Chain Filing Angles

[topchippyles]

11 minutes ago, Stubby said:

Ah . I get were you are coming from now .

Christmas is coming 🤭

[Stubby]

Just now, topchippyles said:

Christmas is coming 🤭

Yea but don't count on it . The fish bit I mean .

[Mick Roseblade]

Ok ,so moving on from fishy tales,

I started this thread with a question about top plate angles. Now I have checked my chain specs and most of them are 30 degs whilst some quote 28 degs, Since i don't think 2 degs is going to make any significant difference I will stick to 30 degs.

When it comes to side angle that's another level of confusion.

Just to make clear, I am using an Oregon 620 grinder. The chain vise does not tilt, it only slides back and forth.

All my chains are 3/8 or .325 round ground and a mixture of full chis and semi chis.

When it comes to the 10 deg tilt angle that some of my chains are supposed to have, I have no choice but grind at 0 deg. So I have my vise centred to 0 deg. If I move it to 10 deg back or forward it makes no visible difference to the working corner. The only difference I can see is that my top plate angle seems to be changed from 30 deg to more like 35. and the gullet has more of a knife edge than if done at 0 deg.

I can see why the tilt is used when using a round file, but for a grinding disk, I dont see how it helps.

As far as the tilt angle for the disk (side plate angle), I see many different angles quoted 55 degs to 80 degs.

I have been grinding at 0-30-60 with the correct size disk for the chain. I tried to put a round file into a tooth yesterday and noticed that the hook was excessive. Ie when the file was resting against the top plate and the gullet it was nowhere near touching the back of the hook.

I set my grinder depth stop such that it gets the gullet without touching the tie straps and gives a flat grind to the top plate. I know this will give a misshaped hook so I am not looking for perfection.

If I change the side plate angle down to eg, 55 deg, I get an aggressive but short lived cut and the hook is even deeper. If I go up to 70 deg the hook seems a closer approximation to that from round files but a top plate ground at 70 degs is a long way off 55 degs which is recommended on some of my chains.

I experimented a bit and found that if I grind at 65 degs it seems to give the best shape to the hook on both 3/8 and .325 chains regardless of make or model and a reasonable compromise of aggression and strength.

Since I assume that we are trying to approximate the tooth profile that would be given by a round file (but with the advantage of a flat grind rather than a hollow grind) when grinding with a disk, I dont understand why so many different angles are quoted, especially when filing with a round file if done at the correct height, that angle is almost impossible to guestimate and is set by the size and height of the file anyway.

I am not after a hot saw, nor am I a production cutter, I use farm grade saws  currently 435, 455 and 570 Huskys, although I have used Stihl saws previously. I am just looking for a good all round saw that cuts smooth and straight.

So, am I missing something here?

 

[Stubby]

8 minutes ago, Mick Roseblade said:

Ok ,so moving on from fishy tales,

I started this thread with a question about top plate angles. Now I have checked my chain specs and most of them are 30 degs whilst some quote 28 degs, Since i don't think 2 degs is going to make any significant difference I will stick to 30 degs.

When it comes to side angle that's another level of confusion.

Just to make clear, I am using an Oregon 620 grinder. The chain vise does not tilt, it only slides back and forth.

All my chains are 3/8 or .325 round ground and a mixture of full chis and semi chis.

When it comes to the 10 deg tilt angle that some of my chains are supposed to have, I have no choice but grind at 0 deg. So I have my vise centred to 0 deg. If I move it to 10 deg back or forward it makes no visible difference to the working corner. The only difference I can see is that my top plate angle seems to be changed from 30 deg to more like 35. and the gullet has more of a knife edge than if done at 0 deg.

I can see why the tilt is used when using a round file, but for a grinding disk, I dont see how it helps.

As far as the tilt angle for the disk (side plate angle), I see many different angles quoted 55 degs to 80 degs.

I have been grinding at 0-30-60 with the correct size disk for the chain. I tried to put a round file into a tooth yesterday and noticed that the hook was excessive. Ie when the file was resting against the top plate and the gullet it was nowhere near touching the back of the hook.

I set my grinder depth stop such that it gets the gullet without touching the tie straps and gives a flat grind to the top plate. I know this will give a misshaped hook so I am not looking for perfection.

If I change the side plate angle down to eg, 55 deg, I get an aggressive but short lived cut and the hook is even deeper. If I go up to 70 deg the hook seems a closer approximation to that from round files but a top plate ground at 70 degs is a long way off 55 degs which is recommended on some of my chains.

I experimented a bit and found that if I grind at 65 degs it seems to give the best shape to the hook on both 3/8 and .325 chains regardless of make or model and a reasonable compromise of aggression and strength.

Since I assume that we are trying to approximate the tooth profile that would be given by a round file (but with the advantage of a flat grind rather than a hollow grind) when grinding with a disk, I dont understand why so many different angles are quoted, especially when filing with a round file if done at the correct height, that angle is almost impossible to guestimate and is set by the size and height of the file anyway.

I am not after a hot saw, nor am I a production cutter, I use farm grade saws  currently 435, 455 and 570 Huskys, although I have used Stihl saws previously. I am just looking for a good all round saw that cuts smooth and straight.

So, am I missing something here?

 

Phew . Just use a file .

[Mick Roseblade]

When I was 3 years old I was involved in a road accident which left me with permanent nerve damage.

I have impaired muscle control and tremors, mild, but enough to cause problems with such things as hand writing and using files and handsaws.

So hand filing for me is hit and miss and always will be, I am 62 now, its not going to get any better.

[Stubby]

Just now, Mick Roseblade said:

When I was 3 years old I was involved in a road accident which left me with permanent nerve damage.

I have impaired muscle control and tremors, mild, but enough to cause problems with such things as hand writing and using files and handsaws.

So hand filing for me is hit and miss and always will be, I am 62 now, its not going to get any better.

Ok . Sorry to hear about that . I too have lots of bits of metal in me from a road accident . I was 50 though at the time . I know what you mean . I am 68 now and things take forever to heal .  All I can suggest is do what you are doing by experimenting and find what cuts best . good luck bud .

[openspaceman]

34 minutes ago, Mick Roseblade said:

So, am I missing something here?

 

I doubt it.

 

True a file gives a hollow shape to the top cutter  but its not very significant so the grinding disc just averages out the angle where the  file would cause a slight curve in the top plate. The main thing that does the work is the sharp corner (or tip with a full chisel.

 

Wood is slightly abrasive so too shallow an edge dulls quickly and being thin is more susceptible to damage which is why the angle of the disc sharpener to the top plate is fixed and only the  angle to the tooth is variable.

 

Out of the box all files are ground  not filed.

 

I'm dyspraxic but find filing no problem, if I did I'd be happy to grind them.

[Mick Roseblade]

30 minutes ago, Stubby said:

Ok . Sorry to hear about that . I too have lots of bits of metal in me from a road accident . I was 50 though at the time . I know what you mean . I am 68 now and things take forever to heal .  All I can suggest is do what you are doing by experimenting and find what cuts best . good luck bud .

Thanks, Its a minor issue most of the time, but I am just trying to be more consistent so I thought a grinder would be a good solution.

[Mick Roseblade]

8 minutes ago, openspaceman said:

I doubt it.

 

True a file gives a hollow shape to the top cutter  but its not very significant so the grinding disc just averages out the angle where the  file would cause a slight curve in the top plate. The main thing that does the work is the sharp corner (or tip with a full chisel.

 

Wood is slightly abrasive so too shallow an edge dulls quickly and being thin is more susceptible to damage which is why the angle of the disc sharpener to the top plate is fixed and only the  angle to the tooth is variable.

 

Out of the box all files are ground  not filed.

 

I'm dyspraxic but find filing no problem, if I did I'd be happy to grind them.

It is true that out of the box they are indeed ground, but they are done individually before the chain is assembled. Once you sharpen them with a file you get the round profile. All I am saying is that I am trying to approximate that profile on my grinder with an already assembled chain and sometimes badly hand filed teeth. I am aware that if you file to high with a round file it causes problems as does filing to low, as you say "too shallow an edge dulls quickly "and weakens the teeth by causing excessive hook.

I am just looking for the sweet spot to get a good all round compromise with a grind disk.

[5thelement]

56 minutes ago, Mick Roseblade said:

It is true that out of the box they are indeed ground, but they are done individually before the chain is assembled. Once you sharpen them with a file you get the round profile. All I am saying is that I am trying to approximate that profile on my grinder with an already assembled chain and sometimes badly hand filed teeth. I am aware that if you file to high with a round file it causes problems as does filing to low, as you say "too shallow an edge dulls quickly "and weakens the teeth by causing excessive hook.

I am just looking for the sweet spot to get a good all round compromise with a grind disk.

Have you got a stone to re-profile the grinding disk? 
I have only used a grinder to reshape and sharpen harvester chains, I would have to reshape the disk occasionally to get the desired result in the cutter.