blade tension strain guage

[Cedarman]

Have any of you used a blade tension strain guage?  Any thing to be aware of.  Also what values have you found that work best for your blades?  We use 2 different bands.  Simonds 1 1/4" x 042  and Woodmizer 1 1/4 x 042.
Thanks in advance.

[sgschwend]

I haven't used one, but I think having one is a good idea.  It would help the user setup different saws.

I am probably like most folks who go by a force setting.

Strain has no units since it is the ratio of the length change versus the overall length.  The shortfall of a gauge is that the saw is not uniform, there are teeth, gullets, and even welds.  Therefore the reading will not match any specific area of the saw, but would give a usable reference point, just like the force setting does. 

Sounds way to technical.

Lets see who's gauges are recommended and how much $$.

[Larry]

Been waiting for the right time to show off my new $7 gauge from the auction...nobody else knew what it was...hence the low bid.




The auction was at a high end cabinet shop.  The owner used the gauge to set up Lennox Trimaster carbide blades to cut figured veneer 1/16" thick.  Since those Lennox bands are over $200/band he wanted to maximize the life along with getting consistent thickness on pricy veneer.  He was a firm believer in the gauge.

I used it on my re-saw to check the saw gauge (which was off) but as of yet not tried it on the sawmill.

It's a nice tool to have around but not near nice nuff to pay the new price of one.  You can do the same thing with a caliper.

Band Tension

[Chico]

 Very nice tool and very useful .You  can also use a back gauge and feeler gauges for this purpose as it measures the length of the back, really the only way to maximize the tool would be to track the blades either punching or marking your settings into the blade jmo
Chico

[Cedarman]

Larry, there are those of us that pay full price so others like yourself can get a good bargain at an auction.  I do not begrudge you your good fortune.  Lucky for you that I wasn't at the auction. 

Woodmizer sent me a digital tooth setting guage instead of the strain guage.  They will have it to me tomorrow.  I was ready to play with it today.  You know how it is when you get a box and are ready for fun and it turns out wrong.  I was so disappointed.  Sometimes even the great company Woodmizer stubs their toe.  They are human after all, even though they usually come through like supermen.

[John Bartley]

That $200 / $7 Lennox blade tension gauge is simply a dial caliper that clamps to the saw band (no offense intended - $7 is a screamin' deal!). You can do exactly the same thing with a $25 dial or digital caliper and a pair of "c-clamps". No matter how fancy your gauge is, you still need to know the amount of strain for your particular saw band. Once you know that, calculating the stretch using Young's Modulus is simple math.

cheers

John

[MartyParsons]

I have been playing around with ours. It works pretty sweet. There has been lots of comments about running blade loose vs tight. Every mills seems to be a little different. The thinner the blade the more tension you can get with the lower pressure and the thicker blade you can turn the tensioner up as far as you want and still not get to the recommended tension. 
I think you better have good drive and idle bearings. If you have an early model WM I am not sure the bearings will take it. I think the new mill bearings will take a lot more. Well I know they are twice the size on the idle side. So 1999 and up LT40 through LT70 should be fine. Earlier than 1999 take caution. I may not be exact on the early year. I will look and give you exact revision for the bearing change. (We have seen very little bearing failure on the Drive / Idle wheels that I am aware of. ) LT15 and LT28 we can get way more tension than spec. So just dont crank it up with out a gauge.
Marty
I am not sure about anything else but WM maybe other owners of other brands can give their advice.

[WH_Conley]

Marty, I am running a 97 LT40HD at 3000 psi on the guage, double bearings on idle side, replace at 700-900 hours. Have replaced the drive side one time, may have been more of a lube problem than tension problem. No longer have sheet metal on that side of mill, can see the filler tube. Currently have 3500 hours on the mill.

[bandmiller2]

Mayby its just me but I don't think its all that critical if your in the ballpark with band tension.Probibly the least you can get away with,some logs you need a little more tension.What is most important is to be able to repete what you find best.I like the pressure gauge on the mizer but a heavy spring and legnth measurement works also.A sharp well set band is the holy grail of bandmilling along with alignment.Frank C.

[MartyParsons]

The blade tension gauge gives us a picture at what may be happening to a mill that is not performing. I think once you have a mill checked you will realy know what the tension is on the blade. Then you can use common sense. The LT15 and the LT28 uses a 2500 lb red plastic , rubber, ( I am not sure what it is made of) that works well. If the blade get hot and gets longer it expands with it. Just like a spring. Springs seem to get weak, change over time ( from what I am told) WM used them at the begining and there are many mills out there still using them.
I have been putting the tension gauge on the blade bring it to tension then run the mill on a couple of cuts and install the tension gauge and remove the pressure to see how much is changed. Also check to see the crome tension rods are not sticking or to see where the pressure may be going beside the blade. You are measuring how much the blade moves in the cross section, so a thinner blade will move more with less tension and the thicker blade willl require more pressure to move it the same distance.
Marty
I am glad to share what I have learned, I hope this helps. I am not an expert.

[Cedarman]

Got my new guage yesterday. Put it on the WM and checked it out. The guage is right on. Then I put it on the Baker Scragg where it is tension up by guess.  We were running right where we needed to be.  But in the past we had been overtightening by a good deal.  I am glad I spent the money on the tensioner.  We had been breaking blades way too soon.  I haven't checked the WM multihead out yet, but it runs blades forever so I know I have no blade tension problem there.  There is a guage on it.

This makes me believe that there must be a very reliable way to check tension on a mill to veryify that tension is correct.  Trial and error is costly and without a guage of some sort, impossible to reliably tension to correct tension over an extended period of time.

[coastlogger]

What #s  ie 12000,15000,etc  are you getting on the strain gauge, and how do you determine the optimum. A couple of weeks ago we talked abt this, I researched it a bit and came up with 15000 as optimum,(turns out I have been cutting with 12000) am interested to know what others have found out.
clgr

[Cedarman]

I am using .042 x  1 1/4".  I checked it on the LT 30 HD and in the middle of the orange (highest range), it read about 25,000#. I effectively used the WM to make sure it was reading right.    Then on the Simonds redstreak, same size blade, we set it to 25,000.  I found out the guys had been setting the tension at about 40,000 and didn't know it was that high on the scragg.