Learning curves with new equipment,very bad

Bruce Evans

Bruce Evans

Joined
Sep 26, 1999
Messages
4,486
I love the idea that I finally got the new equipment in the shop,but now the problem of learning how to use it as I try and get a knife made.
Using the surface grinder on a blade and it warpped on me while surfacing it off.Then I quenched and tempered the blade then surfaced it again and guess what? it warpped again only worse,bad enough it dug in and stalled the motor.Well I over came that suprise and got the blade all surfaced and finish ground.This was great but as the hand sanding process started I noticed funny shiny lines in the riccasso and part of the side of the blade were I surfaced it flat.Now I didn't think much about it at first because I hadn't seen this before and thought I could rub it out.Well that didn't work they just got real shiny and raised above the rest of the blade.Was told by a friend that I hardened the steel in these places with the rock on the surface grinder.So went back to belt after having 20+ hours in the hand rub and it was finished at 2500 grit so nice.Figured I could grind these marks off and start over.NO WAY,they stayed there and so it is stuck in the pole in the smithy waiting to be made into Damascus.Lost a whole weekend on this one,but live and learn,a new rock instead of the one that came on the machine and smaller bites on the passes and the next blade I hade hanging around came out fine--So far--a quick small rub of the ricasso showed no signs of the mysterious lines of the other blade.
Man I hope I figure this stuff out soon,I want to make a knife and get to forge some more steel...The yard is now a part time deal as I told Mom I had to quit neglecting my promises that I made in my own shop..So I should start getting caught up again soon,sorry to all that have been waiting on me and thanks for all your patience and understanding.I have been missing all you guys.
Bruce
 
Bruce,
I also learned the surface grinder the hard way. I'm pretty good on it now 10 years later. If I can answer any questions, feel free to post, email, or call.
It will get better. :)
 
You just need some practice Bruce, some very careful practice.

How's about I send you about 30-40' of barstock for you to surface grind, for me.
I won't charge you for the learning opportunity. ;) :D
 
Does seem strange without you posting here as much as you used to.:( I need to pick your brain about something , so I will give you a shout soon or you can call me.
 
I also learned the hard way on the surface grinder but with damascus. I had this two tone in straight lines showing up but only after I etched the blade. It ended up being the grinder wheel was hardening the steel while I was grinding. I was even using a coolant flood. I switched to a coarser better quality stone and kept it dressed from then on. No more troubles.
 
How does a surface grinder work? What's this about a stone? I thought it was a belt...:confused: ...so naive...:footinmou :o
 
There should be a book called "Zen and the Art of Surface Grinding" it can be one of the most frustrating things on the planet. Some days the steel just wants to rise up and meet the stone... and some days it goes perfectly. If I could just figure out how to predict which days are gonna go perfectly, I could spend the otherr days on the milling machine!
 
yeahup light cuts about .0005 to .0008
much over that you'll burn the steel
like Bruce said a good dressed wheel
I find if you cut one side just so much, then flip it over
and take the same on the other side worked well
you are still messing
with stresses from side to side. and don't let it warp to much
or the M/chuck won't hold it down. it takes
some playing with..it helps too if you grind your stock
with it diagonal on the chuck if you need a wheel (stone)
let me know Bruce.
I got some new ones I want to try out and see if they're any good..
these are 7" x 1/4" X 1/2" 3600 rpm pretty standard.:)
 
My surface grinder is out in the garage. To use it the other day I had to run a heater on it for about an hour to get the grease to warm up enough so that it wasn't killing my arm to move the table back and forth. This has been one coooollllld winter! :(

It didn't take me long to figure out that I was burning the steel when I first got the thing. Those brown streaky spots were a dead giveaway not to mention the warpage. It quickly became apparent that I could only go a half thousandth at a time and I usually make that in two passes.

I think I got too fine a grit in the wheels. What grit should you use for knifeblades? I'm thinking I got 150 and 220 wheels if I remember correctly. Probably I should be using 60 grit right?
 
Peter,
I use 46 grit open porousity wheels, Norton 32AA and 5SG. Sometimes it shocks me at the clean, fine finish you can get with a 46 grit.
 
46 grit? That's amazing....Well, I have to order from MSC soon anyway so it looks like I'll be tacking yet more items on there. I'm never going to make any money at this stuff, that's for sure! :p
 
Bruce, To many toys at one time for you seems to be the problem. I'm sure it won't be long till you get a handle on them all and blow us all out of the water as if you don't do that already!
 
You need to get the material flat with no bows in it. The problem is that the magnetic chuck can pull the bow out of the steel. You grind it flat and when you turn the chuck off it bows again.
You need to lay the metal on the chuck with the magnet off and check all around it with feeler gauges and find the gaps. Use shims to stop the magnet from pulling the workpiece flat. Grind the top flat then turn it over and grind the other side flat. You will probably want to normalize the steel first so the grinding stress doesn't cause the steel to warp. The steel can crawl around on the magnet too while you are grinding. Especially if it has a bow in it. Use a pretty large piece of steel that is thinner than the one you are grinding and butt it against your workpiece to help hold it in place. Hope this advice helps.

Tom
 
Thats some good advice..........too bad Bill Ankrom doesnt post here (does he even have a puter?????)

He worked on a surface grinder/tool and die grinder his entire life in a machine shop.......He does stuff with those things that you wouldnt even dream of.
 
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Originally posted by pendentive
How does a surface grinder work? What's this about a stone? I thought it was a belt.
------------------

Dan, there's a picture of one at the bottom of Peter Atwood's shop tour linked below:
http://www.realrates.com/knives/shoptour.htm
 
yes, I know what a surface grinder looks like, but can anyone explain how it grinds? Is it like a planer for metal?
 
For knifemaking, I surface grinder should be used with the intention of making a piece FLAT, or making similar pieces all the same thickness, i.e. lockspring and blade. We really shouldn't think of them in terms of stock-removal, per se, rather than as a flattening device.

If you take much more than .005 at a time then you better be prepared to see some things you won't like. Feed it slowly. Try to think of yourself only taking off the high spots. Run it back and forth until you make contact. Make light passes.

The steels we use should not be so succeptable to warpage, but if you think about it, you are heating up one side of the material, and the other side is this huge chunk of metal - just sucking whatever heat is in the material out the other side! No wonder! :D
 
Dan,
The base (magnetic chuck) moves left and right (X) and front to back (Y). The grinding wheel is mounted on a chuck above and moves up and down (Z).
On my hydralic one you start the table moving back and forth, bring the wheel down and set it to the depth of cut you want, turn the hydralics on and it starts moving back and forth and either toward you or away from you. The wheel cuts material off the top of the steel. When you get to the other side, drop the wheel down a few thousandth and go back the other way. Water soluable oil, coolant, is being pumped on the wheel and steel while this is being done.
I always try to remove equal amounts from each side. CPM steels are notorious about bowing.

Did that help explain it?
 
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