Plunge line secret ?

S

seatrout

Joined
Dec 17, 2006
Messages
1
Hello,
I am a newbie and I have made 6 knives (1095) in the last year.
Besides practice, what is the secret to nice square plunge lines.
I am using a small belt grinder. How do you keep getting the belt
back in the same place each pass ? Is the secret a stiff belt, filing or
sanding before HT. I am pretty happy with the other aspects of my knives,
but the philosophy of the plunge escapes me. I have even glued alum pieces
to the blades for guides. It helped but not good enough.
Thanks for your help.
Mike
 
I grind my plunge line first. Not all the way but just enough to establish a line. When you're grinding and moving the blade back and forth lengthwise and the belt hits the established plunge, it will stop there and you'll know you've reached that line. Makes sense? Just stop when you feel the belt hit the line because if you keep moving the blade it will grind the plunge back.
 
Hi seatrout,I found it helps if, when starting your grind, start a little forward of the theoretical final plunge line. Start with a coarse belt. When you have established your bevel and move to finer belts start sneaking up on the final plunge line.After roughing,use lighter backed belts you can track so they roll over the edge of the platen or wheel and finish the shoulder by moving into it like that. The other "best tip" I can give you has already been stated by IG :) That is the one that helps the most by far.
 
All of the above also some people use a round file and file them in. I use a dremel to clean them up before and after heat treating. A clamp on file guide is very handy when grinding and filing to get them the same.

YES Welcome!
 
If you want clean and matching lines, go with what Bruce Bump said. Stop the file cut at least 3/32" short of the spine, or grind line, so that you can get a nice roll out blend.
 
welcome......hope you deal well with frustration...dont worry, just grind and you will keep moving foward :) Stop and try and figure it out and you will fall behind;)
 
As has been said here: a GOOD grinder that allows precise tracking control and practice!! After you've made a couple of 100 knives you'll start to get a feel for it.
 
blgoode said:
Stop and try and figure it out and you will fall behind;)
Click to expand...

So true :) I think the phrase that has been pretty popular as of late is...... " Just do it "

Seriously though seatrout , I have used all of the suggestions mentioned here.They all work. I still use my foredom to clean-up or blend a bugger now & then. My biggest asset to finishing has been my "Diprofil" . If you try the file trick I have found it beneficial to grind a "safe" flat on the round file so that you don't end up with a little trench next to the plunge. That can be a pita to get rid of.
 
David Wesner said:
So true :) I think the phrase that has been pretty popular as of late is...... " Just do it "

Seriously though seatrout , I have used all of the suggestions mentioned here.They all work. I still use my foredom to clean-up or blend a bugger now & then. My biggest asset to finishing has been my "Diprofil" . If you try the file trick I have found it beneficial to grind a "safe" flat on the round file so that you don't end up with a little trench next to the plunge. That can be a pita to get rid of.
Click to expand...

Great idea on the "safe flat" David!
 
I have found it beneficial to grind a "safe" flat on the round file so that you don't end up with a little trench next to the plunge. Having a brain phart i guess and can not envision what you mean?!?
the trench is not a result of angle?? The round file tapered?? Sorry
 
By theory, if you have a trench, then your bevels are not down enough. The plunge cut should stop where the acual cutting edge begins, same as your primary bevel.
 
Here ya go Tommegow. They say a pic is worth a thousand words. You can plainly see my scriber pointing to the land that has been ground onto the full length of the file. I use it by laying the land onto the Blade and moving the file into the plunge thereby "cleaning it up". The "trench" would "theoretically" be created by not grinding the land onto the file and removing material underneath the file rather than just up against the "shoulder or plunge" This obviously will work best on a flat or convex ground blade verses a hollow ground blade. The other pic is the Diprofil I mentioned,with a soft stone (that very quickly conforms to the plunge geometry) I am able to clean them up lickity split ;) .In fact I use it for the entire Blade . I rarely use emery paper anymore, instead using "die makers polishing stones" to finish. LRB , I am not quite sure how to respond ? Maybe this post cleared it up ?
 
Back to my reply. I layout my edge with a marker. Two parallel lines. I grind to the lines, and use a round file to cut the plunge in. The plunge cuts stop at my lines, same as my grind. There is no left over trench, unless I file beyond the scribed lines. That's the way I do it, but there are always different ways to do different things by different folks. Whatever works best for the guy doing the job.
 
Check out Harvey Dean's flat grinding video for a really good look at how to do the plumge cuts. If you have a KMG or similar grinder, you can start them with the work table in place so that you are straight in all directions.....cheating yes, but who cares? :D You can use the filing guide too, but only on a grinder that lets you grind from both sides. Doesn't work as well on a Jancey or I would guess a Wilton. But you WILL eat up your filing jig eventually.
 
There's no such thing as cheating when it comes to grinding knives. Most knifemakers use the grinder workrest. The workrest is a very useful part of the grinder, which is why grinders usually come equiped with one!

The secret to grinding is experimenting and working at it long enough to find the combination of method and machinery that allows you to make the knife you want. If you are lucky enough to get a job working for Bob Dozier or one of the other Greats who can teach you to grind, then you'll save yourself a lot of time. Otherwise, get back out into the shop and stop fooling around on the computer! :-)

BTW The Wilton type grinder is one of the best machines out there for knife grinding. Mine is in virtually daily use for more than 10 years.
 
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