Crazy idea re: abrasives

Re: Crazy idea re: abrasives

Dan Clermont in Burnaby

>Hi Denis,

Diamond paste is readily available from several sources such as Lie Nielsen and Tools for Woodworking.

You can use MDF or anything you consider flat or concave (whatever you choose)

Loose sillicon grit and I would assume a Shapton in loose form would also be messy and you would have a hard time containing the grit. That is my experience from flattening plane soles.

Dan Clermont

Maybe not...

Scott Burr in rainy Ben Lomond,CA

>Makes sence if you got something to hold the medium. Like you said, paste. Hmmm, almost like sandpaper...yea, your crazy. :^)

great idea...

bill tindall

>It is called diamond powder or paste on cast iron and it cuts times faster than the water stone abrasive. As a result only one grit size is needed for typical sharpening. 1 micron diamond will put an edge on a tool, even a highly abrasion resistant tool such as M4, right off the power grinder with a 60 grit wheel. With luck people will catch on to how fast and CHEAP this approach is and someone will begin selling cast iron plates.

Valve grinding compound

Bill Houghton, Sebastopol, CA

>I can't recall what the abrasive is, but, last time I checked, the corner auto parts store carried valve grinding compound for seating automotive valves. Comes mixed with water or with grease, not terribly expensive. You might experiment with that, to try out your idea.

I've seen loose powder abrasives offered as a product in WW mail order catalogues in the past, too - haven't paid much attention lately, so I don't know if they're still on offer.

Re: Crazy idea re: abrasives

Jim in Burlington On

>I've got a feeling that ultra fine abrasives that makeup a 30k stone are very expensive. Your substrate might actually be considerably more coarse than the cutting powder negating the use of it.

the challenge to be solved...

bill tindall

>the secret to effectively using an abrasive is to be able to capture it in some flat surface so that the grit remains stationary while the steel moves past it (or visa versa).

The binder captures the grit in a stone or sheet abrasive. Capture is more a challenge for a loose abrasive powder. The reason diamond works so well on cast iron is that the diamond is exceedingly tough as well as hard. Under pressure it embeds in the cast iron and becomes immobile. Silicon carbide crushes to easily to be a good loose abrasive. Diamond powder is very cheap ($25 worth will last a life time) so there would be little reason to use the ceramic aluminium oxide abrasive used in the stones. The challenge and expense is to come up with something to embed the abrasive in, a marketing opportunity waiting to be plucked. Once one moves to diamond then all the steels become equivalently easy to sharpen.

Couple comments/questions

Denis Ch�nard, Orl�ans, Ont.

>When using stones it is expected that the stones will dish in use and need to be flattened on a regular basis. With sandpaper on glass, or on a granite plate (which I'm using) the abrasive gets used up before flatness becomes an issue.

On cast iron, doesn't the surface become dished too? Does one need to get the cast iron plates re-flattened on some kind of schedule?

Also, can one get finer than 1 micron diamond paste? That's about 6000 grit, if my memory serves me right. Therefore my original wish for 15-30k abrasive powder. Granted, it won't work with some exotic alloys, but all I'm using is A2 or HCS, so that's not a concern for me now...

DC

Re: diamonds too small for girlfriends

paul womack

>Also, can one get finer than 1 micron diamond paste?

Yeah. 1/4 micron

http://www.eternaltools.com/viewproducts.asp?txtRangeID=36

Watch out for FEPA vs CAMI when people quote grits.

I assume there are equivalent suppliers in the USA.

BugBear

Re: diamonds too small for girlfriends

Wendell @ Murphy, TX

>Joel at www.toolsforworkingwood.com sells 1/2 and 1/4 micron Norton water based paste.

Wendell

Re: the challenge to be solved...

ThomD

>SC works just the same way, and as you mention it breaks down quickly which means one doesn't get the effect of a consistant stone, though one just keeps sprinkling grit on the surface until the heavier work is done. Very messy, like bathing in ink.

Substrate

Bill Houghton, Sebastopol, CA

>Joel mentions MDF or maple as substrates - is cast iron better than either of these cheaper alternatives?

Re: Substrate

Wendell @ Murphy, TX

>Here's my experience so far with diamond paste. I started with straight MDF as a substrate. The paste didn't seem to cut worth a darn. Apparently, it was just soaking into the mdf. Next I tried acrylic. The lower grits 45 and 15 microns work beautifully for me but I was underwhelmed by the 1/2 and 1/4 micron results. I felt I was getting a better finish off of the Scary Sharp system I am trying to move away from. I tried looking for some cast iron plates with no luck so decided to try the steel Kanaban plates that are sold to use with loose carbide power to flatten the backs of tools. These really didn't work with the finer diamond paste. I have some hard maple around that I am going to try. If that doesn't work acceptablely, I may just have to bite the bullet and buy some expensive cast iron plates.

Wendell

Substrate, similar experience

bill tindall

>You experience follows mine exactly. The diamond has to stick up to work. the porus substrates like wood etc. just eat the grits. Plus on these porus substrates how does one get rid of the grindings? they just accumulate and choke the abrasive. Not worth wasting diamonds on.

I think that as one tries the finer grits with an grease vehicle that the grease layer is thicker than the diamonds are tall and cutting action gets poor. While 60 micron on acrylic is better than 60 on cast iron, 1 micron did not work well for me either. By going to a diamond powder and glycol lubricant I got acrylic to work well with 1 micron. But acrylic is grabby compared to cast iron that is "smooth", I suppose because of the lubricity of the high graphite content.

Re: Couple comments/questions *LINK*

Phil Smith

>Diamond powder is available in a very wide range of powder sizes. See attached site to get an idea of the particle size that is used commerically. 1/4 micron is readily avaiable but sizes much smaller are available if you look. Looks like the Swiss go down to .025 or .05 micron in size. At this size you are talking about a very fine mirror finish.

I have done a lot of lapping in the last year with no apparent dishing of the cast iron. Still have the other side to use if it does dish.


http://www.vanmoppes.ch/?id=1/2/2/2/1

Re: Substrate

paul womack

>Intuitively (always dangerous) there has to be relationshpi between the texture of the substrate and the size of the particles.

It seems to me that if the texture is coarser than the particles, the particles will simply end up sitting in hollows and doing nothing.

(as a separate comment a substrate that absorbs your lubricant and moves/swells/degrades must surely be a bad idea)

BugBear

Re: Oh mama!

paul womack

> Looks like the Swiss go down to .025 or .05 micron in size.

BugBear

Re: Substrate, similar experience

William Duffield, on the Cohansey

>I've had similar experiences recently with the 0.4� diamond that Joel sells. I've been using it to polish carbide for burnishers. It doesn't stick around long enough when applied to either rock maple or to acrylic. Thus, I seem to be using a lot of diamond and a lot of time to get the carbide to a mirror finish. I'm still having difficulties removing all the deeper scratches from previous machining and polishing steps. Note that the carbide is harder and more difficult to polish than any tool steel. It is inappropriate for cutting edges however, because it is much too brittle.

I tried lignum vitae, but it didn't work any better than the maple. I have some other candidates I will try, including dogwood, but not until I've done some experimenting with binders.

Note that the diamond I am using is in an aqueous carrier. Therefore, MDF, which is not waterproof, is not an appropriate substrate.

I've tried a couple of the small diamond hones made by DMT, the cheap ones with the diamond embedded in a metal plate on a plastic stick. Even the blue "super fine" leaves scratches that are much too coarse for my application, and the rotating carbide digs into the nickel, ruining it.

On this week's Hand Tool Chat, we discussed this and other issues. David Barnett offered several suggestions, some of which I think I remember, offered in no particular order. I haven't tried these yet.

First, he suggested that phenolic should work better than acrylic, I think because it is tougher, not as sticky, and more tolerant of high temperatures.

He suggested alternative woods that he finds work better than maple. These include boxwood and holly. He mentioned another species, which I can't recall right now.

I think perhaps his most important tip was the choice of an appropriate binder, to hold the diamond grit onto the surface of the wood. Whatever is chosen must be hard but still flexible, easy to apply as a thin, consistent film, bond well to a wooden substrate, and readily available to hand tool woodworkers. His answer is dewaxed shellac.

I'll report back after I get into the shop this afternoon and try this out.

atomic sharpening

bill tindall

>It is probably unnecessary to sharpen with atom sized diamond particles. At some point in sharpening one stroke of the plane will result in wear that will render the edge in the same state of dullness that a coarser grit would have produced. I wish I knew, from data, what point of edge refinement produced optimum utility. I know that by the time I decide to shapren that the edge is vastly duller than when I started. Would refining the edge another step result in longer time between sharpening? Elliot's data has the answer. It lies in the initial slope of the dulling curve. Someday I intend to have at this analysis.

I know you were teasing, but

Bill Houghton, Sebastopol, CA

>I doubt you could sharpen with carbon atoms anyway.

,05 micon is just 300 carbon atoms thick!

bill tindall

>