Need Help w New KMG and Plunge Line

CDHumiston

CDHumiston

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Joined
Feb 17, 2009
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I got my new KMG up and running. However I am still having a hell of a time getting my plung line correct. I also seem to have problems keeping my passes at the same angle. My blade ends up looking like I'm trying to file it at 3 diffrent angles on each side.

I Need Help!! Please...
 
Well, I'm a beginner too but what I learned is that there are slightly different ways of doing things. Are you hollow grinding or flat grinding? Some people grind the plunge in a little first before going on to sweeping passes on the rest of the blade. The way I do it is to mark the location of the plunge lines with a marker and start grinding at 45 degree angle from that line all the way down the blade to to the tip, getting it as close to my scribed center lines as possible. Once that happens I decrease the angle and start grinding the flat (I flat grind) on top of the previous grind (eventually it will blend in if done correctly and consistently). After that I essentially "ride the flat" making sweeping passes and "walking" the grind up to the desired height. You should keep in mind that it will take time to get the motions down and your passes smooth and even on both hands let alone your dominate hand. Also, keep in mind that you need to be patient and not too eager to walk the grind line up. What Hp are you running on your motor?
 
the plunge line on flat grinds is the hardest part at least for me. I just started to do hollow grinds and found it way easier and have a real nack for it. had the 10 inch contact wheel since i bought the grinder lmao what was i thinking
 
What grit belt are you starting off with too? I rough grind with a low grit but that is also because I am using a motor with little HP. Hellgap is right about the plunges on flat grinds. They appear to be a little more tricky than with hollow grinds IMO and may require more clean up before and after heat treat.
 
Hey, I'm having the same issues with my Craftsman...you mean to tell me the KMG doesn't just figure those things out for ya??!!:D

Seriously, I'm a beginner too, but I've found this file guide very handy for getting plunge lines started......set the lines with a file, then take the guide off as you start grinding.
You may also consider putting the call out for someone in your parts to come out to spend some time with you and show you some things to get started. I did that and found it well worth the 12 pack I provided.
After that....it's practice forever!
IMG_0639.jpg
 
I am flat grinding with the platen attachment. I also have an 8" contact wheel. I'm running a 1.5HP Leeson motor with a KBAC Drive Controller.

I did try the 45 degree angle approach on my last blade and it started out good. When I started making passes at a lesser degree to grind the blade down it just went from bad to worse. I'm having trouble keep one smooth grind line.

I'm starting off with a 60 grit belt.

Thanks,
 
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Chris , make a few passes and start a flat that you can feel when it is layed against the platen . Then look at the blade to see where the grind lines will end up when done . If the lines need to be moved up toward the spine or edge , just slightly change your pressure in that direction until you create a new flat you can feel and it will blend in eventually with the 1st. one . As Murdock said , ride the flat . Don't try and make radical angle changes . Time and practice . You can use a file guide on the blade with a flat platen , just make sure your belt does not run off the edge of the platen .
 
This may sound bassakwards but if you are running 60 grit ceramic belts, run them faster and use less pressure,They will cut better and not cause as much drag on the blade and cause your grind lines to go haywire.
Stan
 
Here's the process that really helped me learn.

1. Scribe centerline on blade.
2. Grind 45 degree bevel on each side of blade within .020 of center line (gives you a total of .040 edge.
3. Use a bright light and a pair of magnifying lenses if your vision is not perfect while grinding your blade. (this helped me a lot!)
4. Look straight down on the blade and place on platen with about a hair's distance between the belt and your nice even .040 edge.
5. Make a smooth pass keeping a hair's distance away from that edge. No need to apply much pressure as you learn how this works. Just use a good fresh belt and light pressure. Concentrate on keeping your elbows tucked in and moving your whole upper body as a unit when making the pass.
6. With each successive pass, just keep that hair's distance away from your .040 edge. The grind will smoothly walk up the blade.

Once you get comfortable with this process you can start adding more pressure and higher belt speed. Be sure you are not rushed and take your time. Have fun!

Eric

cdhumiston said:
I am flat grinding with the platen attachment. I also have an 8" contact wheel. I'm running a 1.5HP Leeson motor with a KBAC Drive Controller.

I did try the 45 degree angle approach on my last blade and it started out good. When I started making passes at a lesser degree to grind the blade down it just from bad to worse. I'm having trouble keep one smooth grind line.

I'm starting off with a 60 grit belt.

Thanks,
Click to expand...
 
Thank you all for the advice so far. I think it has helped already by making me realize a couple mistakes I'm making.

I know I have been moving my arms too much instead of my upper body. I was definately putting to much preassure on the blade.

I am using quality belts, I will try and speed up the grinder and keep the preassure to a minimum.

One other question; Tool Rest or No Tool Rest...
 
Try to learn without a rest...you will become a better grinder if you do not use one. It takes longer to learn..but the results are much better and you are able to grind a much wider variety of grinds. If, for example you are grinding a curved blade...you must use a single point on your rest...say the spine of a bolt to let the blade pivot upon. Same goes for a recurve. Just learn to not use a rest.
 
No tool rest. Besides the points mentioned above it can also be dangerous if the gap between the belt and the blade is too big for the size stock you are working on. It can suck the blade tight down and either jam between the rest and the belt or shoot it out towards your foot. Besides you don;t want your hands getting sucked in after the blade. I lost a blade or two two this but never had a ny damage to the hands. I say use it for profiling and what not but not grinding your primaries.
 
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