DIY Alaskan Mill - Question on bar nose sprocket

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Demonical

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I put together an Alaskan Mill, built with 1" square steel tubing.

I've been running it with a 372XP 30" bar. Recently I ordered a 395XP and so I made some mods to the mill, which extend the bar clamps.

Now the clamp at the nose of the bar is over the point where the nose sprocket is.

Question: if I'm tightening the clamp on that point could it damage the nose sprocket? At 5:42 on the video you can see it very clearly, how close the bar clamp is on that sprocket.

Also am I ok to post this Youtube video link?
 
Clamping like that will likely ruin your bar sprocket. You want to be clamping further back behind the hollow part around the sprocket. Alternately you can drill through the center of the sprocket & put a bolt there to clamp onto but you will then need a shim at the saw end to level it up. Looking at your setup, as your posts are fixed anyway I would suggest you drill the sprocket & the bar & then bolt it to the mill to mount it. That will have the benefit of being able to remove the chain without taking the saw off the mill. You may be able to remove your bucking spikes & slide the mill far enough back for your current setup to work. If you go that route ensure there is clearance between the mill & the saw or it will damage your case
 
Clamping like that will likely ruin your bar sprocket. You want to be clamping further back behind the hollow part around the sprocket. Alternately you can drill through the center of the sprocket & put a bolt there to clamp onto but you will then need a shim at the saw end to level it up. Looking at your setup, as your posts are fixed anyway I would suggest you drill the sprocket & the bar & then bolt it to the mill to mount it. That will have the benefit of being able to remove the chain without taking the saw off the mill. You may be able to remove your bucking spikes & slide the mill far enough back for your current setup to work. If you go that route ensure there is clearance between the mill & the saw or it will damage your case
Ok, I kinda figured it's not ideal. And to be honest I wasn't sure what you meant about drilling the sprocket.
I've been milling all afternoon and no issues (I think), saw has been cutting great.
I'm sure looking forward to the 395XP and just using the 372XP for falling n bucking.
 
Ok, I kinda figured it's not ideal. And to be honest I wasn't sure what you meant about drilling the sprocket.
I've been milling all afternoon and no issues (I think), saw has been cutting great.
It's unlikely that you'd notice anything more than a bit of extra heat in the tip before the sprocket is toast.
Here's a pic of one that's drilled. It was also clamped too close to the sprocket causing the bearings to bind & over heat. The only thing the operator noticed was the chain going a bit slack after the sprocket disintegrated
IMG_20210321_202213.jpg
& one showing how the mill attaches
IMG_20210321_210017.jpg
If you decide to drill your sprocket use a good sharp stepped drill (or start small & go up in drill sizes) & go slow. The steel is hard & will harden further if you heat it up pushing on a dull drill bit
 
Many choices - here are a couple
1) (see option 8 in diagram,) throw away the lower half of the mill nose clamp,
- drill a hole thru the middle of the nose sprocket to suit a bolt
- drill and tap a hole thru the upper clamp face of the mill to suit the bolt thread
- bolt bar to upper clamp of mill.
2) (see options 3 and 4 in diagram) Keep both nose clamps - but temporarily remove the lower clamp
- drill a hole though thru the middle of the nose sprocket and insert a small short high tensile bolt through the hole - cut bolt so no thread shows through the nut
- drill short (recessed) holes in the upper and lower bar clamps that will fit the bolt head and nut (if you don't drill a recessed hole that's option 3 in diagram)
- replace the lower clamp and clamp down hard - onto the bolt rather than the nose. teh recess method is better because even if the bolt loosens a bit the recessed should stop the moving to make contact with the clamp bolts - that's whey option 3 is not that good but Option 4 is very safe..
Depending on how long your bolts are #2 can be faster to undo than #1

nose-options-jpg.325845

For a full description of these options see
https://www.arboristsite.com/commun...nts-tips-and-tricks.93458/page-2#post-1507640
If a hole is drilled thru the bar at the inboard end (see photo below) or use a GB mill or any mill that doesn't use an inboard clamp this has teh advantage that the chain can be removed from the saw without removing the saw from the mill.
This is my small mill with the 441 powerhead and 25" bar. teh nose end on this mill uses option 4
bottom.jpg
This is the 880 on a mill with custom bar bolt mounting system - the other end uses option 8.
It looks impossible but with a slight contortion the chain can be removed from this saw without removing the power head from the mill
880five.jpg

I hope that is not too confusing
 
I made the mistake of clamping the sprocket once. It slowed the sprocket down and my chain speed dropped, luckily I noticed it before any damage happened. I loosened it off a bit and the sprocket turned faster as well as the chain. It was not as tight a clamping as I wanted but it got me through the day, the next time I was out I had a bigger bar and didn’t need to clamp that close to the nose. Lots of good alternatives outlined above and I would t recommend running the setup like I described regularly.
Happy cutting :).
 
^ For the record I switched to a commercial mill on day 2. I never noticed any issues with my bar sprocket, and I think I got away without doing any damage to it.

For what it's worth, I prefer my DIY mill to the commercial mill, as my welded steel mill is stronger, more solid, has fewer nuts/bolts to deal with. That commercial mill has 14(!!) different nuts/bolts to keep tight, and we had several nuts work loose on us, which has never happened with my mill.
 
^ For the record I switched to a commercial mill on day 2. I never noticed any issues with my bar sprocket, and I think I got away without doing any damage to it.

For what it's worth, I prefer my DIY mill to the commercial mill, as my welded steel mill is stronger, more solid, has fewer nuts/bolts to deal with. That commercial mill has 14(!!) different nuts/bolts to keep tight, and we had several nuts work loose on us, which has never happened with my mill.
My large DIY mill has more than 40 bolts on it and I've milled over 100 logs with it and only one bolt ( a brass 3/4" screw cap) has come loose in that time.
The screw cap was the top of my aux oiler and it fell onto the moving chain and smacked me fair in between the eyes.
Luckily I had a full face polycarbonate shield on at the time - I subsequently replaced then brass cap with a black poly one.
That photo was taken on the day of the "incident" - see how it's got a piece of white foam stuck into the top of the Aux Oiler tank.

All the other bolts are either Loctited or have a locking nut.
The height adjusters are all-thread rod and the vertical mill rails are locked in place by over-centre cams so don't need a spanner to tighten them
Over centre cams are used in a couple of other places to permit spannerless adjustments.
The only other thing that has come loose a few times is the clutch nut.
Complete-Mill-.jpg
 
^ That's a really nice looking homemade mill Bob.

I like the idea of Loktite on the bolts, and/or the use of locknuts.
As I said, all my (6) bolts have locknuts on them.

With that commercial mill, we had the inside bar clamp come loose and it slid over right to the edge of the bar, but thank goodness I caught it before it got into the chain.
 
^ That's a really nice looking homemade mill Bob.
Thanks.
I made that mill in 2007 and posted heaps of photos about the build.
I had no logs to mill at that stage so had no urgency to get it running and was able to spend a lot of time designing and building it.
When the site lost most of its photos back in 2012? most of them got lost but was able to go back and insert some again.
There are a few photos in this thread that shows that mill when it was adapted to suit my 880 (I can still use it with the 076)
https://www.arboristsite.com/commun...-bil-mill-to-take-the-880.87987/#post-1369623
 
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