Sawzall Blade Teeth - How?

[meintsi]

How are the teeth cut into the band material for a sawzall/jigsaw type blade?

Are they ground, laser cut, or other?

Any info would be appreciated.

Remember...
"If you don't use your head,
your going to have to use your feet."

 

[1ranger2]

Don't know why it would matter ... used to be punched and ground for jig saw. Band saw/sawzall appears to be simply punched and tempered. Care to discuss how they make Orings?

 

[Vonmagnuson]

O-rings are molded. That's simple.
How do they make ball bearings so perfectly round?

 

[MikeMilburn]

Well, how?? ...Mike

 

[1ranger2]

Good question. I've been wondering how they make ball bearings so precise for ages. Someone?

 

[chassisdeeziner]

Ball bearings....if I remember what my college roommate told me (he iterned at the Timken plant in SC).....

It's all about surface tension. A blob (excuse the technical term) of molten metal is discharged from a nozzle into air. The surface tension of the material causes it to assume the shape of a sphere (some theory here about spherical shapes being the most stable) as it free falls. The molten ball falls into a bucket of cold water where it solidifies. After that, there are some secondary ops to get the surface finish right).

 

[MikeMilburn]

Sounds about right, I remember watching a show awhile back on PBS about making lead shot for muskets way back when. The used to take molten lead and drop it from a height into water, you'd think the resistance of the air would cause the drop to form in the shape of a raindrop but apparently not...Mike

 

[1ranger2]

Timken bearings are top of the line. Is your roommate still there? The answer, it seems, lies in the "secondary ops" for the precise finish. Not asking for trade secrets, just a general idea. I threw this out at break this morning with some of the old mech eng guys and they were as puzzled as I was. Don't think it was ever covered in any of my classes. One guy suggested maybe a ball mill? Thought they were used for a different purpose. Can't be too hard - they've been around for ages. One of our co-workers "knows everything" but he doesn't know this. More imput would be appreciated.

 

[patdaly]

Im not so sure the secondary ops. might not be some form of Cryo. or other post manuf. process. The reason I say that is does anyone else remember the Shuttle mission where one of the Experiments was to produce a more perfect Bearing? I seem to remember that they thought the Vacuum of space would allow a more perfect drop?

 

[rcinhb]

Hi,

Many years ago I saw some ball bearings being lapped. The lap used two 6 foot diameter cast iron disks with pitch and lapping compound. The upper disk was rotating, and I can't remember if the lower disk rotated or not. The lower disk had a very fine spiral groove in the surface.

Rough but reasonably round balls were introduced into the center of the lower disk at the beginning of the spiral. While in the spiral groove, the balls rotate within the groove and also move through the spiral. By the time the ball gets to the outer edge of the spiral, it has been lapped to the proper diameter and it is also spherical because of the raandom rotation of the ball within the spiral groove has lapped off all the high spots.

If you imagine hundreds of small balls inbetween the two lapping plates, then it is apparent as to why the process can produce balls with such precision in the diameter.

Ever made meatballs or spherical cookies? You make a meatball by parallel but counter movement of the material between the palms of your hands. Similsar deal here

 

[metman]

CHASSISDEEZINER,
I'm curious how your roommate learned this at Timken. Timken does not make ball bearings. They only make tapered roller bearings. I also assumed that Timken made ball bearings until I became involved with bearing design and analysis.

Jesus is THE life,
Leonard

 

[tomwalz]

Timken gets really serious about bearings. They seem to know an awful lot about related issues. Also making a perfect circle or cone can be similar to making a perfect sphere.

Tom

P.s.
I don't have a relationship with Timken. It's been awhile but I just like the way they do things. They take a lot of pride in making a simple product supremely well and they seem to really care how well it works for the actual user.

 

[metman]

Tom,
Yes I have had the same experience with Timken. If not the leaders in bearing metallurgy, they surely are among the top runners. Bearing life has been dramatically improved over the last 25 yrs or so be reducing the size and count of non-metallic inclusions from improved meting/remelting practices. Consequently Timken has become a prime supplier of specialty steels.

Jesus is THE life,
Leonard

 

[1ranger2]

Thanks for the input ~ Richard's theory of lapping makes a lot of sense.