# did 30 seconds cutting steel at standard speed ruin by band saw blade?



## dansawyer (Apr 14, 2019)

The band saw is a 30 year old Craftsman 12 inch. Life time use is less that 10 hours. I had forgotten about steel requiring a speed reducer. I purchased a 80" (6' 8") x 1/2" x 14tpi Imachinist Metal Cutting Bi-metal M42 blade. I proceeded to cut a single 3/8 inch diameter steel rod. The cut went smoothly and quickly. I was satisfied I had solved by steel cutting problem. 
I then was distracted by another project and moved on. To get to the point the next project with the band saw was to cut a 3/8 by 3 inch piece of 6061 aluminum. This was a disaster. The saw cut very slowly; less than an inch per minute. The aluminum became very hot. 
Did I ruin the blade with the single steel cut? Is this the wrong blade? 
The blade still eels sharp. I have been cutting steel with bi-metal reciprocating saw. Those blades seem to last for about 1 square inch before they noticeably feel dull. The band saw blade feels more like the unused end of the cut off blade then the worn cutting area. 
Videos show band saws ripping through aluminum like it was wood.


----------



## kb58 (Apr 14, 2019)

For steel, it's typically 150-200 fpm, while aluminum is up around 1000-2000 fpm - note the huge difference in speed.

Also, a fabricator told me that with most mild steels (depending upon source and quality) it's a gamble what's in it. They melt down all sorts of steel, including ball bearings buried in donor material. If one of those isn't completely melted, and you try sawing through it, yeah, it can get ugly. I've run into something like that myself, where it was cutting just fine, then just stopped. Cut in the other way and it stopped at nearly the same point. Just sayin'

Oh, and don't overlook tooth type and count. The rule of thumb is 2-3 teeth on the material at all times, so if you're cutting sheet, that needs 14-18 tpi, but for 3/8"-thick material, it's only 8 tpi. Admittedly, using the wrong count doesn't hurt, but very much affects cutting speed and whether the blade tends to load up (remember, add wax when cutting aluminum).


----------



## Cobra (Apr 14, 2019)

If you had the blade speed set for wood, then yes, likely the blade is toast.


----------



## projectnut (Apr 14, 2019)

Blade speeds for cutting metals generally much slower than wood.  My horizontal metal saw has speeds of 60, 100, and 160 feet per minute.  The harder the metal the slower the speed.  If the bandsaw you are referring to is a wood saw the blade speed is an all likelihood too fast.  Standard wood saws have a blade speed between 1,500 and 3,000 ft. per minute.  At the very minimum you knocked the set off the teeth, but if you are running at the speed required to cut wood you probably ruined the blade.
As for the tooth count.  The rule of thumb is a minimum of 2-3 teeth in contact with the material and a maximum of 24 teeth.  With less than than minimum number of teeth are engaged you're likely to knock a tooth off the blade.  With more than the maximum number of teeth engaged you're likely to fill the gullets and cause the blade to slip on the wheel, pop off the wheels, or break.

Here's a link to a Lenox Guide to Band Sawing:


			https://www.lenoxtools.com/Guides/LENOX_20Guide_20to_20Band_20Sawing.pdf


----------



## Latinrascalrg1 (Apr 14, 2019)

Did you attempt to cut the steel again to see if the blade is actually dull or if its the different material thats the problem?


----------



## Asm109 (Apr 14, 2019)

Slow cut and hot Aluminum are two sure signs of a dull blade.  Yeah, one steel cut toasted the blade.


----------



## rgray (Apr 14, 2019)

dansawyer said:


> I had forgotten about steel requiring a speed reducer.


So your bandsaw is still at wood cutting speeds?



dansawyer said:


> I purchased a 80" (6' 8") x 1/2" x 14tpi Imachinist Metal Cutting Bi-metal M42 blade.


14 tpi is very slow in aluminum, and the teeth like to plug up making things  hot.



dansawyer said:


> Videos show band saws ripping through aluminum like it was wood.


Cutting your aluminum on a wood bandsaw works well. Speed is up and teeth are open and don't plug up.
Have to be carefull starting a cut as there will likely be only one tooth contact at first.
The cutoff piece will be cool enough to hold in your hand when done.


----------



## pacifica (Apr 14, 2019)

dansawyer said:


> The band saw is a 30 year old Craftsman 12 inch. Life time use is less that 10 hours. I had forgotten about steel requiring a speed reducer. I purchased a 80" (6' 8") x 1/2" x 14tpi Imachinist Metal Cutting Bi-metal M42 blade. I proceeded to cut a single 3/8 inch diameter steel rod. The cut went smoothly and quickly. I was satisfied I had solved by steel cutting problem.
> I then was distracted by another project and moved on. To get to the point the next project with the band saw was to cut a 3/8 by 3 inch piece of 6061 aluminum. This was a disaster. The saw cut very slowly; less than an inch per minute. The aluminum became very hot.
> Did I ruin the blade with the single steel cut? Is this the wrong blade?
> The blade still eels sharp. I have been cutting steel with bi-metal reciprocating saw. Those blades seem to last for about 1 square inch before they noticeably feel dull. The band saw blade feels more like the unused end of the cut off blade then the worn cutting area.
> Videos show band saws ripping through aluminum like it was wood.


A dremel with an alum oxide bit, 1/8" diameter and you can resharpen the blade. Leave it on the saw while you sharpen. Might take 30 minutes


----------



## projectnut (Apr 14, 2019)

You must have far more patience and skill with a Dremel than I do.  On my Startrite saw the blade is a little under 8 1/2' long.  That translates to 1350+ teeth @14tpi. Even if you did manage to stay conscious and sharpen all the teeth I doubt there would be enough set left in the teeth for them to clear the chips through the kerf.  At $26.00 per blade I'll just go over to the Ellis factory about 10 miles away and have them make me a new blade.

Just a heads up, I usually get about 2 years use from one of their bimetal blades if I run it at the right speed.


----------



## rwm (Apr 14, 2019)

I have done this by forgetting to change the transmission. The blade is probably toast. $50 lesson. At least that is what I pay for Bimetal Diemaster.
Robert

For the record, my usual technique to ruin a blade it to cut thin stainless and rip off a group of teeth.
R


----------



## pacifica (Apr 14, 2019)

projectnut said:


> You must have far more patience and skill with a Dremel than I do.  On my Startrite saw the blade is a little under 8 1/2' long.  That translates to 1350+ teeth @14tpi. Even if you did manage to stay conscious and sharpen all the teeth I doubt there would be enough set left in the teeth for them to clear the chips through the kerf.  At $26.00 per blade I'll just go over to the Ellis factory about 10 miles away and have them make me a new blade.
> 
> Just a heads up, I usually get about 2 years use from one of their bimetal blades if I run it at the right speed.


It's interesting you criticize something you've never done.


----------



## projectnut (Apr 14, 2019)

I'm not criticizing you or your skills.  I'm just saying that given the ordeal that the blade has already been through I would not spend the time and effort needed to attempt to revive it.


----------



## stupoty (Apr 14, 2019)

pacifica said:


> It's interesting you criticize something you've never done.



I don't know man , it definitely looks like you would need nearly saintly patients.

but it could be an interesting form of meditation I guess 






Stu

Edit , he says it took him about 2h at the end.


----------



## pacifica (Apr 14, 2019)

stupoty said:


> I don't know man , it definitely looks like you would need nearly saintly patients.
> 
> but it could be an interesting form of meditation I guess
> 
> ...


I leave the blade in the machine , much faster than opening and closing vise. Last blade I did took 45 minutes for 700 teeth. The blade is sharper than a factory blade when done. Also I use +2 magnification.


----------



## stupoty (Apr 15, 2019)

pacifica said:


> Last blade I did took 45 minutes for 700 teeth.


Thats quite impressive, maybe I will have a go on a spare blade I have kicking about.




pacifica said:


> Also I use +2 magnification.


I'm always tempted to get an opti visor kind of thing 

Stu


----------



## Latinrascalrg1 (Apr 15, 2019)

stupoty said:


> I don't know man , it definitely looks like you would need nearly saintly patients.
> 
> but it could be an interesting form of meditation I guess
> 
> ...


Is this a video on how NOT to sharpen a bandsaw blade??? I mean unless overheating the cutting tips in the process is to be desired which is pretty obvious in the video I would look for a better example!

I spent more then enough time sharpening chainsaw blades in my life to know just how unfun and monotonous that task can be but on the flip side i know how expensive and wasteful it is to not maintain a sharp chain not to mention the fact i NEVER had any free time and I Usually Always had more free time then wastable cash so if i wanted to eat Right I had to keep those chains sharp or it would be a mac & cheese kinda night!   Anyway I eventually learned to Not "Hate" it so much and found the meditative therapy potential to be quite soothing at the end of a hectic day.


----------



## stupoty (Apr 15, 2019)

Latinrascalrg1 said:


> Is this a video on how NOT to sharpen a bandsaw blade??? I mean unless overheating the cutting tips in the process is to be desired which is pretty obvious in the video!



I am no expert on blade sharpening , I was just curious at the time taken to sharpen one.  

He is using it to cut wood though so in his case perhaps he can afford a little loss in hardness ?

Interestingly the Wandel just dabs the teeth and doesn't worry about the gullet bit.






Stu


----------



## Technical Ted (Apr 15, 2019)

How does your blade "feel" by touch? How does it look? You can use a magnifying glass if needed... If it feels like it has good set and sharp teeth and looks good you should be OK. If it's so dull it can't cut you should be able to tell.

Ted


----------



## ezduzit (Apr 15, 2019)

Asm109 said:


> ... Yeah, one steel cut toasted the blade.



This is the correct answer. The blade is shot.


----------



## pacifica (Apr 15, 2019)

stupoty said:


> I am no expert on blade sharpening , I was just curious at the time taken to sharpen one.
> 
> He is using it to cut wood though so in his case perhaps he can afford a little loss in hardness ?
> 
> ...


The blades I sharpen have set , to the left and right. The problem with his jig(in the video) is he doesn't take that into account. I use a small diameter stone that fits in gullet, and don't leave it there long enough to heat up the metal.I tilt the dremel either up or down so I maintain the set.The top of the hook receives one or two strokes from a diamond stone(taking off the burr).
When I did my carbide wood bandsaw blade(800 teeth) I used eze-lap  1/4 by 1/4 by 6 diamond files  https://smile.amazon.com/gp/product/B002RL84BW/ref=oh_aui_search_asin_title?ie=UTF8&psc=1. Took  an hour but the carbide blade stays sharp for years.  That lenox blade has right set, left set and a straight tooth all in a row. clean the  blade before starting.


----------



## stupoty (Apr 15, 2019)

pacifica said:


> I used eze-lap 1/4 by 1/4 by 6 diamond files



Yeah the diamond files sound like a fairly sensible thing to sharpen with.

Stu


----------



## pontiac428 (Apr 15, 2019)

First time I tried cutting metal with my newly reduced drive pulleys on my 14" Enco, I was sure I had the blade moving slow enough.  I turned that imported 14 TPI saw blade into a smooth bimetal steel belt in seconds on 1/4" mild steel.  I was still pushing 1000 IPM, so obviously needed to change out more pulleys.  Oops.  That was long enough ago that I don't feel bad about it anymore.


----------



## rwm (Apr 16, 2019)

The video with the jig actually looks viable. Of course any of us would build it out of titanium and automate it with motors and solenoids! However, how much do I need to sharpen the blade to replace the missing teeth? 
Robert


----------



## pacifica (Apr 17, 2019)

This looks fast and accurate:  



. No good if you break the teeth,


----------



## rgray (Apr 17, 2019)

rwm said:


> However, how much do I need to sharpen the blade to replace the missing teeth?



Just smooth that area so the blade doesn't jump on the stock when it gets to that spot and keep on cutting, get your money's worth..


----------



## MrWhoopee (Apr 21, 2019)

Bear in mind that on a bi-metal blade the teeth are high-speed steel, the band is not. Missing teeth cannot be replaced by grinding new ones into the band material. Typically, one would just grind a taper on the teeth following the missing ones so that they don't grab and get ripped out too.


----------



## ezduzit (Apr 21, 2019)

MrWhoopee said:


> ...Typically, one would just grind a taper on the teeth...



Typically one would simply throw it away and buy a new blade.


----------



## MrWhoopee (Apr 21, 2019)

ezduzit said:


> Typically one would simply throw it away and buy a new blade.


Yes, but if it's a $100 blade and you don't have it, or the job needs to be finished today and the replacement can't be had until tomorrow.....


----------



## ezduzit (Apr 21, 2019)

MrWhoopee said:


> Yes, but if it's a $100 blade and you don't have it, or the job needs to be finished today and the replacement can't be had until tomorrow.....


 
That blade was not $100. And you need to keep a new spare blade standing by.


----------



## Latinrascalrg1 (Apr 21, 2019)

ezduzit said:


> That blade was not $100. And you need to keep a new spare blade standing by.


Not everyone has the ability to have spare everything in their shop "just in case" mr Murphy shows himself!
Nor is everyone into the "Throw Away world" many seem to be in.....

The tip for relieving the next few teeth after the missing teeth is a very good tip.


----------



## ezduzit (Apr 21, 2019)

Latinrascalrg1 said:


> Not everyone has the ability to have spare *everything* in their shop "just in case"...



Come on!

Do you resharpen dull razor or jigsaw blades? No, you keep spares of items that get used up.


----------



## MrWhoopee (Apr 21, 2019)

We had a rush job brought to us on Wednesday, delivery due first thing Monday morning. The material arrived late Friday afternoon and I asked 3 machinists and our "saw boy" to work overtime on Saturday. At about 8:30 Saturday, the "saw boy" came into my office very distressed, telling me he had torn some teeth off the blade. He had replaced it with our last spare blade and promptly did it again by trying to resume the same cut. I kept my cool, grabbed a die grinder and relieved the teeth behind the missing ones. He learned a couple of important lessons and we made delivery.

As a rule, you wouldn't do this, and it won't help if the blade has been fully dulled by excessive speed. It is one of those tricks to keep in your bag when the situation requires it. When I worked in a saw shop, we routinely resharpened bandsaw blades for commercial woodworking shops. Razor blades and jigsaw blades are fairly cheap. To the newbie hobbyist, the immediate loss of a $26 blade is very discouraging, even more so if he doesn't know why. Some people have more time than money, so attempting to resharpen a blade is a personal call and, if not effective,  is still educational.

FWIW, I have been buying Chinese bi-metal blades for my HF 4x6 for about $16 apiece (2 at a time, so I have a spare). They have proven to be wholly adequate. If cost was no object or I was doing production work for profit, I would buy Lenox.


----------



## Latinrascalrg1 (Apr 21, 2019)

ezduzit said:


> Come on!
> 
> Do you resharpen dull razor or jigsaw blades? No, you keep spares of items that get used up.



well lets say you bought a saw blade that you did pay $100 for that was still in relatively good condition if it wasnt for a few missing teeth, would you still be so willing to throw it out?


----------



## ezduzit (Apr 21, 2019)

dansawyer said:


> The band saw is a 30 year old Craftsman 12 inch...80" (6' 8") x 1/2"...





Latinrascalrg1 said:


> well lets say you bought a saw blade that you did pay $100 for that was still in relatively good condition if it wasnt for a few missing teeth, would you still be so willing to throw it out?



Your hypothetical is far from the OP's situation, where he completely destroyed a very cheap blade. However, just to answer your hypothetical, I would cut out the tiny fraction of an inch (a few teeth at 14 TPI) and re-weld it.

I have ruined blades. Once I tried cutting a portion off a deep socket to re-purpose it. Wow! Was that hard!  Barely scratched the socket. Threw away the blade. These are expensive but good lessons.


----------



## Latinrascalrg1 (Apr 21, 2019)

ezduzit said:


> Your hypothetical is far from the OP's situation, where he completely destroyed a very cheap blade. However, just to answer your hypothetical, I would cut out the tiny fraction of an inch (a few teeth at 14 TPI) and re-weld it.
> 
> I have ruined blades. Once I tried cutting a portion off a deep socket to re-purpose it. Wow! Was that hard!  Barely scratched the socket. Threw away the blade. These are expensive but good lessons.



Funny that you say my Hypocritical is way off base when i was referring to your comments above in which you were talking about missing teeth on a bandsaw blade and how you suggested to just throw it away when a "fix" was suggested by another member to avoid throwing it away!    I  personally dont see how im off base as you say but im willing to listen as to why you think I was.
  BTW why is it now you change your answer from replace to now repair? Was it simply because of the hypothetical $100 value?


----------



## ezduzit (Apr 21, 2019)

Latinrascalrg1 said:


> ...why is it now you change your answer from replace to now repair? Was it simply because of the hypothetical $100 value?



I didn't change my answer.

To the OP: throw the ruined blade away.

To your hypothetical "relatively good condition $100 blade with a few teeth missing" repair.


----------

