Nose Sprocket Rescue - Illustrated!

[apn73]

Philbert, thanks again for posting over in my thread about the chainsaw incident. I finally have the storm damage all cleaned up and am now able to think about something else. I was looking at the sprocket tip on my Tsumura guide bar and it's got 4 rivets holding in the sprocket, and the dimpling on the rivets is very obvious on one side. I've never toyed with these before, in the absence of a chain breaker, what's the best and/or easiest way to take those rivets out? I've got basic hand tools, so no saw shop or machine shop at my disposal, at least not without having to pay for it.

Worst comes to worst, I've got a decent OPE about 8 miles from the house, and may have to buy replacement rivets from them anyway. Thanks in advance for any guidance that you can provide.

Best,

 

[Philbert]

You can drill the rivets out, as long as you are going to replace them. Or, you can use a narrow punch (or even a hardened nail of the right diameter), with the rivet centered over a hole in a block of wood.

Again, it is a replaceable nose sprocket that most people would toss out and replace. You have nothing to lose, and a lot to potentially learn or gain in satisfaction

Philbert

 

[apn73]

Thanks again Philbert, I found a drift pin that's just the size and hopefully the rivets come before being destroyed.

 

[Woodslasher]

A few more trashed tips from bars that I saved. The tips are from Oregon 28 inch and a 36 inch bars. The 28 was pretty nice and received a near-new salvaged tip from another bar whose slot was butchered and an extra rivet from a previous tip kit. The 36 looked pretty toasty but fortunately the chain groove is clean and smooth or it'd be scrap. A bit of sanding and it looks way better in my opinion. Can anyone tell me what the SZA means?

 

[Philbert]

Oregon made / makes a lot of bars for OEM applications, specialty packaging, etc., and some of those had non-standard markings. A guide to standard markings is attached. You could try calling their Customer Service folks and asking:
1-800-223-5168, Monday through Friday 6:30 AM - 4:00 PM PST

Are you going to open those tips up and see what they look like inside?

Philbert

 

[Woodslasher]

Maybe, it’d be fun to see if the innards are as trashed as the outers.

 

[Philbert]

Maybe, it’d be fun to see if the innards are as trashed as the outers.

Inquiring minds want to know!

Philbert

 

[dynodave]

Very good thread
I had not seen it before though
I also had curiosity in 2017
Ugly but runs OK with a shot of grease now and then

 

[Woodslasher]

Can anybody tell me where I can find a 3/8 12-tooth nose sprocket? It doesn't matter if it's Stihl, Oregon, Windsor, or whatever, I just need a twelve tooth sprocket for testing purposes.

 

[Wood Doctor]

E-bay has lots of them. Ads for them rarely tell you how many teeth. Prices on these have jumped a bunch. I recall a few years back paying about $10 apiece, but that's history.

 

[Woodslasher]

E-bay has lots of them. Ads for them rarely tell you how many teeth. Prices on these have jumped a bunch. I recall a few years back paying about $10 apiece, but that's history.

All the ones I saw were 11 tooth. Do you have any links to the 12-tooth ones?

 

[Philbert]

FYI- here is a link to a related thread, that some might find of interest.

https://www.arboristsite.com/thread...ip-sprocket-in-a-stihl-rollomatic-bar.368071/
Philbert

 

[PapaWhitebeard]

I sure am glad you didn’t get injured. I was just telling another guy on this forum earlier this week “I never want anyone to find me dead on my back acre bled out, chainsaw in hand, having accidentally killed myself by cutting my leg off or whatever” because I’ll become a winner of the “Darwin award” (ie those folks that are deemed not fit to continue to live—cruel award yes but I didn’t make it up).

That’s why *especially* if I’m working alone I wear the chaos, the gloves, the helmet, the facemask, the glasses or goggles or whatever… (shrug)

I’m like… (shrug) deep in the overkill zone on this. But this thread is proof that stuff happens. Thank goodness for safety equipment. Thank goodness for Kevlar

 

[bwalker]

I might be inclined to gently burn the chap material out with a torch before resorting to pushing out the rivets.

 

[PapaWhitebeard]

I might be inclined to gently burn the chap material out with a torch before resorting to pushing out the rivets.

Yeah Kevlar burns… it burns yucky but it burns for sure

 

[Philbert]

I might be inclined to gently burn the chap material out with a torch before resorting to pushing out the rivets.

Wouldn’t that gum up the rivets, as well as char the bearings, oil / grease, etc.?

STIHL nose sprockets also have thin shims on each side.

Not all chaps use Kevlar. Some use HDPE, polyester, and other fabrics. The Clogger blogs contain good technical information on this.

It might be an interesting experiment to try on a scrap bar.

*Note that the bars I ‘rescued’ in this thread were from a controlled demonstration at a GTG, showing how chaps can work on battery powered, and other, saws. But the basic information also applies to unintentional chaps strikes.

Philbert

 

[bwalker]

Wouldn’t that gum up the rivets, as well as char the bearings, oil / grease, etc.?

Not all chaps use Kevlar. Some use HDPE, polyester, and other fabrics. The Clogger blogs contain good technical information on this.

It might be an interesting experiment to try on a scrap bar.

*Note that the bars I ‘rescued’ in this thread were from a controlled demonstration at a GTG, showing how chaps can work on battery powered, and other, saws. But the basic information also applies to unintentional chaps strikes.

Philbert

It might get some residue into the bearing area, but who cares. All kinds of gunk gets in there during normal operation. We are not dealing with a precision device here. As soon as the chain rotates the sprocket is going to be supplied with oil so it will be lubricated.
As for grease. I haven't greased a bar tip in years. It's not needed.