Improper chain seating?

[large edward]

Sorry about the dark picture, but this doesn't look right to me.... Can anyone tell me if this is the "normal" way a chain is supposed to fit over a bar sprocket? It looks like it would easily come off. Problem? Thanks.

 

[computeruser]

Could it be a case of 3/8" pitch chain on a .325" bar?

 

[retoocs555]

Could it be a case of 3/8" pitch chain on a .325" bar?

I agree

 

[upandcommer]

looks like a close enough fit to be mini 3/8 aka 3.65 sprocket and full 3/8 chain

 

[woodfarmer]

what is chain pitch?

chain not compatible with the bar, pitch of chain could be .325 and the bar requires 3/8?

 

[GitWood]

chain not compatible with the bar, pitch of chain could be .325 and the bar requires 3/8?

I would say that it is the other way around. That is definately a 3/8 chain (Oregon 72). The teeth on the sprocket are spaced more closely together than the drive links on the chain. More than enough to be the difference between 3/8 and 3/8lp. I would say 3/8 chain on .325 sprocket nose for sure.

 

[JeffHK454]

Man the sprocket is sticking way out of that bar, could that be a poorly located tip?

JH

 

[large edward]

Thanks for the input. Both the chain (Oregon 72) and the bar (GB Power Tech) are supposed to be 3/8, and that is how the GB bar and packaging is marked, model #UHL20-50SG. It is supposed to be 20" 3/8 pitch bar for 70-link chains, and the chains I received were marked as 72LG-70 link. Anyone else have any ideas?

 

[cuttinscott]

The bar is a .325" instead of a 3/8"

Scott


with 72LG

with 20LP

 

[large edward]

Thanks cuttinscott, I think you nailed it. Probably pretty unusual for a bar to be improperly marked by the manufacturer. Unfortunately, this set up was sold to me (on-line) as part of a new saw purchase.

 

[Urbicide]

Is the drive rim/sprocket correct?

 

[large edward]

Urbacide, I just confirmed that the sprocket is 3/8 - 7 (Dolmar Power Mate). Oddly enough, it appears to have been installed upside down, i.e., the solid side was inboard and the side with the hollowed cavities was out, just opposite of the two illustrations in the PS5100S owners manual, though no mention is made in it of any proper orientation. Should that matter? Might it pose a heat dissipation problem or anything else? Inquiring minds... Thanks.

 

[Urbicide]

I can't say if it would really make a difference which way the rim was installed. It wouldn't hurt to flip it around so that you could read the nomenclature on the side. I believe the rim on my 372XP is solid on both sides.

 

[SawTroll]

looks like a close enough fit to be mini 3/8 aka 3.65 sprocket and full 3/8 chain

The regular 3/8 and the 3/8 lo-profile are actually the same pitch - .367 or so....

 

[SawTroll]

I agree

Me too - the nose sprocket is a .325 one, regardless what the package says.

 

[large edward]

Well I discussed this with my dealer today (who happens to be a sponsor of this forum) and he stated it's fine, not a problem and he even looked at the same setup in his shop to confirm that.

What's interesting though, is that in GB's part numbering system for their saw bars, an SG designation = 10 sprocket teeth and an SL (I think it was) designation = 11 sprocket teeth. This GB bar is stamped an SG, but has 11 sprocket teeth (counted them more than once).

Either GB has deliberately changed this 20" 3/8 bar to an 11-tooth sprocket to work on a Dolmar PS-5100S, or I have a mismarked bar. My real concern is, however, safety. I tested the saw this afternoon in some dry firewood and it kicked ass.

Comments or advice? Thanks.

 

[Lakeside53]

If the pitch is correct, it shouldn't matter how many teeth a sprocket tip has.... assuming the bar tip is profiled for it. If someone has fitted a larger sprocket in a bar designed for a small sprocket, well that's just nutz.

It's not fine. I have never seen a chain ride around a tip like that unless there is a problem. Buy a bar that fits the chain. It's unsafe.

 

[large edward]

Uwharrie, if you're out there, I would sure like to see your response to these comments. I was planning on using the saw tomorrow, but some are suggesting that's a bad idea. Thanks.

 

[Uwharrie]

I agree, as the picture shows it's not correct. I sent you a PM and we will do whatever to correct it. Tony

 

[ol'homey]

They put an 11 tooth sprocket on a bar tip that was designed for the smaller diameter 10 tooth sprocket. I wonder how many bars they made like this?