Straddle Chain

[Philbert]

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.

https://www.arboristsite.com/community/threads/scratcher-chain.271236/

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.



A member on another site 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]

This loop has a 0.298" pitch, and o.o80 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.



Philbert

 

[Deleted member 149229]

Back when those were common the manufacturing time would be enormous and also the cost to sell compared to today’s chains.

 

[Philbert]

Back when those were common the manufacturing time would be enormous and also the cost to sell compared to today’s chains.

I assume that the thinner bars (or wider kerf) required, might have also been an issue.

Philbert

 

[farmguywithasaw]

Cool

 

[Justsaws]

I would think that the scratcher type cutter would be less likely to pull the drive links to the side compared to a hooked cutter like chipper. Having the chain pulling to the side would be more of an issue with the straddle setup. Hard to close the rails, would have grind deeper into the bar.

Nice photos, thank you for posting and thanks to the person for helping get you some chain. Very nice.

 

[Chris Ross]

Nice pictures.

 

[svk]

Very interesting!

I’d be curious as to the inflation adjusted cost of those old chains. In this day a pro chain is somewhere at or a little less than an hour’s wage. Would be willing to bet it was a lot more then!

 

[Franny K]

The depth gauge is part of a tie strap not the cutter like now.

 

[Philbert]

The depth gauge is part of a tie strap not the cutter like now.

Good point. In this location, it also rotates as the chain passes around the nose - wonder if that provides any effective kickback reduction.

Philbert

 

[farmguywithasaw]

Good point. In this location, it also rotates as the chain passes around the nose - wonder if that provides any effective kickback reduction.

Philbert

.
I think it would increase kickback because as it rotates it would fall away from the tooth as it goes around

 

[Deleted member 149229]

.
I think it would increase kickback because as it rotates it would fall away from the tooth as it goes around

And as it rotates to the center of the bar end it would be the highest point on a bore cut.

 

[pioneerguy600]

The RPM of the saws that used straddle chain was so low that kickback was greatly reduced, the Disston saws were one slow cutting saw.

 

[sawnami]

The RPM of the saws that used straddle chain was so low that kickback was greatly reduced, the Disston saws were one slow cutting saw.

In the sequence, the left and right cutters just scored the area of wood to remove and the left, center, and right rakers chiseled out the area in between.
Max RPM on my DO-100 is 4000 and then that goes through a gear reduction.

Sent from my SM-T900 using Tapatalk

 

[pioneerguy600]

In the sequence, the left and right cutters just scored the area of wood to remove and the left, center, and right rakers chiseled out the area in between.
Max RPM on my DO-100 is 4000 and then that goes through a gear reduction.

Sent from my SM-T900 using Tapatalk

Watching that Disston cut brings fond memories of my dad and his brother competing in the woodsmans meets, they could cut 3 cuts clean through the same stick with a manual crosscut faster than the powersaw. Saws back then were just coming into a semi useful tool.

 

[pioneerguy600]

The early scratcher chain was modeled to what the crosscut saw teeth setups where, with alternating scoring points that scored the cut and the real rakers took out the curl, the wood left from the left and right scoring points. My dad was camp filer for crosscuts and manual bow saws, he could file them so sharp and well he was kept busy full time. He taught me and I still have all his tools for that type of work, he just never really caught on how to file modern chainsaw chain, that fell to me. Just a note though, modern chains do not have rakers, those bumps are depth gauges....LOL

 

[sawnami]

The early scratcher chain was modeled to what the crosscut saw teeth setups where, with alternating scoring points that scored the cut and the real rakers took out the curl, the wood left from the left and right scoring points. My dad was camp filer for crosscuts and manual bow saws, he could file them so sharp and well he was kept busy full time. He taught me and I still have all his tools for that type of work, he just never really caught on how to file modern chainsaw chain, that fell to me. Just a note though, modern chains do not have rakers, those bumps are depth gauges....LOL

So you're probably familiar with one of these.

Sent from my SM-N950U using Tapatalk

 

[pioneerguy600]

Offset tooth ring saw blade,yep. Have seen or used about every type of blade with teeth on them over the years, even owned and ran rotary and band blade mills , if it cuts wood or metal likely have had experiences with them. The Buller tooth set, no never seen that one around here.

 

[Philbert]

Just a note though, modern chains do not have rakers, those bumps are depth gauges....LOL

YES!

I try not to 'trigger' guys too much with this, but do point out that if you call it a 'depth gauge' it describes what it actually does, and then filing it makes sense!

Philbert

 

[pioneerguy600]

YES!

I try not to 'trigger' guys too much with this, but do point out that if you call it a 'depth gauge' it describes what it actually does, and then filing it makes sense!

Philbert

Yes, the depth gauge and a true raker do totally different chores and it irks me for some reason when I read posts where chainsaw depth gauges are called rakers but I have learned to ignore the reference and just move on.