Lapped/ground steel for infill build

[Andrew Nemeth]

I'm about to start my first infill build and, after flattening the sole of recent restoration, I'm rethinking the economy of buying precision ground or lapped steel plate. I originally intended to buy cold rolled plate and flatten it with sandpaper on granite but after seeing how much sandpaper I went through (about 10-15 sheets) and the time involved (4-6 hours on a 603) I'm pretty sure I didn't save any money. Many of the blogs and posts I have read about first time infill builds have mentioned they would use flatter stock the next time if they didn't have access to a machine shop. So, the question is, how do I go about sourcing the plate? Are there any online suppliers and specific products anybody recommends? Would it be more economical to have it flattened by a machine shop locally?

I should mention I'm only looking to purchase enough to make a few shoulder planes (equivalents to LV/LN small and medium) unless I can convince a few other creekers to do a group purchase.

Thanks for any direction that can be provided,
Andrew

[george wilson]

I have never made an infill plane using precision ground steel stock. It won't be very flat by the time you hammer the dovetails out. Some I know do use it,though. I used "black iron" from thick sheets available free from cut offs in the sheet metal shop in the museum. The scale can be murder to get rid of. I suggest acid.

[Steve Voigt]

Raney Nelson (Daed toolworks) is a big advocate of using O1, which is already ground flat. A little Googling should turn up some of his comments (I think he's even posted here a few times).
Victor machinery in Brooklyn has good prices on O1 and a low minimum ($20 or $25, I think).

[Andrew Nemeth]

George,

Your opinion is duly noted. How flat do you make the side of the plate facing the infill before laying out and cutting the dovetails? Is citric acid strong enough or would you recommend phosphoric or something even stronger for cleaning the scale?

-Andrew

[David Weaver]

I used it for two of mine. I'll probably use it again after I get through the current kit plane, who knows when that will be.

I like O1 precision ground stock, and to lap it, I use an 8x42 piece of shelf glass (just a flat piece of glass) with 4 inch wide aluminum oxide PSA stick down paper on it.

The reason I like O1 is because you can comb cut it, it works easily, it files nicely. Everything on it works a little slower with the file and the saw, etc, but there are no surprises. When it comes time to lap it, it laps well on the sandpaper. Mild steel goes over the abrasive sheets like gum (my last plane was an 18" long shepherd kit with a mild steel bottom).

The drawback is that peining the dovetails takes a bit more effort with O1, and O1 precision ground is a LOT more expensive. But to me working with no power tools on my first three planes other than a cordless drill and a belt/disc sander, I prefer the precision ground.

You're really going to want to machine the sides and bottom of the plane after the infill is in it, and there's not going to be anyone local who can do that properly. I can't remember what holtey does, I think he has precision peining blocks for his planes, but you're not going to have that option. What I'm saying is that it will be easier to build it precisely, draw file most of the junk off of it and then lap it.

Presuming you're doing dovetails.

You need a good long run of sandpaper from a PSA roll, though, you can't screw around with sheets, it's a waste of time and paper, and you'll soon be well past the cost of a 10 meter roll of mirka gold. The infills (precision ground O1 or mild steel) will not lap as easily as a cast iron plane, either, so be ready to split the lapping up into several sessions.

[Zander Kale]

Is citric acid strong enough or would you recommend phosphoric or something even stronger for cleaning the scale?

I use vinegar to remove the scale from hot rolled mild steel, followed by a knotted wire wheel.

[Brian Thornock]

I am finishing a pair of infill shoulder planes right now. The first one I made, I used regular HRS from the BORG. However, it took way to long to flatten the stuff up. The pair I am working on now have O1 for the sole and precision ground 1018 for the sides, both of which I got from ENCO. Total cost for stock for sole, sides, and blades was about $70. It is so much better. I am not dovetailing mine, I am doing through pins, and it has stayed much more square than my prototype, and I haven't even fine tuned the squareness at all. I totally don't regret it, as the savings in time and frustration (not to mention sandpaper) is worth every penny. I think one thing I will do for truing and such is get sanding belts and cut them to lay them flat. Should be a cheap way to get some very robust sanding media. If you plan to do all O1, onlinemetals.com is slightly cheaper than ENCO, but ENCO has a lot of the other stuff you will need (cutting fluid, chucking reamers, taps, etc.).

[David Weaver]

You want PSA stick down rolls.

Anything else (including sanding belts) will dub the edges of whatever you're lapping and leave a dissatisfying result.

PSA stick down will probably be cheaper, too. Whatever is available in premium aluminum oxide (mirka gold, whatever) is best. Anything higher on the food chain of sandpapers (purple, blue zirconia, etc) doesn't actually amount to much in high pressure low speed application (like hand lapping). I'm not sure it lasts longer than regular aluminum oxide, and value-wise it definitely does not.

You can try to stretch a sanding belt as much as possible and you'll still have evidence of a dub from it. I went the same route first, too.