Home made Krenov irons?

[Dave Cav]

I'll preface this by saying I haven't ever made a Krenov plane, although I have the book...

I'm thinking of doing a shop project for my second year students of making Krenov style planes. Most or all of them would not be able to buy Hock or other ready made irons and my program can't afford them, either. I was thinking of using old truck springs. The steel is reasonably high in carbon, and the thickness and width should be about right. If we are careful when we cut them out using a plasma torch we might even be able to get away without having to mess with re-tempering and annealing, although that might be the basis for another lesson in tempering. I know leaf springs aren't ideal but the price is right, and for high school students it should be OK. If they really like the planes they can always get a Hock iron later. Any comments or suggestions? Plan B is to get a few pieces of 3/16" x 2" O-1 steel and then temper and anneal it, but that would involve a bit of expense I might not be able to handle.

[David Keller NC]

Truck or car springs generally aren't hard enough for a plane iron. I suspect hardening and tempering will be necessary to prevent the edge from folding over.

I suppose this is obvious, but there's a real risk here if you've students that have never been exposed to hand planes. The risk is that to save just a few dollars, some of the students may conclude that hand planes are poor tools if the irons don't come out very well. Unless you're working with really underpriveleged students, consider that a Hock iron for a Krenov-type plane is probably gas money for the week.

One idea here is to call Ron Hock and see if he'd give you a discount for the quantity you'd need and for the purpose (which might be considered charitable contributions). And while you can certainly make irons from O-1, hardening and tempering is not all that easy. Yes, it certainly can be done and is done all the time by blacksmiths and some of us on the board, but for ideal and consistent results you'd want to send them out to a local metal treating firm, making the cost very near buying the Hock irons.

[Bob Strawn]

I have been making stuff out of old truck springs for years. Used to make armor and such in the SCA. Lately I have been moving up to stuff that is a bit more predictable, but with spring steel, you can make tools that are quite a bit better than most that you buy these days.

To anneal properly, Get or order a bag of pearlite from a garden center or coop. Heat the steel red hot and then let it cool in the pearlite. This will make the spring steel soft enough to work. The spring steel will be way thick enough. Keep the steel cool when grinding so you don't loose carbon. If it gets past amber as they grind, they are burning the steel and will need to remove the metal that was scorched. Have each student make 2 blades, the one that has been burnt the worst should become the chip breaker. When you drill through the annealed steel, be sure that coolant runs freely over the drill bit and the metal to keep it from hardening and destroying the drill.

When the blades are ground and shiny, paint the steel with a wet mix 15 parts boric acid, 1 part iron oxide. This will work as flux and keep the steel from oxidizing and it will stay shiny. You can use a few fire bricks and a rosebud tip on a Acetylene torch to heat treat the blade. Keep the steel almost cherry, never sparking, for about 5 minutes and then plunge it into a large bucket of warm salt water. Despite what folk say, brine (salt water) is a gentler quench than straight water. Evaporation is reduced. If the water in the bucket is stirred to a spin first, an even quench is facilitated by the moving water. A few bits of scrap from the springs should be treated like this first to determine the correct temper. Use these to determine the best tempering. After quench and before temper, the steel should be handled carefully so as not to drop and possibly fracture it. It is generally good practice to temper right after quenching.

Get a frydaddy and a good cooking thermometer for tempering. Put the blade or blades in the basket and lower it into the oil. Let the blades stay at temperature for about an hour before quenching again and setting the temper.

Start experimenting on temper at about 400 degrees. If a file does not work the steel it is too hard, if it won't hold an edge it is too soft. The lower the temperature you use to temper, the harder the steel will be. If I were going to guess at the right temperature, I would guess at 375, but in many cases that will be way off. Really it depends on the spring.

Get at least one Hock blade as a reference. Hock is the gold standard.

Bob

[Michael Faurot]

Have each student make 2 blades, the one that has been burnt the worst should become the chip breaker.

I don't know how thick a piece of leaf spring is, but if it's 3/16" or greater, you can simplify things and do away with the chip breaker entirely.

[James Scheffler]

I'll preface this by saying I haven't ever made a Krenov plane, although I have the book...



As an alternative, you could try some of the replacement blades for Asian planes that Lee Valley carries. They're quite a bit thinner (3 mm), but chances are they would make a decent plane. A 1.7" high speed steel blade is $16, but there are also some cheaper ones.

Lee Valley also has a line of blades for wooden planes that are 3/16" thick. They're around $10 cheaper than the Hock blades, but that may not be much help. I have one of those for a plane I'm just finishing up. It's an impressive piece of steel. :)

None of these come with chip breakers, but that actually saves a step in making the planes.

Jim

[Brian Kent]

A report on the irons Jim just mentioned. I have tried twice. The one with a regular wedge still vibrates a little. The one with a screw cap is my best block plane. The biggest one in the pictures is my first try, using an iron from a broken down woody that I got very cheaply on e-bay. It works beautifully.

[Bruce Haugen]

A lot of the older truck spring steel is 5160 (it is frequently known as OCLS - old chevy leaf spring). Google that for a whole bunch of info on its workability and how well it hardens. It is likely to be a bit lower in carbon than O-1, which is what Ron Hock uses for his carbon blades that are not A2. If I understand this correctly, 5160 has 60 points of carbon, and 1095 has 95. Someone please correct me.

I'm in the end stage of making a Bowie knife, needing only to get it hardened. From what I've read, it works really well for that application.

Brucer

[Matt Evans]

Dave,
I would order the steel from a place like MSC Online Metals also has pretty good selection. Get O-1, already annealed. If you order a longer length you can cut to size, and get the steel pretty inexpensively.

The only tricky part for most people is the hardening and tempering. This, for someone with a high school art department kiln at his disposal, would be easy.

[Derek Cohen]

I'm thinking of doing a shop project for my second year students of making Krenov style planes.

Dave

JK did not start off using Hock blades. He used old block plane blades, old Stanley bench plane blades he shortened by cutting off the rear.

I suggest you find some old Stanley blades and cut them down the centre. What difference does it make if the plane is narrow - it is a project. Half a 2 3/8" blade (around 1 1/4" after smooothing) would make a nice block plane or mini smoother.

De-temper the blades by heating to red hot leaving them to cool. Later re-temper - easy enough. Or just take a chance and cut with a Dremel, cooling the steel as you go.

Regards from Perth

Derek

[Joel Goodman]

If you don't want to get into the metalworking which might be pretty neat and if you can live with the thinness of the iron and the quality of the steel Stanley replacement block plane irons 1 3/8th (5 slot) are $6 or iron and chipbreaker set for #3 (1 3/4th inch) are $13. It might me worth an experiment and try building a plane with one of them to see how it works. Also a quick google search came up with 01 steel 1 3/4 X 36" 3/16" thick for about $36.

[David Keller NC]

Dave - You've a fair number of reasonable options listed in the replies (and I'm really serious about contacting Ron Hock - he may be willing to sell you a small quantity at his cost).

How many students are you trying to accomodate? If it's a small number, it occurs to me that this is a worthy charity project. There may well be a local metals business that would be willing to donate, or perhaps even through SMC (you'd have to contact the moderators about setting that one up). I would be willing to contribute.

And one warning - I've gotten a fair number of bars of flat-ground O-1 from McMaster Carr and MSC that were supposed to be annealed. They weren't - it took me a couple of ruined hacksaw blades to figure that out. I say this because if you've access to an industrial oven you can probably anneal the bars yourself, and hacksawing the blade blanks, in my opinion, is preferable to an oxy acetylene or plasma torch cut, which tends to leave a really rough bead behind that has to be ground off. If you can talk a local machine shop into donating some time on a water-jet cutting machine, that'd be even better.

[Ron Petley]

If you are going to make the blades, you can buy 01 thick enough so you do not need a chip breaker, and wide enough to make good plane blades, all you need is to cut it to length.
Grind most of the bevel first, not totaly or you will end up overheating the bevel, and then quench and heat treat it, then you can finish the bevel on stones.
If you are heating steel to quench, heating to "cherry" is very subjective, heat it slowly, from the non bevel end, and when it is at the right temp a magnet will not stick to it, do not heat it above this temp, hold that temp for a few min, and you will be good to quench. Overheating during quenching lowers the blade quality.
Cheers Ron.

[Rob Young]

As I understand things, Hock Tools can't make group discounts directly due to their distributor agreements. Check with a nearby Woodcraft for a group purchase.

Second option for pre-made would be St. James Bay tools. http://www.stjamesbaytoolco.com/

Give him a call too. His blades and breakers are less expensive but will require more work to hone and prep than the equivalent Hock irons. You are trading off time for money, the Hock irons will be nearly ready to go right from the package.

[Dave Cav]

Thanks, everyone. Lots of good information here. I am a little reluctant to get into any serious heat treating because my class is only 55 minutes long from bell to bell, and I only have one class that would be doing this project. (I have 4 classes of 1st year students and 1 class of 2nd year students.) Hock irons are probably out of the question, as most of my students are not very well off. About 65% of the students in our high school are on free or reduced price lunches, and the percentage is probably quite a bit higher for my particular students. The Lee Valley asian plane irons look like a great deal, though. I might get a couple of them and make a plane or two and try them out, and if they work I may approach the Lee Valley folks about a quantity discount as I would be buying about 25 of them.

[Sam Takeuchi]

How about this, how about asking for plane iron donation here. I mean I don't know if that's allowed or what not on this board, but as far as your intention goes, it seems like it's for a good cause. I think many people have a couple of blades they don't do anything with. I don't know how much it cost to send a plane blade in the US, but it's worth a shot I think.

[James Scheffler]

A report on the irons Jim just mentioned. I have tried twice. The one with a regular wedge still vibrates a little. The one with a screw cap is my best block plane. The biggest one in the pictures is my first try, using an iron from a broken down woody that I got very cheaply on e-bay. It works beautifully.

Those look really nice. How did you make the screw cap? From the pictures, it looks like it's a piece of brass attached (glued?) to a wooden wedge. Where did you get the brass thumb screw?

Thanks,
Jim

[Ted Calver]

Dave,
Kudos to you for considering such a cool project. Slight thread drift. Call me a cynic, but from what I read in the newspapers in our area, being caught with something made of metal with a sharp edge on it gets you suspended from school. Shoot, seems like even drawing a picture of something sharp will do it in some places. When I was a kid we all had cub scout knives in elementary school and played Mumblety-peg during recess. Regretably, times have changed. Is your school ok with this kind of project?

[george wilson]

If truck springs are made of 5160,that means only .60 carbon. That is a poor carbon content. It will harden,but will have poor wear resistance. 01 steel has 1.02 carbon,much higher,and a great deal better. 1095 has .95 carbon,which is also fine.

You would be better off buying some 01 precision ground stock the right width,sawing it off,hardening and drawing,then grinding the bevel last.

To harden 01,or any other simple steel,heat it till it is turning orange(cherry is a vague description). Don't overheat,or you will get blisters on the steel,which means it's burnt. Use of a magnet is a good idea,used by many. Don't get the magnet too hot,or it will lose its magnetism. Even rare earth magnets don't stand much heat. Dip the magnet in water after each test of the steel. Quench in automatic transmission fluid. We used it for years in the toolmaker's shop. Sand it clean enough to see the naked steel,and draw it to a dark brown color.

It is necessary to grind the bevel last,because the blade will warp if quenched with the bevel already ground on it,and you won't be able to get it flat again unless you grind it flat and lose much thickness.

I have never gotten a piece of 01 that was already hardened from MSC or anyone else. Who knows what is possible though,with all the overseas manufacturing.

Buying the 01,and sawing off 4 or 5 inches for each student will be your cheapest way out unless someone is willing to help. You probably would have to stay overtime and harden the irons if your students haven't the time.

You could probably get used transmission fluid and strain it through several layers of panty hose in a funnel. We kept a 5 gallon pail of it. YOUR QUENCH needs to be large enough to not get heated much when you quench a plane iron in it.

I do not recommend warm salt water. It should be room temperature,or it may not harden the steel as hard as it should. Then,your subsequent tempering will be off,and come out on the soft side.

To make a proper brine quench,stir in ice cream salt thoroughly until a potato will float in the brine. That gives you a 7% salt solution. I don't know why ice cream salt is best,but it is recommended.

Brine is only for water hardening steels,like 1095,1075,etc. In steel parlance,the 1 means iron,the next 0 means no other additives. the last 2 digits refer to the carbon content. 1095 means plain iron with .95 carbon.

Since you cannot usually easily find 1095 in sizes for plane irons,I recommend 01. Cost per student will be only a few dollars compared to buying finished irons.

[Brian Kent]

How about this, how about asking for plane iron donation here. I mean I don't know if that's allowed or what not on this board, but as far as your intention goes, it seems like it's for a good cause. I think many people have a couple of blades they don't do anything with. I don't know how much it cost to send a plane blade in the US, but it's worth a shot I think.

I agree with Sam. I think it would be worth it to see who could send an iron - any plane iron - for the sake of this class. It is the kind of helping hand that shows 25 kids what they can do in tool-making and gets them another boost in a hobby or job.

If others think this is a good idea I would be willing to start the post - either here or in "Sawmill Creek Classified". I have one I could send in. Since the planes can be any size, then any old irons, or new from good sources would work.

[Johnny Kleso]

Please Forget The Truck Springs..............................

I hope never to see Thuck Springs as a aource for steel again.......

Tool Steel is cheap, why do you want to work many extra hours to save a few bucks and not have 1/2 as good steel.. You have to spend time finding, buying, cleaning and sanding and when done you have a curved piece of steel......

ENCO (use-enco.com) page 818 has Starrett Brand 1/4 x 2 x 18 0-1 Tool steel for $25

If you sign up for their news letter ön the front page you get a free shipping code evey month for orders over $50.. Steel shipped free youcant beat this deal...

You can also find deals on eBay but you have to spend the time..
Home>Business & Industrial > Manufacturing & Metalworking > Metals & Alloys

I have a 1/2 done tutorial on my site for heat treating..

No More Truck Steel Talk Please

[Richard Magbanua]

How about using the Muji replacement blades. They're cheap but work well. I know their planes receive good reviews. I'm happy with mine.

http://www.leevalley.com/wood/page.aspx?c=2&p=46322&cat=1,230,41182,46334

[Dave Cav]

Thanks again for all the info; I think for the time being I'll forget about trying to make the irons out of anything, and probably just order a couple of the Lee Valley asian plane irons. When we get to the project I'll have the students make the plane body and then use one of the irons I have to try it out. Then if they want to use it they can order their own irons and have them shipped to their home; that way I will get around having to worry about them carrying sharp plane irons around the school.

[george wilson]

Jeez! Schools are so woosy these days! When I was in Alaska,the boys carried sheath knives. No one ever got hurt. I helped a boy make a rifle stock in the mid 60's. no one said,or thought a thing.

[Dave Cav]

I know what you mean. I carried a pocket knife with me every day when I went to school a long time ago. At my school I am almost surprised they haven't made me lock up the chisels; I suspect if the principal knew I had chisels, and how sharp I try to keep them, he WOULD want me to lock them up.

I DO keep the hand planes locked up when not in use, but only because some of them are vintage #4 and 5 Stanley Baileys, and the others are pretty decent Stanley Handyman planes, and I don't want the kids destroying them. Normally I only let 2nd year students use them, and then only for specific jobs. First year kids have to settle for rasps, files and Porter Cable 1/4 sheet sanders, but they are happy enough with those.

[Jeff Wittrock]

It is a shame to see how careful schools have to be now, even with legitimate shop tools and projects, but I can understand the caution.

I still remember one shop project in particular that I made as a kid. That semester, I was reading "A Tale of Two Cities", and so I thought I would be real clever and make a model guillotine. Not a particularly tasteful project, but what would you expect from a 14 year old.

Anyway, it was very small, and not particularly dangerous, so the shop teacher didn't mind. Unfortunately, some of the other kids thought it was a pretty cool idea and started build their own scaled up versions. Some of these were big enough to chop ping pong balls. Luckily the shop teacher had the foresight to put and end to these before any fingers were lost or the Principal saw them.

I imagine as a shop teacher you have to have nerves of steal and the patience of a saint.

Good luck with the planes. I think it is a great idea for a shop project.

-Jeff

[Bruce Haugen]

it's not just elementary and high schools. I have a friend who was a student in CNC machining at a local community college. As a final project in the class, she had to design and build a project, and she chose a folding knife. She was told she could make it but not put an edge on it because that would violate the college's policies on weapons on campus. She is 40 years old, and there were no kids in that class.

[Sam Takeuchi]

It's not the schools that are responsible for over-reactive response for anything with edge. It's the society as a whole became so distant from hand tools of any kind, they are afraid of them. They don't freak out with kitchen knives, because they know what it is for and they use it often. But when it comes to other things, they don't know exactly what they are for and think of the worst things that can be done with them.

Also the problem is, because people became so distant from bladed tools, they don't know how to handle them. And they do dumb things when they get a hold of them. So it further reinforces the idea that these things are dangerous and act like they want to ban the thing from their surroundings, and it goes back to my point above once again. I think it goes back and forth until even toothpicks are banned from schools (I bet there are schools that don't allow students to have scissors already. Just a few more years).

If you think about it, pencils make a good piercing weapon. But no one minds that. When was the last time you heard someone going on a rampage with a plane iron? Or chisels? Even worse...a dovetail saw :D But they mind these things, people get scared if they see someone walking around with these things, because they don't know and don't care to know.

[Richard Magbanua]

I think this is a very litigious society and, as a result, we have learned to become very careful. On a personal level it's probably a good thing 'cause I know I wouldn't trust someone not to sue me for something dumb they've done. But as a whole it makes people paranoid to do things that were normal years ago.

[george wilson]

We were making single shot pistols in college in 1959! I remember when I was in High school,though,the shop teacher used me as a sort of teacher's aide. He had me take apart an 8" blade folding stiletto some kid was found with. That was understandable,as that kind of knife really had but 1 use.

I recall an incident from the 50's where some kid brought a butcher knife from home,and asked the shop teacher to sharpen it. He did. Then,the kid stabbed him with it and killed him.

Those incidents were so few and isolated,you never heard about them. This whole downward slide is because they decided to let lawyers advertise in the 60's,after years of long debate. That's all I'm saying about lawyers.

[Don Orr]

I'm sure I have some old plane blades I could send if it comes to that.

As for weapons in school-the upper level shop class at our school made full size functional CROSSBOWS ! Every year, regularly, no problem. I always carried a pocket knife-still do. Wouldn't feel right without it. Sad commentary on our society that these things have gone the way they have.

Good luck with the plane project Dave. Don't forget to post the results.

[Augusto Orosco]

I like the donation idea and I think your project is great and timely! I don't have any irons to part with, but I would be willing to 'sponsor' one of your students. Once he or she finishes the project I will mail you (or the school, or whatever address you choose) any Hock blade of your choosing.

Just PM me if you are interested.

[george wilson]

I had forgotten to finish my tale of early high school shop doings. We were allowed a great deal of latitude back then,but 2 teachers did get in trouble. One was a printing teacher who wanted to impress upon his students the quality of detail that his photographic equipment could do. He photographed,and made a printing plate of a $5.00 bill,one side only. I don't know how far his punishment went,but the FBI did investigate the shop. Since they printed the school's yearbook,they had high quality equipment there.

The metal shop teacher did get fired. He was gone so much that his students managed to put together a still!! Whenever I had gone there to use a metal lathe,it was always a din. Misbehaving students making torches pop like machine guns,etc.!!

[Brian Kent]

http://ca.news.yahoo.com/s/capress/090917/world/eu_germany_school_attack

[george wilson]

The first major school violence I can remember in any school I was in was in 1964. I was teaching shop in Portsmouth,Va. Just before the first bell rang,the whole school erupted in screaming students running everywhere. Some kid hit another in the head with a pipe. The assistant principle searched everywhere for it. He finally discovered that the hoodlum had put it back in his locker. It was a bloody injury,but no one was killed,at least.