View Full Version : how to get straight grinde lines


beast
01-16-2003, 11:45 AM
i started with forgeing and i made some crude knifes they work just not as good looking as what i see here.how do you guys get things so straight and crisp. ps love the site i've inproved a lot with the tips here thanks:D

Ray Rogers
01-16-2003, 12:09 PM
Honest to God, Beast, the only real answer to that is practice, practice, and more practice. No jigs or other devices, no special equipment, just practice.

Most everyone grinds with the edge up, working towards a center line scribed on the blade, ebows tucked into your sides, and sway your body a little to move down the blade. Most guys work bare handed to better feel the heat build up in the metal.

It's a special skill, acquired by hard work and dedication. It's a great feeling when you pull that blade off the platen or wheel and see that you finally got it right for the first time .....

beast
01-16-2003, 12:29 PM
thanks i just got a delta 1" and i'm trying the edge up thing on a small hunter but how do you scribe a center line on a forged edge?:confused:

Jan Dox
01-16-2003, 01:42 PM
When I forge a knife and have reached final form close enough,
sometimes I grind just on sight,watching the edge, marking the spots where I have to grind more with a marker. Other times I profile the blade and mark the middle of the flat on the edge the same way as on stock removal blades. (with a scriber I made of an old file, on a flat piece of granite). Your blade has to be forged symmetrically enough and the "flats" even.(or the grinder could have helped a bit allready).
That's the way I do it; More experienced friends could do it differently, I'd like to know too.

Jan

beast
01-16-2003, 01:49 PM
thanks jan i'll try that. my bigest problem is near the spine. if i get it close i take a pic.

Jan Dox
01-16-2003, 02:01 PM
I don't really have a problem near the spines of my knives as I only do convex or (near) flat grinds, not hollow grinds. (I don't have a suitable grinder for hollow grinding).
At this moment I try to forge the flats as flat and true as possible to eliminate most of the grinding or filing; (More on that is on "The Outpost forum".)

Have fun,

Jan

GANNMADE
01-17-2003, 08:35 AM
it takes alot of practice ,tilt the edge towards the platen.
start from where you want the blade to start.
pull it to you then push it away .work the blade like you would
a file . do one side till it is about center then start the other side.

http://www.brisa.fi/grind1.html

Jamey Saunders
01-17-2003, 08:54 AM
Ganmade, that's a pretty neat site. I've bookmarked it. The style knife that the guy makes isn't my cup of tea, but the information and pictures are great.

As for grinding, like everyone else said, "practice". I would suggest that if you're going to be making many knives that you at least invest in a 4x36 belt sander with disc sander. I think you can find this combo machine on sale at www.harborfreight.com (http://www.harborfreight.com) for well under $100. I made flat-ground knives on one of these for years before I got a Wilton Square Wheel. My direction is now going back toward flat ground knives, so I need to re-build my sander. It did much better at flat grinding than the Wilton, mainly due to the fact that there is more belt to do the work.

[EDIT]
I just checked Harbor Freight, and the sander pictured below is $79.99. About half what I paid for the one I have when I bought it fifteen years ago.

http://www.harborfreight.com/cpi/photos/05100-05199/05154.gif

If you get one of these, the first thing you need to do is make a sacrificial platen to go under the belt so you don't damage the standard platen. This will also help keep the item from having the slightly "rolled-over" edge where the belt arrives at the blade and leaves the blade. That's kinda hard to describe. Maybe I'll try again later.

GANNMADE
01-17-2003, 09:25 AM
im working on rebuilding my shop ,not taking order till after
feb.I need a band saw first. But i am working on building
a 2x72 sander.The 4x36 would be great for large blades.
harbor frieght has a store here in houston.I'll check
it out next time i go to TKS.:D

Jamey Saunders
01-17-2003, 09:32 AM
Keep in mind that this is not an overly powerful machine. It only has a 1/3 HP motor. The first thing I did on mine was rig up some pulleys and put a 1HP motor underneath the thing (it was on a metal stand). This kept it from bogging down. Once you do that, though, it's a wonderful machine. Unfortunately, the motor got robbed to go on my table saw when it smoked the motor. Now that I'm starting to forge, I'm looking at it as the ideal machine for cleaning up my newbie forge marks and getting a perfectly straight blade. I wouldn't try hollow grinding any knife without my 2x72 Wilton, but for flat grinding, it just doesn't have the surface area to do the job quickly and efficiently. Besides, 2x72 belts are expensive, especially when you add in shipping. You can go to Lowes or Home Depot and get the belts for the 4x36. They're cheap enough to be disposable.

GANNMADE
01-17-2003, 10:08 AM
I KNOW YOU CAN USE A BUFFER WITH A COUPLE SISAL
WHEEL AND 925 DARK GRAY COMPOUND TO GIT
RID OF BELT MARKS .

sixgun
01-17-2003, 10:23 AM
I cant figure out how you grind on the (Harbor freight model )I really like it , was going to get the small delta but then I seen this post. I looks like the sides of the belt track would hit the blade . I just dont see how your grinding??
I know Im not very clear , It looks like you dont have enough room to grind the blade, It looks like the edges of the belt track would hit your blade.
One more ?....Can you get many grit sizes for this grinder?
Thanks
Six

Jamey Saunders
01-17-2003, 10:36 AM
I only used this for flat grinding, and only after I made a 1/4" thick sacrificial platen to go under the belt. I made the platen slightly narrower than the belt, so I could track the belt to the exact edge of the platen, thereby giving me a sharp plunge cut. I had better luck flat grinding with the belt horizontal than vertical, but it's personal preference.

How I made the sacrificial platen:

I took a piece of 1/4" mild steel and cut it a little shorter than the standard platen. I cut it 3-7/8" wide (narrower than the belt). Then I drilled four holes in it. I cut the heads off of some bolts and selded them into the holes. These became the mounting studs. I used an angle grinder to smooth the welds. Then I drilled four holes in the platen and bolted the mild steel plate to it. This raises the belt up a little. It gives you room to make a plunge cut. Unless you are grinding on 1/2" steel, your plunge cut will never be more than about 1/8", so the 1/4" plate gives you enough clearance. If you want more clearance, 3/8" plate would be fine, too. Just remember to round off the edges of the plate where the belt tracks onto and off of the plate.

sixgun
01-17-2003, 10:41 AM
Thanks so much, I will give this grinder some real thought Where might I find a pice of mild steel to make the platen from?
Were you able to find the grit sizes easy?
Thanks so much
Six

Jamey Saunders
01-17-2003, 10:56 AM
For mild steel, check your local junkyard or welder. If you get it from your welder, he can go ahead and round off the top and bottom edges of the steel and weld in the studs.

The belts are readily available from places like Home Depot or Lowes, even Wal-Mart. They go up to 220 grit (I think), but once you get a 220 grit worn out, it will give you a finer finish. Once you get the finish as fine as you can on the sander, you finish the old fashioned way -- sandpaper and elbow grease!

Jan Dox
01-17-2003, 11:00 AM
I have a grinder like that. I use zirkonium belts which I order on size from a specialized company.They do work a lot better on steel than belts from the hobby-and DIY shop and do not cost much more.
I use the grinder as it is , horizontally, but mounted backwards;
The small wheel that sticks in the air on the photo, is my contact wheel (2.5")and I grind with the belt going up and away from me.
This way I have a lot of clearance around the belt and wheel.
This isn't as dangerous as it looks because of the low speed of the belt .(sparks do not come higher than a few inches).
When flat grinding and the belt grabs the blade, it is thrown against the wall instead of towards me.
I also have a more conventional grinder with a 6"stone right and a 2" by 32" belt on the left side.

Jan

beast
01-17-2003, 11:45 AM
thanks jamey
i have a 4x36 grinder and i'm going to but a sacrificial platen on it this weekend. i cant get over this site and how helpfull every one is thanks again:D

Jamey Saunders
01-17-2003, 11:52 AM
No problem at all.

Hope this helps. Worked really well for me when I was flat grinding.

fitzo
01-17-2003, 01:54 PM
Only thing I'd add here is to suggest that one should grind both sides evenly, taking a little from each side and approach the center equally from both sides. The reason is that stresses build up quite quickly on the side being ground. Flipping sides frequently help keep these stresses even. Uneven stresses result in warpage when HT'd.

Have fun. Practice makes perfect. Failure is to be expected and the only real sin is to make the same mistake more than once...

GANNMADE
01-17-2003, 03:17 PM
hey ,micarta would be good also,or a piece of teflon cutting
board would work.anyways check these out.

http://ckdforums.com/showthread.php?s=&threadid=11593

http://www.mijneigenfavorieten.nl/knivelinks2/

Jamey Saunders
01-17-2003, 03:51 PM
Wow! That second site is great! I've got it bookmarked.

As for the platen, I'd stick to steel, since the platen will get hot when you're grinding. My considerable experience with teflon leads me to believe that it would melt and create a real mess. Micarta would also wear more quickly than steel, and believe me, the steel platen will wear, and wear quickly. The back side of a belt is a lot more abrasive than you'd think.

C L Wilkins
01-18-2003, 07:34 AM
A fairly inexpensive way to flat grind is to use a disk sander. They are not that expensive and you can use 3M spray adhesive to attach any grit paper needed. A rubber backing is recommended. Making it reversible is desirable.

Delta and Harbor Freight both sell these. You can get a variable speed model from Uncle Al at http://www.riversidemachine.net

SVanderkolff
01-18-2003, 10:03 AM
try these guys www.sandpaper.ca They are really good people and will get most of the grits and sizes you need at a whole lot cheaper price than a retail store. They also carry the 2 X 72 it just isn't up on their site yet. The big rolls of sandpaper are great for hand sanding. They will ship stateside as well. Once again I highly recommend these people I have been dealing with them for the last 4 years.
Thanks
Steve

beast
01-29-2003, 11:56 AM
i just got this one done not there yet but better thanks to all your help. thanks
the blade is an old coil spring from my fathers caravanhttp://pic5.picturetrail.com/VOL67/897749/1638841/19263628.jpg

Jamey Saunders
01-29-2003, 12:11 PM
Looking good, Beast!

Has your father figured out why his Caravan is leaning over to one side?:D :D ;)

Phydeaux
01-29-2003, 11:49 PM
Now that's what I call good recycling! Did you use the steering wheel to make the scales? I wonder if my brother in law would miss a spring off his bimmer.....

One of my friends who grew up in the Phillipenes, said that the locals like to make thier machetes out of truck springs. He did not specify any particular make.

Phydeaux

beast
01-30-2003, 06:21 AM
Phydeaux the scales is an old chunk of maple with a green stain