Thinking about building a grinder....

C

cgdavid

Joined
Sep 12, 2005
Messages
85
I've been looking into purchasing a grinder but the 'want' (kmg) factor is pushing the thing a bit higher on the cost scale than I really want to go at this stage in the hobby. So, thought I'd check into building one.

Belt grinders look fairly straight-forward to build and even though my skills are a bit rusty after a lot of years away from metal working, I think it's well within my abilities.

Anyway, what I'd like to ask a few questions about is idler/tension pulleys.

Years ago, i used an item that was basically a stud that was held onto an idler arm with a nut. The shaft had a bearing built into it for the idler pully to turn on. The outside sleeve of the beaing had a threaded end on it to hold the pulley on the shaft. For the life of me, I can't remember what these things were called. Thought a google search would turn up something to remind me but it didn't. Can one of you get me going in the right direction as to what these are called?

second, can anyone point me in the right direction concering idler/drive wheels that will work for a grinder.

If this doesn't pan out, I'll return to the coote/grizzly debate I was having with myslf again.

Thanks....Curt
 
Curt ,Look in a few knife supply catalogs.They sell idler arm assemblies.The wheel is usually a 2" metal contact wheel,but it can be any practical size you can track. While there are several guys on this forum who have the ability to build a first rate grinder,most home built units are merely a stop gap until you can get that KMG or Bader.If you build it yourself,it has to be really beefy.1/4" to 3/8 metal throughout,and at least a 2"X2" arm.
I would say do a few extra jobs and save up the couple of hundred difference and get the KMG in the first place.You will be glad you did in the long run.
 
By all means make your own !

I don't understand why so many say to bite the bullet and shell
out hard earned dinero for a commercial unit when one is just
starting out.

Heck, I am in love with me home made grinder and simply
can not imagine a better one, period, commercial or otherwise.


http://www.knifeforums.com/forums/showtopic.php?tid/752550/

For quite some time I thought this design was somehwat original,
till I discovered Goddard's "Big Red" in one of my books. May be
I saw it before I designed mine and this is how I got inspired :)

In any event, the thread above has all the information you'd need
to build your own. I strongly recommend using buffer/grinder as
the foundation for it - this way you will have dual-functionality unit
in your arsenal: belt grinder AND buffer. I wish the RPM were a bit
lower for buffing - may be 2500, but 3600 is PERFECTLY useable for
buffing. Stay with 6 or 8" diam buffs and you'll be fine.

Again - buffer is single MOST DANGEROUS tool in the shop -
make sure you understand why .
 
Edited: nevermind, it worked about the 5th time I tried that link!
 
Thanks all. Good info. Answered my questions. I figure even going with new materials and commercial contact/idler/drive wheels, I'd be right around the $250 - $300 mark.

Now the other side of the equation is finding the amount of time to think the thing through and actually build. (Nothing is ever simple with me--just as the wife.)

Since all of you know so much, tell me, where do I get more shop space to do all this fun stuff? :D
 
I am in process of building new grinder same as KMG. Looks like great grinder and lots of good remarks about it. Hope to have complete buy Jan 2/06.
 
rashid11

Just went back to look at your grinder again. Have a couple questions if you don't mind. Forgive me if the answers are there (I'm a see-and-do kind of guy. will read the instructions if I HAVE to :o )

How is tracking adjusted?

Is the grinding jig used to do all of the grinding or just the rough out? Basically, I've not used this kind of setup ( angle grind for the bulk stock removal and files form there) and can't see how you would go around the 'belly' of the blade edge.

Thanks!...

Curt
 
Build your own by all means, but use some KMG components, that way if you do get a KMG later, you can just switch them over. In fact you can switch over non-KMG wheels and attachments since generally they will need their own arm anyway.

The KMG is was group desinged online from what I heard. Where is that thread anyway?
 
Unless your set on using comercially available wheels try looking into tool box casters the wheels on my hmdgrinder are cast aluminum tool box casters I just cut the rubber off them and mounted them to my motor and trued them up using some 100 grit paper and they run great the drive wheel is about 4in and is hard mounted to a shaft with a pulley setup on the other end. the idler/tracking wheel is about 2.5in and has flange bearings in it which work fine for now but are going to be replaced later on. My contact wheel is wood and works ok but thats were I would put the money at for something commercial. To get maeasurments and stuff for mine I just layed a belt on the floor sat the wheels in there and started cutting the metal for supports to fit. Good luck
 
Curt:

>> How is tracking adjusted?

There a turnbuckle+wire going from top of the arm with the tracking
roller to a bolt in one of mount holes on the buffer's right "neck".

By turning it, I get remarkable tracking, all with 1/2 of a turn,
and I don't think there's an easier way to adjust tracking, turn
buckle being right in front of you, yet far from the belt or any
moving parts. No tools reqs - just turn it with your hand.

The tension of the belt/springs will track belt to the left, turnbackle
moves the tracking roller so it tracks to the right. And with turnbuckle
you can set it anywhere in between :)




>> Is the grinding jig used to do all of the grinding or just the rough out?

It is up to you. The jig gives a very good precision - as you can setup
any grinding angle you want and it will hold nice and steady for you.
It is also safer this way, as there's no chance of your hand slipping into
the belt.


For narrower blades, I am starting to hand hold when grinding - it is
a bit quicker, but less precise. Yet I find some macho pride in ability to
free-hand grind it like that :)


I have done complete blades, with very nice looking grind lines using only the jig.



>> Basically, I've not used this kind of setup ( angle grind for the bulk stock removal and files form there) and can't see how you would go around the 'belly' of the blade edge.

It all works like magic. I don't use hand files to file the blades, outside
of choil area (it helps to have it nice and round, as oppsed to square, before the heat treat, as square cuts always act as tension risers).

I did have the same doubt about grinding the belly of the blade with that
jig, but it worked out great.

For example, let's say you have some curvy belly, as in french-shape
chefs knife. The grind line with the jig will follow the blade edge's outline
exactly.

And again, the jig is not my idea, I learned it from a grinding video I rented from technicalvideorentals.com
 
rashid11

Thanks...

Still struugling with the idea that grinding in a straight line will follow the 'belly' of the blade .. I'll have to mess around with that idea a bit. Will it work with hollow grinding to?

Curt

BTW.....

Thanks everyone else. again, very helpful.
 
Curt -

the DVD I borrowed the jig idea from - they used it with contact wheel, in hollow grinding setup, so yes, it will work just fine.
 
the DVD I borrowed the jig idea from - they used it with contact wheel, in hollow grinding setup, so yes, it will work just fine.
Today 03:50 PM
I "borrowed" that jig design from you :) Do you have a work area to hollow grind on?? I am still waiting on my 0-1 to come in so I used your jig to flat grind an oak knife blade yesterday. Got a pretty good grind line on the wooden knife blade for a first timer.
 
My practice material was some HRS (hot rolles mild steel) from Home Depot :)

Smooth, fluid, even strokes are the key to nice even grinds.
Keep the blade moving or you will get the 2" mark.

Use sharpie/magic marker to see just where you're grinding.

I first take off material by blade's cutting edge to about the thickness
I want to have before HT and then expand the grind toward the back,
being careful not to grind at the cutting edge anymore.

Blue the blade's edge (before griding) and use a caliper (HF's $16
6" digital caliper highly recommended) to scribe the scribe 2 lines, separate by desired thickness.

For example, let's say we are working on .100 material.
1/2 is 50. Let's say we want 30 thou thickness, so we'd need
to substract 1/2 of that from 50 to get to 35. Set 35 thou
on the caliper, lock it and scribe the edge, using edges as guides.
At the end, you will have 2 lines, separated by 30 thou.

Use them as rough guide, but check with caliper. You don't want
the edge to be too thick/thin. And of course you'd want dift thickness
for paring knife compared to a Commando blade :)


And don't worry about using file caliper in such caveman fashion -
it will still outlast the craftsman :)
 
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