Straddle Chain

Philbert · Oct 15, 2019

When chainsaws were in the early stages of development, a number of different saw chain designs were also tried. Some cutters were based on manual crosscut saws, called 'scratcher chain', which was common until the forerunner of 'modern' saw chain was patented by Joseph B. Cox, the founder of Oregon Chain, around 1946.

Things that we take for granted, such as drive links running in a groove of the guide bar, were not standard. Some chains straddled a solid bar, possibly due to the difficulty or cost of cutting a groove all the way around a solid piece of metal.

@ajschainsaws very generously shared with me a loop of straddle chain, which is different from our conventional chain in other ways as well. I don't know if the drive links meshed with the drive sprocket along their sides, or if those recessed cut-outs at the bottom played a role.

With the 'drive links' on the outside, it has 2 different 'tie straps' on the inside, including a form of bumper link (reduced kickback?). Also, it uses straight gauge rivets.

What is also interesting is that most straddle chain (as I understand it) was made very early on, when scratcher tooth chains were used. This loop has chipper teeth.

Philbert

Philbert · Oct 15, 2019

This loop has a 0.298" pitch, and 0.080 gauge.

Mike Acres very informative website shows a Disston, scratcher type straddle chain, dated at around 1948:
http://www.acresinternet.com/cscc.n...963cd301d169b02a88256e170011ab5e?OpenDocument

But I did not see this particular loop, and there are no markings on the chain that I can see. So, I am not sure of the manufacturer or the age, since it is in very good condition. Maybe @ajschainsaws received some packaging with it?

Link to original post: http://opeforum.com/threads/what-brand-of-chain-is-this.14947/page-2

Philbert

ajschainsaws · Oct 15, 2019

Philbert said:
This loop has a 0.298" pitch, and o.o80 gauge.

View attachment 203559

View attachment 203560

Mike Acres very informative website shows a Disston, scratcher type straddle chain, dated at around 1948:
http://www.acresinternet.com/cscc.n...963cd301d169b02a88256e170011ab5e?OpenDocument

But I did not see this particular loop, and there are no markings on the chain that I can see. So, I am not sure of the manufacturer or the age, since it is in very good condition. Maybe @ajschainsaws received some packaging with it?

Link to original post: http://opeforum.com/threads/what-brand-of-chain-is-this.14947/page-2

Philbert

I will check the crate with all the bars and chains in too see if there’s any
Of these chains with packaging

Dub11 · Oct 15, 2019

@sawnami has a saw that uses this I think.

sawnami · Oct 15, 2019

Dub11 said:
@sawnami has a saw that uses this I think.

It's a Disston DO-100 with a straddle scratcher.

Sent from my SM-N950U using Tapatalk

hseII · Oct 15, 2019

sawnami said:
It's a Disston DO-100 with a straddle scratcher.

Sent from my SM-N950U using Tapatalk

Wow

Sent from my iPhone using Tapatalk Pro

sawnami · Oct 15, 2019

hseII said:
Wow

Sent from my iPhone using Tapatalk Pro

Here's a video of it cutting.

Sent from my SM-N950U using Tapatalk

Philbert · Oct 15, 2019

sawnami said:
It's a Disston DO-100 with a straddle scratcher.

Very pretty saw.

How well does the oiler work? Do you end up with oil all along the sides of the bar? Any other things those of us with conventional bars and chains might not think about with the straddle chains?

Thanks.

Philbert

sawnami · Oct 15, 2019

Philbert said:
Very pretty saw.

How well does the oiler work? Do you end up with oil all along the sides of the bar? Any other things those of us with conventional bars and chains might not think about with the straddle chains?

Thanks.

Philbert

Thank you!
It oils profusely with a curtain of oil covering the bar. It uses crankcase pressure to push oil out of the oiler valve. It's controlled by an adjustable needle at the oiler outlet. The bar is very thin and rigid. There is no flex at all in the bar. The links that are seen on the outside of the bar are what meshes with the sprocket which has clutch plates integrated into it to absorb shock loads. The whole saw is unique. It doesn't have a carburetor. It uses a form of mechanical fuel injection.

Sent from my SM-T900 using Tapatalk

Philbert · Oct 15, 2019

sawnami said:
The links that are seen on the outside of the bar are what meshes with the sprocket which has clutch plates integrated into it to absorb shock loads . . . . The whole saw is unique. It doesn't have a carburetor.

Love to see a photo of the links meshing with the sprocket, if you get a chance. No rush.

No carb? That is unexpected!

ajschainsaws · Oct 16, 2019

sawnami said:
Thank you!
It oils profusely with a curtain of oil covering the bar. It uses crankcase pressure to push oil out of the oiler valve. It's controlled by an adjustable needle at the oiler outlet. The bar is very thin and rigid. There is no flex at all in the bar. The links that are seen on the outside of the bar are what meshes with the sprocket which has clutch plates integrated into it to absorb shock loads. The whole saw is unique. It doesn't have a carburetor. It uses a form of mechanical fuel injection.

Sent from my SM-T900 using Tapatalk

Amazing design thanks for sharing this information I have several loops of this
Chain and it’s great to know what saw uses them

sawnami · Oct 16, 2019

I found a pic of the sprocket when I had it dissembled and of the chain in my filing vise.

Sent from my SM-N950U using Tapatalk

deye223 · Oct 16, 2019

I would have thought that scratcher chain would cut a lot faster as it technically cuts like a saw bench ......

sawnami · Oct 16, 2019

The max RPM on that Disston is 4000 RPM and it's a gear reduction drive to boot so chain speed is fairly slow.

Sent from my SM-N950U using Tapatalk

sawnami · Oct 16, 2019

Here's a couple pics under the drive cover.

Sent from my SM-N950U using Tapatalk

Dub11 · Oct 16, 2019

sawnami said:
The max RPM on that Disston is 4000 RPM and it's a gear reduction drive to boot so chain speed is fairly slow.

Sent from my SM-N950U using Tapatalk

SmartSelect_20191016-082538_Samsung Internet.jpg

90cc with gear reduction, old timey thinking is kind of funny.

Did anyone else use this straddle chain?

AuerX · Oct 16, 2019

sawnami said:
Here's a video of it cutting.

Sent from my SM-N950U using Tapatalk

Incredibly cool

Makes cutting wood look outright soothing!

Philbert · Oct 16, 2019

ajschainsaws said:
I have several loops of this Chain and it’s great to know what saw uses them

I don't know if your loops are interchangeable with the Disston one shown. Might be differences in pitch, gauge, drive link profile?

Philbert

Philbert · Oct 16, 2019

sawnami said:
Here's a couple pics under the drive cover.

These are great - Thanks!

I expected to see a sprocket with a divider that the chain could straddle, like the bar, to keep in on track. But it looks like there is some kind of 'splitter' (?) to guide the chain onto the bar?

Philbert

ajschainsaws · Oct 16, 2019

Amazing information everyone;e @Philbert i will check the other loops of chain and see if there’s any variations

Straddle Chain

Chainsaw Enthusiast

Chainsaw Enthusiast

Axes never run out of Gas

Saw R skeery

Here For The Long Haul!

AKA - Karenberly's Husband

Here For The Long Haul!

Chainsaw Enthusiast

Here For The Long Haul!

Chainsaw Enthusiast

Axes never run out of Gas

Here For The Long Haul!

AIR FUEL SPARK VROOOOOM

Here For The Long Haul!

Here For The Long Haul!

Saw R skeery

Constantly Confused

Chainsaw Enthusiast

Chainsaw Enthusiast

Axes never run out of Gas

Similar threads