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Thread: Forming chisel side bevels.

  1. #16
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    Quote Originally Posted by Tom M King View Post
    Thanks. I've been wondering about that "stone".
    Tom; you may find the following of interest by Stu. http://www.toolsfromjapan.com/wordpress/?p=564

  2. #17
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    Stewie; apologies if you already knew this but thermal cycles give your chisel the best chance of avoiding any sever warps and be left with some nice fine grain. There is no way of knowing whats in that vintage steel without going to a lab (at least to the extent of my knowledge) but treating it like a fairly simple steel (1095) seems logical. Normalize 3 times at 1400-1500F is pretty much all you need; there is no point worrying about finer temperature margins or a more varied heat range when we are only working off the hypothesis this steel is 1095 like. If the steel does warp (with the fact that it'll need a quench while having those side bevels and a bevel at the tip I'm certain it'll warp at least a little) then its not the end of the world.

    IMG_1627.jpg
    That shiny shim is an old old router plane blade.

    here's a chisel I made and did some unspeakable experiments on during HT, it came out bowed pretty severely (back of chisel way out, convex) so after a first snap temper I brought out the clamp and shim, did some eyeing, clamp so its flexed the opposite way of the warp. You want to have it go past straight a little, and then toss it in your oven for a full temper cycle. I quench when the time is up by just dropping the whole apparatus in a sink full of water; there is no phase change here happening so the steel isn't going to crack or warp or do anything unless there was a crack in the first place. Many knife makers quench in between temper cycles; its not a magic thing you need to do just something you can do to save time instead of waiting for your stuff to air cool and in this case save a lot since theres a lot of warm metal in this apparatus. There's also a metallurgical aspect but it's not very relevant considering our lack of knowledge of the steel and the what I assume is going to be a quick HT set up with a propane torch of sorts. It's not really too important even if we did, it's a hairsplitting difference. Important thing is it's not going to harm your chisel (unless it has a fatal crack anyways which would fracture during use).

    Anyways it'll come out quite different, maybe even bowed a little the opposite way. You can chase it to near flat a few times, don't worry about a few extra temper cycles.

    You will be surprised at what you can do with hardened steel, this is 1/4" stuff hardened all the way up the tang and it'll handle a little flex just fine. The clamp holds the flex and then the heat sets the flex albeit there is a little bit of springback.

    I've done this straightening method a fair number of times now. It is important that whatever the shim and piece is sitting on won't flex or flex too much when being clamped. I've used a pizza pan before.

    IMG_9872.jpg
    IMG_9889.jpg
    The first knife I made; had a slight warp which was corrected with the help of a pizza pan. the rim of the pan acted as a shim.



    IMG_1628.jpg

    Having the chisel bowed so that it presents as slightly concave on the back side is probably the easier way to go. Especially if you want a chisel thats flat the whole way. This was 30 seconds of work after my final temper.

    Btw Stewie, I don't think you'll like the Big black brick from Stu for flattening an entire chisel's back, water stones go out of flat and then you having to lap it every couple minutes with silicone carbide is just a hassle. I realize that Sigma engineered it to stay flatter than other coarse stones but as soon as its a little out of flat that only gets magnified onto your chisels. Your chisel will look flat and when move on to finer grits you start realizing it really isn't. If the stone is releasing particles then its going out of flat, and if its not then its glazed and not cutting anywhere near what it should be. Nature of the beast I guess. You'll like it for doing your Paul Sellers bevel and fixing nicks and stuff. I could be dead wrong though.

    Apologies for the low res, I use an ancient iPad and iPhone. I assure you my very ill mind made sure this chisel was lapped to absolutely micro scratch free, none of those fine lines that come apparent at any other angles that is the usual standard for mirror polish. Of course in actual use I immediately scratched it up when sharpening on natural stones.
    IMG_1637.jpg

    Best of luck with your endeavours.

    Vince

  3. #18
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    Vince; appreciate the quality of advice you have offered within your post. Can you some further comment on the differences between normalizing and annealing the steel.

    regards Stewie;

  4. #19
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    Quote Originally Posted by Stewie Simpson View Post
    Vince; appreciate the quality of advice you have offered within your post. Can you some further comment on the differences between normalizing and annealing the steel.

    regards Stewie;
    Stewie; For our purposes with making cutting tools:
    annealing is making the steel nice and soft so we can file it etc. There are a few ways to go about this but heating up the steel to a specific temp and then letting it cool slowly (stick it in some ash, vermiculite) is the oldest and is what i what have done in your situation with this unknown steel. A Sub critical anneal would’ve been suitable too but perhaps too hard to do without a proper setup.

    Normalizing: heat to a specific temp, hold it for just a little while and let air cool in still air. This is repeated a varying amount of times but a triple cycle is pretty safe. Often the temp to reach is lowered each time. This allows for even and fine grain to be achieved. It also removes as much stress as possible. Technically normalizing is a form of an annealing process but in the knife making world and ours a big distinction is made because annealing as described above in the first paragraph forms coarser grain with carbon clumped together; unsuitable for fine edges, not the best prep for a quench either (by itself). Great for being machined. Fully spheroidized anneal is the softest and easiest state of steel to machine. The sub critical anneal somewhat circumvents this annealing = not even and large grain problem. Normalizing preps the grain to be the best it can. A huge factor in warp prevention. Many steels when normalized can be worked pretty alright without having to be annealed.

    The reason I would bother with normalizing with this chisel is because I don’t know what sort of annealing has taken place but if it’s gone from hardened to soft with an annealing of sorts then I would take the time to form new fine and even grain (important to prevent chipping and general problems) and erase any sort of uneven cooling stress or other uneven formation problems from haunting me after the quench. Yikes, run on sentence much.

    Theres a lot I’ve left out which other well more informed members here might frown upon or add on to but I think keeping it simple is a good way to ease one self into this world. There are many different problems that present with different steels and situations, many of which I am not familiar with. I have no professional training in this field (or any field yet) I just read and make some crap so take this writeup at your own risk.

    Vince

  5. #20
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    Vince; appreciate the additional information.

    I am somewhat limited by the single heat torch I have available in my workshop. The following shows the colour change when annealing, The steel is then left to a slow air cool.


  6. #21
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    Stewie, a couple firebricks and some mods to that torch and you could get a good even heat treating forge going. Look around on the web to see if there are any weed burners near you on the cheap, like 10-20$. I wouldn’t pay more than that since I could make a forge burner with 25$.

    Are you heating the steel to a blue temper like in the picture and then filing it? Or is the colour a by product of coming down from critical temp. If it’s the first then that certainly works for the shaping and is similar in theory to a sub critical anneal (though a SC anneal would still be preferable) but it definitely needs a thermal cycling to not have the previous hardened state mess with the attempt at the rehardening.

    Can you get the chisel to critical temps with that torch? I am sure it is more than fine for marking knife blade sized pieces but for a chisel even a more suitable torch head in a well made paint can sized forge would struggle getting an even heat along the length of the chisel. The thickness and length of pieces like this is good reason to make your own small forge burner. I just can’t see anything but a tiny bit of the chisel tip getting to critical temp with that torch as it is without a forge like enclosure.

    It’s a slippery slope that’s for sure, there is immense fun in making blades and tools. At least for me.

  7. #22
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    Vince; I am heating the steel to a blue temper as seen within the photo, before filing.

  8. #23
    Based on my own experience/trouble with re-hardening chisels....

    Do one all the way through start to finish and test it out on wood before you do a second one. This includes annealing and working the side bevels... And if you do like the results - I recommend you do them one at a time start to finish to avoid running into doing the same wrong thing to a whole batch of them....

    You may like the results, you may not... You may decide it's way too much trouble because they do warp and it's a lot of work to re-flatten them... And some come out very chippy compared to the toughness of a factory chisel... Or sometimes inexplicably softer... Or you may decide you really aren't satisfied with how it works on wood compared to unmodified versions.... And you want to know this before you ruin a whole set of chisels....

    Or you may love them...

    I ended up with a big stack of steel bananas from my rehardening experiments... And in general - a quality factory chisel outperformed the ones I rehardened.... Generally mine came out much more chippy than theirs and I still don't really understand why... I ended up scrapping the majority of the chisels I rehardened after I have used them more.

  9. #24
    A comment.... "Blue" like that is around 550-600 degrees F. That's more what's considsidered "Drawing the temper" rather than proper "Annealing".

    This is actually not all that bad... Though I would stop at brown or purple/black rather than going to blue.... I would just try them out after you are done (without further rehardening) to see how you like them... You will likely find that they work just fine - this degree of tempering is well within the range of what you are likely to receive with current modern wood chisel production - assuming something like O1 or W1 steel you would get 58-60 Rc....

    And ironically - with my Aldi chisel experiment - an hour at 475F actually left them with an edge that held up better than factory.... So sometimes, it's worth the experiment...
    Last edited by John C Cox; 07-10-2018 at 9:57 AM.

  10. #25
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    Vincent Tai - how do you flatten/sharpen the backs of your chisels?
    AKA - "The human termite"

  11. #26
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    Quote Originally Posted by Chuck Nickerson View Post
    Vincent Tai - how do you flatten/sharpen the backs of your chisels?
    I use a few different methods.

    If the chisels are flat but the surface quality needs to be addressed then water-stones can be suitable. I avoid using water stones to flatten.

    If the tools need flattening then 80-180 grit PSA (to start with) on a surface plate or if its really in bad shape then PSA paper on a longer piece of float glass. I prefer to start with 180grit. I move up through each next grit and go up to 2500 sandpaper. I spend plenty of time on each sheet of paper, exponentially more time on the finer grits and I replace the paper a few times. This is not really at all necessary but I like things micro scratch free for at least one stage in its life. A good foundation from every stage means I can get a pretty darn near perfect mirror off of 2500 grit. It becomes important to spend more time on the 1500+ grits to let the grit break down quite a bit and contribute to a finer finish.

    a mirror full length is really only possible with a chisel that you've made or has the tang out of the way, or the finely lapped ones for Veritas. This process I've describe I use far more on plane blades then chisels.

    Another alternative is using lapping film but this can be costly but it is easier to get that micro scratch free finish this way. With some of the crazy fine films and a delicate balance of pressure and strokes A noticeably "better" finish can be obtained.

    All this polishing is fun but flat is paramount so all these abrasives are on known flat surfaces and I am careful not to lap in a bow or twist or let a twist or bow continue.

    these methods can easily be modified for any level of polish you desire. My affinity to a scratch free finish is not something you need. Many if not most WWs would regard the time spent as a waste and it arguably is. But knives have long been constantly brought to high levels of finish and it is not that much work to do the same with some woodworking tools.
    Funny thing is I have no problem muddying up a mirror polish by honing on natural stones.

  12. #27
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    The task of modifying the firmer chisels to bevel edge chisels has been completed. After the initial annealing process, the steel maintained more than adequate hardness not to proceed further with later heat treatment. (Thanks to John C. for that advise.) Likewise to Vincent Tai. on his advise to stick to flat surface sanding when flattening the full length of backs. ( 120, 220, and finished on 400g). The front bevels were honed up to 13000g.

    Stewie;



    Last edited by Stewie Simpson; 07-21-2018 at 11:44 PM.

  13. #28
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    Great work Stewie. Hey, I actually picked up one of those Simonds files and it turns out that there's close to an eighth of an inch bow in the center. Can I still use the file for this purpose (obviously using the convex side to form the bevels)? Thanks.
    "The reward of a thing well done is having done it." - Ralph Waldo Emerson

  14. #29
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    John; the 1/8" bow shouldnt cause you any major problems when forming the side bevels. If you are going to include flattening the full length of backs, then complete that task prior to shaping the side bevels.

    Stewie;

  15. #30
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    Nice work Stewie. Looks like a "daily user" or "first grabbed" set of keeper chisels.
    David

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