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Guero
02-18-2005, 07:36 AM
While I am awaiting delivery of my new bandsaw blade I got to wondering if these blades should be "broke-in" in some fashion. I'm pretty confident I can set the blade up as it is supposed to be in the machine, with correct alignment and tolerances of the blade guides as well as cranking down on the tension knob when I'm ready to cut. Do you run the blade for a while without cutting anything to allow it to better conform to the wheels/guides or do you just go straight to work with it?

topct
02-18-2005, 08:43 AM
I don't think I've ever heard of breaking in a saw blade of any kind. However, taking a few light cuts at first probably wouldn't hurt. You could see that it is tracking right before you plowed into something.



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Gene

pgmrdan
02-18-2005, 08:57 AM
I know my blade is 'broke in' when it's dull. http://bbs.homeshopmachinist.net//biggrin.gif

A blade doesn't require breaking in. In fact, I've never heard of breaking in any cutting tool whether metal working or wood working, unless you consider 'sharpening' breaking in.

Just use it.

cwhorton
02-18-2005, 09:07 AM
A Lennox blade rep told us to "break-in" a new blade by running it on some material with a very very light feed pressure, in fact, just get it into a cut so the teeth are at their full gullet depth, then hold the blade off for a few complete revolutions. After that, just business as usual I guess.

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Charlie
Eastern Maine, USA

Bruce Griffing
02-18-2005, 09:43 AM
Bandsaw blades often break due to cracks that originate from the back of the blade. A good practice is to round the corners of the back of the blade with a stone. This is done with the blade installed and moving. Doing this will also help prevent the back of the blade from catching on curved cuts.

Guero
02-18-2005, 09:45 AM
Thankee for the responses. I asked because I remembered having heard at some point in my life that initial lights cuts were useful in "breaking the blade in". Perhaps that was old technology, however, since I know there have been some changes in the last decade or so in blade manufacturing. I'll do what Charlie suggests - go with a extremely light feed, etc.

Michael Az
02-18-2005, 10:17 AM
Yes, there is a break in for a new blade. If there is any chance you have a bunch of aluminum to cut, that will do it. If not, then reduce the feed 50 percent for a while like another poster mentioned.
Michael

lynnl
02-18-2005, 10:21 AM
Somewhere, a couple of years ago, I read that it was a good practice to make a few initial cuts on soft stuff like brass or aluminum before using on harder mat'l like steel. As I recall, the writer was attributing that advice to one of the blade manufacturers.
I haven't followed that advice tho. Just too lazy I guess.

precisionworks
02-18-2005, 11:08 AM
All the big names (M K Morse, Lennox, Starrett) have fairly detailed break in instructions. They say that proper break in burnishes the extremely sharp tooth edges, gives longer blade life, better cut quality, etc. Here's a short article:

http://www.industrialmachinery.com/Parts/sawblades/sawblades.html


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Barry Milton

Guero
02-18-2005, 11:29 AM
Thankee Barry. Now that is exactly what I was looking for.

Your Old Dog
02-18-2005, 02:18 PM
I recently read it was best to take some light cuts on round stock for first few cuts. It made sense to me. When I was gun engraving I would draw the handchisels over some 4/0 emery paper to "pre-ware" the tool tip to keep is from breaking so easily. Razor sharp engraving chisels are extremely fragile if you don't pre-ware them. I figure a bandsaw to be not much more than hundreds of chisels on a ribbon of steal.

I makes sense to me that round stock would be easier on the blade for first few cuts than square stock as the energy would likely be trasfered to more than one tooth much quicker. Until that happens, you have several hundred pounds pressure on each fragile jagged tooth till more teeth are fully engaged.

ray....

pgmrdan
02-18-2005, 05:20 PM
Some of the 'break in' information here sounds more like deburring because the manufacturers are too cheap to do it themselves.

darryl
02-19-2005, 01:45 AM
I would tend to think that the first 20 seconds or so of the blade cutting something is going to break off most of the flashing or burring off the teeth. During that time, those particles need to be able to exit away, so the blade shouldn't be deep into a cut, just entering a half-tooth depth or so into the 'break-in' piece. Maybe make a few separate entry points into the break-in piece. I'm no expert on this, but it seems logical to me.
During normal cutting, each tooth would carry its chip away in front of it, but during break-in, the flashing will be jamming along side the blade. You'd probably want to use light pressure to minimize the effect that this unusual swarf could cause to the blade. I think I actually may have ruined my first replacement blade by not going easy on it for the first short while.
Now I'm going to check out that link that Barry posted.

torker
02-19-2005, 08:32 AM
Actually I've sort of wondered the same thing. I've run a lot of band saws for wood cutting, from 14" hobby saws to big saws in shake mills. We were always told to "joint" the blades before cutting with them. All this amounted to was holding an old grinding stone (lightly) against each side of the blade for a few rotations. This was supposed to knock back any errant teeth so they all cut the same. It does make a difference in the finished product and the blades seem to cut smoother. I've never tried it with a metal saw...figuring that the hard stuff I was about to cut would take care of it for me.
Russ

Spin Doctor
02-19-2005, 12:07 PM
While blades in Metal cutting saws should be broken in the biggest single source of blade failures IMO is the lack of sufficent tension of the blade itself. A properly tensioned blade should be in the range of 40 to 50,000 psi of tension on the blade

mochinist
02-19-2005, 01:47 PM
That chart is nice if you have a super duper expensive bandsaw and can accurately control the speeds and feeds. When you put on a new blade just take it easy for the first few cuts, I have put on new blades on are bandsaw at work and proceeded to cut 316 stainless. The blades are fine and usually last us about six months. We only buy lennox blades, they are the best. Starret also makes a fine blade.

Pgmrdan claims he knows his bandsaw blade is broken in when it is dull http://bbs.homeshopmachinist.net//confused.gif. That is weird never heard that before, most machinist I know would tell you that when the blade is dull it is time to change it.

spope14
02-19-2005, 02:04 PM
On this board two years back, i heard of this for the first time. Being a teacher, thus in charge of all aspects of he shop, i got tired of th blades going to hell after a month, so i tried th break in of cutting brass as suggested then on all my blades. I would cut four pieces off out of 1 1/2" diameter or four little pieces out if 1 1/2" square brass - little slices, moderate feed.

In the two years since, I have probably changed three blades total on my horizontal bandsaw and my vertical bandsaw combined (I use the Matrix II blades from Starrett). before, it was four to five a year each. Out of the three, one was due to complete ignorance an misuse by the operator, or it would be two. Taught this to the welding teaher as well, he replaced one in the two years where he would replace three to five a year before.

I have a 17 year track record of teaching this stuff, and this "break in", be it a wifes tale, witchcraft, or whatever....I swear by it now. Does not matter how or why, it works. Maybe it is just the fact that by breaking in a blade, you tend to be more careful in actual opertion, and take that 'extra step' of ownership and pride in your work - rather than just bulling through th job......

precisionworks
02-19-2005, 06:40 PM
SpinDoc, read an article years ago about setting the tension with a musical pitchpipe. Used to do it that way until it got to be second nature. Sounds like the lowest string on a guitar.

Guero
02-19-2005, 06:51 PM
Well, I got my replacement blade today and placed it on the bandsaw. I appreciate all the responses. I'll be breaking it in by following as closely as I can the instructions on the webpage posted by Barry. Since this blade cost me as much as it did, I would prefer it last as long as possible. I also agree that tension is very important and the best rule of thumb I've heard for the small Asian bandsaws is to just crank down as tight as you can on the tension knob.

Spin Doctor
02-19-2005, 07:43 PM
<font face="Verdana, Arial" size="2">Originally posted by precisionworks:
SpinDoc, read an article years ago about setting the tension with a musical pitchpipe. Used to do it that way until it got to be second nature. Sounds like the lowest string on a guitar.</font>


Oh yah that will work seeing as I can't caarry a tune in a paper sack and have a deaf ear to start with

PS. To quote Leo Kotcke my singing voice is like goose farts on a windy day

[This message has been edited by Spin Doctor (edited 02-19-2005).]

Tom CPM10V
02-19-2005, 10:59 PM
#1: As I recall, many years ago, Fine Woodworking magazine ran an article that recommended [1] running HSS blades for cutting wood, and [2] running VERY high tension. Soon there were letters to the eds indicating users were breaking the upper wheels spindle on 14" bandsaws.

#2: One blade mfger recommends running lowest practicable tension on their blades: to tune their blades, crank up the tension and progressively reduce it until blade begins to vibrate noticably, and then snug it up slowly until a 'sweet spot' is reached.

I have found lots of truth/merit in [1] dressing the back of the blade irredspective of material to be cut, and [2] dressing the sides to cut wood or rigid foam s m o o t h l y.

precisionworks
02-20-2005, 12:47 AM
Tom, I remember that article. The popular homeshop 14" bandsaws (Delta & clones) are limited in frame strength,brearing load capacity, and have the ability to properly tension a 1/4" blade, not much more. Metal cutting saws typically have a boxed frame, heavier bearings, and normally run higher tension (as SpinDoc mentions).

On the woodworking saws with rubber tires, it's best to release blade tension at the end of use. Otherwise the rubber will take a set & get lumpy. I've never seen a recomendation to release tension on a metalworking saw, in fact Lennox & Morse say it's unnecessary.

I agree with everything you said, as it applies to woodcutting saws. The metalwork saws use a different set of rules.

pgmrdan
02-20-2005, 07:23 AM
Are you guys really serious? I came back to see what was added after about 2 days. I'm having a hard time believing you guys are seious with this topic.

Do you break in your hacksaw blades? How about your hammers and screwdrivers? Should I use a new punch on aluminum the first few time to burnish the point before I use it on steel? http://bbs.homeshopmachinist.net//biggrin.gif

Spin Doctor
02-20-2005, 08:57 AM
While I remember the Fine Woodworking article (some of the stuff they have is great, but some of the stuff in realtion to machinery and the lack of real mechanical knowledge displayed is laughable sometimes IMO)it did bring up bth use of musical tones to set the tension and the use of a Starrett Saw Blade Tension Gage. As if we all have one of those in your box. On our Marvels at work when doing PMs on them We would check the hydraulic tensioning setting for accuratecy. Throwing the gage on we'd run the blade tensioning screw to the stop as required and the saws would always come out right around 40,000#. But for a Home Shop converted 14" Delta'/clone. Let's see, 40,000PSI tension on a 1/4" blade on a 14" band saw equals a total of 250LBS of tension on the blade. This is assuming that the blade is .025 thick and has no teeth for a width of .25". The area of the cross section of such a blade is .00625 square inches. Let's assume a 4TPI blade then we are talking around 160 to 180 LBS of tension on the blade. Not knowing the pitch of the blade tensioning screw I have to guess at the torque required to reach that but 10 FTLB sounds reasonable. For metal I really don't think that blades over 1/4" wide should be used in the converted 14" band saws anyways. At work I use 1/4" blades in the Do-All MetalMasters we have as I find the blade just about right for most contour sawing

pete913
02-20-2005, 10:02 AM
According to both Lennox and Morse, to name two manufacturers I know of, there is most definetly a break in procedure for bandsaw blades. People who don't follow it are normally rewarded with short blade life, broken teeth etc. I know a few guys who USED to run our large vertical hydraulic feed bandsaw at work who thought blade break in was a lot of BS. their blade life was sometimes measured in minutes. the guy who runs it now, his blade life is more like months.

J Tiers
02-20-2005, 11:09 AM
I have certainly heard of a break-in on hacksaw blades, use them on non-ferrous for a while before cutting steel with them. Reasons in detail inknown to me, but it seems to make a difference.

A bandsaw is just a long hacksaw. But many/most folks will have a couple of hacksaw frames......

I have ONE bandsaw, an old Atlas. If I replace the blade, I can guarantee that I will cut whatever I have to on it right away. I have never cut brass on it, and hardle ever aluminum.

I think I can gurarantee that if the blade breaks getting some cutting work finished out in industry, it will be replaced, and go right back to cutting off the prehardened 4140....Nobody is gonna bother waiting two weeks, two days or two minutes cutting something else to "break it in".

precisionworks
02-20-2005, 12:03 PM
Operators who don't follow manufacturer's written procedures make those sellers very, very happy $$$. If you have more money than time, it doesn't matter. Most of us don't.

Thrud
02-20-2005, 12:38 PM
I always slightly round the back edge of the blade in vertical bandsaws - they ALWAYS cut better - expecially in wood. This would work on standard band saws as well. Tiy round the backside of the blade while the saw is under power

Jim Bass
02-20-2005, 01:14 PM
Many years ago an old machinist that was mentoring me stopped me while I was running a mill with a new end mill that was chattering a little. He took a stone and gently ran it up and down the cutting flutes once, then said "try that". The chatter stopped and the finish was better. When I asked why that was, he said "the cutter was too sharp". After many years I think I figured it out. Run your finger down the cutting edge of a new end mill. Run a stone up and down the cutting edge and now run your finger up and down it. It should be smoother. I think what causes the chatter and poor finish is a new cutter does not have a fine edge on it like when you hone a knife. I have noticed the more I pay for a cutter the finer the edge seems to be. I always hone reground cutters, that makes a world of difference. Maybe that is why breaking in a bandsaw blade is recommended. The shop I work at only one person is allowed to change bandsaw blades and he always backs off the feed on the first cut.

Yours, Jim

mochinist
02-20-2005, 01:21 PM
<font face="Verdana, Arial" size="2">Originally posted by pgmrdan:
Are you guys really serious? I came back to see what was added after about 2 days. I'm having a hard time believing you guys are seious with this topic.

Do you break in your hacksaw blades? How about your hammers and screwdrivers? Should I use a new punch on aluminum the first few time to burnish the point before I use it on steel? http://bbs.homeshopmachinist.net//biggrin.gif</font>

Are you serious? The manufacture recommends a break in and you still don't believe it. Comparing hammers screwdrivers and punches to a bandsaw blade is just moronic. I agree that some of the guys on this board tend to be perfectionist and read into something like breaking in a blade and take it alittle to serious. Saying that I dont think it is a bad thing, it is there time and money and if gets them a longer blade life then more power to them.