Please check my square grinder wheel specs - considering a cbn wheel

[B_Turner]

Can someone please check my specs on my silvey pro sharp grinding wheel?

I am considering having a prototype cbn wheel made just for grins.

Where's what I am thinking:

diameter 7 inches (don't see a reason to go full 8)
thickness 3/16
arbor 1 inch
angle of longer bevel relative to top 16 degrees
angle of short edge bevel relative to top 65 degrees

width of abrasive on longer (top) bevel from top outer corner .2 inches
thickness of outside (short) edge .095 inches

Both Top and bottom of wheel must be flat for a diameter of 4 inches.

Don't know if the other models of silvey square grinder dress the wheel different or not. Anyone know?

 

[R DeLawter]

Silvey grinders are designed to use the 8" wheel and I thank that is one advantage to them.
Are you thinking cost as the reason to go smaller?

 

[mdavlee]

That sounds about right. I would have to measure mine to know for sure.

 

[B_Turner]

Silvey grinders are designed to use the 8" wheel and I thank that is one advantage to them.
Are you thinking cost as the reason to go smaller?

With a conventional wheel (my favorite is the blue ceramic wheels) the 8 inch is nice on my 510 and prosharp as the extra size has then running cooler than smaller wheels.

My thinking is typically the cbn wheels (like the ones I run on my bench grinders for HSS tool sharpening) have a pretty heavy carrier. Usually at least twice the weight of a conventional wheel (or more).

Since one of the big advantages of the cbn wheels is they run so much cooler, I think trading a little diameter for much less extra weight seems like a positive overall.

The silvey wheels only start out at 8 inch anyway, and end up closer to 6 before I swap them out.

And cost is a factor in a smaller wheel, but a lesser one.

I was wondering what wheel bevel angles other folks come up with on theirs.

 

[B_Turner]

That sounds about right. I would have to measure mine to know for sure.

I was hoping someone would be curious enough about their own wheel angles to measure....:msp_smile:

As a reality check before I sent off my specs to be implemented.

 

[srcarr52]

I'll throw an angle finder on mine tonight.

I'd probably go with a 7.5" wheel. When the wheels are new at 8" it's hard to get the top plate as shallow as I'd like (~12deg) and when the get to worn people won't be able to do 25+ deg top plate race chains, but I don't know what diameter that starts to happen at.

 

[w8ye]

The wheel angles on my swing arm is 80 and 20

 

[Philbert]

Subscribing just to follow and learn.

I keep seeing instructions and comments describing the angles on the finished cutters, but have been looking for at least some 'starting angles' for dressing the wheels.

Thanks.

Philbert

 

[srcarr52]

I measured my dresser setting to be 16 and 63 and my stone is 7.25 in diameter right now but I still have the thing backed out as far as it will go. So I think 7" diameter would be good.

 

[w8ye]

The difference in angles is probably because of mine is a swing arm and yours is a Prosharp

 

[w8ye]

LGX chain turned out nice with a 18 degree outside top angle and 88 degrees on the side. The inside was around 43-44 degrees. This is within the realm of acceptability for a square chain. I measured a factory Oregon 72CL chain and I got 16 degrees on the top plate, 86 degrees on the side, and 55 degrees on the inside top

 

[Philbert]

Here's a PDF on the Stihl USG square ginding attachment.

Thanks for posting that. Never used a USG grinder - looks like it needs its own training class to operate!

Philbert

 

[srcarr52]

LGX chain turned out nice with a 18 degree outside top angle and 88 degrees on the side. The inside was around 43-44 degrees. This is within the realm of acceptability for a square chain. I measured a factory Oregon 72CL chain and I got 16 degrees on the top plate, 86 degrees on the side, and 55 degrees on the inside top

I'm trying to get less than 15 top plate. Stihl chain come at 12. The side ends up around 85 and the inside is more than I'd like but it cuts nice and holds a good edge.

I have a razor sharp which should use angles real similar to the swing arm.

 

[w8ye]

You would figure it out on the USG but the wheel angle is a complement of the angle you are used to.

 

[B_Turner]

Thanks for all the info. I'll try to digest it.

note: I don't think the wheel bevel angles and the cutter angles are the same in the sense that it depends on how the wheel meets the cutter.

I've never needed to think about it before as my pro sharp has the built in dressers that have dealt with it.

Also I have my PS set in the middle positions so that is another factor in the equation.

 

[w8ye]

There you go . . .

The two grinders work completely different

 

[B_Turner]

According to my PS manual (measures pretty close to this) the middle position on the dressing arms yields

42 degrees inner top angle
20 degrees top plate angle (relative to the chain chassis, not each cutter)
2 degree side plate.

This has always worked so well for me I've never felt a need to change it.

The wheel is held horizontal and the chain is angled downward and to either left or right depending on which side the cutters to be sharpened are. The whole assembly moved straight into the wheel which is a nice feature because dressing the wheel doesn't change the effective angle.

When I bought it (maybe 10 years ago?) I tried all the Silvey square grinders and found 1) they were all primitive for the price 2) the PS was the best but most expensive.

For anyone on the fence, my advice is grab a square grinder while you can. It changed my life and I could never go back.

Also I am considering going with .085 for the side. I never run .404 so that should be plenty.

 

[B_Turner]

Here's a PDF on the Stihl USG square ginding attachment.

Check out the angles suggested.

Are these what other people are using?

It's what I had my borazon wheel made at ten years or more ago.

How's your borazon wheel working out? What grit did you go with?

I am leaning towards 80 grit because my 80 grit cbn grinder wheels tend to "plug up" less when cutting really soft metal as compared to very hard hss. for my turning tools I prefer my 180 grit cbn wheel for a better finish.

If the chainsaw cutter wasn't so soft I'd prefer more like 100 grit.

What I maybe do is take a chain cutter off a reel and try grinding by hand on a few different cbn grit wheels. I have 60, 80 and 180. Very little metal to come off a chainsaw cutter so maybe the finer grit no problem.

Although chainsaw cutters can't get very sharp due to the chrome anyway (unless removed like racing chain). So anything finer than 100 grit is probably wasted.

 

[B_Turner]

My borazon wheel has worked out well and I would guess it's ground maybe 4 or 5 hundred chains. I don't know what grit it is but it is quite a bit corser than the soft stones. Thinking back now I believe I bought it in 1992 so I've had it about 20 years. I lived in the mid atlanta area....Delaware back then and bought it based on the Stihl rep in the area suggestion. I didn't pick up the PDF's on the USG Square Grinder attachments but just a couple of years ago from Stihl. It took some time to get. I hadn't used the USG square grind in ten years and had lost my original instructions evidently when moving. This wheel is heavy steel with only about 1/2 inch of borazon along it's edge.


When I recently bought a CBN wheel I got a dressing stone. I didn't realize they ever needed dressing. My borazon wheel may well need dressing, too.

I think it depends on what you are grinding. With mine with HSS around Rockwell 66 they never need dressing. With softer stuff I think they do.

Do your cbn come with ao for a dressing stick?

 

[B_Turner]

The CBN round ground wheel I got a year or so ago came with a small white rectangular block for dressing. I don't know what it is made of.

I've seen cbn wheels listed with Aluminum oxide dressing sticks. I have old ao wheel pieces I might try that on my prototype if it seems to need cleaning.

I am glad to hear your borazon square wheel worked out. The only real issue I was wondering about is whether the corner of the wheel could cut into the inside if the cutter. Since no abrasive can be bonded to the corner of the wheel itself. Thanks for your report. I was not aware of anyone using a steel wheel for square so I am glad to hear about it.

I have a cbn bench grinding wheel with abrasive on the top and side, and in fooling with that it was not clear how clean an inside corner it could cut. I was hoping since with a chain cutter actually very little metal has to come off, the abrasive on each bevel of the wheel would simple "meet" in the corner and do the removal of the material.

Funny, I notice I have about 3k posts and only 27 credits. Pretty impressive, no?