Bandmill Blades Breaking

[HaroldCR - AKA Fla.-Deadheader]

I presume then that you finish the cut after you reinstalled the blade.

 Correct

[Tom the Sawyer]

My mill (Timberking B-20) has never thrown a belt.  Broken blades have gouged a chunk out a few times but I have never had to stop and replace a belt - just changed it later during my normal maintenance.  I never return the saw head with the blade in the previous cut, I raise it at leaset 1/2" above the top of the board and then bring it back.  The B-20 really flies coming (gigging) back.  I have knocked the blade off of the wheels, either by not raising it high enough before gigging back  , or by trying to back out of a cut for some reason (hitting a spot on the log too wide to pass without trimming, hitting something in the log) with the blade turning.  Knowing that, I normally will stop the blade engine, wedge the board up and then back it out. 

Having never thrown a belt is probably because the TK mills use a tight-fitting belt (B56 for the B-20).  Some other mills use a loose-fitting belt, like a B57.  I have heard they are much easier to change but sometimes get sawdust under the belt.  Tight-fitting belts can be a pain to change, even after watching the video.  The video shows them changing a belt while the wheel is off the mill, clamped in a vise.  I change mine on the mill.  It seems to take three hands but a couple of small C-clamps and two old screwdrivers get it done for me. 

I accidentally ordered the wrong belts the last time.  I ordered BX56 instead of B56.  The "X" denotes a cogged belt but I decided to try them.  They have been working fine and, they were significantly easier to install.  I normally get about 75 hours on a set of belts.  I think they have been on there at least that long.

FYI, I run about 1/4" in front of the flanges on the guide wheels with 1/4" below tangent.  I am running the updated guide wheels from TK that have a grease zerk built in.  This is an improvement that TK came up with, years after my mill model went out of production.   

[bandmiller2]

I too run tight belts, and believe they are less prone to damage. Some like flat top, myself I like a slight crown, they seem to work ether way. Putting the belts in hot water and using soap helps as does a couple of old butter knives. Its the same as mounting a tight tire on a rim. Frank C.

[Stevem]

The video shows them changing a belt while the wheel is off the mill, clamped in a vise.  I change mine on the mill.  It seems to take three hands but a couple of small C-clamps and two old screwdrivers get it done for me. 

I too looked at the TK video on belt changing and am prone to try and change the belts on the mill (when I get the mill and when a belt needs changed).
Was questioning why they didn't use soapy water to help ease the belt on.  Used all the time in changing tires!

And if you take the wheel off, to put it back on you are supposed to use a torque wrench to get the proper tightness.  Another tool to lug around!

Looks like I'm going to have to buy a whole set of tools for the TK .  The Lucas came with most every tool I need.

[furu]

Any decision on delivery?

[Tom the Sawyer]

Stevem,

Your mill will be much easier to work on, with the swing away doors and nothing in front of the wheels.  My B-20 has a 2x2 vertical post in front of the wheel.  For me, it was much easier than taking the wheels off.  I have tried the hot water method but the stove is about 200' from the mill.     I do use soap to lubricate the belt but the cogged belts were significantly easier to install. 

I bought extra tools when I got my mill, but only because I would be milling on the road and didn't want to be switching tool boxes all of the time.  I can only think of two 'tools' I bought to work on the mill that wouldn't be in most people's toolboxes.  One was a Cook's blade leveling device (a straight edge that clamps to the blade to make sure the blade is level to the mill bed.  The other was a V-belt tension gauge, which probably should have been in my toolbox, but I had never bought one.

[Stevem]

Checked with TK, mill is due here the first week in March.  I am excited.  Been sawing at a local (zombie) mill for custom orders and seeing where the band mill will (I hope) make my life easier.  Sawing mostly smaller oaks that the Lucas just doesn't do well with.

On the changing the belts:  TKs video shows beating the hub nut off with a hammer and 16" crescent but to reinstall they spec a torque of 150 ftlb.  Cant see caring around a precision wrench in the cab of my pickup that is seldom used.

Figuring on a tool box like an old ammo box to carry with the mill, all "new" tools or duplicates of my present tool stock.  But that's as I go to see what I need.  Already bought a torpedo level as per TK suggestion.

Belt tension gauge?  What's that for?  TK directions says to just line up the dots on the tensioner  spring housing/barrel?  What would you tension it to? Is there a spec somewhere?

[Tom the Sawyer]

I wouldn't beat on any fastening device, except a nail, with a hammer.  It should only take 151 ftlbs to take it off
I would think you could change your belts without removing the wheel.  That is the way I do it and it is probably easier on the newer mills.  Hopefully, someone with that model will chime in.

I have found it very handy to have a toolbox on close to the mill, with an extra set of tools just for the mill.  I actually found a poly tool box at Tractor Supply that fit nicely between the frame rails.  I have one in front of the operator's station that has lubes, tools for pulling nails, chalk, and my PPE.  I mounted another one at the front end of the mill and it contains a first aid kit, fire extinguisher, and PPE for clients/helpers (dust masks, ear muffs, ear plugs, eye protection, goggles, and gloves - I'd hate for someone not to be able to tote boards because they left their gloves at home. ).

The blade tension gauge is built into the saw head.  The tool I was referring to is a spring loaded tool to check for proper tension on the drive belt.  There is a formula, I don't have it memorized, for the number of belts and the distance between the pulley centers, etc.  You put a straight edge across the pulley tangent and use the tool to deflect the belt a specific distance - it shows how much pressure it took.  I have the proper tension for my mill written down, I'm sure you could call Jason and he could tell you the proper tension for your mill/engine combination off the top of his head.  I use a 2' magnetic level for setting up my mill, although I have considered mounting a couple of permanent level vials, like I have seen on RVs.

[furu]

Earlier in this thread I asked about the actual tension that folks were using on their blade in actual pounds of tension after Harold recommended a lower blade tension than a lot of folks use.
Never saw a response as to the actual real tension on the blade. I decided that I would do some measurements on my mill and post some numbers.
It seems that each manufacturer has their own method of tensioning the blade and thus it is a challenge to do an apples to apples instead of an apples to oranges type of comparison.
Backwoods sawyer points this out in how WM has a different style tensioner and "good tension" is at 80 psi on that style tensioner. TK uses a gauge in which the tension is set properly at 1200-1400 psi readings.  No real way to actually figure out who has more tension or less or what is excessive with all the different methods for setting said tension.

For several years now I have run 80 psi in the air bag style tensioner, up from 60 psi in the manual.
 

Cooks has different measuring setting device from either WM or TK.

Since I have a TK mill, I think in TK terms which is in reality nothing other than a base line for that specific  brand mill.
TK for example previously recommended that you tension the blade by:
“Turn the blade tensioner until the gauge reads 1,200 pounds.”
 
A little over a year ago they modified their recommendation to:  
Turn the blade tensioner until the gauge reads 1,300-1,500 pounds for 1-1/4” blades and 1,800-2,000 pounds for 1-1/2” blades.”

Cooks has some recommendation for "real" tension on saw blades.  I quote their recommendations:

Standard tension settings for:
1 to 1.5 inch blades         16000-17000 lbs
1.5 inch blades                 17000-18000 lbs
1.5 x .050 or .055 blades      18000-20000  lbs
2 inch                                        18000-22000  lbs

Higher settings (Faster cutting less longevity)
1-1.5 inch                                   18500-20000 lbs
2 inch                                         19000-23000 lbs

I collected data on my TK mill to see what the TK recommendations resulted in "real" blade tension and also I was curious as to how linear the tension increase was as I increased the gauge psi on the TK tension device.  See picture/graph and note that it is a rather linear increase.  Well there is no picture as for some reason after I upload the picture it says unable to access)  It is a near straight line  with the Mill gauge reading on the x-axis and the Tensiometer reading on the y-axis)

Mill gauge psi      Tensiometer (measured using a Lenox tensiometer)
500                            2600
750                            7500
1000                        12400
1100                        14000
1200                        16000
1300                        18000
1350                        18750
1400                        19400
1450                        20800
1500                        22500

TK’s new recommendations falls in line with the higher setting that Cooks recommend on blade tension and their older/previous recommendation matches up with the bottom of the Cook’s recommended standard tension setting.

[backwoods sawyer]

Made a few test cuts at lower tensions today with a new out of the box saw. air bag had 60 psi so I started at 65, then 70, it wandered, in cedar 75 was was cutting ok, but had to go back up to 80 in Doug fir.

[Tom the Sawyer]

furu,

Thanks for doing the research and for all of the details.  My B-20's manual also said 1200 lbs., although I would watch the blade for flutter while I was tensioning it and modified the tension to reduce flutter.  I have found that, for woods like cedar, hackberry and walnut, it cuts just fine at 1100 lbs.  For woods like oak, locust, hedge or mulberry, I'll raise it back up to 1250 lbs., give or take.

[HaroldCR - AKA Fla.-Deadheader]

 Good info, maybe.  A story my Dad told me years ago, when he was a Kaiser-Frazer dealership mechanic.

 Oil pressure gauges read 5-8 Psi on engine oil, so, factory guy had the faces changed to read 15+ PSI, so customers were satisfied. 

 Nothing to really do with Furu's excellent info, though. On another forum, a member clamped a sliding caliper to his blade, on the mill, and at whatever the recommended setting was supposed to be, he actually stretched the blade a few thousandths. 

 My starting of this thread was to give some insight to those that had problems with excessive blade breakage. Maybe someone can do some research on bearing life at those high pressure settings. Once a mill is sold, manufacturers need to sell parts to help cash flow, same as car dealerships.

 

 

 

[furu]

We used a 3/8" ratchet that tightened the tension bolt, until it got tight, then, engaged the drive belt and watched where the blade ran on the guide rollers. We could change the tracking of the blade with more or less pressure on the blade tension bolt.
 Also, we ran on the middle tread rib on the tires, and, that had a little give, also, being a rubber strip.
 I just don't see all that much tension being necessary.
 More than anything 1/8 to 3/16 down pressure on the blade guides will hold the blade steady, IF you set and sharpen correctly. I can't imaging solid block type blade guides not causing problems heating the blade from friction.

I remember from Tim Cook's excellent discussion of and about his mills the criticism that he leveled against some mill design that did not have anything other than brute force tensioning of the blade.  His video certainly left the impression that Cook's was against any tensionning device that did not have "give" in it to absorb shocks and stretching effects.

From your description it appears that you tension and set tracking with the same tension bolt.

We could change the tracking of the blade with more or less pressure on the blade tension bolt.

Interesting design.  

The problem that I see with setting tension with a ratchet is consistency.  Of course you do it each time so you have a consistent feel.  But what if the threads are a little stiff from corrosion, piece of dirt or sawdust or easier due to grease.  What if you use a different size ratchet one day as your other one was misplaced.  One mill manufacturer tried to eliminate that variable by using a torque wrench to set blade tension.  That at least removes one of many variables but many still exist.
The thing is without actually measuring the blade tension with a tensiometer none of us know what our different mills techniques for setting blade tension actually result in.  If the blade does not flutter or it thrums at some level when tight is all dependent upon the one who is doing it.  It would be interesting to actually get a group of sawyers together without any additional aids and have us set our blades tension and then measure the actual real tension that we are running.  Might surprise us a lot.

I do know in my case that I have a large data point for not running tension too low (but what is too low).  I had my drive wheel turning inside the blade wearing down the belt and did it in an amazingly short period of time.  Without the tension being high enough the engine was driving the wheel and the energy could not be transferred to the blade due to lack of blade tension thus it slipped big time and wore a belt very quickly.

[mountainlake]

Made a few test cuts at lower tensions today with a new out of the box saw. air bag had 60 psi so I started at 65, then 70, it wandered, in cedar 75 was was cutting ok, but had to go back up to 80 in Doug fir.

 It would be interesting to know what tension you are getting on a Lennox tension meter at different air bag pressures. I like the idea of a air bag tensioner which should have good give compared to a hyd tensioner.   Steve

[HaroldCR - AKA Fla.-Deadheader]

 When you build a mill from scratch, you learn a lot. We built a lot of adjustment devices in the design. When I showed my son a brochure, and said we were going to build one, he gave me that "look".   He is an excellent welder and fabricator and still thought I was nutz.

 As I stated previously, we ended up using Munks blades and they are as accurate blade after blade, as anything we tried before. The company has no dog in the hunt for selling machines and parts like mill manufacturers. WM sells their own brand of blade and makes money with resharps. They have a stake in how they teach their customers.

 My point is, a 19" band wheel is stressing the blade in the tight radius. They have NO give at the wheels.

 We used trailer hubs and tires. The rubber tire HAS give, so shock absorption is a non issue. We use Cooks roller blade guide system. Works well with lots of adjustment capability.  We don't "stretch" our blades, the tires allow for knots, clumps of bark, and, if paying attention, you "hear-feel when something is going wrong and shut down to investigate.

 Cooks recommend their blade roller, to take the curved "set" out of a used blade, after using on hard "steel" wheels. I don't know anything about Cooks mills. We could not afford to buy a mill at the time we needed one. After several years, Cooks, WM, TK ,etc are still in business, so, I believe they make good equipment.

 As far as "pre set", we still watch the blade as we run up the RPM's, and, if it runs a little toward or away from the roller guide flanges, we adjust accordingly.  We run our mill by "feel" watching how it performs, like operating a bull dozer. There are no levels or other handy devices on dozers. You climb on, do the deed and watch how it comes out, adjusting as needed. Actually, we have 2 adjustment bolts, one for tension, the other for blade travel on the guide rollers.

 At an agri show, in Moultrie, Georgia, Dave Mann, head honcho for Wood Mizer, heard me discussing how I changed one of their features when we built our mill. He was talking to a crowd, and, as we turned to leave, he asked us to hang on a minute. He had guessed we were the ones that built an open sided cantilevered mill, like WM's. I was ready to hear about copyright infringements, as we had heard from many people, because we copied the WM design. Actually, he was interested in what we said and asked several questions about what and why we built the cantilever design. I told him, and, he wished us good luck with the mill.

 I bought a used Peterson Swing blade mill for down here, to cut BIG-hard logs. I had asked a lot of questions on another forum, and got feedback from Peterson when I talked about building a swing mill. I was even invited to visit their factory, in New Zealand, by one of the owners, and was told I would have access to their "design-research" room. Apparently, they like free thinkers that try different ideas.

 My son took over the sawing when I moved down here, but, he just didn't catch on to the whole reading the log, getting the most out of it, and, he was working alone. Our mill was set up for 2 people system as I did the sawing and Ed did the heavy work.  Kirk and Buzz actually saw the mill in action.

 If this comes across as bragging, or, being an expert, it is NOT my intention. I just call 'em as I see 'em, and always try to help anyone that asks questions. I just pay close attention and keep the blade in the log, rather than worry about a few pounds of blade tension. All my concerns were worked out on the build(s) of 2 mills. I was told by many people that we could not build a functioning mill and we could NEVER keep a blade from running off a mill.

 Have y'all read the thread where I taught a complete stranger, online, how to sharpen blades AND change the profile? Sawmill Squaw was the student and she is married to a hard headed guy. She did what I explained and her husband bragged all over their area of how she did a better job than the ones they tried at getting their blades sharpened. She simply paid attention and asked questions, same as y'all here.

 This is why I asked for input and to keep things civil. Blade tension is not some magic trick. Just find what works for YOU and keep doing it.  

[red oaks lumber]

well written harold  !!!

[HaroldCR - AKA Fla.-Deadheader]

 Thank you. I sometimes get carried away with my comments. 

[HaroldCR - AKA Fla.-Deadheader]

See if this works. The dreaded band blade tensioner.

 NOPE

[furu]

I collected data on my TK mill to see what the TK recommendations resulted in "real" blade tension and also I was curious as to how linear the tension increase was as I increased the gauge psi on the TK tension device.  See picture/graph and note that it is a rather linear increase.  Well there is no picture as for some reason after I upload the picture it says unable to access)  It is a near straight line  with the Mill gauge reading on the x-axis and the Tensiometer reading on the y-axis)

Mill gauge psi      Tensiometer (measured using a Lenox tensiometer)
500                            2600
750                            7500
1000                        12400
1100                        14000
1200                        16000
1300                        18000
1350                        18750
1400                        19400
1450                        20800
1500                        22500

TK’s new recommendations falls in line with the higher setting that Cooks recommend on blade tension and their older/previous recommendation matches up with the bottom of the Cook’s recommended standard tension setting.

Now I can include the graph of the data since Kirk got the photo upload working again.  (Thanks Kirk)

I am now able to include the graph of the linearity of the blade tension vs the blade gauge on the TK.  While there is some minor bobble in the data  it is not much and is pretty straight.  (I was in a hurry, the light was low and I am certain I could have done a more accurate job of data collection)
The vertical axis is the Tensiometer reading and the horizontal axis is the mill tension gauge.

[bandmiller2]

As far as mill tension data goes that's about as predictable as you can get. Furu, have you ever tried clamping a Vernier caliper to the band and then tensioning it, would be interesting to compare it to that tension meter. (at least for us poor folks) Frank C.

[furu]

I can try it but I am not certain what I would use to do the clamp that would work without being too cumbersome and heavy.  Most all my clamps are welding clamps.  The caliper  prongs are all sloped as well. 

I can take a look but I am in the middle of planting season and I have a lot of seedlings to plant and protect from the infamous Aplodontia rufa.  I will get back on that but please don't turn blue holding your breath.

[red oaks lumber]

are you guy's suggesting the band stretches in lenght as it tightens? i know it will when it heats up.

[HaroldCR - AKA Fla.-Deadheader]

 Yep, if you tighten it enough. That's why I don't like solid steel or 19" wheels and V belts. Once they are smashed into the pulley groove, then what

 One day, I need to visit my Buddy with the wide band mill blades, over 6" wide, and see if they get curved from running over steel wheels. His sharpener is so worn out, the whole advance mechanism jumps around and his tooth tips are tungsten or something and they don't use any liquid cooling. ??  Y'all should see the sparks fly out of that thing when they sharpen.

 Where is that guy that ordered some Munks blades a couple 3 weeks ago? Looking to see if he proves me wrong about them.

[bandmiller2]

Furu, where are you located mate, up here in Ma. we still have snow piles. I've never tried it but they say if calipers are clamped on a band and then tensioned you can read the stretch. Probably a couple of vice grips would do the deed. My band mill just has a heavy compression spring, I just collapse it and don't have any idea how much tension. Its been OK for the last 15 years so it must be close. Frank C.

[backwoods sawyer]

On the munksfor saws I have only ran three of the saws, noticed a wave with the first one, changed guides wave went away. Have not broke a saw out of this batch, however I was just milling soft redwood and the saws were changed mainly do to milling dirty logs.