Grinding Rakers

[biggenius29]

I have always hand file my rakers, but am starting to grind chains for other people and I am not about to hand file all their rakers.

How do I set up a grinder for rakers. Do I set everything up at 0-0-0 or what angles do I set up for?

 

[mtngun]

Here are a couple of threads on the subject.

http://www.arboristsite.com/showthread.php?t=121883&highlight=raker

http://www.arboristsite.com/showthread.php?t=111460&highlight=raker

If you grind the rakers at zero degrees, you'll have to go back and round them over with a file, which defeats the purpose of using a grinder. Hence, If I were going to do rakers with a grinder (which I don't) I'd set the grinder at perhaps 80 degrees so the rakers would be ground at an angle and wouldn't require additional filing.

 

[lambs]

I use 90-0-0, 1/4 inch wheel

You may be able to avoid hand filing, but if I were doing a lot of chains I'd find a used grinder and put a 1/4 inch wheel on it dedicated to the depth gauges.

When I do my chains, I grind the cutters, then use a Stihl depth gauge tool and hand file 1 depth gauge down to the proper height, then set the grinding wheel over it and adjust down until it just nicks the depth gauge I just hand filed. Then I turn the grinder on and grind every depth gauge in turn with that setting. I finish up by using a flat file to round off the front of each depth gauge. I leave the chain in the vise and just slide it along and give each gauge 1 stroke to round them back off.

I have tried a Harbor Freight cheapo grinder set at the 60 degree angle with appropriate dressing of the grinding wheel to use as a dedicated depth gauge grinder. Doesn't work. The HF grinder is just too flimsy.

 

[B_Turner]

Here are a couple of threads on the subject.

http://www.arboristsite.com/showthread.php?t=121883&highlight=raker

http://www.arboristsite.com/showthread.php?t=111460&highlight=raker

If you grind the rakers at zero degrees, you'll have to go back and round them over with a file, which defeats the purpose of using a grinder. Hence, If I were going to do rakers with a grinder (which I don't) I'd set the grinder at perhaps 80 degrees so the rakers would be ground at an angle and wouldn't require additional filing.

I occasionally use my silvey 510 to set the rakers if I have a bunch of chains to do. Partly because I hate how expensive flat files are these days.

The manual said 90 degrees if I recall correctly (has been years) and to grind in the opposite direction than you would that cutter to keep the chain from jumping to the side.

I round the top with a stroke or two of a file.

 

[BobL]

Here are a couple of threads on the subject.

http://www.arboristsite.com/showthread.php?t=121883&highlight=raker

http://www.arboristsite.com/showthread.php?t=111460&highlight=raker

If you grind the rakers at zero degrees, you'll have to go back and round them over with a file, which defeats the purpose of using a grinder.

yep.

Hence, If I were going to do rakers with a grinder (which I don't) I'd set the grinder at perhaps 80 degrees so the rakers would be ground at an angle and wouldn't require additional filing.

It depends on how hard your wood is. If the rakers are going to be ground flat (not horizontal to the bar but a flat and sloped ) then it makes sense to file the raker tops at greater than the cutting angle.
This is what I mean by the "Cutting angle"

How much more that the cutting angle the rakers should be sloped is the real question. Rakers penetrate a surprising amount into (especially softer) wood and a few degrees above the cutting angle may not be sufficient for the leading flat shoulder to catch and increase friction. The optimum degree of flat contact versus peaked contact is also a tricky one.

Here is a close up of the raker from the above picture.

The red line is the cutting angle, the blue line is the trailing flat (and should be short to minimize friction but not so short as to allow too much wood penetration by the raker, The black line is a slightly curved leading flat and should really be slightly more curved since the green line points to a small shoulder which could increase friction and should be removed. All in all it's still a reasonable raker for aussie hardwood

If your cutting angle (this is determined by raker depth - or the other way around) is 6º then a sloped raker top angle of 10º might not still be enough and the raker might penetrate wood enough to catch on the non-rounded raker shoulder. If you use a raker angle of say 20 or 30º or more to avoid catching the non rounded shoulder, the the raker will penetrate further into the wood at the same raker depth and make the chain grabbier. All this is why it is usually easier to leave a little flat 1/16 - 1/8" on the raker top and the round over.

The raker profiles used have to take into account the cutter angles (mainly hook), raker depth, raker top angle, length an curvature of leading and trailing raker flats, wood type, available power, length of grandmas nose, etc You just have to suck it and see what produces the most chips the quickest for your setup. As usual I have over analysed and sometime gut feel will work just as well or maybe better?

It is possible to shape a wheel to grind a rounded raker but because it constantly wears the wheel needs to be reshaped.

 

[biggenius29]

I occasionally use my silvey 510 to set the rakers if I have a bunch of chains to do. Partly because I hate how expensive flat files are these days.

The manual said 90 degrees if I recall correctly (has been years) and to grind in the opposite direction than you would that cutter to keep the chain from jumping to the side.

I round the top with a stroke or two of a file.

I just picked up a 510 and am getting it tommorow I hope. Is the Silvey able to do them right or not? Right now I am going to dedicate my old grinder with a 1/4" wheel for the rakers.

I am hopeing this setup will be a good set up and I will be able to crank through the chains.

 

[B_Turner]

I just picked up a 510 and am getting it tommorow I hope. Is the Silvey able to do them right or not? Right now I am going to dedicate my old grinder with a 1/4" wheel for the rakers.

I am hopeing this setup will be a good set up and I will be able to crank through the chains.

It does okay, but it would be better to dedicate a grinder because the wheel can be dressed for the rakers and you don't have to mess with the depth adjustment. With a single grinder for rakers you have to set it much higher and then set it back down for regular sharpening.

I only use my 510 for rakers when I am doing a big batch of chains.

These days I mostly use my 510 setup with a 1/8 inch wheel for 1/4, .325 and 3/8 lp and for cleaning out the gullets on the square ground chain from my Pro Sharp.

In terms of my 510, for 3/8 I tried a bunch of wheels and ended up preferring the blue ceramic wheels. I hated the resinoid wheels that came with the 510 - slow and hot. I never tried the fancy cbn or diamond style wheels. They sound good, though.

For some reason the Silvey 1/8 resinoid wheel work out okay. Maybe because there is so little metal to remove on a small cutter.

 

[AIM]

Where do you buy these other grinding wheels?
I've looked around and can only find the pink ones like I have on my grinder.

 

[B_Turner]

Where do you buy these other grinding wheels?
I've looked around and can only find the pink ones like I have on my grinder.

You can buy aftermarket 8 inch gray and white wheels (waxed and unwaxed as well) from places like Baileys and Mdsns. I figured out that any of the bigger Silvey wheels for their square grinders fit the 510 fine.

I have bought maybe 10 aftermarket salmon white and gray wheels from both of the above, and have been very dissapointed with the quality both of the compound, and how sloppy the hole has been cut. If you swap wheels at all, that ends up wasting material to true them each time.

In other words, the salmon wheel that comes with a ProSharp for example is a much better quality wheel than I have seen in an aftermarket salmon wheel. To the point that I will probably never again buy an aftermarket wheel except for the blue ceramic wheel or maybe one of the boron type wheels.

The blue ceramic stone not only performs better IMO, it is a better made wheel and I've never had a bad one. Cuts literally three times as fast as the stock 510 resinoid wheel (or faster) and with MUCH less heat. You have to dress a little more, but that's actually good as it gives a fresher stone surface.

 

[alderman]

I've sharpened chains for others but I refuse to touch the rakers. I think raker depth is a personal preference thing and should best be left to the owner. Thus I don't need any other equipment than my Oregon 511.

 

[Racerboy832]

Any dealer I took my chain to never touched the rakers. 50% of the time the teeth came back blue too. Spent the 99 at HF for one of those grinders. Now I do the teeth and rakers on the same grinder. Set the first raker with a Gauge and fly through the rest.

 

[madmarksolomon]

Question, depth gauge height in orientation to the cutting tooth, or all depth gauges same height, one you get with hand file using a depth gauge and the other with a stationary grinder. I've never used a grinder for the depth gauges so I guess my questions is witch is better.

Love the pic B-Turner "Excalibur"

 

[Philip Wheelock]

FWIW, the local Stihl shop tech grinds cutters but files depth gauges by hand.

 

[7sleeper]

Here is a very nice video of a fellow with an el cheapo grinding the chain and the rakers. I like his technique! Although I usually file the rakers.

[video=youtube;f3m_ErOrzHY]http://www.youtube.com/watch?feature=player_embedded&v=f3m_ErOrzHY[/video]

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