23, optional log post, log turner, hydraulic toe boards, cam dogs, stainless bunk covers, JPT setworks

marri
marri's picture

JP, can you increase the diamater of the clutch drive pully this would have the same efect as increasing RPM?\n John

aquacanis
aquacanis's picture

JP, What I am doing with my 16 hp Briggs and Stratton is putting a larger drive pulley on the motor side. My mill is homemade which I want to show you pictures of next spring. I am going from a 4.25\" double belt drive sheave to a 7\" (double belt) diameter drive sheave. This allows the engine to run at the desired 3200 rpm (as recommended by Briggs) and it gives me the 5700sfm of the blade that I am looking for. My engine governor never even kicks in as I now saw so I suppose the loss of torque with the bigger sheave will make the governor kick in once in a while but I am certain the 16hp should be up to the task. Is your drive sheave a clutch also (like in centrifugal) clutch?

aquacanis
aquacanis's picture

JP, Whatever Briggs and Stratton recommend the rpm of the 23 should be is where you want to run. I have not looked it up but John is correct when he says to run according to the Briggs and Stratton specs. Certainly a bigger drive sheave could be handled by the 23 hp motor. I am believing now that the extra torque needed will be less than the hp needed if running too slow a spm on the blade. It may actually take less torque if the blade is cutting at its peek efficiency. I'll let you all know how I make out in the Spring of 2006. Have a merry Christmas and a Happy New Year. \n \n Bruce K.

JP
JP's picture

Looks like most of us are dealing with the same problem-- thanks Robert for the printed spec. I am concerned about using a larger drive wheel since the blade rides on it and a 6 -1/4\" pully would hump the blade up about 1/2\"-dont know what this does to the system??-Ill talk agin with Norwood also. It would be nice to find a clutch designed for the 23 hp and about 6 to 6 1/2\" od. Im thinking that cutting at the full 5700 sfm would be somthing /// JP

LM2000,23hp: NewHolland 30hp tractor/igland 3000winch: log arch. JP setcut dial.

Robert in W. Mi.
Robert in W. Mi.'s picture

Quote:
This allows the engine to run at the desired 3200 rpm (as recommended by Briggs)
I've been around small B&S engines (and other brands) for many years, and i've yet to see a 16hp rated for 3,200 rpm's. If It is, then it's just derated from 3,600, and would have no problem running at 3,600 for the short time a sawmill saws.\n \n All of these engines are rated with there MAX hp at 3,600 rpm's and then as you slow them down there hp also goes down.\n \n My guess is,\"if\" your governor has never kicked in while your sawing, you need to get an more agressive band, or increase your feed speed.\n \n I can hear the governor kick in on my 23, so i know it will with a 16...\n \n Robert

LM2000 with bed extensions, Vanguard 23, optional log post, log turner, hydraulic toe boards, cam dogs, stainless bunk covers, JPT setworks

aquacanis
aquacanis's picture

Robert, I have no doubt that you are correct about the gov. should kick in. I am just getting into the true science of sawing and I know I will learn a lot. I am also engineering minded enough to understand the stats. 3600 is the design hp but 32 usually runs around 95% hp and that should be enough to saw most boards and let the governor kick in when needed. Am I correct?

marri
marri's picture

Just for interest the preformance chart of a Vangard 23hp\n John \n \n Vangard 23hp preformance chart.

marri
marri's picture

Robert, you a right that most small motors are rated at 3,600 rpm for maximun hp. In aquacanis's defence about 3200 rpm as it max hp he is not corect. However if the motor is put under a slight load I believe that the rpm would drop to 3000 to 3200 rpm because the maximum torque drops of dramaticalyafter about 3000 rpm.\n On the Vangard 23hp the maximum net BHP is only about 20.5bhp and the maximum net torque is only 30.3 ft-lbs at 3900 rpm, while the maximum torque of33.1 ft-lbs is achieved at 2600 to 2800 rpm. At 3200 rpm the torque has droped to 32.4 ft-lbs and the net bhp has droped to about 20 hp.\n With this in mind an engine speed 3200 rpm would be a better speed to caculate band blade speed.\n I don't know if this makes sence. :) \n John

Robert in W. Mi.
Robert in W. Mi.'s picture

I run my mill wide open when sawing, just like i did the last one. It's also the way i run everything else around here that's getting worked. That's what the goveror is for, to keep the engine from overspeeding and to add fuel under load.\n \n Yes the torque goes up when the motor slows down, but if you have a big enough motor in the first place, it won't slow down all that much.\n \n I already paid Norwood to work all this out for me, i'm \"not\" going to try to outsmart them now. My saw works just fine the way it's geared right now, so i won't be makeing any pully changes on mine. Installing an even bigger pully will only work the engine even harder, and slow it down even more when it's under a tough load.\n \n Also, the \"B\" belt that's on there now will easily hold the 23 hp my engine is rated for, so i don't see why it would need a double pully with two belts???\n \n Robert

LM2000 with bed extensions, Vanguard 23, optional log post, log turner, hydraulic toe boards, cam dogs, stainless bunk covers, JPT setworks

aquacanis
aquacanis's picture

Robert, I never run any piece of equipment wide open. Not my Kubota diesel tractor, my Ford 8N or my 16hp sawmill. I run my tractors at 3/4 throttle and my sawmill at around 3200. I know a lot of guys that have run their Kubotas wide open when mowing and they rebuild the engine every 8-10 years. Mine is a 1974 and still running strong. For me personably I just don't believe in running an engine at full throttle constantly. In a 6 hour sawing (don't forget, I am an old retired guy) I shut the engine off about two maybe three times. It is running at 3200 rpm the rest of the time. I think this is very easy on the engine. I thought the governor worked two ways on most engines. Doesn't it prevent overspeed as you say and also increase fuel intake upon sensing a heavy work load on the engine?

JEMoore
JEMoore's picture

I've been going to stay out of this because I thought you guys were getting way too technical for me. But I just gotta say I agree with Robert on this one, especially on the sawmill and lawnmower-type engines. I have also always ran this type engine \"wide open\", that is why you have the governor. The manuals say 3/4 to full throttle. I think the full throttle on the 20 Honda keeps it about 3/4 anyway. I know my riding mowers work much better at full throttle and I have never had an engine problem in .....well almost 40 years :) \n As Robert says the companies have already figured this out.......unless you guys just want to have fun calculating all these speeds :) Have a good one.......\n \n Jerry

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