Just checking - rim sprocket

The rim sprocket (hopefully pictured below) is what drives a saw chain at the back/engine end...yes?

I've been nutting out a thoroughly ridiculous chain sharpening station which mimics the line a chain runs along the bar and from the engine, and will be needing to chase up an otherwise trashed one of these to assist in being able to move the chain along (manually) and adjust the chain's tension in the station. I just want to be sure of what I'm asking for from the repair shop's rubbish bin.

I'll need either this sprocket (and maybe parts from a clutch assembly) or an otherwise knackered, but still moving, tip and sprocket.

I'm sure y'all will think I'm a (bigger) twit for coming up with this, but when the whole thing is done I'll post the piccies :)
http://i.ebayimg.com/00/s/MTU5MlgxNj..._id=880000500F

Quote:

---

Originally Posted by RedShirtGuy

The rim sprocket (hopefully pictured below) is what drives a saw chain at the back/engine end...yes?

---

Yep

Quote:

---

I've been nutting out a thoroughly ridiculous chain sharpening station which mimics the line a chain runs along the bar and from the engine, and will be needing to chase up an otherwise trashed one of these to assist in being able to move the chain along (manually) and adjust the chain's tension in the station.

---

Err . . . . . tension is not needed to sharpen a chain. I just put an older shorter bar in a vice and drape the chain on the bar and move the chain with the file - like this.
http://www.youtube.com/watch?v=vWwLE...FNZlrNObDo2KXg

The bar is short enough so the chain drapes under the vice.

Thanks Bob.

I always thought that it helped to have the chain a bit tight to keep it level and with even pressure on tooth, but if that's not the case then I don't need to make anything and can do it just the way you've shown. Dang...this thing was going to be cool :U

Just because you don't need it doesn't mean you shouldn't build it :D

Quote:

---

Originally Posted by NCArcher

Just because you don't need it doesn't mean you shouldn't build it :D

---

Absolutely - have you seen my chain cleaner?

http://www.youtube.com/watch?v=IauN8GMUCy0&list=UUpmo3NbRPFNZlrNObDo2KXg

Love it, but you should have hooked it up to the table saw instead of the drill :U

Maybe I missed something Bob.... with the chain cleaner.

Pls don't get me wrong - very inventive.

My questions are these : -

1. Why not just put the bar of the chainsaw in the vice and start the saw and then use the wire brush to clean the chain? It seems imaterial to me what powers the chain - the engine designed to do so, or a battery drill?. There may be a perfectly valid reason that escaped me like noise & fumes of the CS engine for eg (or the chain oil the CS pumps out onto the chain).

2. How come it's not dangerous to put your unprotected hand on the running chain? Your gloved hand you used to lean on something while using your un-gloved hand to test the chain. Was it running backwards or something? Just the idea of putting flesh anywhere near a running chainsaw chain, to me is counter intuitive for safety reasons - what am I missing?.

Your probably one of the smartest guys on the forum... so what am I missing that's obvious pls?.

Quote:

---

Originally Posted by Timless Timber

1. Why not just put the bar of the chainsaw in the vice and start the saw and then use the wire brush to clean the chain? It seems imaterial to me what powers the chain - the engine designed to do so, or a battery drill?. There may be a perfectly valid reason that escaped me like noise & fumes of the CS engine for eg (or the chain oil the CS pumps out onto the chain).

---

The main reason for not doing this is I still value my fingers.

The rpm of even an idling saw is around 2500 rpm - at these revs the clutch will not engage and drive the chain
The rpms at which the clutch just engages e.g. 3000 rpm can still easily be stalled by something like a brush AND it is extremely foolish to put a brush and your hand anywhere near the chain at these revs
The rpms required so the chain does not stall will be around 4000 rpm so even more dangerous.
The battery drill drives the chain at 500 rpm with much more torque that even a big saw can drive it at 3000 rpm.

Quote:

---

2. How come it's not dangerous to put your unprotected hand on the running chain? Your gloved hand you used to lean on something while using your un-gloved hand to test the chain. Was it running backwards or something? Just the idea of putting flesh anywhere near a running chainsaw chain, to me is counter intuitive for safety reasons - what am I missing?..

---

Correct - running backwards at only 500 rpm - another reason I would not put the chain on a saw backwards and run it at say 4000 rpm is it will stuff the sprocket and the chain.
But at 500 rpm on an worn sprocket the chain does not get munted.

It was incredibly counter intuitive to put my hand on the running chain given I have been around chains saws for 50 years even if it was low speed running backwards.
The reason I did this in the video was to show that it was safe to use your hands and a brush near the chain in this configuration.
BTW do not run the chain the other way as it will still make a mess of your knuckles and it will not stop easily - those batter powered drills have a lot of torque at low speed.

I have used the chain cleaner maybe half a dozen times since I found out the easiest way to clean a chain is to run the saw so that the chain gets liberally coated in oil and let it sit for a couple of hours and then just hose it off with a hose. Sometimes the gunk sticks harder than this so I apply some diesel and leave it and it usually comes off.

The reason I had a glove on was I had crushed the index and middle fingers of that hand (to the bone - :oo:) about 3 months before and they were still very tender. The main reason I showed this was that I too am good at making useless things :D

Thanks - that makes a lot of sense now its explained.

You make some useless things, and I'm an expert at making mistakes! We could be brutha's from 2 different mutha's :o :D:wink:

i use an stuffed bar in the vice if im sharpening a chain not on a saw, but that dosent happen verry often.

it is much quicker just to sharepn a chian in teh feild than change them over.

bob - why clean teh chain? because i can is an acceptable answer.

\

Quote:

---

Originally Posted by BobL

...It was incredibly counter intuitive to put my hand on the running chain given I have been around chains saws for 50 years even if it was low speed running backwards...The reason I did this in the video was to show that it was safe to use your hands and a brush near the chain in this configuration...

---

Isn't that the hard way of proving it is safe, after all if it wasn't, good bye fingers :doh:.

I think it is dangerous to show anyone doing this, even if it was backwards and relatively slow. I ran my fingers over mine backwards whilst it was stationary and still tended to catch my fingers on the back of the teeth and the sharp edges on the rakers where I had lowered them. So if moving at all, probably Ok for wire brushing, but I am positive it was cause injury to my fingers.

Perhaps yours are smoother from the wire brushing.

Quote:

---

Originally Posted by dai sensei

Isn't that the hard way of proving it is safe, after all if it wasn't, good bye fingers :doh:.
I think it is dangerous to show anyone doing this, even if it was backwards and relatively slow. I ran my fingers over mine backwards whilst it was stationary and still tended to catch my fingers on the back of the teeth and the sharp edges on the rakers where I had lowered them. So if moving at all, probably Ok for wire brushing, but I am positive it was cause injury to my fingers.

---

I agree it is potentially dangerous to show anything other than wood to be cut approaching a moving chain. The biggest danger is probably what Timless Timber said that someone may think "Why not do this with the engine running".

One thing we forget that even sharpening a still chain with a file is potentially dangerous if the file slips and I have skinned my knuckles a couple of times this way, and when I was younger I managed to opened up my thumb to the point where I should have probably had a stitch or two.

Carl,while I like to sharpen a clean rather than a dirty chain, the reason I decided to make this cleaner was I cutting some Tuart logs which make a real mess of the chain. The resin forms a black coating over the chain especially the cutter edges so that makes it hard to see the rounded cutter edge glint that needs to be removed to achieve any sort of sharpness. Anyway, as I said in my last post, I have used the chain cleaner maybe half a dozen times since I found out the easiest way to clean a chain is to run the saw out of the wood for 30 seconds or so, so that the chain gets liberally coated in oil and let it sit for a couple of hours and then just hose it off with a water jet. Sometimes the gunk sticks harder than this so I apply some diesel and leave it and it usually comes off.

i leave my "spare" chians in wd40, it removes all the crap from them.:U

Bob just for the record - I don't think ya make useless things mate - volcano orange things, but not useless!!!:wink:

Quote:

---

Originally Posted by Sigidi

Bob just for the record - I don't think ya make useless things mate - volcano orange things, but not useless!!!:wink:

---

Cheers Sidgi, I was thinking of starting a thread on the 10 most useless things I have made.