Woodlands HM126 VS Wood-Miser LX50Super

[GBar]

I'm also in the market for a Woodland Mills HM126 or the Wood-Mizer LX50 Super.  I really like the taller rails of the WM LX50, but do not like the guide roller system with the small back edge on the bearing roller and the fact that there is ONLY one roller on the top of the blade and the need to have that roller guide press the blade down, deflecting it approx 1/8" to have solid continuous guide contact on the blade.  This is a poor design with no guide on the bottom side.

As a woodwork for over 40 years, I have never seen a bandsaw with guides on one side.  Solid blocks (on both sides is the industry standard on some bandsaw and newer rollers (left and right on some bandsaws), so WoodLand Mills wins with their engineering in this case.  Also, Woodland Mills has an independant bearing guide for the back of the blade.  this is standard on all bandsaws I have used including the bullet proof Tannewitz or Oliver 36" bandsaws of the 1930s.  I used to rebuild auctioned machinery as a young pup, and have seen a lot of engineering solutions.  Guides on both sides of blade and movable guide set up to the work is critical to have a straight running bandsaw blade.  even then, dull on one side will make the blade wander.

So why would WM design the guide this way?  interested in comments from the users of these entry level mills.  Do you see any wandering on the down side.

P.S. read the complete LX50 Super manual and surprised by the adjustments or lack there of.

[ladylake]

 You dont need a bearing on the bottom and should run 1/4 downpressuer which controls the blade good.  1/4  down pressure cuts straighter  than 1/8 .  Steve

[Magicman]

I do not have an "entry level" sawmill but why should Wood-Mizer not use the the same blade guide setup that they and the other top of the line manufacturers use on their non-entry sawmill platforms?  Top only rollers with down pressure works and works very well.

If a blade is "injured" on one side and pulls away from the blade guide, a bottom roller is not needed, a fresh blade is needed.  The only times that I have had a blade to pull away has been after a nail strike.

[jpassardi]

The advice given above is accurate. Roller guides are the preferred setup.
Take a look at Steven Cook's (Cook's Sawmill) video where he discusses roller guides.
Higher end mills use them because they perform better.

[Magicman]

The blade is not just floating along.

Adding a bit of physics; a blade under 2500-3000 lbs of tension with 1/4" of downward deflection from the band wheels is not gonna deflect downward away from the blade guides unless the blade teeth are seriously damaged such as a nail strike as I mentioned above.

 "Sandwich" style blade guides actually will create heat as the blade rubs on them which is one reason that they are not used on higher end sawmill designs.

[GBar]

Thanks for the replies.  appreciate the experience.  for the record, I do like roller bearing blade guides. but like them on both sides of the blade with little to no contact to blade. I prefer the bearings (roller or blocks be back a couple of thousands so rollers do not turn or just slightly turning, especially the back roller bearing. On vertical bandsaws, I align the blade to track straight without any guides and then move the guides in to not deflect the blade.  When properly set, there is little to no heat.

Debating the heat issue: In the case of the roller bearing deflected with constant pressure to the blade, this friction will create more heat than properly set guides that are not touching.  But the heat may be insignificant...and a non issue...as there is way more heat generated from the blade to wood friction.

And you guys do have a point, the deflected blade will be held with constant pressure (1/4" was mentioned) and tracking will be good.  Blade wandering due to dull on one side is a whole different issue ...not the tracking controls.

attached is a picture of rollers on each side of blade and one in back.

Thanks for the insightful feedback.  

[beenthere]

GBar

You may find out you have more to learn. 

How long have you been sawing logs? 

[SawyerTed]

A wood shop bandsaw and a bandsaw mill while they have mechanical similarities, the operational differences are the key to understanding why the guides are different. 

I won't review all of the operational differences between shop saws and sawmills.  It doesn't take a in-depth study to begin to note the differences. 

Those operational differences like cross cutting, ripping, blade geometry, speed of cut etc all play to why bandsaw mills have a different guide set up. 

A couple of notable things about mill roller guides.  One is blades do not ride on the rear flange when cutting.   If the blade rides the flange, something is wrong (guide adjustment or blade tracking) and blades will break.  Two, guides on a band mill play a role in maintaining the blade parallel to the sawmill bed. 

[GBar]

Beenthere and SawyerTed,

Thanks for the comments and "yes" I do have a lot to learn about bandsaw mills. Which is why I posed the comments, opinions, and questions. My exeperience comes from wood and other manufacturing industries (multiple domains from rough milling to fine product production), engineering, and aerospace systems testing. As mentioned, I rebuild older machines for a wood manufacturing plant, as well as made custom tooling with carbide, etc.  so my experience is broad, but a rookie at bandsaw mills.  I applied general engineering principles from one domain to another.  This may be out of context.  But did welcome feedback and knowledge.  So thanks.

However, it appear top tier WM to have the setup of rollers and wear blocks (part description:  Block, Blade Guide Wear) where the blade is contained on both sides.  therefore, my picture (out of convenience was a verticle bandsaw) was just to illustrate the concept.  I stand by the engineering concept of guides on both sides.  Not to say the one side deflection method does not work. The former being my preference in design engineering.

SawyerTed - there is no way the blade does not hit and rest on the rear flange of the WM guide roller bearing while operating.  Under cutting load, that blade has to have a back stop. take that away and the blade will be forced off the tracking.  wheel alignment tracking is only for idle under no load.

[ladylake]

 If you want to break a lot of blades have the rear support adjusted to close to the back of the blade, it should be adjusted 1/4 " behind the blade and only hit when the blade is dull and need changing/ Ted is right.  Steve 

[SawyerTed]

Those "wear blocks" are an option in the High Performance Blade Guides.  The High Performance Blades Guides are an option in addition to the roller guides.  I have them on my LT50.  The jury is still out on how they do.  The High Performance Guides get mixed reviews and reduce cutting width.  

Blade tension, guide adjustment and tracking hold the back of the blade off the flange during the cut. 

Blade tension, wheel crown/belts and tracking hold the blade on the wheels.  The pressure of feed should not deflect the blade to rub the flange on roller guides. 

Typical small bandsaw mill blades are 1 1/4" wide and wider and are .040 to .055 thick.  If they deflect to touch the guide flange during the cut, they will not cut flat.  

Blade tension is usually 1,000s of pounds on a sawmill band.  The LT50 uses a hydraulic tensioner and tension is 2,800 pounds minimum up to 3,500. 

If the back of the blade rides the guide flange, the blade will heat unevenly and it will break.

This is where first hand experience differentiates itself from transferred knowledge from other machines.  

[ladylake]

 
I'll add when the back of the blade hits the flange the blade is bending around the flange causing the gullets to crack.  Steve

[Peter Drouin]

I do things a little differently, I have a 1008 lt40 supper with a Cat 50 h diesel.
I turn the blade tension until the needle points to 6+ o'clock. never a problem. I set the guide rollers down the 1/4"
Like WM wants, I set the blade on the rollers years ago like I was told.

I had my share of crack gullets. A long time ago I moved the rollers to be 1/8" back with a small tilt to the inboard side of the blade coming in. I run 1 1/4 55 tur 7. dubbel hard. My blades go 3 or 5 sharpening. I still brake blades now and then. But, no crack gullets, Mosley I have sharpened past the hard part of the tooth. and just toss them. If I have a blade that gets hot it's dull. With 7800 hr on the mill, My 3ed and last WM still cuts a flat as an Iron for all that the Cat will give me.

I cut W and R pine, hemlock, R and W oak. mosley. 
 

[SawyerTed]

SawyerTed - there is no way the blade does not hit and rest on the rear flange of the WM guide roller bearing while operating.  Under cutting load, that blade has to have a back stop. take that away and the blade will be forced off the tracking.  wheel alignment tracking is only for idle under no load.

There's much still to be learned.  

Most bandsaw mills have a blade engagement mechanism such as an idler pulley or clutch.  The wheels and blade do not turn when the motor is at idle.

There's lots of YouTube videos that show the engaging and disengaging of the blade.  

[GBar]

I do have a lot of practical experience and engineering knowlege, but wise enough to know I have a lot to learn.  We all do SayerTed.  By the way, I have over 40 years experience in wood industry, and as a forman of manufacturing plants, etc. Will not list my full resume, but have experience with verical resaw bandsaws with automatic power feed systems.  Those machines share many of the same priciples as the horizontal sawmills.  However, each manufacture designs their machines different, but tend to copy what is built from the competitors.

I researched all the WM manuals and the recommended distance from the back of blade to the flange on guide roller is 1/16 to 1/18 (inner/outer).  Setting to 1/4" back (blade to flange) is more than recommended and could be the reason for blade breaks.  This 1/4" reference may have been misunderstood from the 1/4" blade deflection requirement.

The heat transfer function of the heat transfered from the flange to back of the blade is insignificant and less than a cool block or guide block.  it all depends on the force and surface area. properly set guides will not create significant heat to blade due to many factors (mass of blade to guide being the most, adding fluid cooling dynamics air/water and conductive transfer to main wheels).  Most guide blocks or cool blocks are made with carbon impregnanted to provide lubricant...and designed to wear.  The WM blocks on the LT40 LT50 are ceramic.  those and the roller flange take the heat and not the blade.  I venture to say the blade breakage is from excessive deflection and not heat from the guides.  properly set guides assist is less blade deflection.  as mentioned earlier, there is way more heat generated on the blade from sawing the material.

as for tension, the formula is: force on wheel divided by blade cross section x 2 (e.g. T= Force/(blade thickness x 2).  For .042 thick blade with 3000 psi tension, this equates to 3000 X .084 = 252 lb force.  Tension should be adjusted per the thickness of the blade per the LT40 manual, which has a nice chart.  Go up in blade thickness - go up in tension.  The LT50 manual seems to have omitted this chart.

I still like guides on both side of the blade and like the design of the MW LT40 LT50 guide roller/block system.

for what it is worth, i'm impressed with the WM LT40 and LT50 documentation. 

[ladylake]

 Gbar, no matter how much experience you have unless you want to break blades keep the flange 1/4 behind the blade in higher powered mills cutting fast using lower hook angle.  1/16 and 1/8 may have worked for low powered mills cutting slow with a higher hook angle .   Steve

[Old Greenhorn]

Gbar, I too spent a lifetime working in industry, mostly metals machining and manufacturing. I began learning how to rebuild machines as a little kid because every machine my Dad had, he either got for free or as scrap. He would tear them down to the casting and rebuild from the ground up. That's how I learned and by the time I was 15 or so, I was doing some of my own rebuilds. When I started my machine shop business I did the same thing, getting old cheap iron which was better than new stuff and rebuilding from the ground up. Made for solid equipment that I knew every inch of, so repairs were dang easy when they came up.
 Later in life I became a tool designer for about 20 years, made a lot of fancy high production fixture designs, some automation, and did some machine design. You never stop learning.

 Now with respect to your original question: A vertical band saw almost always has freeboard on both sides of the blade, meaning the parts you cut rarely come near the blade guides or interfere. That means the designer has plenty of room in the area to put symmetrical guides, bearings, or whatever. The same applies to a horizontal cutoff bandsaw.
 On a horizontal band mill this is not the case. A critical design consideration is getting that band as close to the deck as possible for the dog board (last) cut on a cant. This is widely accepted as 1" plus a tiny bit of safety clearance. At the same time, the moveable guide should be as close to the outside of the cant as possible, which means, the guides cannot protrude down to catch the mill bed as they pass over it. This presents a design challenge, which is solved by putting substantial sized rollers with adequate bearings on the top side of the blade and biasing the load against them with downward pressure. Since the rollers move (rotate) with the blade there is negligible heat generation in this method. The roller flange is mostly there as a safety device for when things get wonky. They will keep that blade on track when it breaks so it goes in a relatively predictable direction and not in the operators direction. With proper tension and blades wheels set right, as well as good feed rates, that blade should not come back against the flange until there is a failure.
 I'd also like to point out that the rollers keep the blade parallel to the bed at all times. With a guide block system, which has to be set up with a gap of about .010" between the blade and block the guide blocks do not contact the blade until the blade deflects which is already too late to prevent some wandering. Once the guide block makes contact, the heat generation rise goes way up leading to earlier failure. I run a manual mill at home with guide blocks, and for some income I run an LT50 with rollers, so I have dealt with both. I have a lot more hours and BF on the LT50 than I have on the manual, for good reason.

 As far as recommended settings go, and you are right, WM makes very good manuals, I will point out that those are good solid starting points. However as time, experience, and years of milling experience pile up, we all learn things that sometimes go beyond what is generally accepted. WM recommends 2500-3000 psi of blade tension if I recall what the sticker says. But many of us know that you have to keep it at 3500 or more for happy milling. The more experienced WM techs with lots of milling time will tell you this. I don't know why they never updated the sticker and manual. The same applies to the gap between the back edge of the blade and the flange although personally I don't see this as critical in so far as others do. The gap only need overcome any natural steel flex during normal operation which is actually quite small.
 As good as the WM manuals are, they can't possibly get it all right. I went through a lot trying to get our de-barker setup correctly because they had so many revisions to the design that the manuals and their tech staff could not keep up with the variations some of which were fundamentally different in operation. So I reverted to good design practice, figured it out for myself and we now have a happy running de-barker with nearly zero issues for almost a year now.

 YMMV, and experience is a great teacher. With an open mind and inquisitive approach, you should do just fine. I put a lot of weight on what these experienced sawyers here have to say even if it doesn't make sense initially. As I work through it, I find it making more sense. I trust them. Were it not for them I would be blowing and going on the LT50 and fixing things better than they were when I started.
 Best of Luck!

[SawyerTed]

Blade guide alignment video from Woodmizer on an LT15.  

At 30 seconds in, the technician mentions what happens when the blade rubs the guide flange.

https://youtu.be/pVged-Q6Us0

Regarding experience, I have milled nearly 250,000 board feet of lumber with two separate Woodmizer mills.  The majority of that lumber was cut in 3.5 years on an LT35 Hydraulic. The LT50 is just now beginning to be used as much as it should.  It's cut more than 50,000 board feet of lumber so far.  

That's a drop in the bucket compared to others here who have millions of board feet milled to their credit.

The Forestry Forum is a learning community from which I try to learn something every day.  Without this community, I never would have accomplished what little I have.  

[MartyParsons]

Hello, sorry I did not read all of the post. 
   The roller guide system on the LX50 Super is very similar as all the other mills Wood-Mizer manufactures. Wood-Mizer has been building mills since 1982 and when they first started they had a top and bottom roller set up. The roller is adjusted with 1/4" deflection and angled so the blade is lifted if it comes against the back of the roller flange. So it should be adjusted toward the idle side 1/64th. This has always performed well in all applications. On the larger HP mills like the LT40 Super LT50 and LT70 there are some options for Hi Performance sandwich guides. I comment that the only time the blade comes in contact with these is when the blade is dull. If the blade runs against these all the time friction causes the blade to get hot and most likely on just one side of the blade, this also changes the profile and change the cut performance of the blade.  I hope you chose the Woo-Mizer mill. We have been working with them since 2002 at our location in Pennsylvania. If you have questions you can reach us. We also have a LX50 Super G 14 set up for demonstrations. We would be glad to load a log and let you take a few cuts. Thanks!
Marty

[GBar]

Hey Tom L,
Outstanding and professional post.  Solid point on the wandering blade vs guides.  And SawyerTed had a good point earlier about blade heath (sharpness or other issue) having the greatest effect on wandering and the guides only do so much.
The point you made about the last one inch cut on the cant and the blade deflection makes a lot of sense, and concur the roller friction is insignificant to the heat generation from the cutting. I maintain that guide blocks also have insignicant heat build up on the blade, when properly maintained.

You also make a solid point about documentation is a starting point.  I do not always agree with documentation and of course as you mention, revisions are a natural evolution, with experience as the input to change. I'm sure you have, like I have, supplied documentation feedback to manufactures when we notice errors or mistakes, or just some improvements.

As for guide distance, I normally run all guides within 0.001 or touching...so all bearings are slightly moving. But back off all guides when tracking blade initially...then bring in the guides. Never noticed any heat on blade after running idle for a few minutes, even with rubbing blocks. Not to say the blocks do not get hot, but little is transferred to blade. As mentioned many of the guide blocks are designed to wear and lubricate the contact point.  There is natural wear increasing the clearance, so they have to be adjusted frequently.  And also run the adjustable guide set as close to the work as practical. In your experience with horizontal metal bandsaws, the cooling fluid plays a big part in keeping the blade cool/sharp. of course the speed is greatly reduced.  I have yet to break any blade on any bandsaw: verticle, horizonal metal cutting, or re-saw machines (from 1" to 3" blades).  

As SawyerTed eluded to, once wander and increased workload are evident, we changed out the blades early.  In the industry, we never resharpened bandsaw blades...due to variety of cost factors and production time.  So maybe this is why blade breakage was rare for the other guys, but I have not broken one yet...knock on wood.  maybe I get to experience a blade break on the bandsaw mills given the increased load factors. Of course we sent out our carbide cutters to sharpen...but that is totally different cost factor.

One final point.  3500 psi is not that much force on the band.  I never finished my earlier comment.  That pounds per square inch (psi) is on the section width of the band.  So for a .042 x 1.25 (negate the .25 due gullets) is .042 square inches.  Since the band over the wheel has two sides, the force on the wheel is doubled, so double the .042 or .084 cross sections.  multiply .084 by 3500 = 294 lbs.  it is like a weight of 294 lbs is place on the wheel tension.  or flip the saw verically and hang a 300 lb weight on the bottom wheel.  that is not that much IMHO.

Thanks for all the tips and knowledge as i make my machine choice.  Very helpful!

[Old Greenhorn]

Just a couple of follow up points. 
 Frist, you are equating the guide setup on a vertical industrial wood bandsaw to that of a lower end horizontal bandsaw mill. These two designs are not even close in comparison or purpose. You industrial vertical has guide rollers and blocks (much of the time) and your face is in proximity to it most of the time during use. This means it is easy to observe when things are wearing, either blade or guides. Not so with the sawmill. First, the sawmill only had backup rollers (which should stay out of play anyway) and the guide blocks are the only thing to keep that blade from deflecting. Contact with those = friction and heat= not good. Coolant/lube does a little to help this, but can't do much when the blade is dull. Second, you cannot easily observe that cut as it is happening on a sawmill and only have end results to judge by.

 Second, I think your physics are a little off in your understanding of blade tension. The 'number' you read on the gage is just a relative number for that machine design, based on force and the area of the piston in question. How much force it exerts on blade tension is a very different number and only relates to what the gage says in a linear way. For example: 3,000 psi on a 1" piston does not exert the same force ae 3,000psi on a 2" piston. It is pressure X area that gives you the actual force. Then you have to figure out how that force is split up around the circumference of the band wheel, and that force is not equal all the way around, it will be highest at the 9 o'clock (or 3 o'clock) positions and least at the 12 and 6 o'clock positions. That's a lot of complicated math, with ray and vector force calculations, best I can figure.
 So the best way to get the actual blade tension is with a tensiometer, which works by calculating based on allowable deflection with a known force. Or you can use a very pricy stress gage with a computer. This subject was discussed at length as I recall a few years back, here on the forum.

 So the blade tension gage reading is just a reference point that does not directly translate to what amount of tension that blade is actually under. Since many of us are running wills with a one inch piston, we can relate to what others are seeing and learning. But when trying to figure things out for yourself, you always have to pay attention to these details and account for them. I have no idea what kind of tensioning system your verticals have, I have seen all types, mostly with springs, but never paid much attention to the actual number because it was relative. We knew a 1/2" blade got 'this much' tension, a 3/4 got 'this much', and so on. We put reference marks on the tension gage dials to make it easier for everyone.

 Anyway, these are just a couple of points for you to ponder and in the end, each of us does what we think is best for us.

[GAB]

as for tension, the formula is: force on wheel divided by blade cross section x 2 (e.g. T= Force/(blade thickness x 2).  For .042 thick blade with 3000 psi tension, this equates to 3000 X .084 = 252 lb force.  Tension should be adjusted per the thickness of the blade per the LT40 manual, which has a nice chart.  Go up in blade thickness - go up in tension.  The LT50 manual seems to have omitted this chart.

I still like guides on both side of the blade and like the design of the MW LT40 LT50 guide roller/block system.

for what it is worth, i'm impressed with the WM LT40 and LT50 documentation.

GBar Sir I question your statement.
I just went and measured the diameter of the piston rod on my LT40 and it is 1" in diameter.  1" in diameter gives you an area of .7854 sq. in.
So if you take 3500 psi and divide it by .7854 sq. in you get 4456 pounds of force pushing the idler wheel and tightening the band.
I use 1.25 x .045 bands so the narrowiest band width in the gullet area is 1" x .045" thickness  x 2 = .090 sq.in.
Take 4456 pounds and divide it by .090sq.in. and you get 49,511 psi for a blade tension.
Please note that this assumes no friction and that the blade tension is the same on the entire band.  I don't disagree with what OG wrote, I'm just not smart enough to factor it into the equation.
So for my mill with a 1" piston it is:
gage pressure divided by .7854 (piston area) divided by the blade area x 2 = blade tension in psi.
Example 3000 divided by .7854 divided by 2(1.0 x .045) = 42,441 psi.
GAB

[DanMc]

What a fantastic post from Old Greenhorn!

I may need to print that one and stick it on the wall for future reference.