Source for ground mild steel plates

[Patrick Chase]

In my previous thread somebody asked about a source for ground mild steel or cast iron plates. I answered that I've gone through a friend's machine shop, but somebody else brought up Speedy Metals and Online Metals.

It turns out that Online Metals in particular sells Blanchard-ground 1018 (mild steel) plates in appropriate thicknesses.

With shipping they end up more expensive than the Veritas plates per unit area, but I think the Online Metals ones may be better with fine-grit (1 micron and below) diamond compound, for two reasons:

Roughness. The Veritas plates are milled rather than ground, and the surface texture looks like the aftermath of a fly cutter, though I doubt that's what they used. Veritas claims that the texture helps the plates hold diamond particles, and I think that's true for coarse grits, but they mostly seem to scratch tools when used with fine-grit paste. Back when I was using the Veritas plates exclusively I ended up lapping the ones that I paired with finer-grit pastes on sandpaper to "soften" the milling marks. Blanchard-ground plates should be smooth enough for fine-grit paste out of the box.

Flatness. The Veritas plates have a 4-mil flatness spec, and I've seen examples that are warped by a few mils lengthwise. That translates to a couple tenths of a mil across the width of a 2" chisel or plane blade, which is a nonissue for coarse particle sizes because the next grit down will be aggressive enough to quickly fix that sort of mismatch. It becomes a problem with very fine pastes because they take forever to remove any geometry mismatch from the next plate up. Fine-grit lapping plates have to be dead flat or at least identically warped, and blanchard-ground plates should also do well in this respect. As I noted in my previous post, MDF also has enough "give" to mitigate small flatness mismatches, so the other option is to just use that for your finest grits.

I ordered a 3/8" thick 8x8 plate for kicks to see how they work. I'll probably cut it into a pair of 4x8s.

Online Metals is the retail arm of Thyssen-Krupp, so they're extremely reputable.

[Gerry Grzadzinski]

McMaster-Carr has a 3/8" 4"x12" precision ground plate for about $37.

They don't specify a flatness tolerance, but the thickness tolerance is ±.001"

[Nicholas Lingg]

https://na.dmecompany.com/Catalog/Ca...gDetailId=1031

[Tom Bussey]

There is a difference between flat and parallel. It can be bowed like a banana and still be the same thickness. However precision ground plate should be flat enough for most woodworkers.

[george wilson]

Enco and MSC Co. sell precision ground low carbon steel. Looks just like precision ground tool steel as far as looks go. A nice,pretty finely ground surface. Much nicer than Blanchard ground. Oh,my friends at Victor Machinery Exchange in Brooklyn.New York probably sell it cheaper.

To tell the truth,by the time a guy beats the dovetails together on a plane,he possibly will have wasted the nice surface,and will have to file and sand the whole thing to get the surface finished again. I have found cold rolled mild steel sheet to be quite useful. And cheaper.

[Mark Fisher]

Precision ground plate is probably annealed prior to final grind......should be pretty darn flat.

[george wilson]

It is as accurate as any other tool steel. But,it may not be as true after having the dovetails peened together.

[Paul Saffold]

Lee Valley has them but only size is about like a sharpening stone.

[Patrick Chase]

Lee Valley has them but only size is about like a sharpening stone.

See my original post - the Veritas plates are milled rather than ground, and that has both advantages and drawbacks depending on the use (LV and Veritas are one and the same)

[Paul Saffold]

Wow, I certainly was asleep at the wheel on that one.

[lowell holmes]

I have to assume you fellows are talking about flat plates for lapping and sharpening.

I am completely happy with wet sandpaper on my granite plate that I bought from Woodcraft. It is indeed flat.
I only mention as an alternative to flat.

[Patrick Chase]

I have to assume you fellows are talking about flat plates for lapping and sharpening.

I am completely happy with wet sandpaper on my granite plate that I bought from Woodcraft. It is indeed flat.
I only mention as an alternative to flat.

Sandpaper is only an alternative to very coarse (large-particle-size) diamond pastes. I have 45, 15, 3, 1, and 0.25 pastes in common use. 15 is #1000, so that's the finest one that overlaps sandpaper. In my experience the economics in terms of sandpaper/paste expended per grinding session are comparable (and both lose badly to waterstones in that respect), but diamonds are a lot faster and do better with really hard steels.

[Tony Zaffuto]

The LV Spring 2016 catalog arrived today and the Veritas honing plates are pictured. Definitely have the look of a fly cutter, with a flatness tolerance of .005" over the entire 3" X 8" plate. On page 148 of their 2015-2016 LV has pictured their Veritas lapping plate, which is ground to a tolerance of .001" over the entire 4" X 12" surface. The lapping plate also has grease grooves milled into the surface.

For my purposes, I use a granite plate, but not with loose diamond or Sc grit: IF I use it, a quick spray of 3M #77 adhesive, with a sheet of 3M Sc paper affixed is it. I don't get too anal on flattening or lapping (but then again, I have a full machine & tool making shop in my plant, and on occasion, I have had one of my tool makers grind plane soles flat and/or square).

[John K Jordan]

I have ordered several times from Online Metals and found them to be fair and prompt and the products as advertised. I bought steel, aluminum, and brass.

JKJ

[lowell holmes]

I will have a set of planer knives sharpened and Back on the planer in 20-30 minutes. It suits my needs. I often make rocking chairs and tables, so micro flat is not necessary. All of my grandchildren are rocked in chairs I made. My chairs are 40% machine made and the rest chisles, shaves, and knives.

I'm glad Tony spoke up and let me know I'm not the only one using granite.

It also is a good reference surface for visual check flatness of a surface. It's large enough to accommodate checking large surfaces for flatness.