Are FOP really progressive depth raker generators?

[BobL]

when using a WIXEY DAF the rounded corners and inset magnets recesses limit the contact area over which the cutter edge - raker angle measurements can be made.

Here's what I mean

This diagram shows on the left a side cross section of the DAF. The two arrows show the contact area that should be used. If a cutter or raker encroached into the inset magnet recesses or rounded corner areas, an incorrect angle reading will be made.

To facilitate this the right hand side diagram shows how I clamp a rebated wood block to the blade to ensure only the small contact area is used.

 

[Philbert]

Getting pretty obsessed on this, aren't you BobL? (have you considered seasonal variation of the rebated wooden block yet, effect of the tides, . . ).

Seriously, your insights have been very interesting.

Philbert

 

[BobL]

Getting pretty obsessed on this, aren't you BobL? (have you considered seasonal variation of the rebated wooden block yet, effect of the tides, . . ).

Yeah I have been thinking that wearing my underwear on the outside might harden the cutting edges.

Seriously, your insights have been very interesting.

Cheers Philbert, all I was doing was looking for a more practical way of using the DAF. It's certainly quicker that the vernier caliper method.

 

[Philbert]

BobL,

1. Rather than zeroing the DAF on the naked bar, couldn't you place a straight edge across the tops of a few cutters to set your zero? Then pull the straight edge to measure your raker angle? Seems like it would do the same thing and save a few steps.

2. Once 'we' have decided on the procedure, have 'we' decided on the target depth gauge angles for cutting, ripping, hardwood, softwood, etc?

(would send you more rep if I could - maybe some of the other followers of this thread can fill in for me!)

Philbert

 

[BobL]

1. Rather than zeroing the DAF on the naked bar, couldn't you place a straight edge across the tops of a few cutters to set your zero? Then pull the straight edge to measure your raker angle? Seems like it would do the same thing and save a few steps.

I've played with this but ultimately I guess it depends how far you want to go .

Ideally the zero reading should only need to be done once for the whole chain provided that spot is marked on the bar so it then becomes the reference place above which to take all measurements.

Using the tops of cutters either side of (or adjacent) to each raker as the zero position is the ideal zero position because that is the actual angle the wood is being cut. But this requires zeroing for every raker even if the zero is taken above the same point on the bar. I have measured the zero angle at the same place on the bar for adjacent cutters for new chain and there is a variation of +/- 0.2º, while for used chain with slightly different cutter lengths it's +/- 0.6º . Some of this (esp for the new chain) is because one is measuring on top of an object which is sitting on top of another and the small variations that produces - see below.

This zero variation of 0.6º for the used chain should indeed be added to my +/- 0.4º filing variation so my final actual cutting angles are indeed 6.3 +/- 1º which translates to raker depth variation of +/- 16%.. If this was a problem I would feel significant chain vibe/chatter and while I do see some it's about the same as when I use a regular raker gauge.

There are ways to reduce both zero and filing variations the most obvious one being making sure the cutters are the same length and more careful filing of the rakers. Either way, f one wanted smoother cutting it would make sense to rezero every time above every raker.

Remember the zeros have to measure carefully because of the ways bars curve and cutters slope, a straight edge can only sit on top of the outer tips of two adjacent cutters, the straight edge then is able to rock side to side, so both the straight edge and DAF have to be held square to the back support block. No big deal but I just found it easier to slacken off the chain and lift and pulling the chain away from the bar so the DAF can sit on the bar and take one zero reading.

2. Once 'we' have decided on the procedure, have 'we' decided on the target depth gauge angles for cutting, ripping, hardwood, softwood, etc?

Yep - The matrix is rather large. eg other cutter filing angles, engine size and power/powerband, type of chain, sprocket size, dirty versus hard etc. As long as I make big chips and don't bog the saw I'm good.

 

[Justsaws]

Good stuff BobL.

 

[BobL]

Good stuff BobL.

Cheers JS.

Here's a vid showing how I set the rakers on my milling chains with a DAF.
http://www.youtube.com/watch?v=FSr9j2EDoqk

Sorry about the squeaky file - my good one was at the milling yard.

The first reading is the zero reading, the rest are raker readings.
The 6º angle being used translates to a raker setting of around 0.040" for that length cutter.

I don't do this every time I touch up the rakers. I touch up the cutters (2-3 strokes) after about every 32 sqft of milling, whereas I free hand the rakers (~2 strokes) after every 3-4 touch ups. I reset the rakers like this off the mill after every 2-3 days of milling when I swap out the chain and flip the bar.

Here's a vid of me sharpening.
http://www.youtube.com/watch?v=vWwLEuY5Iao

 

[Philbert]

"F.O.P. - The Movie!"

Love the sound track - too bad you just missed the Oscar nominations announced today.:-(

Seriously, it is helpful to see your process in action.

Thanks.

Philbert

 

[Dale]

Hah !!! Alot of your fellas obsession, but more apparent, your knowledge, runs so much deeper than mine. It's humbling to follow along to these types of threads.

I'm a guy that field sharpens (I'm sure most of you would think I'm using the sharpen term loosely) the cutters with a hand file, and takes a few swipes at the rakers with a flat file, then I'm on my way again.

 

[BobL]

HI'm a guy that field sharpens (I'm sure most of you would think I'm using the sharpen term loosely) the cutters with a hand file, and takes a few swipes at the rakers with a flat file, then I'm on my way again.

about 90% of the time that's exactly what I do too!

The other 10%, as SWMBO says, I should get a life!

 

[PogoInTheWoods]

about 90% of the time that's exactly what I do too!

The other 10%, as SWMBO says, I should get a life!

Ditto Dale on both the fascination with the actual physics detail provided and everyone else's takes that have been generated with this thread, but also big
props to ya BobL to know that 90% of the time ya don't practice what ya preach and put yer pants on one leg at time like the rest of us -- (providing a
bad chain somewhere along the line hasn't unexpectedly prohibited the latter.)!!!

So in conclusion, I'll take a SWAG that I'd be way better off using the FOP than not, but it would be a more precise device if it's design referenced the front of the cutter behind it rather than the rear of the one in front of it.

Great thread. Great interaction. Tremendous enlightenment. Thanks.


Also just finished going through the Carlton .pdf pamphlet. Great fundamental
info there, too. Highly recommended regardless of your bar/chain loyalty. All about saw chain, not about Carlton 'till the end where they get into the FOP,
which, after all, this thread is all about -- and presumably where the actual and literal definition of its function was initially contemplated and ultimately
questioned here.

Whatever. Something tells me I'm better off with one than without one fer more precisely trimmin' the toenails on this here wooden leg.

Poge

 

[willsaw4beer]

Hands down this is the best thread on AS as far as I'm concerned.. A bigger, faster ported muff modded whatever saw is only as productive as the chain it's cutting with. The information in this thread on how to maximize your saws cutting performance is the best collection of necessary theory and technique to do it on your own on the entire internet.

Bout to get a nice Starrett 0-1" od mic and hopefully a vernier caliper in the next couple days. A DAF is next after those...

 

[lambs]

I'm sold, and cannot wait to try this out....

Went to my local Woodcraft store this week and checked out the two DAF's they stock. I bought a Beal "Tilt Box". It was one dollar more than the Wixey, but it has a flat bottom and uses a regular 9 volt battery. It's also supposed to be a bit more accurate, but at this level of accuracy I don't think it's a factor. I bought it because the top and bottom are level.

I think I'm going to also try using it to set up the grinder and ensure I'm getting what the indicator marks say I'm getting.

I put an old bar in my bench vise, and using the Tilt Box I leveled the bar in the vise right over the middle of the vise. I then put a length of new Stihl RSC (3/8 pitch) in the bar and checked the drop from top of cutter to top of raker. It's pretty hard to hold that box in place and verify you have it resting on top of both with my old eyes, so I used a white cloth behind the chain so I could see "daylight" between the chain and the Tilt Box. I measured about 4 degrees (like I said, hard to hold it perfectly still).

Then I took a loop I am about to grind and checked it the same way. Cutters are about 1/3 worn. I adjusted the depth gauges the last time I ground it using a Stihl depth gauge tool. This one checked in at 1.7 degrees. I checked a couple of adjacent cutters to make sure.

I think I understand now why my ground chains don't cut quite as well as when new.

I'm supposed to cut wood Saturday, and weather permitting, I just may be running a used chain with the angle set to 4 degrees. I bet there will be a difference.

 

[Philbert]

First Attempt - Photos Attached!

OK, I am convinced, although, I may still need some refinements / coaching. Here are some pics of my first attempt:





I have the 6 degree angle set and the block of wood - what's next?

Philbert

 

[BobL]

.
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I have the 6 degree angle set and the block of wood - what's next?]

How about a 9" angle grinder?

 

[BobL]

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I then put a length of new Stihl RSC (3/8 pitch) in the bar and checked the drop from top of cutter to top of raker. It's pretty hard to hold that box in place and verify you have it resting on top of both with my old eyes, so I used a white cloth behind the chain so I could see "daylight" between the chain and the Tilt Box. I measured about 4 degrees (like I said, hard to hold it perfectly still).

It's much easier to hold vertical if you place a block of wood behind it

Then I took a loop I am about to grind and checked it the same way. Cutters are about 1/3 worn. I adjusted the depth gauges the last time I ground it using a Stihl depth gauge tool. This one checked in at 1.7 degrees. I checked a couple of adjacent cutters to make sure. I think I understand now why my ground chains don't cut quite as well as when new.

1.7º - yeah that explains a lot.

 

[tdi-rick]

Bugger you Bob, now I'm measuring the bloody raker angle with the DAF too.....:censored:




FWIW I've just finished filing a 98DL Windsor semi-chisel chain and with the cutters back about 1/3 the 37509 FOP is giving me around 5.7*+- 0.2 so far, so not too bad.
With that FOP on that chain I'm using a 5.2mm file to get the top plate angle I feel it needs.

 

[BobL]

Bugger you Bob, now I'm measuring the bloody raker angle with the DAF too.....:censored:

FWIW I've just finished filing a 98DL Windsor semi-chisel chain and with the cutters back about 1/3 the 37509 FOP is giving me around 5.7*+- 0.2 so far, so not too bad.

That's pretty darned good!

How's it cut!

 

[tdi-rick]

That's pretty darned good!

How's it cut!

Better than out of the box, it surprised me how aggressive yet clean cutting it was in a block of old Box

I was pretty slap happy taking those angles today, I just zeroed it across two cutters then laid it from the raker to the cutter without any rear squaring/support, so there will be some error but you'd piqued my curiosity.

I had three chains to sharpen and a stack of other stuff, so couldn't spend too much time mucking about, having said that I cleaned the gullets right out on that particular chain and rounded the rakers off reasonably nicely too and I was supposed to be getting ready to go out to lunch :monkey:

Next thing I'll be pulling the chain apart, thinning the cutters and rakers.......

 

[7oaks]

As said before, by other members...One of the best threads on the site. I've learned a bunch and will try this the next time I sharpen. Thanks Bob...