sharp blades are diving

[levans]

I sent ten blades to be sharpened some were .045 11/2 and some were .035 11/2 I put one of the .045 on the mill, lt40hd, and it was fine, cut like new, later I changed to a .035. I remember thinking it was sharp because I cut myself turning it right side out. On the first cut the blade dived down in the cant. I've never had a problem from the place that does my sharpening so I wrote it off as a fluke. Then the next .035 blade did the same thing, has anyone else ever had this problem? I'm thinking they we're setup to set the .045 blades and didn't change the setter when they changed over to the .035 blades so the set was not enough, just a thought, I don't know much about setters.
I've talked to the sharpening shop and he will redo the blades at no cost.

Levans

[Dan Sawyer]

Levans,
There are a couple possible issues you may have encountered with these blades.  The set doesn't sound like an issue as long as the set is balanced to each side (if the goal of setting was to set to .022, than by balance, I mean .022 to each side.  If it was set to .018 on one side and .022 to another, you would likely get wavy cuts).

But, I would assume this is not your problem.  It sounds like your blades have developed convexity.  As the blades go around and around the wheels cycling at high speeds, the blades tend to form a curvature in the opposite direction called cross camber or convexity.  You can check this with a straight edge.  You can remove convexity with a blade roller and your blades will cut like new.

Another potential problem could be that your guides are worn and need to be replaced. 

Just a couple thoughts.  Good luck solving the problem. 

[NMFP]

Even if your blade guides are worn, and the new bands worked, something has happened.  I can almost 100% say that Dan Sawyer is correct.  Roll the bands and then try them, I bet they will saw perfectly!

Have a customer that was sending to a well known sharpening service and had the same issue, except it happened with about 35 bands.  He was told to box them up and send them in and they would regring and set and all would be well. 

I happened to stop because he wanted me to start sharpening his bands,  I took 10 home, rolled them and took them back in about an hour.  Worked perfect and he hasnt sent a band to the sharpening service since.

There have been a few customers that I will load the roller on the back of the truck for and roll the bands at their location.  It has gained alot of work, and reputation. 

Try rolling the bands and try it out.  Your bands are thinner so rolling will be necessary.  I typically never roll .055 bands but frequently roll .045 and .042 bands.  The thinner they are, the more concavity they will conform!

[Chuck White]

When you mentioned that you turned the .035 right-side-out, it kind of caught my eye.

Do all of you blades have to be inverted after they come back from the sharpening service?

You didn't mention inverting the .045 blade but you did mention it on the .035 blade.

I'm thinking maybe only one side of the .035 blades was set, and that's why they were diving.

[levans]

Chuck, all of the bands do have to be inverted, I just didn't mention it on the .045.

Dan, call Me thick but I don't understand what you mean by rolling the blades ???

[customsawyer]

Levans in the process of rolling a blade you are trying to get the length of the back of the blade to match the front of the blade. Everything you do with a blade is done with or to the front of the blade and it will develop a cup effect to it do to this. So if you roll the blade between a roller it will make the back of the blade a tad longer thus fixing the cupping effect.

[kelLOGg]

I took 10 home, rolled them and took them back in about an hour.  Worked perfect and he hasnt sent a band to the sharpening service since.

Tim Cook at Cook Saw tells stories like that.

Bob

[NMFP]

Kellog,  Its the truth.  I dont like to say it but manytimes, I have capitalized on someone elses mistakes and the service of rolling a few bands and returning them has proved valuable to the customer and also shows credibility.

I just picked up sharpening for a veneer producer in the area because of my reputation for knowledge, quality and reliability.  In total, I am now sharpening about 160 bands per month plus my own which is about 30.  I must be doing something correct!!

8) 8) 8) 8) 8)

[ladylake]

Why do you run .035 bands.   Steve

[levans]

Steve, I just wanted to try a thinner blade, and just out of the box they out cut any other blade I had as far as speed and length of time between blade changes. If convexity is the problem and I can correct it I think I would prefer the .035 over the .045.

Larry

[kelLOGg]

Kellog,  Its the truth.

I didn't mean stories as in lies but actual real events, literally, just in case there was a misunderstanding. I have talked with Tim several times about band rolling and have come to respect the need for it. I don't have a roller because it is an expense I can't pony up for right now, not because I don't think it is necessary.
Bob

[bandmiller2]

Wile lurking around the local Harbor Freight store I noticed a geared roller setup with a crank and an assortment of rollers for beading sheet metal and outher tasks.Its built heavy and with some modification of rollers bet it would roll bands into submission.I may study the matter more fully,it taint cheap if I recall $169.00 but real heavy duty. Frank C.

[bandmiller2]

You fellas that own rollers how do you determin you have rolled them enough,does it seem like it takes alot of force to level them.?? Frank C.

[kelLOGg]

Wile lurking around the local Harbor Freight store I noticed a geared roller setup with a crank and an assortment of rollers for beading sheet metal and outher tasks.Its built heavy and with some modification of rollers bet it would roll bands into submission.I may study the matter more fully,it taint cheap if I recall $169.00 but real heavy duty. Frank C.

Frank, you mentioned HF before in regard to rollers. I would be VERY interested in what your findings are. Those who have band rollers - how about a description of the process? YouTube would be great.
Bob

[bandmiller2]

Kell,I'am flattered someone even remembers what I say.I'am driven more by curiosity than necessatity as I don't have any real problem with my bands diveing outher than the worn out one,and we all catch a wave once in a wile.Being kinda cheap when I come across the right device I'll experiment.Stay cool mate. Frank C.

[customsawyer]

To determine that I have rolled the blade enough I use a blade from a utility knife. I hold the edge of the knife blade across the body of the saw blade from the bottom of the gullet to the back of the blade and see where there is day light underneath the knife blade. It will show daylight under the edges or the middle of the knife blade showing which way the saw blade is cupped.
This is the only pic I have of my roller. The next time I am over at that shop I will try to get some better pics for you guys.


 

[sdunston]

Sounds to me like those blades need rolling, but I dont understand the 035 blade on a LT40, Does WM even recomend that on a 40?

[Chuck White]

What are the symptoms of a blade that needs rolling?

I have sharpened my bands, on average, 6-8 times and sometimes as many as 10 times before the blades crack or break.

I do understand that the inside of the band may become concave after a while, but I really don't seem to have been bothered by it!

[levans]

customsawyer,
From the descriptive post I've read so far and from what I can see of your blade roller I think with a visit to My treasure pile I may be able to build a blade roller. It seems the problem is the blade has become concave on the inside of the blade,if the blade is inverted and then run thru the roller with a slightly rounded roller on top, with the bottom roller flat or slightly concave.
If I'm way off on this let Me know. ???

Larry

[customsawyer]

Most times when a blade is in need of rolling it will rise in the start of a cut due to the cup in the blade.
Levans you don't have to invert the blade. What you are doing is making the back of the blade longer so it don't matter if done from the inside or the outside of the blade.

[NMFP]

You can easily use an inexpensive bead roller for forming sheetmetal to make a band roller.  Typically, a 1.25" band will need rolled one time and a 1.50-2" will need rolled 2 times.

You can use the roller from HF as long as you have a guide to make sure the band is consistently held and uniformly rolled.

When I roll, I put as much pressure on the band as I can and still be able to turn the handle.  One the 2 machines I built, I use a 110v motor with a foot pedal so that I have both hands free to handle the band.

[Dan Sawyer]

Levans,
The responses above are all correct.  Rolling a blade is a very simple and quick process.  Customsawyer is exactly correct in the blade will typically rise when beginning the cut. 

The wider the blade, the more often it needs to be rolled.  The art of rolling a blade also referred to as benching was originated with wide band (4" - 16").   

[levans]

This is one of those head scratching things, I know the blade has become concave from running but, how long would it take to flatten out if the blade were inverted and put back on the saw? Not trying to saw with it but just running to flatten the blade ??? ,if it has taken hours of running for it to become concave it's sure not worth it to run it that long inverted to flatten it back out.

[customsawyer]

You can't just run the blade backwards. It will need to be sharpened that way and will need to cut that way to get the same amount of flex that you have put into the the other side.

[WH_Conley]

I think what he is getting at is if you turn the blade inside out and try to reverse the concave part. Would it take minutes or hours. No sawing involved, just try to reverse the stretch.