Circle mill blade wobble

[ddcuning]

When we started up the mill and set the speed on the saw, we still had blade wobble. I sent both my 54", F and 2-1/2 style blades off to be hammered to 600rpm and they are supposed to be back this coming Thursday. Lesson I learned, send the shanks and bits with blades to be hammered. I didn't and had to wait a couple extra days to get the bits and shanks to them. Anyway, when I took the blade off the mill, it looked as thought I had wear on the mandrel surface that comes in contact with the blade. The tolerance is only 10 thousands so it needed to be checked. Thanks to scsmith for making the drive and checking out the mandrel. The mandrel was only 3 thousands out so well within tolerance. The "apparent" wear was some build up that came off with a wire brush and we noticed the surface where the dowel pins are installed was somewhat raised. I can sleep easier tonight thanks to Scott. I was not looking forward to removing the mandrel from the saw and having it machined. So, with that behind me, I can install the hammered blade with confidence that the mandrel is not going to cause a problem. I will need to set the lead once the blade is back on but I should then be ready to saw. I am going to harvest a tree from a friends place on Saturday morning to try out the mill provided we get the blade back on Thursday as scheduled.

Dave C

[Ron Wenrich]

Sometimes you need to get your collars turned.  Especially if someone has put on the saw nut too tight.  Collars can be turned on the mill.  The outside collar can be turned in a machine shop. 

Why did you take all your bits and shanks out?  You should have your saw hammered whenever you change your shanks.  You shouldn't be taking all your shanks out when you change your teeth. 

[bandmiller2]

Dave, every saw I've seen will wobble a little, even when their right.The proof is when they straighten right up in the cut. I'am not talking about a lot of wobble here but just dectable when up to speed. If their chattering in the guides they need work.A good way to check your foundation is to run up to speed and shuttle you carriage back and forth boath empty and loaded. Any weak spots and the saw will wobble as you go over it. Collars are not flat where they clamp the saw but should have a tapered outer band1/2"or so wide so only the outer part of the collar hits the saw. Last year I junked an old metal lathe, should have saved the compound rest cross feed,attach a small grinder to the tool post and used it to true up collars on the mill, next one I run across. Stan Lundstrom's pamplet gives the specs for collars. Frank C.

[ddcuning]

Ron, we took the bits and shanks out to remove the blade. I had just sharpened the carbide bits and didn't want to damage them when taking the blade off. Once I had the blade off, I called the saw shop to see if I needed to put the bits and shanks back in for hammering and was told no which was bad information. Lesson learned. Normally when I change teeth, I do only change one at a time. We did check the collars and they are not worn as I had thought.

Frank, before hammering the blade I had what I thought was excessive wobble after we made sure the speed was 600rpm. If I had to measure it, it looked like about 1/2 to 3/4". That seemed excessive to me and I would rather start out being hammered and know everything is correct anyway. Since I don't know these blades, who knows what they were hammered to in the past. Understand about the collars. Now that we know they are round and not warped, I am going to check the taper. It got dark on us last night and couldn't check them. From what I read, the collar should be tapered 0.002" to 0.003" to the inside.

Dave C

[bandmiller2]

Dave  seeing as you have never had the saws hammered your doing the right thing at least you can eliminate that for a variable.I believe the taper you read about is just on the outer raised ridge inside the collars.If I recall they tell you to rub chalk on the outer ridge and scrape a straight edge across.It should just scrape chalk on the outside of the ridge. Frank C.

[Ron Wenrich]

I've always used the chalk for collar, then put it on the saw to see if it leaves a continuous ring on the saw.  If there are gaps, then the collar isn't supporting the saw right.  I've also used paper shims to get rid of wobble.  I've never seen it recommended, and its an old sawmillers trick.

I had a saw doc that wondered how much worthwhile his work was.  He could hammer a saw to spec, but that didn't mean it would run on the mill.  He told me of a story where he sold a mill a new saw, and it would never work on that mill, no matter how many times it was hammered.  He sold it to another mill with no problem.  The original mill bought another saw and had no problems.  His theory is that a saw will settle in to where it runs as good as it can.  That doesn't mean it never needs hammered or that doesn't need to be tuned to its running speed.  It just means there are certain limitations to what hammering will correct.

[ddcuning]

Thanks for the tip guys, the use of chalk is a great idea. According to "Circular Sawmills and their efficient operation" both the mandrel and the collar are supposed to have the taper to them. My blades come back tomorrow so I will be checking the faces as soon as I can. At least I know they are not out of round. I had heard the tip about shimming them with paper. Thanks again.

Dave C

[ddcuning]

Wow! It has been almost a month now and my blades just came back on Thursday from being hammered. After the last post, I did go use the chalk as Ron suggested and it worked great! The result was that both the mandrel and the collar were flat. With a lot of patience and time, I was able to rig up a system were I ran the engine and slowly eased a stone against the mandrel and re-established the taper. I then turned the collar backwards, secured it with the nut and repeated the process. Both mandrel and collar are now tapered correctly.

As I said, tithe blades came back on Thursday. The report from the saw shop was that my F blade is in perfect shape, was bad out of tension but hammered out with no problems. No oversized shanks were needed. The 2-1/2 blade was a different story. It hammered out but about a third of the saw needed third and forth oversized shanks and it was a miss match all over. No consistency in the wear. He cautioned about using this blade for anything but softwood and only then as a spare. It also had some damage where some metal had bed hit. I am going to look at a replacement next week and maybe sell the 2-1/2 to some artist somewhere.

One thing the saw shop mentioned that I was curious if you guys had heard. My F blade has 52 or 54 teeth ( I can't remember exactly, too early this morning.). Due to the number of teeth the saw shop said the blade should only be used for softwood. He said I needed a blade with less teeth for hardwood or that I could alternate every other tooth on the saw between a worn tooth and a new tooth and it would saw fine in hardwood. He said alternating between new and worn would simulate a blade with less teeth. Makes sense, just wondered if anyone here had heard that before?

Dave C

[Ron Wenrich]

Alternating teeth is used often for guys that don't have enough power to pull all the teeth.  I've never used that method, since i have always had sufficient power.  Number patterned saws are normally for softwoods.  The lettered saws are for hardwood. 

I used to run F pattern saws.  They had more teeth, and in theory should cut faster.  But, I switched over to B pattern saws.  They have fewer teeth, but their gullets are 1½ times bigger.  That means I can put more sawdust in the gullets of a B over that of an F.  The B is also better for larger sized logs.  We run a higher average diameter log than many mills.  Small logs went to firewood. 

[bandmiller2]

Dave you have A 190 hp Cummins diesel you should have power to spare to pull that "F" pattern saw. It used to be quite common to alternate every other tooth when there were a lot of small handset mills and small power plants.A big reason Belsaws were/are so successful is the saw they supplied had fewer bits and could run with lighter power.If you going to run alternate bits be sure the fallow bit is short enough to not make a cut.A local business used to remill old used timbers the sawyer told me that he would leave the fallow bits very blunt said if he hits nails it limits the damage and the blunt bit punches out the metal,I'd take that with a grain of salt though. Frank C.

[ddcuning]

Frank, sorry should have also given you credit on the chalk idea. Thanks for the input.

I feel pretty confident with my engine pushing 190hp that I can muscle through what I throw up there. Maybe the guy at the saw shop would have altered his recommendation if he had known that info.

Thanks for the input. I am going to look at getting another blade so that I have a good spare. Two new boxes of 2-1/2 8/9 came with the mill but no blade that they fit. The 2-1/2 that I have is a 7. I am hoping the blade my friend has for sale is an 8/9 so I can use the boxes of bits I have.

Thanks again guys!

Dave C

[ddcuning]

Pouring rain yesterday in NC. Glad the mill is under the shed! I ran the blade up to speed and it looks great, very stable. I would say 90% of the wobble is gone now that it has been hammered. Last thing on my to do list was to check the lead. Come to find out, the back of the blade was 1/4" closer than the front! I set the lead to 1/32" (front closer than the back) and now it should be ready to run. I am going to gather some logs next week and see how it does. I am so anxious, I started looking around my yard wondering what I could cut to try out the mill with! It has taken some time to get all of the adjustments done but it should finally be 100% ready to saw.

Dave C

[beenthere]

Good that things are coming together for you.

What did you have to adjust to reset the lead and how much trouble was it?

[Ron Wenrich]

Setting lead is done by adjusting where the bearing sits in the holder.  It can be done at either end of the mandrel.  Some mills have more than 2 bearings, and those in the middle have to have the set bolts loosened up so there isn't any pressure there.  You also have to loosen the saw guides so there is no pressure on the saw. 

To check the lead, I always use the same tooth on the saw.  I check the distance from the tooth to the headblock at the guide end of the mill.  Then, I move the saw and the carriage to the splitter end of the mill and measure again.  If it's good, you can tighten everything up and saw.

1/32" of lead may be enough, or maybe not.  It's a good starting point. 

[ffpup]

My 00 Vance Mill requires 1/16 inch of lead or it wants to cover me up with dust on the return stroke, and that gets my Carhart toboggan all dirty >:( Then I get crossed up! Dave who hammers your blades?

[ddcuning]

Ron described it well. I have been told to always adjust the lead using the bearing at the saw mandrel and not on the sheave end so that is what I did. As Ron said, I marked a tooth on the front edge of the saw and measured to the face of the first ell. I then moved the carriage so that the first ell aligned with the back of the saw. I rotated the saw to the marked tooth then measured between the tooth and the first ell again. I loosened the jamb nuts on the adjusting bolts on the mandrel bearing and made adjustments until the back of the saw was 1/32" further away from the face of the ell than the front. The process took me about 20min since it is a repeat process until you get it right. I know this repeats Ron's instructions, but just stating what I did.

With regards to hammering, I sent the blades to Union Grove Saw & Knife in Union Grove N.C. They pick up and drop off in Siler City twice a week so it was easy the get the blades to them. Siler is only about 15 miles from my house.

Dave C

[Ron Wenrich]

I was also told to adjust from the front bearing.  But, with mills that have off bearing belts, the access to that bearing is limited.

[bandmiller2]

Seems every sawyer has his pet way to judge lead on his mill.I start with the mentioned 1/32 or a hair more.I cut a cant and see if the back of the saw just ticks the cant on gigback that means its right.If the back of the saw makes fairly constant contact on gigback I suspect not enough lead,and conversely if no contact probably too much lead.Anouther indication of too much lead is if the saw tends to pull the last board away from the last headblock.Once you find the right lead for your mill and saw measure it and wright it on the wall. Frank C.

[ddcuning]

Frank, I will check it and adjust as we get going. I plan to get some logs next week and get some sawdust made. I am taking two weeks off from work mostly to do some sawing. I am sure no one else in my company uses their vacation time that way!

Dave C

[ddcuning]

When the blades came back from hammering, they did say the shanks were loose in my 54" 2-1/2 blade so I found a replacement this week. Ended up buying a new in the crate 52" 2-1/2 x 7 blade and a 3x9 blade which I am not familiar with. The 3x9 has a lot fewer teeth in it than the 2-1/2 x 7. The 3x9 had one oversized shank in it but the 2-1/2 x 7 was all standard size and all tight. It had surface rust on it so it was hard to tell if it really was new but one swipe with some 200grit sandpaper and you could tell it had not been used before. It was still in the crate and had a packing list enclosed bag but the packing list had long ago been eaten by moths. This will be a good replacement for my other 2-1/2 which was worn out. The issue I have now is that I have a 54" 2-1/2 that is worn out and don't have a need for and I have a 48" F blade that has some damage that I don't need. I may just put them both on Ebay and see what they bring. The good news is that I should be set for many years of sawing with the two good blades that I have and we will see how the 3x9 works out.

Dave C

[bandmiller2]

Very good Dave its handy to have a spare or two. If you cut larger diameter logs you may want to use  the #3 saw as it has more gullet capacity. The 2 1/2 shank saws shine in smaller knotty type logs  due to the large number of teeth. I have three usable saws a 44" "B" pattern,50" "F" pattern and an old Diston 48" I have on the mill now. Myself I prefer the "B" pattern due to the larger gullets and the slower feed and power required, in other words this old codger doesn't things happening too fast. The Diston gullet is close to the B. With the different sized saws you will have to move the saw guide, I have several drilled and tapped holes, for when I switch saws. I'am sure you will have one saw you prefer, hopefully they will all prefer the same lead, If not be sure you wright it down on the shed wall to save time when you swap. Frank C.

[bandmiller2]

In buying used saws its important to be sure bits and shanks are available.You done good Dave as everything you bought has a supply line behind it.My old Diston is headed down a dead end road but I've got new bits and shanks and a spare set of bits so it can live for a wile.Its good form to keep a supply of bits and shanks for any saws you use. I have read, don't know how true it is, that The #3 pattern may be the next gonner, hope that's an idle rumor. Frank C.