Checked my blade tension

[Ben Cut-wright]

The hydraulic system gives you a visual key of how your band is performing too.  If the band is heating up then the gauge pressure will drop, I doubt you will be able to see that on the spring, I know I can't see that on my 35 as is has a similar compression set up.  On my 70 it's an air gauge, because it's a hydraulic over air system, but the gauge does the same thing for me, if I notice it dropping then I know something isn't right or the band is getting dull, etc.  

Personally I think the complete upgrade will be money well spent.  It won't take many diving bands wrecking lumber, that should have been avoided, to pay for itself.  

The LT40 with spring blade tension does give enough visual indication to compare favorably with a pressure gauge.  Can't speak about the accuracy of either method afa actual strain variances from initial settings, haven't felt the need to experiment.  It is quite normal for blade tension to lessen during the first few cuts and the setting can relax.  After that I NEVER reset tension for that blade session.  IF the blade cannot maintain the reset it is replaced or other cause is found.  


It is my thinking the simple spring method has fewer negative outside influences to consider. For me, the other methods do not offer enough convenience to warrant their expense and added complexity of components.


I'm not advocating against upgrades. As you state, most are well worth the money and may eventually pay off.  Goodness knows I've done many upgrades and do not regret any.  But....the spring tension device serves its purpose well and the simplicity suits me. 

[D6c]

In going over parts diagrams I think I've come up with a plan.  WM is closed until after Christmas so I'll wait and bounce it off them before proceeding.

There is an upgraded wheel assy. ( 016120 - $285.33) that has one double row bearing instead of two separate bearings.
I will make my own axle shaft to match up to the new wheel and my old axle housing.  
You can get a wheel kit but the axle it comes with is too short for my mill.  (newer axle housings are shorter than mine)

I have a Danly Extra heavy duty 2" spring on order that I'll retrofit in place of the 1 1/2" spring.  It will theoretically give enough tension to put 25,000 psi on the blade.  I'm going to try using the existing tension screw assembly.  If it ends up not being strong enough I'll remake part of it to strengthen it.

I'm sure the hyd. system would be nice but I'm trying to keep cost down.  One thing about a spring, it won't leak down.  If the blade heats up a little and stretches the spring will still hold tension.  
With the added tension, if I break a blade it's really going to go BANG!  I might look into adding a rubber bump stop for the sliding wheel housing.

Maybe I'm sick, but I kind of enjoy making mods on the old mill to improve it.  After adding hydraulic log turner, 2-plane clamp, toe boards, side stops, and now higher blade tension, what's next?
Sure would like some more horsepower, and I keep looking at the guide rollers trying to come up with a design that's more solid and easier to adjust.
Never got around to building a set of lift arms either.
I miss having access to the CNC mils and wire EDM when I was working in a machine shop, but I have manual machines in my shop that can get the job done.

[Ljohnsaw]

Sure would like some more horsepower, and I keep looking at the guide rollers trying to come up with a design that's more solid and easier to adjust.

For more HP, just add a Nitrous tank ;)  That should give you a boost (for a little while)!

Not sure what your blade guide adjustments you want to fix up.  The roller pitch/yaw/height adjustment?  The beam tracking adjustment?  

Here is both on my shop-built mill (version 2.0):
The roller is bolted to a piece of round stock (could have used square but didn't have any) that is a very sloppy fit in the 2½x2½x¼ tube.  You can see some pairs of bolts on each side.  The tube is threaded and tightening these bolts move the axle mount around for height, pitch and yaw.  Sliding it in or out as necessary to line up with the proper blade tracking, too.


 
A little closer look.  I didn't need to use any lock nuts, plus didn't have the room on the bottom to be able to get my last board cut without hitting the bunks.

 
Looking a little closer you can see the V-groove rollers that hold the 1" tube at a 45° angle.  They are mounted to the block on the left of the plate and the plate has an arc for the bolt to travel in when adjusting.  It pivots on another bolt further back.  The screws protruding from the top and bottom are there to force the rollers down and up, respectively.  There is another pair of rollers/adjusters way back there.  Between the 4, the angle of the bar can be adjusted and snugged up between the rollers so there is no play.  Surprisingly stiff at full extension.

[Southside]

Put a super charger on it, THAT would be a cool mill!  :D

[D6c]

The blade guides work but are pretty finicky to adjust.  The sheet metal bracket the rollers are mounted on is kind of a  sloppy fit on the shank.  If I took the time, I'd make something mounted on dovetails for solid clamping and fine adjustment.

[ladylake]

I tend to over think things.  When using a hydraulic tensioner, you have an absolute measurement on the pressure gauge.  When using the spring tensioner, you have a mark that you compress the spring to.  But, what if the blades are slightly different lengths?  Not much but what if a blade is 1/10" longer or shorter and you adjust the tension to the mark, how significant of a change would that represent in the tension?  Maybe that is why one blade cuts differently than the last?  Why you sometimes need to increase just a bit more?

Maybe I'm over thinking it...

 Yes your overthinking it, It doesn't matter if the blade is shorter or longer, so long as you tension the spring to the same length ( 1 7/8" on my 2 wide " spring) longer or shorter blades will have the same tension.  My gauge quit working years ago so I just give it 3 turns after getting snug which compresses the spring to 1 7/8", no need to measure it every time.  Steve

[Ljohnsaw]

OK, I think I was looking at it wrong.  For my mill, I look at how much the idle wheel slides on its rails (hydraulic jack moves it) and that is very much affected by the length of the blade.  What I think you are saying is the measurement gauge is for the length of the spring (how much it is compressed.  Make much more sense to me now.