Blade Life Versus number of pilot holes

[Jim Blume]

I often hear folks talking about how many cuts they can get out of each blade. Of course we all have opinions concerning that. I bit too and tried to figure out approximately how many holes I could cut out of each blade. And then it hit my wee brain. To illustrate this better, let me ask, "How many pilot holes are in this project?"

[TAIrving]

One

[Bill WIlson]

Your question demonstrates that the number of cuts (or entrance holes) is not a very good measure of the life expectancy of a blade.  One entrance hole, as in your example, can entail several minutes of actual cutting time, while others may only be a few seconds.  Most of us don't make the effort to record the actual cutting time between blade changes, so maybe the number of entry holes serves as a substitute point of reference.  Frankly, there are so many variables that affect blade life, without some controlled testing, it's hard to make accurate and objective comparisons.  Not sure where this discussion will go, but will be interested in the replies.

[barb.j.enders]

None - you can go in from the side!

 

[Jim Blume]

29 minutes ago, barb.j.enders said:

None - you can go in from the side!

 

Except that the black ring was a part of the whole piece. One pilot hole where the black, red and white come together.

[Jim Blume]

32 minutes ago, Bill WIlson said:

Your question demonstrates that the number of cuts (or entrance holes) is not a very good measure of the life expectancy of a blade.  One entrance hole, as in your example, can entail several minutes of actual cutting time, while others may only be a few seconds.  Most of us don't make the effort to record the actual cutting time between blade changes, so maybe the number of entry holes serves as a substitute point of reference.  Frankly, there are so many variables that affect blade life, without some controlled testing, it's hard to make accurate and objective comparisons.  Not sure where this discussion will go, but will be interested in the replies.

Might not go anywhere, but it may promote some thought.

[preprius]

I always thought about number of inches I am cutting.  But the other factors are thickness. 

The biggest factor is how many really tight turns. 

If I go thru a tight turn I notice a significant dulling.   So technique is important on tight turns.  Like go slow.  Motor speed and feed rate.

[Jim Blume]

Some of my patterns have some extremely long cuts in them. That will throw off the average cuts per blade. I tend to believe that heat is the major cause of blades losing their set and temper. As mentioned previously, the hardness of material, thickness including layer cutting, and speed all have something to do with blade life. But buying blades by the gross brings the cost way down and so I don't even worry about this anymore. When I can no longer feather the cuts, smoothing out the beginning to the end of the cut, I chuck it and put in a new one.

This Yin Yang Tree cut in a two stack of 1/8" Baltic Birch, was one long cut, so to not heat up the blade I ran a slower speed and took it slow on all the tight turns.

[kmmcrafts]

I'm not even sure how to touch this topic because of so many variables so I may have to reply several times when more thoughts come to mind, LOL

First and for most, I probably could give my most accurate reply of most others because I install hour meters on my saws.. Not to keep track of time for a per project like many think I would for pricing my work as the saw "run time" is completely different than actual time to do a project. This is why I always laugh to myself when someone post they run their saw 40 hours a week by themselves. I spend about 40 a week in the shop but only put about 8 - 15 hours a week on the saw in a good week.. many weeks probably not even that much time. 

Anyway, back to the topic, one variable is saw set up.. I can cut nearly 30+ or - minutes ( saw run time ) on my Excalibur running saw full speed on one blade cutting most hardwoods I think.. you can cut that time nearly in half for stack cut plywood, the glues in ply really shorten blade life a lot. But go over to my Hawk BM-26 or 226 Ultra and you can also cut blade life quite a lot.. I think those long arms swinging that blade puts a lot more stress on the blade than those short rocker arm saws.. as my DeWalt blade life is basically same as the Excalibur. To be quite honest I've never really timed how long I can cut on a blade from either saws.. I have the timer more for saw maintenance than anything but I have learned an awful lot by having that hour meter on my saws.. 

Anyway, I gotta get back out to work.. but I think the most accurate way to record blade life is going to be from a set up like I have.. hour meter that comes on with the saw switch and off with the saw switch.. I'd be happy to record some findings if it would interest others.. I mostly use Pegas MFG #3 and 5 and cut mostly Poplar, Cherry, and BBply.. Mostly always cutting 1/2 - 3/4 material by stacking or ? 

[WayneMahler]

I remember having this discussion on another site and forum. Everyone involved had a different answer or point of view. To sort of throw some extra things into the variables. Maple cuts different then pine or birch. Walnut and oak are also different just like working with cherry. Add to that the blade size and speed of blade and feed rate and most theories go out the door. I have found that with many variables we work with that I go by feel. When the bade don't feel like it is cutting easily or cleanly time to change it. When you try to keep track of everything like time on the blade and the variables sort of takes the fun out of scrolling. Just some thoughts for more consideration. For most it is a hobby. 

[dgman]

22 minutes ago, WayneMahler said:

I remember having this discussion on another site and forum. Everyone involved had a different answer or point of view. To sort of throw some extra things into the variables. Maple cuts different then pine or birch. Walnut and oak are also different just like working with cherry. Add to that the blade size and speed of blade and feed rate and most theories go out the door. I have found that with many variables we work with that I go by feel. When the bade don't feel like it is cutting easily or cleanly time to change it. When you try to keep track of everything like time on the blade and the variables sort of takes the fun out of scrolling. Just some thoughts for more consideration. For most it is a hobby. 

I’m with Wayne, I don’t count holes or time cutting or any other variable. When the blade no longer cuts the way I want it, it’s time to change it.

[OCtoolguy]

K.I.S.S.

[Wichman]

I'm always curious if the way I cut impacts the blade life. To find out means keeping some sort of track of how long (or short) the blade life is. Yes comparing cutting inch thick plywood to 1/4 inch pine is apples to oranges, and simple shapes to lots of tight corners is the same. Even at a hobby level you still want to be fairly economical with the blade usage. And that means tracking, a least a little bit, of your blade usage.

[kmmcrafts]

Probably Wayne said it best.. that is why I made a educated guess on my times as I never really paid attention to actual times.. ( I might be surprised at how wrong I may be LOL).  BUT I will go back to my thought process that keeping track of "actual cut time" rather than how many holes or how many projects etc.. would be a way more accurate test... 

Speaking of different wood types.. also consider that the same type of wood can have different density and moisture content.. probably most accurate test would also be done with BBply as in my opinion it is probably the most consistent in density etc. than any other wood I've cut. 

[Bill WIlson]

2 hours ago, dgman said:

I’m with Wayne, I don’t count holes or time cutting or any other variable. When the blade no longer cuts the way I want it, it’s time to change it.

When I show something I've cut to others, the first question I usually get is "How long did it take you to make that?"  People are often disappointed when I them I have no idea.  I also have no idea how many blades I go through on a given project...unless & until I run out.  

I will admit that I sometimes wonder about blade life, but usually only with respect to comparing different blades or different brands.  If I get 2 minutes or 20 minutes out of a blade, it's really irrelevant to me in the context of the project I'm working in.  When the blade is dull, I change it.  Doesn't matter what previous history may have indicated or what my expectations were.  However, if I happen to switch to a different brand and notice an increase or decrease in relative cutting time, then that is something worth noting for future reference.  But even then, blade life isn't necessarily the only factor I consider when deciding what blade to use.  Some blades just work better for me in a given application.  Blade life is one part of the equation, not the singular answer.

[Jim Blume]

Smart folks here!

[jr42]

Not sure about blades but I think it takes 3 licks to get to the center of a tootsie roll tootsie pop. LOL

[FrankEV]

In many hole patterns, it is not how many holes I can cut before a blade breaks, but how many holes I can thread WITHOUT kinking the blade.  When that happens I know shortly thereafter the blade will break.  

The need to use very small pilot holes for many intricate patterns make threading the blades difficult and kinking the blade much more likely.  A #2/0 spiral blade is a snug fit in a #68 drill bit hole and I have broken more than one new blade immediately after trying to thered it the first time only to have it kink.  In patterns that have larger cut outs, a larger pilot hole can be used and if I'm careful, no kinks and the blade will last a very long time.  

[Dave Monk]

Jim, Is that yin yang a segmented cut where you stained pieces different and put them back together?

[Jim Blume]

3 hours ago, Dave Monk said:

Jim, Is that yin yang a segmented cut where you stained pieces different and put them back together?

Yes Dave. I scaled it to approx. 11" and cut it in a 2 stack out of 1/8" BB. Then stained the sections different. Not sure where I found the drawing but had to work on it a bit to make it stronger on a few branches.

I had thought to try and inlay it but got lazy and took the easy way out. LOL

[John B]

I have only designed a few fret patterns, but I set myself the task of making them with as few entrance holes as possible. I believe this ads another level of enjoyment to the cutting process.

[crupiea]

One in that project, nicely done. 

For me some blades will last for days.  At other times i go through a bunch in what seems like minutes. 

I have noticed one constant.  When I am breaking a lot of blades, its always me.  I am not relaxed, not settled in but in a hurry.  I usually step away and get my head right before continuing. 

Another constant is the tighter the area I want to just make it around the corner of, thats also when they will break just to prove to me who the actual boss of the saw is. 

[Mikes shed]

For me I use alot of differnt Pegasus blades as I do alot of intricate work what i have found is that when the blade is not cutting how I like then its time to change it also if the tension is not correct the blades break quicker. and as Crupiea said it is usually me not the aw that causes them to break. a dull blade does not make a good clean cut.