Surface grinder conversion contact wheel question

Chuck Gedraitis Knives

Chuck Gedraitis Knives

Well-Known Member
So I am in the process of converting my surface grinder to run belts. I have been in contact with a few contact wheel companies looking for quotes. I talked to Stephen Bader this morning and mentioned that it would be unsafe to run a 1in wide belt on a 2in wide contact wheel. He mentioned that the belt could compress the wheel enough so that the edges of the wheel sat below the belt, thus wearing the wheel out on the edges. The belt would then not track properly.

I was just wondering what others thought about this? In the research I have done online I have seen quite a few pictures of guys running 1in wide belts on a 2in wide wheel.

I'm considering having a 1in wide wheel made to run 1in wide belts.
Thanks for any response,
Chuck
 
Here's a link to images of my belt conversion: http://jalbum.net/browse/user/album/107079/;jsessionid=1i4kddbr82s9h1eqz2a5hp5xab

My recommendation is to have a 100 durometer urethane wheel made. The only outfit that I know of that can do it is SunRay. Anything less than a 100 durometer wheel will cause your work piece to come out convexed.

I tried 1" belts and found that I didn't like it. The tracking is pretty poor, and I got cleaner, flatter pieces if I maintained full contact across the work piece with each pass...and could only do that with a 2" belt.
Others might have different experiences, but overall I just think a 2" belt works better, and doesn't create the issues that the 1" did. Plus, I still use the same belts (2x72) on the surface grinder that I do on my other grinders.....just easier overall for me.
 
I posted this question and the response I received form Brian Fellhoelter was this.
Sure, a big plus for me is that they are less work.
There's 1" less that I have to run off of the part.
At .050 - .100 cross feed , that is 10 - 20 less back and fourths, PER PASS !
We aren't plunging straight down, full width on the blade, so that extra inch makes a big difference.
Even @ 1", we're double the width of a typical wheel.

The leading edge of the belt wears out relatively quickly, and it's different than a stone.
When a stone wears, it's just not flat anymore, it's still a stone, and still cuts.
Not so with a belt.
The belt will cut much less effectively on that leading edge, generating a lot of pressure.
This will result in higher temperatures, and more likelihood of tossing the part across the shop.
With a 1" wide belt, by the time this becomes an issue, you are ready for a new belt anyhow, so you swap it.
You are more likely to keep trying to push a 2" belt further
You could have 1" of worn belt, and 1" of relatively fresh abrasive.
If you split the belt, you have already swapped by that time, and all is well.

Meanwhile, you are still going back and forth because you are using a 1" wider belt, you'd be down to your next depth if the belt was 1"
So, it's faster, and more efficient.

I did 40 - 50 blades before I decided to try 1", and besides the time efficiency, I didn't get fewer blades per belt.
If I had, I might still consider running 2" belts.

A 1' wheel is easier to keep flat and true, and there is less belt splice/high spots to worry about.

And for the third time, because it's that important (if your trying to make money) a 1" belt is just way less work.

Let's take this little 1" high folder I am working on.
After heat treat, there are 3 depth passes that need to be taken off per side.
I rough the 1st 2 passes with a .100" Y increment per stroke.
Roughly 22 strokes to get a 1" belt off of it.
44 strokes for the 2 passes.
The finish feed is .050" per stroke, so 44 more just for the finish stoke.
That's 88 back and forths...

With a 2" belt, I need 34 strokes per roughing pass, and 64 for the finishing pass.
132 Strokes.

So, the 1" belt is only 67% of the work...

Any day you can speed up a process by 33% is a great day in my book.
 
The difference is Brian is running his converted grinder like you would one with a stone wheel. The only time I do this is on a very odd shaped part that is going to wear the belt uneven. Either way I make the final pass with a perfectly dressed belt and across the entire blade in a couple passes to leave it flat.

If I understand right Ed runs his the way I run mine and that is to sand off the entire blade with the 2 inch belt. Drop the wheel about a half a thousandths and run it again until it's clean or the thickness you want. To do a final pass you need to make sure the belt is dressed so it cuts even across. You also have to make sure the wheel is flat while the machine is running which means you need to dress it on the machine but this is a one time thing when you set it up.

I use gator belts for my final clean up because you can dress them like a stone wheel so they leave you with a flat part.

The important thing is you start out with a new belt on the surface grinder and that belt is never used for anything else.
 
Just to add, even though you have to do some precise measuring to tell you can leave a part more true the way Brian is doing it. Maybe an advantage for folders but if I leave a fixed blade within a fairly large fixed blade knife within a thousandths on the surface grinder that is good enough.

I just don't see the advantage of converting to a belt if your running it like a stone. The stone still cuts when it wears but if you wear the lead edge of a belt it quits cutting and your going to generate heat. When I finish grinding a blade I can almost always pick it up off the magnetic chuck with my bare hands.
 
I do indeed run a belt like it was a stone.
With the exception of depth of cut.
I can very easily take .010" DOC with a belt, I could barely do 10% of that with a stone.
That is the advantage of the belt over the stone, stock removal rate.
And no heat.
I took 6 blades down .020" in minutes the other day, and there was no noticeable heat generated.
I was only doing .005" DOC on that batch, because .010" just seems very unnatural to me, but I have done .010" a lot of times now, and never felt in jeopardy of flinging a part.
Never had a heat issue.
Even when I am finishing with a $2, 400g AO belt, I can easily take off .0025 a pass and get 4 to 6 blades per belt, with life left in it to go on the horizontal grinder.
I stop using a belt before it becomes an issue.
A definite subscriber to the "use belts like they are free" theory.

If I was a "plunger", I would see an advantage to a 2" belt, since I'm not, 1" works for me.
And it works better than a 2" belt for the reasons outlined above.
I've seen way too many parts flung across shops to try that myself.
Bad things can happen quickly on a surface grinder.
I have a scar to prove it, and have witness and assisted on other injuries.
Most knifemakers think the buffer is the most dangerous tool in the shop, I think it's the surface grinder.
My wife and son are not allowed in the grinding room when it is on.

Being primarily a folder maker, truly flat parts are my priority.
I easily hold dimensions to the tenths, just as though I was using a stone.
I believe Chuck is also primarily a folder guy, or at least makes enough of them to want his machine setup to do both styles effectively, and efficiently.

It took years to convince me to try a belt.
As a toolmaker, it just goes against my nature.
Now, unless I need a cup wheel, or need to grind to a shoulder, I'll always run a belt.
 
There ya go Chuck.....perspectives from Bladesmiths, Knifemakers, and Toolmakers......lots of choices for you.
 
http://www.knifewerks.com/Tools/Surface_Grinder.htm

The grinder has changed a little since I first made it.
I bought a larger diameter tracking wheel from Travis Wuertz, and installed that.

Shaft clamps can be bought from MSC for sub $70 to be used as the collar around the spindle, as that piece is the hardest part on the build.
I made my own, but probably would not have if I had found the parts at MSC first...

Dead simple build, I made it in an evening.
 
Brian is right on the amount of material you can remove with the belt but I hadn't thought of taking that large of a cut. I do the plung thing when I remove a lot of material with a belt but I take only around .003-.004 cuts but cover the whole blade with the 2 inch belt but still within around 3 passes I remove the .010.

I think that is faster for me since even with a 1 inch wide belt it would take forever to run it off of an 1 1/2 to 2 inch wide blade.

I guess it's however it works best for your work. Most of my stuff is large fixed blades so the magnetic chuck has a firm hold on it. Little things scare the crap out of me so doing it the Brian does is the safer way on small parts and folder blades.

I guess you have to experiment and see what works for you.
 
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