how do I move on....

[Albert Beerstein]

Tried full comp chain 3/8 regular 7.5° DG on 090 ( 'cause thats what I had), but it cut 110 seconds per metre? very smooth finish . must be something to do with chip clearance I guess? And now my test log is finished, so am I! Thanks for your input Kiwibro and Bob, looking forward to your further analysis of all this Bob!

 

[BobL]

So let me get this straight

For the 660 @ 8.5º the 2Skip is ~ 13% slower than the full comp by , but for the 090 @ 7.5º the 2skip is faster than the full comp by 32%?
This is wierd.

There's no significant difference between the 660 with 2Skp @ 7.5º (106/109s) and the 090 with FC @ 7.5º (110s) or really the 660 with FC @8.5º (114s)

To be honest is gonna take lots more testing than you probably have time for.
For a start you have to repeat all tests on the new log
Plus include 090 FC and 660 7.5º on 2 skip so we can compare apples with apples.

The 090 seems to love that skip chain - it must have something to do with the porposing action of chain where by only every 3 or 4 cutters cut to max depth. I will need to think about it some more.

 

[Albert Beerstein]

All cut times in one place.
Timed cuts in 500 mm wide pine log with squared sides, 1000mm long.

660, 7 tooth, 3/8 LP full comp, TPFA 10°, DG 8.5°, smooth finish, 114 sec/mtr

660, 7 tooth, 3/8 LP 2 skip, TPFA 10°, DG 8.5°, smooth finish, 129 sec/mtr

660, 8 tooth 3/8 LP 2 skip, TPFA 10° , DG 8.5°- - - 67 seconds /mtr! (was quite loaded)

660, 7 tooth, 3/8 regular, 2 skip, TPFA 10°, DG 7°, smooth finish, 106 sec/mtr ??!?

090, 7 tooth, 3/8 regular, 2 skip, same chain as above, 74 sec/mtr…

retest 660 again with same chain – 109 sec/mtr

090, 7 tooth, 3/8 2 skip, 10° TPFA, 8.5° DG, 70 seconds per metre (nearly pulled ME along cut!)

same as above, 2nd try, smoother feed, 71 sec /mtr

090 7 tooth full comp, 7.5° DG, 110 sec/mtr. Very smooth finish.

some of these results are coutner intuitive, and I don't really understand why, the reason I originally went for 2 skip chain ( every second pair of cutters removed) was because I noted that circular saw blades for ripping had 1/2 as many teeth as crosscut blades, but it does not seem to be as simple as that? More testing in the future I guess? Maybe a PHD in saw chain!!?

Bob I have lots of time these days, I wiil do more testing, so feel free to throw me some ideas!

 

[andy]

A quick Off Topic sidetrack.

This Tachometer arrived. It took 10minutes to instal and seems to function perfectly.
It's pretty small and comes with a long enough wire lead to mount it on the Mill Body if one wanted to.
I'll be moving mine to the Mill Body after I'm done doing some falling and clean up with the saw.

 

[Albert Beerstein]

I thought I should add information on a problem I had with homemade 2skip. after using this for a while, I had a problem with the cut diving, and the usual things (sharpen chain,level bar rails, check mill alignment) did not help. It ended up being side wear in the bar groove, caused by my 2skip always leading with r/h cutter, so the following l/h cutter was doing little work, and highly loaded r/h cutters were pulling the chain hard to the r/h side of bar groove, causing uneven wear) a better chain with similar number of cutters can be produced by removing every third cutter of a factory skip chain, then the leading cutter alternates left and right so the load/wear is even.

Andy I fitted one of those tach's to my mill, and it's enlightening seeing how the RPM falls with load, it's very easy to load the saw below maximun torque without realising it!