How thick does a plane iron need to be? was: replacement irons for old Stanley bench plane?
I have a collection of old Stanley planes and I have tuned them up and they are all good “user” tools. I have reground and sharpened the original irons and I’m satisfied with the way they perform. But I hear about people who have put thicker modern irons in old planes and they seem to be happy with the improvement these modern irons provide. I thought I would try upgrading the iron in my WWII era Stanley 4 ½. The existing Stanley iron is laminated steel and is about 80 thousandths thick. Although there are irons up to 140 thousandths available, most irons that are “guaranteed to fit” old Stanleys are 95 thousandths. Not much thicker. I’m not above widening the throat on my 4 ½. Does anyone have any experience with this? Can I really expect a noticeable improvement with a thicker iron? Any feedback appreciated.
Replies
I have a Hock blade in my Stanley #3 and a Lie-Nielsen in my #4. Both are really nice upgrades and neither one did I have to open up the mouth in order for the blade to clear. Since your 4 1/2 is a smoothing plane I would recommend getting either blade. My Stanley #5 still has the original blade and performs just fine because I use it as a fore plane. Don't need gosamer thin shavings from it. Got my smooth planes for that.
Mike
Thicker irons help a lot
As Mike told you, either Hock or LN for the old Stanleys do make a difference. For smoothing planes I prefer the high carbon Hock irons to the A2 irons. If you have the cash get a matching chipbreaker as well. Most old Stanley planes need a lot of tuning before you get the performance you are propably looking for. The face of the frog needs to be flattened and the 4 posts that mate the frog to the plane body usually need levelled so the frog doesn't rock inside the plane. David Charlesworth had a great article in FWW for tuning old planes a few years back. It is available in their online articles if you are a subscriber to their website.
gdblake
I’ve tuned up many beat up old Stanleys to the point that they will do Rob Cosman parlor tricks. I re-grind all the half-done Stanley machine shop surfaces. No matter how rough the condition of the original high carbon steel blades they can be made flat and sharp enough to shave with. It takes some time but I enjoy doing it. With jointers or fore planes or rabbet planes etc. I can’t imagine I could get a better performing plane at any price. Obviously a lot of good work was done with these planes over the last 125 years. But smoothers are more demanding. When it comes to smoothing hardwood panels I still get a little stutter sometimes with the original 80 thousandths iron and chipbreaker even when the cut is less than one thousandths thick. It leaves small but visible imperfections. They can be easily removed with a scraper. I have never used a smoother with a 125 - 140 thousandths iron like all the premium smoothers have. To read the reviews they are incapable of chatter. I wonder how thick an iron needs to be. I suspect the folks that are manufacturing $350 smoothing planes are not going to skimp on the iron thickness even if it’s overkill. Anyway, Lee Valley sells 100 thousandths A2 irons with matching 1/8 inch cap irons for a very reasonable price. I think I’ll try one in my 4 ½ and see how it works.
http://www.leevalley.com/US/wood/page.aspx?p=66868&cat=1,41182
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