Band Saw Blade TPI?

[JWB_Machining]

Hey,

I know this is vague and kind just a judgement call but if you were ordering a band saw blade and your application was to cut all sorts of metals and even wood and you were going to be dealing with various thicknesses how many Teeth per inch would you get on your blade?

If it makes as difference I'm using an old DoAll MP-20, the blade is 13 ft 4" - 13 ft 6" i'd say.

[Geof]

A 'rule of thumb' is to always have three or more teeth in contact at all times with the metal being cut so if you plan on cutting all the way down to 1/8" you need to stick to 18 tpi.

That is a bit fine for cutting large stock and is almost worthless on aluminum so a compromise is something around 14 or 12, maybe down to 10 which will allow for cutting practically anything.

You just have to be careful with a coarse blade because if you forget and stick in a piece of tube with thin walls you will very rapidly strip the teeth off the blade or break it.

[MrWild]

You can't and you shouldn't. I think three blades. When yousay all sorts ofthicknesses, you threw in the towel. Thickparts require fewer teethper inch. Each tooth needs a pressure against it to cutwell, and if yougo with a fine tooth forsheet metal, all you will do is dull it with thick. If you use a wider profile with less teeth per inch, you will snag and break off teeth on the thin stuff. Wood cuts require four or five times the speed (why you have a dual range gear box).

6 teeth per inch for thick stuff.
12 teeth per inch for medium.
up to 24 for thin.

You may think that the 12 is right in the middle, but you suffer at both ends when you try to use it where it shouldn't be. Rule of thumb is three teeth in the part you're cutting.

[DareBee]

In my jobbing shop we also cut a ridiculous variety of material.
If you use a good quality blade, coolant and adjust your feed accordingly you can get away with 1 maybe 2 blades.
Like mentioned above, it is not "proper" but you can't make a living if the blade has to be changed every 20 minutes.

I always buy and run the correct pitch and geometry if I have a big, specific, job or a specialty application.

If you need to do more than 1 cut through a 4x4 (wood) once a week you will want a blade for (lets say solid aluminum) that will double as a wood blade for regular but non-production use.

Anyway - to the blades.
If my memory is good, your saw is more-or-less direct competition for my HydMec S20 and is a top quality machine. Band size should be 13'6" x 1" x .035".

Over the years a have found Bahco, Starrett and Lennox to be my favorites.
I use a heavy tooth 4-6 TPI for almost everything (11ga tubing, 8"dia 6061, A2-D2 solids, you name it).
Currently Bahco has whored themselves out at a stupidly low price for this http://www.bahco.com/files/Bandsaws%...jrshgbrpqi.pdf extremely good blade in OUR size only (13'6").

my .02

[djr76]

If you have an acct with MSC/J&L, they will even send out a saw tech to tune your saw for you for FREE.


I go along the lines to what DareBee says and I use Lennox 4/6 tooth bimetal blades for all my stainless/aluminum/plastic cutting needs. Anything under 3/4 of an inch, I use a cold saw so I have no need for more than 1 type of bandsaw blade.

[Geof]

Of course you can always take my ultimate approach after being frustrated; first, by someone neglecting to keep the downfeed very slow when cut thin stuff with a coarse blade (thereby stripping the teeth off0, second, by the slow cutting on aluminum when we switched to fine tooth blades to combat the firsrst frustration.

Buy two saws, one for steel one for aluminum. The extra capital cost was recouped in about a year as a result of less waiting time.

[DareBee]

As I tried to imply above, you are right Geof.
You are also a completely different shop environment than me.

If my saw ran 8 hrs a day cutting (heck even 6hrs) and half of it was always steel tubing and the other half was always aluminum solid, I would have another saw in here in an instant (and it would be automatic too).

My saw has paid for itself many times, but a second saw would not and it would also take up too much precious fabrication space.

On another note, I tried a 5-8TPI blade for awhile and it generally was too fine so it had poor service life compared to the 4-6.

My guys are pretty good at using the saw correctly. Heck, they are all highly paid tradesmen.

[JWB_Machining]

I went with the Lennox Classic Bi-Metal 1" Wide 4-6 TPI and 8-12 TPI, anything in particular I shouldn't be able to do with this other than things thinner than 1/4'? Basically what is outside the realm of these blades? Thanks for all the info everyone.

[DareBee]

With an 8-12 blade you can cut sheet metal man.
We have no trouble cutting .100 tubing with a 4-6.
Although the 8-12 is the proper choice.
The 4-6 is still too fine if you do find yourself cutting a lot of large aluminum solids or wood.

That is a HQ blade, enjoy