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atty
12-11-2010, 08:56 PM
I have one devil of a time telling when a 4 X 6 bandsaw blade is dull beyond practical use. I use Olsen Bi-Metal, and they generally last a long time, but there's an end to all good things. I just have a hard time admitting it's time.

How 'bout 2 hours to get through 4" Hot Rolled steel, could be A36, 1018, etc?
Standard 64 1/2" blade, 10 TPI, and about 6 lbs down pressure with flood coolant. Should I make funeral arrangements? :confused:

doctor demo
12-11-2010, 09:07 PM
Did You have the saw plugged in? Or were You moving the blade by hand?:D

Steve

Davo J
12-11-2010, 09:26 PM
I cut through a piece of 6 inch round mild steel and it only took 40 minutes with a half worn blade, so I think your blade has gone.
Dave

J Tiers
12-11-2010, 09:49 PM
2 ways to tell.

1) it won't cut

2) it cuts, but wanders all over doing it.

I think you have #1...... with a 10 tooth blade, it ought to 'rip through" steel.

Weer you getting little curls of metal falling out of the blade as it exited the steel? Or were you getting dust?

You coould have a cut pressure issue... which means you may have "rubbed-to-death" that blade. It wants to keep cutting, but not so much that it fills up the gullets and starts to 'glide".

Some "hot rolled" if you don't KNOW what it is, may be 1045 or some other nasty work-hardening stuff. I have a piece of that, all I could do to cut it was slow down and keep on the pressure. If the teeth ever skidded it hardened up like armor plate.

I don't know what poundage of pressure is reasonable, I have a hydraulic damper on mine. I adjust it until I can see that I am getting little curls of metal...i.e. it is cutting to what "looks right", and does not seem to be clogging the gullets of the saw.

darryl
12-11-2010, 10:14 PM
One way to tell for sure- put a new blade on it and see.

Are the teeth pointing downwards? And they should be towards the front also- :)

atty
12-11-2010, 11:57 PM
Thanks guys. I think a fairly new 14 tpi told the story. It cut through in a reasonable time. The slice was also heavy enough to dump my coolant bucket....nice mess on the floor.

Tiers: I think you might be right on that 1045. I tried to face off the slice, and it ate a cobalt tool bit. Had to go to carbide. I was going to make a gear, but I may have to re-think the well being of my gear cutter.

This 10 tpi had the misfortune of hitting the edge of a flame cut. It cut great through the backside, but ground to a halt at the edge of the cut. I had hoped it would survive, but I guess not. Lesson learned on that dumpster diving for scraps.

Appreciate the help.

oldtiffie
12-12-2010, 04:49 AM
If you must cut across the line of a flame/plasma cut edge, mark the cut out and use a good thin abrasive cutting-off wheel in an angle grinder and cut about 1/4">1/2" deep to get away from the heat affected zone. Keep the plate cool while abrasive cutting.

Then put it in your band-saw.

I have assumed that the plate was hot-rolled mild (carbon) steel. If is something else then a whole lot of other issues may open up.

Shuswap Pat
12-12-2010, 08:43 AM
Is the blade gong the right direction?

Pat

jkilroy
12-12-2010, 09:11 AM
10 tpi is too fine for 4" solid stock, you could have 40 teeth in the cut at once. I realize a 4x6 isn't a power packing machine but you might want to keep a 4-6 tpi blade around for such cuts.

beckley23
12-12-2010, 11:07 AM
jkilroy is giving good advice, actually I would recommend a 3-4 variable pitch Bimetal blade, but I don't think the small saws are capable of pulling the cut. A good rule of thumb is to have 3 teeth minimum in the cut, the coarser the pitch the better. You don't want the blade to rub by being gentle, thinking you're going to extend blade life, you want it to cut making chips, not dust. Use a cutting oil, or set up a pump, if possible. I know it's a mess, but your blades will last longer. If you can't, for various reasons, slow down the blade and reduce the feed pressure a bit. You're going have to experiment to see what works best for your situation, and yes, you will go through a few blades for your learning curve.
Don't forget, a new blade needs a break in period, in my case it's about 2-300 square inches at half speed and feed.
Harry

gnm109
12-12-2010, 11:22 AM
Does your bandsaw have a flood coolant system? If not, you will go through blades on a regular basis. My old Enco 7 X 12" had flood coolant when I got it and blades last a very long time on that machine.

The original system had a large open reservoir in the bottom of the machine. It was disgusting. I saw that the new ones have a recovery tank so I modified my machine so that all of the coolant flows back into a tank with no open liquid. The original pump motor gave out so I replaced it with a pump from an evaporative cooler.

If you don't have coolant, it would be a straightforward matter to build such a system. Just a pump and a plastic storage box. You might have to add a sheet of steel with raised edges like I did but that would be an easy matter.

I can't remember the last time I put a new blade in the Enco and I use it quite a bit, mostly on aluminum but the coolant does the trick.

I use Mobil soluble oil, about a cup to 2 gallons with a cup of Lysol. Try it, you'l like it! :D

Here's Mr. Enco gnawing through a chunk of 2 X 2 " 6061.

http://i144.photobucket.com/albums/r188/gnm109/Machinery/EncoRebuildA.jpg

Lew Hartswick
12-12-2010, 11:48 AM
The original system had a large open reservoir in the bottom of the machine. It was disgusting. I saw that the new ones have a recovery tank so I modified my machine so that all of the coolant flows back into a tank with no open liquid. The original pump motor gave out so I replaced it with a pump from an evaporative cooler.


:-) Now you just don't see the "disgusting" part of it. It's hidden in the tank. :-)
...lew...

gnm109
12-12-2010, 12:52 PM
:-) Now you just don't see the "disgusting" part of it. It's hidden in the tank. :-)
...lew...


Correct, but it's easier to handle now. The tank is removable now and I can simply hose it out and refill when it grows a new crop of newts and salamanders or whatever those little things are. :)

fishfrnzy
12-12-2010, 02:12 PM
"Huswap

Is the blade gong the right direction?

Pat"


Very funny. Ha Ha. Did that last time I changed blades. Uncoiled it the way they coled it. Dind't look strange. Start cutting lightly to break in. Not cutting too fast. Push a little harder then a little harder still. Start thinking these new thicker blades really suck. Finally stop the saw and look, crap wrong way. Turn the teeth around ( not an easy thing on a smallish blade ). Now the blade cuts crooked. Out $ 23.00. Lesson learned, again. Did the same thing about 6 years ago, long enough to forget. I guess I need to tell them next time.

Toolguy
12-12-2010, 02:22 PM
The average recommended down force weight of a small horizontal bandsaw is 12 pounds. This is usually measured with a fish scale or similar hooked to the handle used to raise the blade. For thin material, the down force should be much less. I make my blades last longer by running them on the slowest speed in steel, faster for aluminum.

atty
12-12-2010, 05:09 PM
I use Syntilo 9902 for flood coolant when I'm cutting steel. I rarely go to the trouble of using it on aluminum, but maybe I need to start.