question on plunge cut

[mmunds]

I am interrested on hearing how others do their plunge cut from the ricasso. I can do pretty good on most aspects but suffer in this area. Any help or advice would be appreciated. Kind of bites looking down a perfectly finished blade and seeing a mess in this one spot.

[SVanderkolff]

Mark
The only real answer is practice. I do mine on the KMG and its really a matter of doing it many times with lots of patience. One of the methods I picked up from Gene Osborne's video was the idea of moving the plunge back just a bit on each successive gritt change. This gives you plenty of opportunities to get it exact.
Hope this helps.
STeve

[george tichbour]

Practice is the only answer but also pay attention when you are doing practice grinds. You will notice that one side will be better than the other on a consistant basis, this is your dominent side based on a combination of hand and eye dominence. Try grinding the weak side first then using the strong side to simply match the other side. You will find that it is easier using your dominent side to match than the other way around.

I am right handed but left side dominent so I grind my right sides first and match that. Easier to get matching grinds that way.

[rhrocker]

What these guys say, plus, look at other knifemakers plunge areas. My favorite is Terry Primos, he consistantly has the cleanest plunges of any out there. There are others also, but Terry's stands out. It's good to know exactly what it is your trying for, instead of just holding the steel to the grinder, and seeing what developes.

[mmunds]

Thanks guys, I know practice is needed, I used to do a pretty decent job but never got passed a certain point. Do you use the edge of the belt on an exact edge of platen? or clean it up with File and paper? or both? I can get it pretty close, but want to do as good as someone like Terry does. I would agree on his lines being so clean! Thanks again

[hogcat]

Im no pro, but I usually have the belt even with the edge of the platen when roughing out the plunge cuts. Then when around 75% finished with the plunge I have the belt hanging over the platen around an eighth inch or so to round off the plunge. Just use the tracking to have the belt overhang on which ever edge of the platen you are using. I found out not to go back to having the belt even with the platen after rounding the plunge off, cause you will put a grove in the plunge after rounding it out.

[Dan Graves]

I agree with what has been said. One thing to do is after the plunge cut and grinding, use a j flex and let it track about 3/16 (or less) off of the platen and it will give good radius on the plunge. Takes a little practice and fine grits but you can get good results. Practice, practice, practice!!

[Drac]

Also make sure your platen is in good shape. I wore down the first platen I got with my grinder very fast and had problems with both sides matching. I switched over to a different material and with both sides of the platen matching I'm having an easier time making the plunges even. The maker I had shop time with replaced his mild steel with a hardened steel platen which he takes his surface grinder to so it?s true.

Both the suggestions of Steve, with the successive belts, and Dan, with the over run, are BIG things to help improve your work. Outside of that its practice, I know it's never what anyone wants to hear. Your probably like most of us and not ambidextrous. It takes time to get the feel and motions for your off hand.

Jim

[mmunds]

Thanks guys, I really need a better platten to start as mine really is worthless on the edge, I'll start there. As for practice I agree! I will be doing alot of that. Just wanted to figure out the most common way of doing it by machine. I have never been shown or told and appreciate the input. It really helps to be able to take it to the next level. Thanks again

[hogcat]

Also I might add to help. When you are 75% done with the plunge cut, do not stop and hold in one spot while up againt the plunge!!! If you are using a 2" belt, you will see a grove 2" away from the plunge cut. Onless you get the "feel" and tilt the blade away from the edge opposite the plunge while dressing up the plunge cut. You will see after some practice on how you can "tweek" the blade pressure around to adjust which side of the belt is cutting.

[Jason Cutter]

Yeah, practise, practise, practise. You will of course need to work with the equipment you have or need to get. If you do the plunges on a grinder, you will need to figure out what sort of belts you want to use and to make sure the platen / wheel is configured to do it. Flat platens need to have both sides the same in profile, so that both plunge cuts will match. A very good way is to invest in a filing jig ($20 up to $100) from one of the knifemaking supply houses to even up the plunge cut and finish it with sandpaper. It is also useful for a range of other applications.

Last I met up with Shawn McIntyre, he was still true-ing up his plunge cuts with a file and filing jig and finishing it all up by hand. He says its always a bit of a pain to clean up the plunge cuts, and hand finishing can't / mustn't be avoided. I'll take that as gospel.

I myself do my plunge cuts on the flat platen (flat grinds) by tracking a J-flex belt 3/32inch to 1/8th inch off the side off the platen to create a "cupped" plunge cut. I use a 120grit, followed by a 180 or 240grit belt to clean it up and then the rest is finished by hand.

Good luck. Jason.