Couple grinder questions

[jetsam]

Hey all-

After many years of hand filing and Granberg cleanups, I finally decided I wanted speed AND consistency (cue the "learn to hand file" guys), so I went and bought myself an Oregon 520-120 grinder.

I'm on my third chain (well, it's the same old stumping chain that I've ground 3 times to learn on), and have built up a few questions.

Is the chain clamp on these things supposed to be so.... ******? I have 0.50 chain in there. I have to crank it down so hard it screws up the grind angle sometimes. And even when I do get a good bite, the tooth being ground is free to rock forward when the wheel hits it! It doesn't *look* broken. It really seems like a mickey mouse setup for a $300 tool. I already trashed my already-suffering stumping chain by thinking it was clamped when it wasn't. For now I am shimming it with a piece of flashing and holding each tooth down with a screwdriver as I grind..... anyone got a good permanent fix for this thing?

Next issue, the chain advancement stop (on that same clamp assembly) really looks like it can vibrate loose. Only thing stopping it is a plastic nut and a rubber washer. I may take it apart and add a couple nuts so I can tension them against each other.

Last up, and I am sure I will get this under control as I learn a lighter touch, is that there's a lot of slop in how deep you can grind after the depth stop touches down. I don't see any reason that I won't be able to make this work by using light consistent pressure, but it goes against my reflexes to push lighter as grinding load increases.

Oh, and also I didn't like the light bulb, but I soldered in a bright as hell LED from home depot, so that's sorted!

 

[SOS Ridgerider]

I can’t speak to the vise set up on your grinder, as I have the Tecomec Super Jolly which is the same as the Oregon 620-120, but I put some Teflon tape on the threads for the chain advancement stop. That took care of the nut walking out on me during grinding.

I like that light set up you have there. I feel the light is too dim on mine. I bet it’s the same as what came on yours.

 

[jetsam]

I can’t speak to the vise set up on your grinder, as I have the Tecomec Super Jolly which is the same as the Oregon 620-120, but I put some Teflon tape on the threads for the chain advancement stop. That took care of the nut walking out on me during grinding.

I like that light set up you have there. I feel the light is too dim on mine. I bet it’s the same as what came on yours.

That light actually doesn't fit in there with the stock bulb holder (too long + weird threads). I took out the bulb holder and drilled it out to a size in between the diameter of the main bulb and the diameter of the widest part, and reinstalled it upside down to get an extra half inch or so inside there. There's still clearance to the plastic bulb cover even after however many layers of electrical tape I put on there.

I got that one because it was the brightest small LED Home Depot had on the shelf. I could have got one that just screwed in but it would have been less than half the light.



I will try the teflon tape, I have a roll of the nice thick grey stuff somewhere.

 

[Woodslasher]

@Philbert

 

[Philbert]

I’d have to see the grinder.

Philbert

 

[HarleyT]

When I advance the chain, I tug backwards on the chain to tighten it against the stop before clamping, just do it automatically, over time it gets to be a set habit. It holds everything level and straight.
I would just try a few drops of locktite on the plastic "nut", as it should be able to be easily moved back and forth to keep the wheel from touching the stop when tilting the vise.
As far as grinding pressure, I just start out giving light taps, and if a lot of damaged cutter needs to be removed, will make a few passes around the loop.

Also use your dressing brick.

It is good that you like a lot of light, it means that you are watching what you are doing and the angles that you are trying to achieve.

 

[Old2stroke]

There should be a bolt on the back of the vise that can be screwed in to move the rear rail of the vise forward, it's there to allow the chain to be positioned so that the centre line of the chain is on the centre of rotation of the vise, if you screw it in, it will narrow the vise rail opening and give more clamping pressure. The vise will only clamp the link that is in the grinding position and when clamped, the link should NOT move. For consistent accuracy in positioning the chain, It is necessary to pull the chain back against the stop finger before clamping the vise, not only will this remove any slop in pivot points, but due to the angle of the finger, it will press the link down against the rails. Don't know about your grinder but the 510 has a solid downstop for depth control, an adjustable bolt that stops against solid metal and is quite insensitive to amount of pressure by the operator.

 

[Philbert]

I would just try a few drops of locktite on the plastic "nut",

No. This is something that needs to constantly be adjusted, not fixed in place. I adjust this even when sharpening a loop, for cutters that need a 'little more' taken off.

It does not seem to move significantly, on it's own, on my grinders. @SOS Ridgerider 's idea of Teflon tape might be interesting to try. Slightly 'damaging' or 'deforming' the threads on the plastic nut would also make it a bit tighter, if it is a problem.

Grit can get built up in the vise mechanism of any grinder, but the OP says that he has only done 3 chains. Could be some rough edges in the parts ? My first thought would be to disassemble the vise (watch for the spring loaded ball bearings in the base!), and clean up any edges, castings, etc. This has been a very popular grinder for several years, and if it was a design flaw, I would have expected to hear more about it.

As far as 'slop' in the depth stop, it may be that he is trying to force the grinder? Bear in mind that the user is doing the sharpening, not the tool. I grind each tooth, then inspect it, to see if that is what I want. I don't just jam down the wheel and expect the grinder to take care of everything. Same thing with a file, file guide, etc. It is a different perspective when you consider the tool to be an aid, rather that something that is responsible for the result.

I like the idea of the brighter LED light. Maybe reach out to Oregon and it can get incorporated into future versions. Or post it in this thread for others:
https://www.arboristsite.com/community/threads/511a-grinder-improvements-tweaks.197073/
Philbert

 

[huskihl]

I thought the plastic head and rubber washer would be chinsy also. But they seem to hold the stops perfectly in place. Tighten the 2 together a little if something wants to move on it’s own

 

[HarleyT]

No. This is something that needs to constantly be adjusted, not fixed in place. I adjust this even when sharpening a loop, for cutters that need a 'little more' taken off.

It does not seem to move significantly, on it's own, on my grinders. @SOS Ridgerider 's idea of Teflon tape might be interesting to try. Slightly 'damaging' or 'deforming' the threads on the plastic nut would also make it a bit tighter, if it is a problem.

Grit can get built up in the vise mechanism of any grinder, but the OP says that he has only done 3 chains. Could be some rough edges in the parts ? My first thought would be to disassemble the vise (watch for the spring loaded ball bearings in the base!), and clean up any edges, castings, etc. This has been a very popular grinder for several years, and if it was a design flaw, I would have expected to hear more about it.

As far as 'slop' in the depth stop, it may be that he is trying to force the grinder? Bear in mind that the user is doing the sharpening, not the tool. I grind each tooth, then inspect it, to see if that is what I want. I don't just jam down the wheel and expect the grinder to take care of everything. Same thing with a file, file guide, etc. It is a different perspective when you consider the tool to be an aid, rather that something that is responsible for the result.

I like the idea of the brighter LED light. Maybe reach out to Oregon and it can get incorporated into future versions. Or post it in this thread for others:
https://www.arboristsite.com/community/threads/511a-grinder-improvements-tweaks.197073/
Philbert

Yeah, me too. The loctite still helps on mine. Or just get a new knob/nut that has some more grip. I just got a standard wing nut and use loctite.
I just add another drop when it starts getting to start moving on it's own.

 

[jetsam]

I put the teflon on and had a better look at the offending clamp.



The depth gauges stuck in there in the photo are 0.43 and 0.50. Clamped the clamp and slid them over as far as they'll go easily. Looks fine?



In the next photo, it becomes apparent that only the center of the clamp will get complete clamping regardless of chain gauge (all gauges are .050). But that should be OK, we only need to clamp then drive teeth of the link in the middle. Right?



In the next photo, tooth is set up for grinding. The drive teeth are almost but not quite centered on the middle of the clamp. The clamp is tightened so hard that the grind angle has been changed (this is not practical to do when actually grinding a chain). As you can see in the photo, the left hand drive tooth is firmly clamped, but the right hand one is not, allowing the tooth being ground to rock when the wheel hits it. It's not that we have bottomed out the clamping cam... it's that the cam only touches the clamp plate at one point and that's where the clamping happens.



The last photo shows a piece of aluminum flashing that was shimmed in between the cam and the clamp plate. The indentation on the bottom shows the width of the firmly-clamped area that the cam actually rotates against (it's about 2mm).



Also, it is not really possible to clamp the chain firmly without adjusting the grind angle CCW, no matter how tight you screw down the grind angle.

I think I could 'fix' it by taking out the stock blocking that sets clamp width and grinding it down to .060, at the expense of being able to fit larger chain in the clamp. But it seems like a poor clamp to me... for now, just holding the tooth down with a screwdriver as the wheel hits it, and fixing the grind angle every time I tighten the chain clamp... I am getting the feeling that I should have got the $75 version of this tool, at least then I'd have expected this.

 

[huskihl]

In this photo, the tooth that’s up against the stop lever isn’t held tight?

 

[Philbert]

I have a N.I.B. Oregon 520-120 grinder, never been used. Checked it with a number of chains, from 1/4” to .404 pitch, and 0.043” to 0.063” gauge. They all seemed to hold at the cam with modest pressure.

I am not sure what warranty options you may have, due to your modifications, but you might want to reach out to Oregon Customer Service for advice or assistance.

Philbert

 

[jetsam]

In this photo, the tooth that’s up against the stop lever isn’t held tight?

View attachment 886498

It is, but the next drive tooth isn't, and this allows the tooth being ground to rotate counterclockwise when the wheel hits it.

 

[jetsam]

I am making progress, just ground my first .375 LP and got real nice teeth out of it. I did grind every tooth on one side longer than the other (yes, the wheel is centered on the vise).

I read some threads about this (apparently common) issue, and it seems like folks adjust the chain stop when switching sides.

When switching sides, I guess you set it up to just kiss the new tooth, and then keep taking a tiny bit off at a time until it matches the other side, and then leave it there for the rest of the chain?

 

[Philbert]

Figure out which side gets ground shorter, and always start with that side.

Then grind one tooth on the other side, and compare it back-to-back with a tooth from the first side. Adjust until they match.



Philbert

 

[jetsam]

So I have had a chance to go back and grind a couple more chains. Just did a loop of .050 3/8 semichisel at 55/35/0 (35 because it was Carlon's original spec for this chain).

The clamping issue was pretty much resolved through properly re-centering the clamp assembly on the grinder. I still get occasional motion on the angle dial when clamping, but I check it quick every tooth.

The depth stop still seems to want to move a little even with Teflon... I am going to try blue threadlocker and maybe a couple more flange nuts on there. I also plan to come up with a marking system so I can easily see if it has moved at all (it's getting a lot of sharpie marks on it right now).

I am having much more consistent results with a gentler touch and a good set of dial calipers. My tooth lengths were so crazy is that 1) I trusted the machine to do both sides the same, and 2) The amount of pressure I put on the grinder after it hit the stop would vary a lot tooth to tooth.

I fixed 1) by measuring the finished teeth, just barely kissing the first opposite tooth, and then regrinding it repeatedly with about 1/8 advancements on the depth stop until the length was right.

I am thinking about fixing 2) forever by removing the spring and adding a catch to hold it up instead. This would completely standardize the pressure each tooth got, but also be a pain in the ass to operate. We'll see how my technique develops before trying that.

The chain I ground tonight is within .005 on every tooth except one that I somehow got shorter than the others (it's not cut deeper so I wasn't paying attention to then depth stop most likely). I feel like it could have been better, but that's good enough for cuttin' wood.

Progress! Thanks to everyone who helped so far.

 

[huskihl]

So I have had a chance to go back and grind a couple more chains. Just did a loop of .050 3/8 semichisel at 55/35/0 (35 because it was Carlon's original spec for this chain).

The clamping issue was pretty much resolved through properly re-centering the clamp assembly on the grinder. I still get occasional motion on the angle dial when clamping, but I check it quick every tooth.

The depth stop still seems to want to move a little even with Teflon... I am going to try blue threadlocker and maybe a couple more flange nuts on there. I also plan to come up with a marking system so I can easily see if it has moved at all (it's getting a lot of sharpie marks on it right now).

I am having much more consistent results with a gentler touch and a good set of dial calipers. My tooth lengths were so crazy is that 1) I trusted the machine to do both sides the same, and 2) The amount of pressure I put on the grinder after it hit the stop would vary a lot tooth to tooth.

I fixed 1) by measuring the finished teeth, just barely kissing the first opposite tooth, and then regrinding it repeatedly with about 1/8 advancements on the depth stop until the length was right.

I am thinking about fixing 2) forever by removing the spring and adding a catch to hold it up instead. This would completely standardize the pressure each tooth got, but also be a pain in the ass to operate. We'll see how my technique develops before trying that.

The chain I ground tonight is within .005 on every tooth except one that I somehow got shorter than the others (it's not cut deeper so I wasn't paying attention to then depth stop most likely). I feel like it could have been better, but that's good enough for cuttin' wood.

Progress! Thanks to everyone who helped so far.

If your left cutters are longer than your right cutters, you’d need to loosen the vise-centering jam nut and turn the set screw in and try it again

 

[Philbert]

Operating a chain grinder efficiently, and effectively, requires knowledge, skill, and experience, like a lot of things. It’s not ‘automatic’, as some people expect.

You have already described progress; you will just keep getting better, and sharpen without thinking about all the ‘little things’ you are doing.

Philbert

 

[Piotr Pakula]

I like the dust extractor more and in the Chinese sharpener I also did some slight modifications. Oregon, well, this is precisely Italian accuracy, although it's not cheap