Ever try an un-shaped grinding wheel to sharpen?

[watsonr]

It would still give the top plate the correct angle if my brain is telling me correctly. Side plate would be different, probably a sharper angle and would still function. May actually make a chain last longer because of the angle.......
Anybody try it?

 

[big t double]

I wish I would of read this 15 minutes ago I woulda tried one out, I just put a new .325 wheel on my grinder...I have done it in the past because I wanted to see what it did but I never cut with it, I dressed the wheel and resharpened.

 

[paccity]

no but i have played with some semi chisel safety. using my square grinder. had some interesting results as far as speed , now longevity is still unknown.

 

[heyduke]

i have given this some thought in the past. it certainly would simplify wheel dressing. resharpening in the field would require different files, maybe the same ones used for square ground. you might need a round dressed wheel or file to grind the gullet. you might want to dress the wheel at an angle other than 90 degrees to avoid weakening the cutter. it's a good hypothesis. we need some experiments.

 

[MtnHermit]

Ever try an un-shaped grinding wheel to sharpen?

Isn't this an "un-shaped" wheel? It grinds using the flat side of the wheel and gives a straight flat surface to the tooth at a 60 deg angle. Seems this is how all OEM chain is sharpened and only a file or small wheel provides a concave tooth.

 

[AKDoug]

That picture is all sorts of wrong unless someone was trying to take the top of the depth gauge off. The chain should be running the other way.

 

[Philbert]

It would still give the top plate the correct angle if my brain is telling me correctly. Side plate would be different, probably a sharper angle and would still function. May actually make a chain last longer because of the angle.......

I have argued against this point in several threads, so I will try to summarize some of those perspectives here.

- You need to start with the cutter shape that you want, then determine how you are going to achieve that. If you would file your chains with a rectangular file (90* corners), then go ahead and grind with a 90* profile on your wheel. If you file with a round file, then grind with round profiled wheel, and STOP when the wheel reaches the same depth as you would with your file. If you 'square' file with special bevel-edged files (corner angles greater than 90*), then profile your wheel that way. But don't expect to grind differently than you file and expect the same results.

- Grinding the top plate of the cutter with the flat of the wheel does not give you the same hollow grind cutting edge that grinding with a round profile does. You may prefer one or the other, but they are not 'the same', even if the cutter angle (viewed from above) is still 30 degrees (or whatever).

- If you grind or file conventionally with a true 90* edge you will end up with a weak, unsupported top plate at the point/corner, which square ground users refer to as a 'beak'.



- The importance of the side plate edge often gets overlooked (IMO), even though it does a big part of the work, cutting through the wood grain (cross-cutting). Grinding a deeper 'hook' pushes this edge back farther in the cut, delaying it's entry. Several guys will tell you that they like the 'self-feeding' action this creates, but this means that some of the saw's power is being used to pull the cutter deeper into the wood instead of cutting through the fibers. If you ground a deep hook with a square edged wheel, you would push this cutting action back even further.

we need some experiments.

Nothing like good experimental results! Just need them to be objective, and have enough trials to make sure that the results don't apply only to a specific type of wood (or a specific log!).

Seems this is how all OEM chain is sharpened and only a file or small wheel provides a concave tooth.

Round ground OEM chain is shaped round. Take a look at the side plate, or see how an appropriately sized file or dowel rod fits against the ground surface.

Philbert

 

[AKDoug]

I've done some fairly in depth timed testing of round ground done several ways. My fastest cuts are when I go deep with the round wheel, deep enough that I'm just missing the tie plate. However, this same grind will not fit a round file well and makes hand sharpening a pain. Since I don't hand sharpen ever, this isn't an issue for me. When I sharpen chains for customers I adjust based on whether I am the only one who sharpens their chains vs. them hand filing in the field.

 

[watsonr]

That picture is all sorts of wrong unless someone was trying to take the top of the depth gauge off. The chain should be running the other way.

they were, look at the tooth to the right of the wheel... the raker has been ground.

 

[watsonr]

the picture shows the wheel in to low and the beak is formed. If it were just a square wheel and still set to 60 like a round one, the side of the stone would still produce the same angle as before. Doug sharpens the way I do... the side of the stone ultimately shapes the top plate and I remove a good portion of the gullet at the same time, right down to the strap.

Now if you could just push the holder back a little further you could control the side plate better and it would be flat instead of rounded. The square shape of the stone may need changing. The shape would be more of a < but closer to 90 degrees like an L, but tilted and the bottom of the L actually the top and the longer part the side plate.

I've heard of the old timers using a regular bench grinder to do square chain... getting the tooth angle would be all that's required to figure out. I've got some new wheels... I'll be trying it this weekend.

 

[heyduke]

one thing that is interesting about grinding with a square face is that depth of cut is less critical. with a properly dressed rounded wheel if you don't grind deep enough, the side plate angle is nearly 90 degrees, too deep and the beak is poorly supported and, as philbert says, sharpening in the field is difficult.

i have seen quite a few chains ground with an undressed face. i get them in the shop from guys who've bought a harbor freight grinder which comes without a dressing stone or gauge. their poor performance, though, is always due to unskilled work. i've always thought i could make a chain cut well like that. it isn't too much different from square ground. i suspect that the complex curved shape of a conventional cutter imparts a beneficial "lift" like the shape of a sail, wing or turbine.

 

[Philbert]

the picture shows the wheel in to low and the beak is formed

Just lifted that off of Madsen's site as an example.

I've got some new wheels... I'll be trying it this weekend.

Really interested to see what kind of profile you get, and how it cuts. Take lots of good photos!

You asked about an 'un-profiled' (I read as 90* edge) wheel. I started thinking about what you might be able to get with a wheel profiled more like on a Silvey square/chisel grinder, but mounted on an Oregon 511A type grinder. Might not get 'square ground' chain, but might be able to get something in-between?

Philbert

 

[lambs]

I usually make several passes on each cutter, so the first one or two is deep, and the final one is shallow to get the rounded profile back on the cutter. Works for me.

 

[lasmacgod]

My fastest cuts are when I go deep with the round wheel, deep enough that I'm just missing the tie plate. However, this same grind will not fit a round file well and makes hand sharpening a pain. Since I don't hand sharpen ever, this isn't an issue for me.

This is exactly how my grandfather (used to, anyway), father, and I do it when grinding. I don't recall ever seeing a wheel dressed except maybe when new, but I was never around for it if so -- they always had a rounded edge no matter the countless numbers of chains sharpened. Then again, we never used the grinder to take the rakers down. With semi chisel, this method cut faster than filing, but seemed to dull just a bit quicker. Still stayed sharp much longer than full chisel either way.

I now prefer to file, but for other reasons. Similar to why I prefer to cast my own boolits rather than buy them.

 

[Philbert]

Dressing does a couple of things:

- it shapes the wheel to a desired profile;

- it cleans the wheel and exposes fresh aggregate, improving grinding performance and reducing burning.

Even if you want the square profile, you should still dress the wheels periodically.

Philbert

 

[Stihl 041S]

You also have a more consistent form with a radius.
It will last longer.
The square dressed wheel will not stay the same shape as long.

 

[Steve NW WI]

Dang you guys, I was going to bed - then I HAD to see what it'd look like for myself.

I didn't get all the radius off my stone - and to tell the truth, I bought a CBN wheel as much for a consistent radius as I did for the other benefits. My macro photography skills leave a lot to be desired as well.

Here's an unadulterated pic. It'd probably cut wood OK, could use the gullet cleared out more. (Chain is a broken chunk of near new Carlton 3/8 round full chisel.)



Note that the Carlton chain has a bit of a radius on the corner - not as sharp as Oregon or Stihl.

Here's the same pic with some freehand markups showing what it'd look like in theory with a square cornered wheel. Grinder angles were pretty standard 30/60/0.



I might grab a junker chain the next rainy day and try grinding one like this, just for giggles, if someone else don't beat me to it.

Next try will maybe also be with a narrower wheel, I used a 1/4" because it was as close to square as I had - it was shaped for doing rakers before I gave up on that and went back to setting rakers by hand. I don't think wheel width will change much though, that pretty much just defines the radius (assuming a full radius on the wheel edge).

Stihl 041S - it did look to me like the wheel would be constantly trying to revert to a radius as you sharpened - at least until you'd given the chain this new profile and were re sharpening the same grind. The corner of the wheel is doing all the work this way.

 

[Philbert]

Steve, can you show us the other side of the cutter too?

Thanks.

Philbert

 

[Trx250r180]

looks like that cutter would last longer in dirty wood,but cut slower

 

[RedneckChainsawRepair]

I had tried square on my round grinder head, USG. I even shaped a wheel for square. I ended up with a bad beak and nothing like the square chains I was used too.
Maybe close enough for some, but not for me back then.