Some questions for the pros here

DiverTexas

DiverTexas

Well-Known Member
I got my grinding tables all set up now and started on my first blade.

I think I should have notched my plate that will cut the bevel on the blades the same way as I did on the one at the contact wheel. Is that right?

Second question is on the contact wheel table location.

Should the top surface of it be at the center of the wheel or slightly above or below it? As it is now, the table is below the centerline of the wheel.

Here are some pics that hopefully make these questions easier to visualise.





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P1014694.jpg




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Another question on the plate for grinding the bevels.

How do I determine the proper angle to grind my primary and my secondary bevels?

I have the table fully adjustable by just loosening 2 bolts to change that angle, you can probably see it in this picture.





P1014696.jpg




Next a few questions on the blade itself.

I started grinding on it and have it down to a fairly sharp edge, but my bevel is only about 1/4" total. Is that because I don't have enough angle on the grinding table or too much angle? A couple of pics of it too.



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And one final question. As I was grinding out toward the tip of the blade, I could feel the metal getting almost too hot for me to hold. After dipping it in water, I noticed I could see a discoloration on the tip. Is this something I need to be concerned with or will that go away after HT and final sanding?



Here is a pic of the tip.





P1014705.jpg




Sorry for all the questions guys, but this is my first blade and attempt at grinding so any and all knowledge I can get from others will hopefully let me turn out a decent knife.

Thanks in advance for any input.
 
DiverTexas said:
And one final question. As I was grinding out toward the tip of the blade, I could feel the metal getting almost too hot for me to hold. After dipping it in water, I noticed I could see a discoloration on the tip. Is this something I need to be concerned with or will that go away after HT and final sanding?
Click to expand...

If the blade is not HT'd yet, it's nothing to worry about. If it happens after you harden and temper the blade, the tip (or wherever is colored from the heat) could have a soft spot, and might have to redo the hardening. But, since it's before HT, it's nothing.
 
Regarding the blade tip, Mike is right, nothing to worry about pre-heat treat. That is something that you will have to learn to deal with though. The tip is the thinnest part of the blade so it will heat up faster than any other part when grinding. Grinding is all about time and pressure so you will have to ease up when you get toward the tip. I burned the tip off of a few blades when I was learning to grind.
 
Im not a pro here but wanted to say sweet grinder set up and really nice profile on that blade.

I free hand so not sure where the table should go in relation to the wheel.

And yes your angle is too steep if your only getting .25 bevel. Unless your doing a scandi grind.:D
 
Thanks for the input so far guys, much appreciated.
It's a relief to know the tip discoloration is not an issue as the blade has not been heat treated.
This grind ended up being done free hand as the table portion for the platen wouldn't allow me to safely grind for fear of the blade being shot down behind the table. I had visions of it becoming embedded in an area I truly would regret.
Any other input/suggestions would be very welcome.
 
The angled plate at the platen will never allow for a full flat grind. The thickness of the plate at the bottom won't allow for enough adjustment even if you notch the top of the plate. Notching the top of the plate will make it worse because you have a fixed pivot point. Your two alternatives is to go freehand or use a jig on a rest that projects 90 degrees from your platen. Maybe Fred Rowe's bubble jig is another alternative.
Hope this helps.

Rudy
 
I am going to give you some advice , after only 28 years of this . The worst thing that I did when I started was use a tool rest. Learn to free hand grind and you WILL NEVER regret it. Don't let the tool rest hinder the freedom you will have , when you learn to free hand grind. You will get aggravated at first but it is well worth the learn. Good luck !
 
Rudy Joly said:
The angled plate at the platen will never allow for a full flat grind. The thickness of the plate at the bottom won't allow for enough adjustment even if you notch the top of the plate. Notching the top of the plate will make it worse because you have a fixed pivot point. Your two alternatives is to go freehand or use a jig on a rest that projects 90 degrees from your platen. Maybe Fred Rowe's bubble jig is another alternative.
Hope this helps.

Rudy
Click to expand...

I agree with Rudy. If you are set on using a rest/jig check out the jigs thread. I would suggest learing to grind freehand. I dont have anything against jigs, but if you learn to grind freehand you can always use a jig if you want, but not the other way around.
As for the balde heating up, the guys are right, before HT its not a big deal. That being said, try to get in the habit of keeping the blade moving this will keep you from overheating one area of the blade and also from getting the "2 inch mark" on the blade.
One more thing I noticed you said the edge was ground almost sharp. This is what is known as a zero edge, most makers dont do this. It is more common to grind down to about .020" +/- and the use a secondary bevel to bring up the edge. Alot of makers will use a slightly convex secondary bevel.
Hope this helps some.

Sean
 
Glenn Dykes said:
I am going to give you some advice , after only 28 years of this . The worst thing that I did when I started was use a tool rest. Learn to free hand grind and you WILL NEVER regret it. Don't let the tool rest hinder the freedom you will have , when you learn to free hand grind. You will get aggravated at first but it is well worth the learn. Good luck !
Click to expand...

I could not agree more. DiverTexas, get rid of all that extra junk you have hanging on your grinder, keep the platen and the contact wheel. For a tool rest all you need is the original that cam with your machine so you can grind around the profile of your blades. Then learn to grind your bevels free hand. Yeah, it's going to take you a few blades to learn what your doing, but as Glenn said "you WILL NEVER regret it". All those jigs, fixtures, rests, etc hold you back and keep you from learning how to really grind. They limit you to what are essentially just basic grinds. And they don't let you grind any faster and any more precisely. Throw the freakin crutches away and grind!

And where in the world did you find that old Speed Cut? As far as I know they haven't been made in many years. My first grinder was a 2x48 Speed Cut. Made some pretty complex knives on it. It's not a bad machine, probably much better than any of the current bargain grinders.

David
29 years of free hand grinding!
 
Diver

You have made some nice fixtures for your grinder. But as stated above, if you learn to grind free handed, you will be farther ahead in the long run.

One thing I will say. I have done a couple of "runs" where I made 25 or more of the same design with the same grind. Making a grinding fixture was a big help as it allowed the same exact grind to be repeated.

Use your fixtures, make some knives. But as training wheels helped use learn to ride a bike, you will love the freedom you will find when you start grinding freehand. Its all a matter of practice!

Keep at it, you have a great start!

God Bless
Mike
 
Thanks for all the input guys. I will have a go at free hand again tomorrow.
I used a 60 grit belt for my initial attempt, I think I'll drop that back to 80 or 120 for my next try.
 
I dont think you would want to go higher than 80 when doing your rough grinding. I start with 60 most of the time for roughing in.

Sean
 
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