'Invention' of Square Ground Chain?

[Philbert]

OK, so we 'know' that Joseph Cox invented modern saw chain back in 1946 or so, and founded what became Oregon Chain: http://www.oregonproducts.com/homeowner/company/history.htm

His patent for chipper chain was granted first:
http://pdfpiw.uspto.gov/.piw?PageNu...ttp://patft.uspto.gov/netahtml/PTO/patimg.htm

But it appears that he applied for an earlier patent on square ground chain? (granted later):
http://pdfpiw.uspto.gov/.piw?Docid=...patft.uspto.gov%2Fnetahtml%2FPTO%2Fpatimg.htm

I was trying to understand why square ground chain cut faster - I thought that it was a logger innovation. This looks like Joe Cox thought of that first, and later designed chipper chain because it was easier to sharpen (one of his claims). But the patents don't reference each other, as far as I can see, and he appears to have used different patent attorneys to file.

Anyone familiar with this part of chainsaw history?

Thanks.

Philbert

 

[z71mike]

Great read, Philb. Thx bud.

 

[Philbert]

So nobody has a story about a PNW logger who figured out that square ground chain was better because:

? flat cutting edges are better than hollow ground ?, or

? a vertical side plate edge enters the cut earlier than a 'hooked' one ?, or

? one or more angles are more acute ?, or

? the 'boxed' corner cuts better than a 'pointy' corner ? or

?
?
?

Philbert

 

[MustangMike]

I recently got some Stihl RSLK and PFERD 3 square files and I will give it a try when I get my saws back from Randy. Likely I will have something to say about it in late April, I won't get a chance to use it till tax season is done. I'm hoping ported saws and square cut chain will make an awesome combo.

My nephew (MechanicMatt) says he saw a ported 044 at an event that was an absolute animal. I'll have to ask him what chain it was running.

 

[redfin]

Philbert you are a plethora of chain inquistions. I would like to try some square ground soon.

 

[CR888]

l always appreciate it Philbert!

 

[z71mike]

Switching to square is like adding 10cc to your saw. Love it.

 

[Philbert]

Switching to square is like adding 10cc to your saw.

What makes it cut faster?

Philbert

 

[z71mike]

I don't really know. But if I had to take an engineer's stab at it, I'd say it's probably taking a bigger chunk out.

See it like this: Take a regular round ice cream scoop. Dig it in and pull up a scoop of ice cream. Examine the hole it left. Now go get your welder and make a square ice cream scoop with a width equal to the diameter of the round scoop. I would imagine the hole it leaves in the ice cream would be roughly equal to the volume of the prior round hole, plus the new area edged-out by the corners on the square scoop.

That might be why there's a difference. It could also be due to the 2 cutting surfaces of square grind as opposed to one continuous edge on a round tooth. But I can't provide any synopsis on that end.

Hopefully this will start some discussion and we can figure it out. I like this kinda stuff.

 

[RedFir Down]

What makes it cut faster?

Philbert

I'll take a stab at it... When you stop to think about the angles, top plate, hook and side plate that equals a more efficient cutter. That creates more wood chips on your boot faster!!
I built a chain vice thanks to Philberts chain vice thread and have been playing around with file square... im enjoying it!!

 

[mdavlee]

The square tooth isn't pulled as hard to the side as a round filed tooth with it's sharp point. It's mostly in the top plate and a tiny bit of side plate that does most of the cutting. The square top plate is a more efficient cutting edge. Like a sharp chisel vs a hawk bill pocket knife. Both are sharp but a chisel will remove a lot more wood easier.

 

[MustangMike]

My 2 cents ... because the outside of the tooth is square, making the inside square also results in a more efficient cutter. Round file would be like sharpening your knife at different angles along the edge. Round file is easier to do "Good", but properly done square file is "Great".

 

[Stihl 041S]

Any machinist understands a smaller radius is less of a load and square filing is for better chip generation.

At the same time it is not as tough.

 

[sachsmo]

Even an old putz who ran an Acme screw machine learns a bit about reliefs and cutting angles.

Personally, never got into pure square filing, it will no doubt be on me bucket list, but full chisel round can be filed into a pretty fast chain too. (gotta learn to walk before ya run eh?)

 

[Stihl 041S]

Even an old putz who ran an Acme screw machine learns a bit about reliefs and cutting angles.

Personally, never got into pure square filing, it will no doubt be on me bucket list, but full chisel round can be filed into a pretty fast chain too. (gotta learn to walk before ya run eh?)

You be right there.
I can lance a boil. Brain surgery later. Lol
We had Davenports, B&S Swiss style and a 3 spindle 6" multi spindle. Guy down the street had a 3 spindle 12". Massive.
The Davenport 5 spindle were our work horses.
Hey Mo!!

 

[sachsmo]

How ya doing Unc!


Here's a very interesting chain, it came to me several years back with a 50" Cannon Super Bar.


I don't know what the guy/gal was after, and have never seen another sharpened quite like this one?

I have looked it over many times and marvel at the precision and uniformity, my guess is the person had some real thought and time put into this;

 

[Stihl 041S]

Trying out a new grinder and just never cleaned it up??

 

[sachsmo]

Any machinist understands a smaller radius is less of a load and square filing is for better chip generation.

At the same time it is not as tough.

Like anything else, there are trade-offs.

Longer lasting equals not as fast cutting, faster cutting usually means shorter life.


Top fuel Drag Racing teams have figured how to make 8000 Horsepower from 500 cubic inches, unfortunately they only last about 4 seconds before they go BOOM!

 

[sachsmo]

Trying out a new grinder and just never cleaned it up??

Pictures do that chain no justice.

You have to look at it in person to get the impact of the work done.

I can sharpen a drill better than new (freehand) but there is no way I could replicate that chain!

 

[longbowch]

So nobody has a story about a PNW logger who figured out that square ground chain was better because:

? flat cutting edges are better than hollow ground ?, or

? a vertical side plate edge enters the cut earlier than a 'hooked' one ?, or

? one or more angles are more acute ?, or

? the 'boxed' corner cuts better than a 'pointy' corner ? or

?
?
?

Philbert

I don't know anything about square ground chain, but have you ever looked at Madsens site? Seems to be a lot of info there,