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Author Topic: Problem with blade vibration/wobble on a old circular sawmill  (Read 7739 times)

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Offline R Hulen

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I bought an old sawmill and rebuilt it on my property.  I thought all I had to do was simply assemble all the pieces but it has proven to be much more complex than that.

My current problem is a "scary" wobble in the blade when it is at its operating speed.  I just had the blade hammered to run at 600 rpm.   The engine (International U-6 power unit) provides 40 hp at 1400 rpms.   I run this through a 2.3 to 1 pulley system which gives me approximately 90 hp on the arbor.

I had read that the majority of saw problems are due directly or indirectly to the collar.  The collar is 5.5 in diameter and I am using a 40 blade.   I checked the collar with a dial indicator and showed a variation of .005 around the face of the collar as I rotated the arbor. 

Also, I put the dial indicator on the arbor mid shaft and measured a .010 variation on a full rotation of the shaft.  The shaft is a 1 diameter shaft which may be a little small for the 90 hp.  I stalled the saw a couple of times during its initial set up and could have possibly damaged the arbor.     

Can these slight variations be the cause of the wobble in the blade?  If so, can the arbor be straightened or will I need to replace it?  If not, what other causes are there for the blade wobble.

Offline bandmiller2

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Re: Problem with blade vibration/wobble on a old circular sawmill
« Reply #1 on: June 28, 2012, 09:28:38 PM »
It sounds like a Belsaw mill,40" saw and 1 3/4" arbor.I would suspect the bearings can you feel any play.We really need more information,sometimes an unballanced pulley or even belts that have taken a set will cause a wobble and vibration. Oh and welcome to the forum.Tell us more,where are you located. Frank C.
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Offline ALWOL

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Re: Problem with blade vibration/wobble on a old circular sawmill
« Reply #2 on: June 28, 2012, 09:44:02 PM »
 Welcome!
    I know what you mean about setting up a mill being a bit more complex than just assembling the pieces! I have fixed up a few old mills for myself, and some for customers, and it is never quick or easy.
   The 2.3 to 1 reduction will not get you any more hp to the mandrel, but it does raise the torque level. 40 hp is 40 hp, no matter what the speed.
   As for the blade wobble, the .005 runout on the collar is a little excessive. To eliminate some of the runout, try clamping a couple of layers of card stock under each collar and then run the saw up to speed. If the wobble is not as bad, the collars should be machined.
   Also, try measuring the mandrel runout at numerous locations along the shaft, to see if it is really bent. If it is bent, the best course of action is to replace it. 1 3/4 inch sounds really small, even for a 40" saw, but that is about the size of a bellsaws mandrel.
   Good luck, and maybe some pros will come along soon with more advice.

      Alan
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Offline Ron Wenrich

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Re: Problem with blade vibration/wobble on a old circular sawmill
« Reply #3 on: June 29, 2012, 05:19:12 AM »
Wobble is either in the saw, arbor or collars.  ALWOL covered it pretty well.  I assume you're talking about the wobble when the saw is running up to speed.  Are you sure your saw guides are set right?  Sometimes you can lessen the wobble with guides, and sometimes you can't. 

I've used paper shims on collars on small mills.  On the bigger mills, we have the collars turned.  When you spin your saw, you should be getting some sort of wobble that you can measure at the guides.  Get to where the saw is at a midpoint between the guides.  Take it off and remount at 180.  If the saw is still at midpoint, its not in the saw.

Using the same procedure, go tooth by tooth past the guides.  As the saw starts to go off center, mark the tooth with a *,o, or - to give the direction its off.   o would be in the center.  The more its off, add extra + of - signs.  You'll find your high spots on the collars.  Shim with paper.  I used this method 30 years ago on an old handmill, but I can't remember which way I put the shim.  Experiment around to find if its the problem.  Not a great fix, but might help you trouble shoot.

One other thing to make sure of is that both the collars are the same size.   
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Offline Sawing 4 fun

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Re: Problem with blade vibration/wobble on a old circular sawmill
« Reply #4 on: June 30, 2012, 12:29:13 AM »
I have learned that if you have your mill in full sun and your blade is allowed to heat up from the hot sun warming one side of the blade it will wobble and shake. Always keep your blade covered from the sun so the tempturature stays even all the way around the blade. It made a big
difference for me. Just something to keep in the back of your head if you are sawing in full sun.
Gordon
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with 01 Frick
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Offline captain_crunch

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Re: Problem with blade vibration/wobble on a old circular sawmill
« Reply #5 on: June 30, 2012, 01:50:16 AM »
Not up on my math as far as pully dia ratio but 40 diesel hp is enough I kinda wondered ifn you got proper rpm at arbor My Belsaw will scare you with blade wobble at under speed or over speed. Mine is hammered for 540 rpm which is pto rpm
Just played with calculator 1400 devided by 2.3 comes to 608 rpm correct me if I am wrong but that is might slow for blade hammered fer 700 and if still on track 2 to 1 would cut hp in half
M-14 Belsaw circle mill,HD-11 Log Loader,TD-14 Crawler,TD-9 Crawler and Ford 2910 Loader Tractor

Offline ALWOL

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Re: Problem with blade vibration/wobble on a old circular sawmill
« Reply #6 on: June 30, 2012, 08:11:41 AM »
   You are right, 608 is to slow for a saw hammered for 700 rpm, but I think he said it was hammered for 600.
   I don't know a lot about IHC products, but I am thinking that a U-6 engine is the same as the Farmall M tractor. It is gasoline, and correct at about 40hp. This means that it is 40hp. Reducing or multiplying the speed to the mandrel has no affect on the end horsepower at the mandrel.

       Alan
There's a big difference between staying busy and making money.

Offline lyle niemi

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Re: Problem with blade vibration/wobble on a old circular sawmill
« Reply #7 on: June 30, 2012, 08:34:23 AM »
Welcome to the site! I set up a mill this winter and the fellas on here were a big help to get all the bugs out of my mill. I thought it was going to be alot easier then it was. I can honestly say I had alot of fustrating moments...lol
Lyle

Offline steamsawyer

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Re: Problem with blade vibration/wobble on a old circular sawmill
« Reply #8 on: June 30, 2012, 12:46:30 PM »
 R Hulen

It sounds to me like it may be a speed thing. Try starting out at a moderate rpm below hammered speed, maybe 450, and gradually speed up to an rpm that is well above the hammered speed. See if it flattens out at any speed, if does then there you have it. As long as  the engine is not running beyond its rated speed you are ok. You will need to set your governor just a little faster to allow for rpm loss when you are in the cut.

Alan... #2
J. A. Vance circular sawmill, 52" blade, powered by a 70 HP 9 1/2 x 10 James Leffel portable steam engine.

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Offline bandmiller2

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Re: Problem with blade vibration/wobble on a old circular sawmill
« Reply #9 on: June 30, 2012, 09:05:04 PM »
Circular mills are a paridox everything looks so heavy and rugged,but their very fussy about alignment,and heat.Foundations must be rock solid,any movement can cause the saw to wobble.Some saw seem to wobble a little but straighten up when their in the cut. Frank C.
A man armed with common sense is packing a big piece

Offline R Hulen

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Re: Problem with blade vibration/wobble on a old circular sawmill
« Reply #10 on: July 01, 2012, 10:21:49 PM »
I have not checked back for a couple of days.  I am amazed at the number of reponses there are to my post.   I have been working on this for many month and thought I had tried everything imaginable but there were many items brought up here that I had not thought of.   

I use a hand held electronic tach and I take the measurement directly off the arbor so I know my speed is pretty close to the 600 rpms.   

The foundation is on 6" concrete slab.  I have elevated the track and husk frame approximately 2' above grade using 6"X6"X3/8" angle. I am sure the mounting is rigid.

I have engine and husk frame completely covered in such a manner that the sun never hits the blade.

I am going to try shem the collar in a manner that will compensate for the .005".   I had already tried using a shem but I did not know about the .005" at that time and I used the shem, at that time, only to assure the collar tightened on it's outer perimeter.  I mentioned below that it is a 5.5" collar. 

I will check the arbor pulley to see if there is a balance problem.  It is possible that vibrations are being transmitted through the belts/pulleys from the engine.

My mill is located in NC, in the piedmont region about 40 miles east of Charlotte.  I will post pictures as soon as I figure out how.  All the castings are identical to a Frick but it doesn't have a manufacturer identified anywhere.

Thanks to everyone for your help.  I will get back and post the results as soon as I have done the above.  It is going to take several day to work through this plus it was 103 degrees today so I probably will not be working on it except the early morning.

Offline Ron Wenrich

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Re: Problem with blade vibration/wobble on a old circular sawmill
« Reply #11 on: July 02, 2012, 05:15:16 AM »
How do you tighten your saw?  If you put the nut on too tight, you can collapse your collars.  I put mine on by kicking onto the saw wrench a couple of times. 
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Offline dblair

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Re: Problem with blade vibration/wobble on a old circular sawmill
« Reply #12 on: July 02, 2012, 10:07:34 PM »
you can machine the collar on the mandrel on the husk , by setting up a cross slide on the track using timbers to get the height . any questions , ask . Oh , welcome to the forum it's the best .
old Appomattox Iron Works circle mill.

Offline sigidi

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Re: Problem with blade vibration/wobble on a old circular sawmill
« Reply #13 on: July 03, 2012, 07:41:48 AM »
I know its not addressing your current issue directly, but you need to run the saw over revs when its spinning free, so that under load it willbe at 600rpm, if you dont then you'll find the rpm will die when in the cut and you'll get even worse wobble.I know its not the same thing but may as well address it now rather than later.
Always willing to help - Allan

Offline bandmiller2

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Re: Problem with blade vibration/wobble on a old circular sawmill
« Reply #14 on: July 03, 2012, 07:46:09 AM »
Before I did too much I'd grab the arbor and feel for play,could be in the bearings or how their mounted.Are the bearings antifriction [ball,roller] or babbit.?also endplay enteres the picture.If theirs play in the shaft and collars everything else is for not. Frank C.
A man armed with common sense is packing a big piece


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