Diamond paste grits

[Matthew N. Masail]

Hi, since the pastes are available in 325 - 600 - 1200 - 3000 - 8000 - 14000 - 50000 - 100000 grits through Lapidary supplies, I have 4 interesting questions about their potential use.

1. could a 1200 grit paste on a MDF disk strop be used instead of a 1000grit waterstone?

2. if you make a MDF "stone" and charge it with compound, can you hone on it up and down and in circular motions like a stone, or will it get cut up?

3. is there anything to be gained by trying the 50000 grit after the 14000.... ? just out of pure curiosity.

4. how long would 5 grams of paste last..?

[george wilson]

David Weaver uses diamond a lot,and he needs to chime in here. Offhand,I'd say that 1200 grit diamond will not yield the smoothness that a 1000 grit stone will,because the diamonds will not break down into finer particles like your water stone will. Diamonds are more like permanent sand paper,and leaves a sanded looking finish. IF you do go to MUCH finer grits,you can make a mirror polished surface with them. It is done all the time on carbide bits for machine tools for cutting materials that need a truly keen,polished edge.

Even when you use wet or dry paper,the abrasive particles break down,load up with slurry,and end up producing a finer surface than it did when brand new.

[Zander Kale]

I have most of those grits but find I mostly just use the mesh 14,000. I do gross metal removal with other methods (like grinders or sandpaper).

1. could a 1200 grit paste on a MDF disk strop be used instead of a 1000grit waterstone?
I use green honing compound on tempered hardboard for a strop, works for me although I think leather works better. For a strop, I would think 14,000 would work better than 1200.

3. is there anything to be gained by trying the 50000 grit after the 14000.... ? just out of pure curiosity.
Not for me, I repurposed my 50k cast iron plate to a lower grit.

4. how long would 5 grams of paste last..?
Years.

[Andrew Pitonyak]

A few links to read (if you have not already)

http://www.sawmillcreek.org/showthread.php?185904-Diamond-paste-freehand-sharpening-system

http://www.sawmillcreek.org/showthread.php?184227-thoughts-on-this-new-sharpening-package-from-Lee-Valley

http://www.sawmillcreek.org/showthread.php?140628-Which-diamond-paste-and-how-to-use

http://www.sawmillcreek.org/showthread.php?86935-Using-Diamond-Paste

[David Weaver]

coarse diamonds only on a harder substrate, like mild steel or cast iron. They'd just tear up MDF or be pressed into it, and at that stage of making an edge you want something that cuts aggressively, not something that rolls around or gets pressed into the substrate and nearly disappears.

14000 grit diamonds is probably 1 micron, which would be a good utility edge, but like george says, diamond will always leave sort of a ragged sanded edge for whatever grit it is. They could be used on MDF, but I think you'd be just as well off using some common polishing compound like autosol, or one of the carving compounds (yellow aluminum oxide or green chromium oxide) on MDF.

I fiddle with diamonds, but generally only use them on HSS tools. Otherwise, I like a stone's edge qualities better, but pastes and powders are a good way to get a fine edge cheaply if you don't want to buy a stone and pay to have something that can flatten it, too.

[Jack Curtis]

... but like george says, diamond will always leave sort of a ragged sanded edge for whatever grit it is. ...

I don't think George said "whatever grit it is" exactly. Quote from George:

"IF you do go to MUCH finer grits,you can make a mirror polished surface with them. It is done all the time on carbide bits for machine tools for cutting materials that need a truly keen,polished edge."

And Bill Tindall and Steve Elliott claim to get wonderful results using only a grinder and 1 micron diamond paste; and Steve has the photos to prove it. Just not with an MDF substrate.

[Matthew N. Masail]

Thanks guys, a lot of good info. I have a bunch off HSS blades and I'm looking for a "in shop" solution. I don't yet have a shop large enough for a stone station. If I did I can imagine a quick trip over there should be no problem. but having a power strop will still be easiar for knives. I ordered the set of 6 micron, 3 micron and 1 micron Diamond paste from Lee Valley so I'll try that out of MDF. maybe I'll give the MDF a coat of Shellac first, it seems to harden it very nicely when I make shop shelves and stuff from it. I also have the green compound so if I get a "scratched" pattern I'll finish up with that.

[Derek Cohen]

Hi Matthew

The selection you chose will do a decent job. I'm coming in late to the thread, so my apologies if I offer a change or two - nothing that will dimish what you have, just add to it.

Firstly, it is always possible to use fewer grits with any honing medium - the compromise includes more work needed on that grit. The reason we have several grits is to spread the work load, and to reduce both the effort and the wear. My preference is to find a balance between the fewest grits to spread the load.

Secondly, the choices offered by Lee Valley are never by chance. They come from careful research and experimentation. Therefore a good rule of thumb is to follow their recommendations.

My recommendation for diamond paste follows the work done with the diamond mesh. I was part of the team that experimented here, and this was a lesson in finding ideal spacings with these meshes. As a result I use 15, 3, 0.5 and 0.1 microns for both mesh and paste. Is the 0.1 necessary? No, but it does add a lift to the edge. Take George's point here - diamond does not break down. With a fine waterstone one may actually approach this level as the stone dries without being aware that this is occuring.

The other grit I would add is a 40 or 45 for grinding the backs of old blades.

Edit: I almost forgot to emphasise the point that David makes: do not use MDF. You need a substrate that with hold the diamond captive at the surface. Cast iron or the steel plates offered by Lee Valley. I made cast iron plates from the soles of broken planes.

Regards from Perth

Derek

[Matthew N. Masail]

Hi Derek, Thanks for clearing that up, but I'm a little confused now... Lee Valley and the answers to my post about a power strop say MDF is fine. but I get that I need something harder... but does it have to be steel/iron?
I really don't want to make a "stone set", I want to make power strop disks for the drill press. I asked about the stone because I wanted to know if the blade will cut up mdf if I strop in the "wrong" direction.

So just to be sure MDF won't work as a power strop with diamond compound? what about "treaded" MDF with shellac or CA glue?

Do I have any good options to make a 6"-8" disk out of? maybe something glued to the MDF.. ?

Eventually I'll get a set of Sigma Power stones.

[David Weaver]

MDF would be fine for the small diamonds, but not something in the 1000 grit range. No matter what you make a power strop out of, you want to avoid ever introducing the iron in the wrong direction, or you'll get a catch and possibly have a flying/bouncing very sharp iron or chisel.

If you want to use the medium grits, then you'll need some mild steel at the very least (that's probably cheapest if you can find some relatively flat scrap, it doesn't need to be pretty stuff. The cheapest mild steel I've seen anywhere outside of a scrap yard is bar stock made for car modification / repair.

[Derek Cohen]

Hi Matthew

In short, you can make and use a MDF power strop as long as you use green compound and not diamond paste. The compound will sit on the top of the MDF, while the diamonds will be buried below the surface and lost forever. It is diamond that demands a harder surface. Diamond is unnecessary for a strop.

If you want to make a potent power strop, you could do worse than copy one I made several years ago. This was simply a layer of chamois leather (from an auto store) glued to a sanding disk, which was used on a disk sander/belt sander combo machine. I used Veritas green compound on this. Remember to hone with the sharp edge pointed away from the turning disk. A flat honing surface is more reliable than a rounded edge.

http://i13.photobucket.com/albums/a262/Derek50/Sharpening/Poweredstrop1-1.jpg

Mk I: http://www.inthewoodshop.com/WoodworkTechniques/BeltSanderGrinderMkI.html

MkII: http://www.inthewoodshop.com/WoodworkTechniques/BeltSanderBladeGrinderMK%20II.html

Regards from Perth

Derek

[David Weaver]

After seeing dereks, I did the same thing with cowhide that I got for about $10 a square foot. It's a nice setup, but early on, I did launch one iron with it, which was an exercise that had some serious pucker factor for a second or two until I was able to clear my head and confirm that nothing had hit me.

[Derek Cohen]

Hi David

Must do:

1. bevel edge facing away from the turn.

2. place the bevel down heel first.

Never had a catch.

I use this for lathe tools only these days. I replaced my plane and chisel blade strops with a sharpening centre alongside my bench.

Regards from Perth

Derek

[Matthew N. Masail]

Derek that is amazing! it's exactly what I need, and I just happen to have a 4" medium quality sander that I plane to replace one day with something better, so now I can make it into a sharpening station and like without the disk. I really like the way you think. I also give you credit in the Israeli forum. hope you don't mind.

I still need a solution to replace the 1000 and 4000/8000 grit stone.

can I go from a 1000 grit stone/belt directly to the compound? or to what grit do I need to get before the compound?
should I make a fine stone with sandpaper (or diamond if I can get some iron) to hone the back? remember I'm trying to work out a system that is water stone (and hence travel) free.

I guess I don't need the diamonds, but it's good to have I guess. I should have ordered a fine grit sanding belt to use as a 1000 grit, almost did, but thought the 6 micron diamonds would be good enough to get a burr. do you have any other suggestions for this?


also, should I glue MDF for the compound or is the back of a sanding pad a good choice?

David thanks for clearing that.... it's better to learn here than the hard way...

Thanks again, I'm getting exited this is really helping.

[Matthew N. Masail]

Hi, can these http://www.supergrit.com/products/products_belts-blacksc.asp in 800grit come after a 120 grit to smooth the bevel and be enough before the compound? or should I get something else/other grits.. ? sorry for so many questions.

[David Weaver]

If the belt on your sander is tight enough (it probably isn't) that would work. At the tension that most bench top sanders work, or most high speed consumer sanders in general, you'll get a lot more dubbing and rounded edges than you want. You could try it, though.

You can use a 1000 grit type stone, or anything of that level around there, and then go right to the disc type that derek shows. the only issue that i've had with mine is that there is a lot of heat if you try to do too much work at one time, but it does a good job if you manage your angles.

Do you have any way to get a flat piece of cowhide a tenth or an eighth of an inch thick? (like 8/9 ounce weight leather). It's excellent on the discs - it stays on tight with contact adhesive, and it's smooth, so you can be "fine" with the work of the edge and still in just a few seconds.

[Matthew N. Masail]

I can try get leather, do you mean to use it without compound? my problem is that I need something to get a quick burr on HSS without a whole water stone setup.... but realistically, am I better off just getting a good set of waterstones + a powerstrop?

[David Weaver]

No, use it with compound if you're following a 1000 stone.

My experience with waterstones is that they will do HSS OK as long as it arrives flat, but for various reasons, all of them are a pain to get it flat. I would use a belt of some sort to grind it and if the iron or chisel doesn't have to be dead straight across, to prepare it for the powered strop, too.

If I were using only HSS and chisels, I would want a 1000 grit diamond hone or thereabouts and the powered strop (like the disc one), though waterstones do work fine.

Though there's debate on it, my thoughts are that stones that work really well with high speed steel have characteristics that I don't necessarily like if HSS isn't what I use most of the time.

Many things work *OK* with HSS (anything except novaculite oilstones or other silica based natural stones), diamonds or diamonds followed by chromium oxide work great. They cut HSS like it's nothing.