Thread: Cast iron for diamond paste plate

Hi Derek,
That could be quite handy and with three of them they could all be lapped to make sure of flatness


Pete

Hi Derek, just a question: a lapping plate like that is faster or slower than a diamond stone? clever idea, anyway

Hi Luca

It is not really possible to make a comparison like this. While DMT does sell a 8000 grit (1 micron) diamond plate, it is very expensive. The next common diamond plate is the 1200 grit (9 microns). The diamond paste I end with is .5 microns (30000 grit), and there is not diamond plate available.

The 40 micron paste hones very fast, and I would say equivalent to a good diamond plate of the same grit. However, I have worn out diamond plates. Diamonds are not forever. Diamond paste, however, is cheap to replenish.

Regards from Perth

Derek

That's a neat idea Derek. Thanks for the post.

Are you able to reliably 'polish' the chisel backs this way as well? Ie. is the flatness of the soles an issue?

Originally Posted by rsser

That's a neat idea Derek. Thanks for the post.

Are you able to reliably 'polish' the chisel backs this way as well? Ie. is the flatness of the soles an issue?

Hi Ern

The chisel I used for the demo (picture below) was a very rough, unflat Witherby. What you see is the result of a minute on the 40 micron paste.



I then moved on to the 10, and then the .5 micron paste, which left a mirror finish.

Regards from Perth

Derek

Quick work!

How do you check for flatness?

The old soles that come into my shed are usually dished.

I don't know what Derek does, but when I get round to using some of the old clunker plane bodies in my shed in this way (I have a couple of 5 1/2s begging for this treatment), I will scrape them down flat after cutting off the toe because I suspect that removing the toe (of the plane , not my toe might release some forces within the cast iron and cause warping, even if the sole was flat before cutting.

Jeremy is right on the money - cut them to size first, then flatten. I used sandpaper. Check with a straight edge.

Regards from Perth

Derek

Have read somewhere that Stanley soles dished cos the cheeks were clamped when the sole was machined.

Also that they were not left in the boneyard long enough before machining.

And as well that machining the mouth brought down the wrath of the flatness god.

Never mind. The efficiency of Derek's method means that I can forswear joining the priesthood of sole scrapers and sacrifice one side of a granite slab measured flat to within a poofteenth of a gnat's eyelash.

PS. Just wondering what happens to the plate over time.

The diamond paste is hardest of all.

HC steel or harder is next.

Cast iron, or granite, next.

Won't the iron succumb to dishing?

Or is there something about the mobility of the diamond grains that means it won't?

Suggest that after two trials of coarse SiC grains on plate glass, flattening a Shapton #120. Actually appeared to improve the flatness of the glass.

Hi Ern

The diamonds bed into the cast iron and protrude above its surface. Anything that is run across the top of the plate is worn away by the diamonds. The diamond grit is immovable, and therefore does not wear the iron plate, unlike loose diamonds.

I have been told that alteratives to cast iron include copper and phenolic resin sheets.

Regards from Perth

Derek

Yeah, sounds logical.

How many backs have you lapped on this rig so far may I ask?

On these plates, just 5 so far ....

1 x high carbon 1/2" chisel (no sweat).
1 x CPM 3V 3/4" chisel!
1 x CM M4 3/4" chisel!!
1 x CPM 10V 3/4" chisel!!!
1 x M4 Stanley #4 plane blade!!!!!



Regards from Perth

Derek