Thread: Keeping a straight edge regrinding tips?

All right guys, I've got pretty good results converting a spike to a spanishish/barber notch. but I want to take a round to a spike (and maybe beyond). but with the round there are two problems I see going in:

1. more material to work with
2. how to keep it straight?!

I'd love to hear your guys experience and ideas. I also have an idea I thought I'd pass on. Sadly taking it to the belt grinder is out, too much heat TOO fast. (but man, it'd be a perfect flat edge).

so this was the only thing I could think of. I have a small 1" wide belt sander somewhere under the big workbench. I was thinking with water trickle (if I can work it out) or without. take a block of wood, route a groove for the edge to lay in, clamp that to the table and then lay the razor in there, thus keeping the belt running in the direction of the edge.

thoughts? grit to use? (I'm not even sure what's available for small sanders) I wish now I had set my belt grinder up to be variable speed. I can get really fine grit belts in 2"x72".

Red

I read about a fellow called the "Ice Man" or something similar a while ago. He has made a machine with two belt grinders so that he can hollow-grind knives with one pass. He got his name because he cools the blades with dry ice before putting them to the grinder. He was so successful that he now sells the machines.

I don't know how practical it is to get/store dry ice, but it's something I've been thinking about...

Regards,
Neil

for sanding stuff look up supergrit they have just about every thing you could ever want
if its not on there site give them a call and the just might have it any how

if you ahve a work rest on that grinder then you ll have no problem making round to spike point
spine down edge up and slide it into the belt (thinking 220 grit ) and it should take just a sec to do (just cool often while grinding and till you get the handle of it take your time

Interesting idea with the dry ice. I wonder how much difference or how much longer that could add to grinding times prior to having to cool the blade down again.

I have a 2x72 that I built and even though the thinner blades heat up very quickly on the lowest speed, I could still grind a round into a spike. Very short bursts of grinding time with a jar of water close by and I'm good to go. I say give it a try. What have you got to lose other than a razor?

Chris L

Thanks guys, I'd much rather use the big one. what is your low speed? I think mines running pretty high, shaft speed is 2750 and I'm running direct coupling to the 6" main wheel on the grinder. I build mine also, bought the grinder portion, built the stand and setup the motor. which route did you go? I think the guy that I got the grinder from was Coontz? anyways, I built mine for major steel work in the shop, not for knives

Red

i have a KMG VS direct driven 1750rpm +/- couldnt tell you the belt speed tho

i work slow most the time less im hogging knife bevels

Originally Posted by Big Red

Thanks guys, I'd much rather use the big one. what is your low speed? I think mines running pretty high, shaft speed is 2750 and I'm running direct coupling to the 6" main wheel on the grinder. I build mine also, bought the grinder portion, built the stand and setup the motor. which route did you go? I think the guy that I got the grinder from was Coontz? anyways, I built mine for major steel work in the shop, not for knives

Red

I built this puppy and it works great. Randy Tuttle has built a few of this same grinder. Mine isn't variable speed at this point; I use a 3 step pulley which is easy to change (takes a few seconds).

I have a 1750 Baldor 1.5 hp motor. I couldn't tell you what RPM I'm running at the lowest speed though.

Chris L

Strange as it sounds, larger grit on the belt actually generates less perceived heat. Although eventually the blade will heat up anyway. The finer grits are the ones where everyone trying to grind a hardened blade will have problems if they don't pay attention.

ChrisL's got it right. Grind only a little and cool often. Don't wear gloves so you can feel the heat. If you see the steel change color, you're too late.

If you try to water the belt at that speed, wear a raincoat. But dont' forget to really enjoy the looks on your family's faces when you come in from the shop too!

I knew that about the grits, interesting how that works isn't it. inclination is grab a real fine belt, but that makes more heat. too bad too, I have some high grit trizac belts I've been wanting to try but nothing has been the right thing to try it on yet.

Chris, you don't need to do it for me, but if you ever are curious about your speed there are equations that will give you the answer. I don't know where I put them last, but you can take your pulley diameters and plug them in and it'll tell you what you've got.

My motor is a 1.5 baldor as well, but it spins at 2700ish.

Red
PS
I remembered, I actually have a device, can't remember the name now, that you can use to find out the speed. It's a little mechanical device looks like a tachometer, press it against the shaft and it tells you the speed.