Question for Machinists!?

[TopCatGr58]

Hard to get with the BAND.....saw!

Hey folks,

Okay, a short while back I got a second band saw blade from Little Machine Shop, was 6teeth per inch, vs. my oem 14T/inch blade. The coarser blade was recommended for cutting my 5.25" diameter Aluminum log slices faster, and it worked.

However, after cutting about 5 or so slices, the blade broke!

It did not separate at the weld, but about an inch or so close to it! Was a clean fracture, like a stress fracture that finally snapped!

So.....I ordered 2 more, only $12.95 ea. Put the new one on, and after only 5 slices, it broke!!!

I then put the 3rd one on, and finished cutting up that log, now have about 9 1.25" thick slices!! But I can't figure out WHY the blades are breaking?!

I've got the tension set just so that the blade is taught, but I can still move it a good 1/2" or so sideways at the long section between the large rollers on the slack=non cutting side! It's not getting HOT at all. The teeth are still razor sharp! I'm not sitting there pushing down on the blade/handle, just letting GRAVITY gently push the assembly down onto and into the workpiece!

Starrett Premium Hard Back BandSaw blade 64-1/2" x 1/2" x 0.025" thick. The 6S blade is for cutting sections over 1" thick. These blades fit the popular 4x6 bandsaw sold by Grizzly, Harbor Freight, etc..

Applications are light to medium vert. and horiz. machines, tool room and maintanence, low alloy, non-ferrous metals. Economical production cutting, increased tensile strength. More accurate and straighter cuts. Improved Blade rigidity for increased cutting rates.

They do sell another blade that is over twice the price, Powerband Matrix II, same teeth set. It's described as a BI-metal blade, a steel cuttng edge welded to an alloy steel back!? I guess you get what you pay for!?

I tried rewelding the broken one back together, but my MIG wire feeder was TOO HOT for it, just melted it! I might be able to find a shop that can weld bandsaws!?!?
T.C.

[Ken Talbot]

I've never tried it on a metal cutting blade, but I've silver soldered lots of wood cutting bandsaw blades back together. I use a fine belt sander and a jig to bevel the broken ends, clamp them in a jig with a fine ribbon of silver between the beveled faces, then hit it with a pencil flame propane torch. I've workken on blades from 1/8" to 1/2" and have saved myself a few buck$ along the way.

[Trikerneil]

When I did my apprenticeship all the vertical bandsaws had a jig mounted to them to cut the ends of the broken blade square. A resistance welder was also fitted so that the butted ends could be rewelded.
The ends were clamped into the jaws of the welder, just touching each other to complete the circuit. A button was pressed which allowed the current to flow. when the joint had reached melting point the jaws moved toward each other making the butt weld. The excess metal was ground or filed off.
A local machine shop may be able to help here.

I have also silver soldered bandsaw blades. You need to scarf the joint to give a larger surface area.

Have a look at:-

www.homemetalshopclub.org/news/jun02/jun02.html


QUOTE

If you use carbon steel blades, the recommended blade tension is 15,000 psi. I use 0.25 in. thick blades which vary from 1/8 in. - 3/4 in. width. For bimetal and carbide tipped blades, the tension should be 25,000 psi or 66% larger than that shown in the accompanying table.

Carbon Steel
Blade Tension

1/8 in. 47 lb.
1/4 in. 94 lb.
3/8 in. 141 lb
1/2 in. 188 lb.
3/4 in. 281 lb.

ENDQUOTE

I think the "0.25 in thick" must be a typo, it's should probably be "0.025 in thick"

[LoserShoes]

If the blade is breaking close to the weld, then it probably was not annealed properly when it was welded. A better quality blade should help.

Also, are you using any kind of a lubricant? A bit of kerosine or wd40 will help keep the blade from gallling and binding, which puts alot of stress on the weld.

Learned to use a bandsaw blade welder as an apprentice, and it definatly takes good technique to weld and anneal the blade to keep it from breaking.

Steve

[TopCatGr58]

Good Customer Service!

Hey guys,

Just on a lark, I decided to write/email LMS and describe what had happened to the new blades. They replied saying that they should not have broken, and are sending me 2 replacements for the 2 that broke, and also a shipping RMA label so that I can send the broken ones back...they suspected a bad batch/lot??

They, too, suggested some lubricant! I guess that's what happens when you grow old!! Just wanted to tell about their good service!!
T.C.

[TopCatGr58]

Well,
I received the replacement bandsaw blades yesterday, will package up the old broken ones and send them back, they provided a return shipping label for FREE!!

Secondly, I've been doing a bit o research on trying to find more stock aluminum in the 5.25" round bar size I use. Yarde Metals is the source I've used for several years, first with their 6061 1" thick plate, and then recently with the round bar, their Cold Formed stuff.

I then found/saw that they also provided round bar in Extrusion format, for about 1/2 the price of the C.F. stuff!! I've done some searching, but can't find any information on the DIFFERENCE between the aluminum in this size having been cold formed vs. Extruded, with regards to strength, machinability, finish, etc.?

Here's a copy of the email I have sent them inquiring about this:

Dear Yarde Metals,

I have been a patron of your Drop Zone products for a few years. I make a simple part for vintage motorcycles out of 5.25" 6061 aluminum round bar. I cut it into 1.20" thick sections, and then mill and lathe it with a simple recess and 20mm x 1.5mm threaded center hole for mounting in combination with adhesive fixing to the motorcycle engine to act as an adapter plate to attach a spin on oil filter.

The reason why I provided this information is in inquiring about the use of your Extruded 5.25" 6061 round bar vs. the Cold Formed version that I have been using. I've done extensive searches trying to find out the difference "if any" between the density, strength, machinibility, finish characteristics of the C.F. round bar vs. the Extruded round bar.

The extruded round bar that you sell is almost 1/2 the price of the C.F. in the same dimensions that I require. Can you tell me whether the above workability properties are the same between these two difference types of round bar??

Anybody here know the answer??
T.C.