how to calculate the angle practically ?

draw the cross section of the drum on it and create a template ? doesnt seem right. the drum is 119" in dia.

some other method please . like water balance etc ?

Just use a long straight edge, laid out as Usbport suggests and measure the angle between it and the knife.

The diameter is pretty important info, and there was no indication the drum was that big. But Lyn's advice is good; use a long straight edge with a 59.5 inch radius to draw the curve of the drum. Anyone with basic carpenter's skills and tools can help you with this.

Or, if this contraption already exists, just tie a string around the center shaft and stretch it tightly so that it intersects with the blade contact point and measure that angle.

Seems simple enough.

This assumes that the drum exists and you don't have any drawings of the device.

Next time plan ahead.

Lay a straight edge on the drum so that the contact point is at the knife contact. This is a tangent to the drum, measure the angle. Measure the angle of the knife and with a little addition and subtraction you have the answer.

thank you so much guys !!

next time i will try to put a autocad file ! i think cr4 must make it possible to change .dwg file to .jpeg format !!

:)

You can always do a screenshot of your cad drawing, which yields a .bmp file. There are various ways to convert that to a .jpg, including Windows/Accessories/Paint.

Or use Windows Snipping tool... This yields a .jpg

Since you know the diameter, (119") then the drum circumference is : 119 x 3.1416 =373.85 ".

Determine the Top point of the drum using a level or other instrument, and lay a small rope from this point to the contact point of the knife, measure the rope, then finally multiply the length by 373.85 and divide by 360 you get the angle in degrees.

Maybe this will work for you:

The calculation for a sector length is --> S = R x Theta (in radians)

S = sector length

R = radius of circle

Theta (in radians) = Degrees x pi/180

Mount a laser to shine a beam parallel to the blade so it reflects off the drum. If the drum is not reflective, wrap a reflective ribbon around it. The angle between the incident and reflected beams can be measured with a protractor.

Modern Technology does make this to easy.

Another way to do this is to extend the knife line onto the side of the drum with an appropriate marking tool, like a pencil or felt-tipped pen. This creates a 'chord'.

Using a carpenter's square find the centerpoint of this chord, and draw a line perpendicular to this chord out to the edge of the drum.

Then rotate the drum so this line and the knife edge meet.

Then draw another line extending the knife line onto the side of the drum. The angle between these two lines, A, is the angle you want. (Or, this angle plus 90 degrees, depending on how you define the angle.)

i assume the trunks of wood? being cut are not pre-perfected polished surface .. cylinders (?? Ø6m or Ø3m truncks .. WTH) .. it's "easy" to calibrate* your apparattus so that from it's position you already know the "current diameter of the trunk and the angle of incident" .. now how many of you loose the job if you set up such an automated "power station" . . . i remember such stuff it's like a small dam of a small river ... where downstream is an operator pathway ramp ?? two of such side by side ??? she-boss spirit of a tree or a money or both by occasion ... (why the society has a second face hidden somewhere .. most always .. <- doesm't apply for kids (not that i remember any examples)) . . . yo, a technical question* (muh-hah)