how fast do you grind?...belt speeds

rfrink

rfrink

Joined
Aug 1, 2000
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After talking to a few different makers, it seems that belt grinder speed is as unique as the makers themselves.

To help me advise customers better, I'm interested in a wide sampling of data from makers about their preferred grinding speeds.

So, what are your speeds and the tasks if you know them....say for:

1) 30-80 grit belts (roughing..?)

2) 120-220 grit

3) 220 + (finishing...?)

If you don't know the belt speed, no worry....let me know your motor speed and drive wheel size...or drive wheel size and speed....I'll figure it out from there. For example: "my BIII motor is single speed 3450 rpm and I use the 5" drive wheel...."

How about the guys with fixed speed machines...What do you do? Say for example, a grizzly, ( runs about 3500 ft/min)... do you run 400 grit belts this fast?

The info gathered may go into an artical on my web site.


Sincere thanks for any contributions,

-Rob
 
Rob
On my set up I have a G@E motor V/S
I think it may be 3750(?)
I do not run it at half that when I am hollow grinding
for 50 grit maybe 1700 Rpm
for 120grit about 800
for 220 about 500
for 320 about 400
for 400 about 350
etc
as you can see I am no speed demon but I have more control at slower speed.Hope this can be of some help to you.
 
Rob,

I'll jump in here with my 2 cents. I'm running a coote with pulleys, 2-3-4 on the motor(1725) and 6-5-4 on the grinder shaft.10" wheel. I run 4 to 4 when profiling and grinding with 36-50 grit belts,(shaft speed 1725) 3-5 with a 400 grit belt for clean up to heat treat(shaft speed 1035) and after heat treat 2-6 with a 120 grit to clean up heat treat scale and grind to finished shape, then 2-6 with 400 (shaft speed 570) then hand sand from there to 2000. I believe these are the correct shaft speeds, should be close anyway :D .

Bill
 
Getting back into grinding, after a looooooooooooooong lay off, due to spinal problems, I ground The bevels in 5 profiled blades a few weeks ago. Took me about 20 minutes to rough grind the bevels on the lot. The belt was a 977 3-M co., 40 grit, the speed was about 30%, on a leeson VS 11/2 HP, setup on a Burr-King.
I have never found speed to be a big factor in blade grinding. I have usually found that it is a knifemakers worst enemy.
This is just me though, others may have a very different perspective.
 
Rob, my ho'made 2 X 72 runs off a 10 Inch drive wheel on one end of a hardwheel bench grinder. The little plate on the grinder says 2 HP and 1750 RPM. Is single speed of course. I use it mostly for roughing with 36 Grit belts, then switch to 120, then 220 to clean up, sometimes 320. Post heat treat, other than knocking the black off with a 120 belt, everything else is by hand.
 
with hardcore grinder 1 1/2h yar, 36-50g 3/4s to full power. 100-220 1/2 power. 220-400 1/4 power on steel slower some times on wood.
 
I do all my Ruff grinding --- Profiling and setting the first grind on the bevels ----- with 60 grit blue zirconia belts On my homemade 2X72 with a 2 horse 3450 rpm motor dierect drive with a 3 inch wheel.
Then move to my 2 horse tread mill moter with variable speed running a direct drive 3 inch wheel at 1/3 speed to do the clean up down to 150 grit aluminum oxide belt Then 320 aluminum oxide before heat treat.Then depending on how thick I left the bevels --If thick I go back to the fast single speed grinder with a half wore out 60 grit to thin it down-- other wise I may take a little thickness off with a half dull 60 on the variable speed then move to a new 150 grit to get to almost complete finish dimensions and to set the back edge in,then I move to a new 320 grit to final dimensions and then I finish the final clean up with a dull 320 grit that has been sprayed with WD-40 as a lubricant..Then I move to the palm grip sander and work down from 320-400-600-800 grit paper then start hand rubbing with either 600 or 800 then finish with a 1200 grit ( I hope to start going finer one day soon)
I was taught the grinder speed and belts from Alex Daniels as he uses the same grits on his blades then starts hand rubbing at 600 grit.He uses variable speed grinders with 4 inch direct drive wheels.All his blades are done on the Variable speed as he has no full speed grinders.
Hope this helps,
Just the way I have found to work.Thanks to Alex...
Bruce
 
Running a 1750 1 hp 240 off the main drive with an equal size dive on the work end 2.5. A 2X48 Speed Cut grinder. I am slower than most, but plenty of power at the critical moments and the slower speed don't wear my belts sooo bad. I really want one of your grinders (variable} 72 so I can progress to the level of some of the other makers. I run four tools off of one shaft powered by this one 1 HP motor. The shaft runs across the back of the bench with pullyes running to the individual tool stations. One Ginder with a hard wheel, two buffing wheels and two more for finer grits. I can change the size of the pulleys to change speed but don't often. Hope this helps. Terry
 
My sander does not have speed adjustment. Australia runs at 50 cycles per second so I think our speeds may be different.
From memory a formular like cycles x seconds divided my pairs of poles.I you guys use 60 cycles I think yours would be faster.I have a 100 mm drive wheel straight of the shaft no pulleys etc.
1 speed fits all I have found learning was hard a high speed however with practice it is not so bad. easy on the pressure.
I use 400 and 600 grit to finish off I find this makes the metal hot
very quick. The only real point in my style of use is that I was advised to get a grooved wheel to keep it cool. I actually find this
grooved wheel a hinderance. I can feel every groove through the belt.
I have used a friends without grovers I like it better. This mainly happens on the fine grit belts with the j weight thin backing. The coarse heavey weight belts are not a problen.
Just a side tip some of the computer hard drives have 2 great flat magnets in them with screw holes. screw them into a piece of wood and they hold the blade without your fingers getting ground off.
Computer repair shops charged hundreds of dollars for the drives a couple of years ago now they throw them in the bin when they upgrade.
 
I have the baderIII with the 1.5hp variable speed leson. Most all my grinding is done at about 20% of full speed.
 
Using a Bader BIII, 2 hp VS, I grind full speed to profile and rough grind the bevels prior to heat treat. After that, about half speed to regrind to final dimensions with finer belts. Sometimes slower for fine work or ivory when I worry about heat build-up. I wish it would run even faster!
 
Rob
I'm using a standard Wilton 1 1/2 HP no v/p
and it's been good for me but at times I
wished I could slow her down about half just for finishing.
I go from 60 or 80 to 220, 30mc,to 15mc, then hand sand 1200,1500,
then maybe 2000, depending on the grain I get from the heat treat
then light buff.
 
Call me "Mr Spreadsheet" 'cause three fourths of my working life is spent in Excel... :rolleyes:

So how do you expect the world looks to me? :D I tried to attach a spreadsheet showing the belt speed / finishing habits of many of the makers in this thread, but only images are allowed and I couldn't.

But if anyone wants the table just write and I'll send it to you. If you like looking at your information in columns, it works great. You can really 'see' how we work, as individuals. :cool:

Dave
 
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