Rim Sprockets and Filing Guides

[Full Chisel]

Welcome to AS!

I would highly recommend getting a Granberg File'n'Joint guide. It makes consistent filing a breese and gets your chains SHARP. You will be able to use it on all your saws.

 

[Teddi]

LCS sells 325/7 rims in "mini" spline for Stihl clutch drum applications. 11892 is for Oregon "small" spline and was never intended to work for Stihls. Your choices for Stihl rims are either to use GB or get bent over by your local Stihl dealer. My local dealer quoted me $16 for a rim for my 261. LCS sells GBs for $1.50 and Oregons for four and change.

 

[SawTroll]

There are of course no evidense open to the public about supposedly secret business deals - but they still are just about everywhere around us.

Stihl is currently are using a lot of Husky and Oregon developments, some because the patents have ran out, and some as results of business deals.

 

[Franny K]

LCS sells 325/7 rims in "mini" spline for Stihl clutch drum applications. 11892 is for Oregon "small" spline and was never intended to work for Stihls. Your choices for Stihl rims are either to use GB or get bent over by your local Stihl dealer. My local dealer quoted me $16 for a rim for my 261. LCS sells GBs for $1.50 and Oregons for four and change.

You are not comparing apples to apples here. I have bought the mini spline genuine Stihl 7 tooth 0.325 sprocket from Apex hardware in Marietta Ohio and it was like $7. If I recall the mini spline picco sprocket was the most expensive at that time and right around the same price. LCS, and yes I have bought one for the price you state. In this you get what you pay for take a micrometer to the diameter and see how much it varies, take a close look at the finish inside the splines where it will contact your drum. The notable thing I think is it has the holes to clear debris on the sides instead of the larger radial holes one usually sees in a 0.325 7 tooth. I kind of doubt the path for those is normal they must have some mass deal at one time.

 

[Swamp Yankee]

How do you know that they are sand cast?

Philbert

Philbert, what process do you think they're made from? It's not PM. forging. part's way to big for MIM and production ones certainly aren't hogged out of bar stock. Please set me straight if I'm wrong.

The most probable candidate is investment cast, also called lost wax casting, read up on it. Most efficient way to produce a part with that net shape. The wax "negatives" are placed in molds then packed with sand, which provides the texture of the outer surface. The particle size or grain of the sand can produce a rough or relatively smooth surface. With a good casting house you can get very good control of the outer surface finish if you specify it.

Fishing up in Maine right now, will look more closely at the parts when I get home.

As to my resume, I'll put my 30 years of mfg. and Engineering casting and molded parts from hand tools to jet engines and military cranes up against someone eyeballing texture and finish.

And, I never said they were not made by the same company, only that being able to tell so by looking at the surface texture of 2 parts is hogwash. A position I still stand behind.

Tennis anyone?

Take Care

 

[Whitespider]

The most probable candidate is investment cast...

The Stihl website claims their rim sprockets are sintered steel... so not cast from molten steel, rather formed from powdered steel under intense pressure at temperatures something less than melting point.

http://www.stihl.com/stihl-chain-sprockets.aspx

Stihl is currently are using a lot of Husky and Oregon developments, some because the patents have ran out, and some as results of business deals.

A lot of Husqvarna and Oregon developments??
How many is a lot??
Which ones can you name??
*

 

[Franny K]

The Stihl website claims their rim sprockets are sintered steel... so not cast from molten steel, rather formed from powdered steel under intense pressure at temperatures something less than melting point.

What does investment cast mean?

I never studied powered metalurgy a lot of nuts and bolts are made that way I understand do they count as sintered.

 

[Franny K]

As to my resume, I'll put my 30 years of mfg. and Engineering casting and molded parts from hand tools to jet engines and military cranes up against someone eyeballing texture and finish.

And, I never said they were not made by the same company, only that being able to tell so by looking at the surface texture of 2 parts is hogwash. A position I still stand behind.

Tennis anyone?

Take Care

Would the simple spark test be of any use in determining this stuff?

 

[Whitespider]

What does investment cast mean?

http://thelibraryofmanufacturing.com/investment_casting.html
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[Philbert]

Philbert, what process do you think they're made from?

You were challenging Sawtroll making assumptions about the sprockets based on their appearance. Then you assumed that they were made a certain way by appearance? Lots of ways to cast things, and lots of variations.

Tennis anyone?

Your court.

Oregon has made a lot of private labeled chains and parts sold as OEM through the years. They used to promote this in a brochure placed in stores titled something like, 'Chances are that the chain that came on your saw was made by us'. Some of these parts may come from multiple sources, depending on where they are sold. Similar looking castings may have different metallurgy, or be heat treated differently, etc. Parts that look the same may be functionally different. Parts that perform functionally the same may be cosmetically different, etc.

I have confidence in both 'STIHL' and 'Oregon' branded rims. The Oregon ones typically seem to be priced a bit lower. Not sure if any of the third party rims ('JAX', etc.) wear any faster or fail more frequently.

Philbert

 

[Swamp Yankee]

You were challenging Sawtroll making assumptions about the sprockets based on their appearance. Then you assumed that they were made a certain way by appearance? Lots of ways to cast things, and lots of variations.

Not so

I made a statement based on knowledge of what volume manufacturing processes would produce parts of that net shape and size with minimal qualifying machining, not solely on the appearance of surface texture / finish of two parts that are deemed "identical" by the naked eye of someone with no apparent experience in these manufacturing processes and no QC or Eng specs to back it up.

Based upon WS' input, sintered metal conpression mold would be a good choice as well as investment cast, both will produce the internal spline within usable tolerances without machining. Need to see the parts, as stated not home to see how the slots are put in machined or as cast.

And as previously stated :

And, I never said they were not made by the same company, only that being able to tell so by looking at the surface texture of 2 parts is hogwash. A position I still stand behind.

which is the point you seem to be deflecting away from.

Take Care

 

[Swamp Yankee]

Would the simple spark test be of any use in determining this stuff?

Ballpark as to metallurgical composition.

Not conclusive proof both parts came from the same manufacturer.

Take Care

 

[Philbert]

Sawtroll was also basing his statement on industry knowledge - the kind that is often shared by reps and industry insiders. Don't underestimate what Niko knows about saws!

Need to see the parts, as stated not home to see how the slots are put in machined or as cast.

I looked at a few rim sprockets I have. On the STIHL and Oregon rims the outside diameter appears to have been machined/surfaced smooth. The inside diameter, slots, and sides all appear to have the same texture. On a 'JAK MAX' sprocket (from Bailey's), the texture appears uniform over the entire sprocket - outside diameter does not appear to have been machined.

Philbert

 

[OldJack]

The Stihl website claims their rim sprockets are sintered steel... so not cast from molten steel, rather formed from powdered steel under intense pressure at temperatures something less than melting point.

The porosity of sintered metal is controllable, so you can spec it to soak up a given amount of oil. I would think it's a case of balancing porosity and strength. Sintered roller chain was used on agricultural equipment at least 30 years ago.

 

[Whitespider]

The porosity of sintered metal is controllable...

That be true... but a lot more than porosity is controllable (and highly repeatable). Strength, durability, and machinability, resistance to wear, deformation, and heat, etc., etc., etc. The variables include the size of the powder grains, the composition of the powder (including non-metallic elements), rate of compaction, heat, and so on... and, depending, the part may receive further "treatments" after forming to change or enhance characteristics.

Given the process of sintering steel, I would guess (it's a guess) that neither Oregon nor Stihl produce their own rim sprockets... both likely farm out the production. I would also guess that the rims purchased in North America are made in a different facility than those purchased Europe... heck, possibly the rims in Vermont are produced in a different facility than those in Iowa. It also wouldn't be a surprise to learn one or more of those manufacturers make the rims for both Oregon and Stihl... or that one or more of those manufacturers are owned (partly or wholly) by Blount International (parent company of Oregon) and/or Stihl International. And, given the number of variables in the process, Oregon and Stihl rims may, or may not, be made to the same specifications/price point.

Of course, that's all speculation on my part... just using my limited knowledge of international corporations and manufacturing for the reasoning.
Could be all Chinese produced... or Mexico... or Uganda... or all of those... or none.
And again, just speculating, I don't see how either Oregon or Stihl could (cost effectively) build in a sintering production facility just to make a few chainsaw rim sprockets... heck, the sprockets would cost 20 times what they do if that was the case.
Naw... my guess is they both farm it out... (it's a guess)
*

 

[Franny K]

Sawtroll was also basing his statement on industry knowledge - the kind that is often shared by reps and industry insiders. Don't underestimate what Niko knows about saws!


I looked at a few rim sprockets I have. On the STIHL and Oregon rims the outside diameter appears to have been machined/surfaced smooth. The inside diameter, slots, and sides all appear to have the same texture. On a 'JAK MAX' sprocket (from Bailey's), the texture appears uniform over the entire sprocket - outside diameter does not appear to have been machined.

Philbert

Have you measured those MAX sprockets outside diameter for consistency both at various places around the diameter and the side with the debris clearing openings vs the solid side? I have some other branded ones that are not finish ground and the side with the cut outs shrunk compared to the other one.

 

[Philbert]

None of the rim sprockets I have are side ported. I have seen that on some older ones.

Interesting point on the finish grind. I assumed that this was done for roundness, final dimension, and balance. I mic'd the (new) JAK MAX sprocket (just for you!) and there was some side-to-side variation on rim diameter of a few thousandths (as well as some concentric variation). I don't know how much of a practical matter this makes, but they do appear to be less precise.

This one just happened to come in a Bailey's order and has not been mounted. Can't say whether it vibrates more, wears faster, breaks easier, etc. At a minimum, they left off at least one finishing step.

All this talk about casting, alloys, etc. got me thinking. Using an 'old days' mindset, when we returned soft drink bottles, you would think that companies would offer a 50 cent 'core charge' on rim sprockets, which could easily be melted down and recast into new ones. So little of the sprocket is actually worn away when it is 'used up', and it does not have to be disassembled or separated into individual components (like a saw chain, for example) to get uniform material.

Philbert

 

[Whitespider]

...you would think that companies would offer a 50 cent 'core charge' on rim sprockets, which could easily be melted down and recast into new ones.

But, it appears, rim sprockets are not made from "melted" (molten) "cast" steel... at least according to the Stihl website theirs ain't.
I could be wrong, but I don't believe it's possible to use sintered steel for sintering again... the whole molecular bonding thing (shrug)
*

 

[Franny K]

None of the rim sprockets I have are side ported. I have seen that on some older ones.

Interesting point on the finish grind. I assumed that this was done for roundness, final dimension, and balance. I mic'd the (new) JAK MAX sprocket (just for you!) and there was some side-to-side variation on rim diameter of a few thousandths (as well as some concentric variation). I don't know how much of a practical matter this makes, but they do appear to be less precise.

Can't say whether it vibrates more, wears faster, breaks easier, etc. At a minimum, they left off at least one finishing step.



Philbert

These do seem to wear in so the differences minimize. The thing I will note is that as you adjust the chain tension it gets tight and loose. The danger of cutting one's fingers moving the chain if gloves are not worn is greater than you are used to. At least when the out of round gets close to 10 thousands.

 

[Philbert]

I'm not a metallurgist, and I don't play one on TV. It was just a thought. Maybe not a good thought. Just a thought . . .

Philbert

P.S. Maybe if someone is really bored, and has a torch, they could try melting down a few old (or new!) rim sprockets and see if they puddle?

P.S.2 - Noticed some minor discrepancies on that STIHL website:
"STIHL spur chain sprockets are permanently attached to the clutch drum by a special soldering process."
"All spur chain sprockets are thoroughly tested again with computer-assisted test methods before being brazed onto the clutch drum"

Also a few typos:
"The teeth of the chain sprocket press against the drive link tanks and the saw chain starts to rotate."

So maybe the spur sprocket teeth are sintered and the rim sprockets are cast? Maybe some are made one way and others another? Maybe technical folks from STIHL, Oregon, and other manufacturers should participate more on A.S. and give us the straight story? Maybe unicorns will show up to mow my lawn . . . ?