Are FOP really progressive depth raker generators?

[Kenlip]

I set the rakers on both my full comp 60" milling chains today.

To read correctly a DAF needs to be held square across the cutter and raker, so freehand holding a DAF leads to an uncertainty in measruing the cutting angle of about +/- 0.3º .

To get around this I clamped a rebated block of wood onto the bar for the DAF to lean up against and so the chain can still slide past easily onto the bar
View attachment 335924

View attachment 335925
View attachment 335923
Measuring the cutting angle is then
1) Remove chain from bar and zero DAF against a marked position on bar
2) Replace chain and mount block of wood as shown
3) Move cutter of interest above marked position on the bar
5) Place DAF down onto cutter edge,
6) Lightly push back of DAF flat up against block and rotate DAF down till it makes contact with the top of the raker.
Care should be exercised to ensure the DAF does not make contact with adjacent rakers and cutters.

Before filing my ripping chains I had an average raker angle of about 4.5º but the range of angles was between 2.9 and 5.2º - ie all over the place.

The raker of interest is then slid a little away from the wooden block and filed, then slid back over the marked position and remeasured.
Repeat until you get 6º

BobL, I watched your Youtube video, and was impressed, but thought I'd experiment with a slight variation of the system.
I made a very rough prototype and experimented with it. This prototype is definitely not a thing of beauty, but it seems to work perfectly. By having a window in the block against which one holds the DAF vertical, one can eliminate the "The raker of interest is then slid a little away from the wooden block and filed, then slid back over the marked position".
Simply measure, file, re-measure. No moving the chain at all until one is ready to do the next raker.

 

[WI_Hedgehog]

This thread is incredible! Thanks @BobL !!!

Klein Tools 935DAG Digital Electronic Level and Angle Gauge, $30 U.S.
Has HOLD, a V-base, seems pretty fast, also rotates the screen right-side-up when upside-down.

I'm going to attach a small piece of steel bar (flat stock) to the bottom so the V-base doesn't mess up the readings.

 

[siouxindian]

well i got learned something today. great old post.

 

[jetsam]

Posting here because this thread deserves to be at the top (permanently), but a bump will have to do!

I started out doing progressive raker gauging with a micrometer, but ohhh it is slow. So I took Bob's advice and got a DAF, which I'd never heard of before.

I was excited, but got inconsistent results. Two things going on there:

1) My DAF (and probably yours too) has an absolute and a relative mode. If your grinder's not 0.0 level, either level it or zero the DAF when you start.



2) Much more importantly: My DAF (and maybe yours too) is sensitive to more than one rotational axis:



It's only out 1.1 degrees while leaned over fairly far on a flat surface, but it gets a lot worse as the measured angle increases:

Zeroed out at around 15°


Same angle but tilted back


..so you can really blow up your raker measurements by not holding the DAF nice and vertical. Seeing as you are already trying to balance it on two little odd shaped pointy things, this is neither easy nor intuitive.

SO...



I think the bubble levels were $6 for a 6 pack on Amazon and the superglue was $4 for a 10 pack at harbor freight. For an extra $10, I have a quick way to see that my DAF is reading true.



Still fits into its little case even.

I don't know if the tilt thing is specific to mine or common to all of 'em, but if you have that problem, here's the answer.

(And @BobL, thank you!! I am a firewood cutter with small interest in race chains, but this thread changed the way I sharpen. I'll never go back to 0.025 plus a couple licks with the file.)

 

[Mike Kunte]

......... aaaaand the main question remains unanswered! Why, after going to all this trouble, does the standard gauge (25thou or 0.65mm) sit perfectly level with the top of the depth gauges, as though one had not used the "progressive" method at all? Apart from a rather snarky "Of course the file-o-plate type gauges are progressive" reply, I have had no solid evidence that they are....
Just a thought...
Anyone?
Mike

 

[jetsam]

......... aaaaand the main question remains unanswered! Why, after going to all this trouble, does the standard gauge (25thou or 0.65mm) sit perfectly level with the top of the depth gauges, as though one had not used the "progressive" method at all? Apart from a rather snarky "Of course the file-o-plate type gauges are progressive" reply, I have had no solid evidence that they are....
Just a thought...
Anyone?
Mike

I don't know why you would even care if FOP style gauges worked after reading this thread... use the "give it a lick if you need to" method in the woods, use a DAF on the bench.

If you put an old 0.025" style gauge on one of my used chains with 6° rakers, it's pretty obvious that the raker is a lot lower than the old gauge is calling for.

If there is some debate about this....

In this badly-scaled example, tooth 1 and tooth 2 are both 5 wood chips (1.5") high. The raker (drillbit) should be filed to 3/4" below the tooth height.



Now we sharpen the chain a bunch of times, causing tooth 1 and tooth 2 to become a little shorter. The front edge of tooth 1 is moved back considerably due to sharpening.



FOP's angle is lowered, and now it says the drillbit should be 1" below the tooth height.

This is a silly exaggeration, but it shows how it works.

As BobL said above, they do work better than a flat gauge, but they don't keep a consistent angle throughout the life of the chain and end up a little shallow (I can actually measure this if you want because I have a couple chains that are down to short teeth.)

Again, I no longer use any raker gauge, so I have no dog in the game, but the FOP doesn't measure a fixed height across the chain's life. It is a second-best alternative for someone who doesn't want to measure their angles.

 

[PogoInTheWoods]

the FOP doesn't measure a fixed height across the chain's life

It isn't necessarily supposed to maintain a fixed height, but rather maintain a more consistent cutting angle over the life of the cutter. The subject is discussed at significant length in a spin-off thread of this one, complete with a software calculation tool and quite a spirited discussion both on and off topic along the way. Worth the read for someone interested in both some additional physics and more than a few practical approaches to why many of the scientific positions are actually a bit hollow due to not considering (or understanding) that the action of saw chain cutting through a log is not a linear process -- regardless of your preference or accepted theory for adjusting rakers.

Compare it to attempting to calculate the subtle differences of a hammer hitting a given sized nail in a given piece of material -- on say, Saturday, instead of Monday.
Well..., there ya go.

So far, this is pretty much the definitive thread on the subject after the author took his lead from BobL's thread here. @Mike Kunte will certainly attest to the level of enthusiasm contained therein -- and possibly also the relatively high level of both theoretical and practical input that managed to occasionally find its way into the discussion. LOL

So if you're the type of person who actually measures your rakers with a DAC, this thread is for you!

https://www.arboristsite.com/commun...epth-gauge-supported-by-software-tool.320388/

 

[jetsam]

It isn't necessarily supposed to maintain a fixed height, but rather maintain a more consistent cutting angle over the life of the cutter. The subject is discussed at significant length in a spin-off thread of this one, complete with a software calculation tool and quite a spirited discussion both on and off topic along the way. Worth the read for someone interested in both some additional physics and more than a few practical approaches to why many of the scientific positions are actually a bit hollow due to not considering (or understanding) that the action of saw chain cutting through a log is not a linear process -- regardless of your preference or accepted theory for adjusting rakers.

Compare it to attempting to calculate the subtle differences of a hammer hitting a given sized nail in a given piece of material -- on say, Saturday, instead of Monday.
Well..., there ya go.

So far, this is pretty much the definitive thread on the subject after the author took his lead from BobL's thread here. @Mike Kunte will certainly attest to the level of enthusiasm contained therein -- and possibly also the relatively high level of both theoretical and practical input that managed to occasionally find its way into the discussion. LOL

So if you're the type of person who actually measures your rakers with a DAC, this thread is for you!

https://www.arboristsite.com/commun...epth-gauge-supported-by-software-tool.320388/

Ah, thanks!

We see a similar phenomenon in the wood burning side of things. You have multiple 'experts' who know differing facts about how exactly draft works and what affects it, but if you polled 100 of those guys you'd probably get 10 who could even tell you what fluid dynamics is. (And those 10 are the guys who will sound least certain on the topic, because they recognize that it's vastly more complex than most people are willing to admit.)

I have found the "measure the angle of attack, not the height" concept provides me with older chains that cut better than new chains- but a quick glance at, for example, Oregon's "how does a chain work" document will tell you that a 6° AoA on the bench is nothing like 6° in wood.

All that aside though... measuring 6° is certainly good enough for my use cases! I am loving the way my older chains cut.

 

[Long Bar 60]

Think I'll just stick to my 50 year old Silvey raker and gullet grinder.

 

[chipper1]

Think I'll just stick to my 50 year old Silvey raker and gullet grinder.

Any pictures of that raker grinder with the gullet grinder setup attached?

 

[Long Bar 60]

I'll take some and then post them here. You can do rakers and gullets with a 120 Oregon round grinder. I think it's a 120. I have one (Oregon round chain grinder) and I have on occasion reset it to do rakers and gullets. Worked quite well. But I find that chicks dig a guy that owns anything with the Silvey label on it (I wish) LOL. Get ya those pics in day or two. Going kayaking all day tomorrow.

 

[chipper1]

I'll take some and then post them here. You can do rakers and gullets with a 120 Oregon round grinder. I think it's a 120. I have one (Oregon round chain grinder) and I have on occasion reset it to do rakers and gullets. Worked quite well. But I find that chicks dig a guy that owns anything with the Silvey label on it (I wish) LOL. Get ya those pics in day or two. Going kayaking all day tomorrow.

I've done them on an Oregon/ Tecomec before, just never seen them done on a silver like that. If you want to shoot me a PM, that would be great too.
Thanks

 

[Philbert]

I've done them on an Oregon/ Tecomec before, just never seen them done on a silver like that. If you want to shoot me a PM, that would be great too.
Thanks

Please post it here so that we call all see!

Always interested in new ideas, tips, or better techniques.

Thanks!

Philbert

 

[PogoInTheWoods]

And so we can all drool over a Silvey.

 

[chipper1]

Please post it here so that we call all see!

Always interested in new ideas, tips, or better techniques.

Thanks!

Philbert

It's not a new idea or technique(its actually older), but rather how you grind gullets if you have a Silvey raker grinder and the gullet attachment. I've never seen it done or found the literature showing how to do it, but I've wanted to figure it out as I already have the grinder/attachment for doing them.
The bummer is I would need to convert my grinder back to manual feed instead of automatic to do the rakers if I'm not mistaken.

 

[Long Bar 60]

It's not a new idea or technique(its actually older), but rather how you grind gullets if you have a Silvey raker grinder and the gullet attachment. I've never seen it done or found the literature showing how to do it, but I've wanted to figure it out as I already have the grinder/attachment for doing them.
The bummer is I would need to convert my grinder back to manual feed instead of automatic to do the rakers if I'm not mistaken.

I don't know what the "gullet attachment" is. My grinder has a pawl that is set as a chain stop. Rotate the handle with the wheel held up by hand and as a tooth goes by reverse the handle stopping the back of the cutter tooth into the pawl. Then you simply lower the wheel down by hand into the gullet as close to the cutter bit as you dare (this is determined by where you set the pawl prior to starting the operation) and deep enough that you almost hit the chain frame (top of the side straps). This too is set prior to the operation. Move on to the next tooth, left, right, left and so on. If I've done some serious damage to the cutter bits while cutting I will use this same technique but actually square off the cutter bit removing all or almost all the damage and leaving all the bits the same length but duller than a lecture by my high school French teacher. What this accomplishes is that as stated, it leaves all the teeth the same length, the gullet gone and lengthens the life of the wheel on the bit grinder by removing all that damaged metal by the cheaper raker and gullet machine wheel. There is still a lot of grinding to be done on the bit grinder and I frequently will grind it almost as far as it needs to be and then dress the wheel and grind the chain again to get that really fine "yea baby" edge. Of course, rakers need to be set after removing all that material.
I removed the automatic raker parts that allow you to just rotate the handle to lower the rakers. I found that the weight of the motor slamming down on top of each raker would wear the motor pivot bearings and create inconsistencies in the depth of cut. My hand and arm are much gentler.
All the guys I cut with remove their gullets with a round file.
I never leave my grinders in camp on the weekends. They always come home.
I'll have to use my wife's phone to get some pictures as I still use a flip phone. Hopefully tomorrow morning.

 

[PogoInTheWoods]

"the motor slamming down on top of each raker..." Seriously?

Wouldn't one figure out that's not how it's supposed to work before wearing out the motor pivot bearings?

Could be why Silvey went out of business.

 

[chipper1]

I don't know what the "gullet attachment" is. My grinder has a pawl that is set as a chain stop. Rotate the handle with the wheel held up by hand and as a tooth goes by reverse the handle stopping the back of the cutter tooth into the pawl. Then you simply lower the wheel down by hand into the gullet as close to the cutter bit as you dare (this is determined by where you set the pawl prior to starting the operation) and deep enough that you almost hit the chain frame (top of the side straps). This too is set prior to the operation. Move on to the next tooth, left, right, left and so on. If I've done some serious damage to the cutter bits while cutting I will use this same technique but actually square off the cutter bit removing all or almost all the damage and leaving all the bits the same length but duller than a lecture by my high school French teacher. What this accomplishes is that as stated, it leaves all the teeth the same length, the gullet gone and lengthens the life of the wheel on the bit grinder by removing all that damaged metal by the cheaper raker and gullet machine wheel. There is still a lot of grinding to be done on the bit grinder and I frequently will grind it almost as far as it needs to be and then dress the wheel and grind the chain again to get that really fine "yea baby" edge. Of course, rakers need to be set after removing all that material.
I removed the automatic raker parts that allow you to just rotate the handle to lower the rakers. I found that the weight of the motor slamming down on top of each raker would wear the motor pivot bearings and create inconsistencies in the depth of cut. My hand and arm are much gentler.
All the guys I cut with remove their gullets with a round file.
I never leave my grinders in camp on the weekends. They always come home.
I'll have to use my wife's phone to get some pictures as I still use a flip phone. Hopefully tomorrow morning.

That pawl is the attachment.
As I had figured, I'd have to remove the motor that rotates chain on mine. Mine had the hand crank removed and then it was replaced with a motor for a rotisserie, this way my chains get bbq lol. I think the motor spins it a bit fast, but I just put a chain on and go back to what I'm doing on the bench, then after a few times around I put another one on. I don't use it that often, but when I'm sharpening a pile of chains at home it sure is nice to have.

 

[Long Bar 60]

Please post it here so that we call all see!

Always interested in new ideas, tips, or better techniques.

Thanks!

Philbert

Well, I got one decent picture but in the meantime I saw the video that chipper1 posted and I can certainly say that things progressed at Silvey between my grinders manufacture date (1970) and when that vid was made. The grinder that I have was originally rented from Silvey by two other guys and myself in '78 or '79. Within a couple of years they parted on the deal and I ended up buying for I believe $300. It has been through many 10's of thousands of cycles since I've had it and it was just this spring that I had the motor rebuilt for the first time and the shop technician said that it really didn't need it. Whether I'm doing rakers or gullets I raise and lower the wheel/motor by hand. This grinder only services me these days, no crew anymore and no other guys that I work with- just me.

You can see that I removed the auto lift and lower arms and it never had an electric automatic chain drive. I'd even forgotten that they made those.

 

[chipper1]

Well, I got one decent picture but in the meantime I saw the video that chipper1 posted and I can certainly say that things progressed at Silvey between my grinders manufacture date (1970) and when that vid was made. The grinder that I have was originally rented from Silvey by two other guys and myself in '78 or '79. Within a couple of years they parted on the deal and I ended up buying for I believe $300. It has been through many 10's of thousands of cycles since I've had it and it was just this spring that I had the motor rebuilt for the first time and the shop technician said that it really didn't need it. Whether I'm doing rakers or gullets I raise and lower the wheel/motor by hand. This grinder only services me these days, no crew anymore and no other guys that I work with- just me.

You can see that I removed the auto lift and lower arms and it never had an electric automatic chain drive. I'd even forgotten that they made those.

Cool. That's how I figured it worked, but I've never seen anyone do it.
Looks like that chain could use a little touch up lol.