Hello All,
A post re: end grain planing discussed, among other things, using magnets when sharpening/honing plane irons. I am developing a plane iron bevel sled for use on the belt sander and sandpaper for shaping/sharpening/honing.
My initial prototype had four 1/2″ rare earth magnets to hold the iron When I shared it on another forum, I got flak for using magnets. I did not get explanations and I did not offer defenses. Further development of the sled includes a clamp but I am still inclined to offer the magnets when this gets marketed. I say this because, as was mentioned in the other post, the metal swarf gets picked up my the magnets. It’s a simple matter to brush them off with a bench brush and keep on truckin’.
Would you please share your opinions?
I have included pics of the original sled and the most recent incarnation. The latest one is made to accomodate a 112 scraper iron at 45*
http://i20.photobucket.com/albums/b202/bacsibob/SharpeningTrolleyBeltSander002.jpg
http://i20.photobucket.com/albums/b202/bacsibob/PlaneIronSled45-1-10-09003.jpg
Please Pray For Our Troops
Semper Fi!
Bob Ross
WalnutAcreWoodworking.com
Replies
Bob, I'm a big rare-earth-magnet fan, but I'm not sure I agree that it's a "simple matter" to brush filings off of one. When I drop one in a pile of sweepings and it's covered with metal debris (hubby grinds things in the shop), it's a PITA to get it cleaned off. In addition to that, the whole mechanism is going to attract filings, not just the magnet.
I'm not clever enough with physics to know for sure what kinds of forces are exerted on the magnets in your application, but what I've noticed in general is that they are much stronger when the pull force is straight up (perpendicular to the attached surface), than if the pull force is exerted at an angle or parallel to the surface. This might influence how effective they'd be.
The magnets on the sled are held flat using magnet cups which are screwed to the angled deck of the sled. I covered the face of the magnets with duct tape (sorry, forgot to mention).
To get metal fillings off loose magnets; I use duct tape here too. Please Pray For Our Troops
Semper Fi!
Bob Ross
WalnutAcreWoodworking.com
Chances are the filings will concentrate themselves near the tip as they tend to move towards the poles of a magnet.However as FG pointed out any filings that get on the magnets are going to do their best to stay there.The holding power is going to depend on friction between the blade and the sled. Essentially the grip has to be excellent, otherwise the blade might move which will rather negate the exercise.
The wheels do wear; I've lost .001" after doing 4 plane irons. They wear evenly so the sled is dropping straight down which does not chage the angle of the iron.
Two 1/2" RE magnets in cups have incredible holding power. The plane irons do not move and must be advanced manually as they are shortened by the sanding/honing action. Please Pray For Our Troops
Semper Fi!
Bob Ross
WalnutAcreWoodworking.com
Bob,
To clean the magnets, use a stronger or larger magnet with a sheet of paper between them. Tap together lightly and the metal will transfer to the stronger magnet. Works for me.
I would like to watch you tap two 1/2" rare earth magnets together lightly! Those babies have some serious pull.
................................................
Men will never be free until the last king is strangled with the entrails of the last priest.~ Denis Diderot
You tap the edge of one on the flat surface of the other.
>serious pull.That was what was going through my mind when I read that !nice Personal Quote you have by the way:
You can't wait for inspiration. You have to go after it with a club.
>wheels do wear; I've lost .001" after doing 4 plane irons. They wear evenly so the sled is dropping straight down I don' see how they can all four wear evenly. Please note if all four wheels are touching with equal load then the blade is not touching the belt. (for long anyway) If the blade is contacting the belt with enough projection to remove metal to correct the dull blade then the two wheels closest to the blade are un loaded and the rear wheels have more load so they will be sanded more than the front wheels.Maybe I am over thinking this and in practice this does not matter. The wheels nearest the blade may still be in contact and turning because of slop in the axle to wheel hole interface.I personally don't care for any sharpening gig that does not allow for radiusing the blade edge. Even blades for finish planes need a bit.And finally if I am going to use a power tool to grind a blade then I might as well hollow grind so the blade can be honed without a jig as so many here recommend. So I would be working at the round end of the belt sander or on a grinder wheel.And finally finally I don't buy it that this will run cool enough not to remove hardness from the blade right at the last fraction of a millimeter of steel near the edge which is the only part of the blade that really needs to be hard.If power grinding a blade then white grind stone is best/coolest. Preferably with water which I have and do not like so I just use a Veritas jig and a diamond plate.After my big old diatribe it just occured to me that maybe you do not turn on the sander but use it as a quick source of fixed sandpaper so would not heat blade.Which brings up another question; do you then go to a stone to hone the blade ? If so this jig is too long and would be falling off the end of the stone.just my train of thought for what it is worthroc who gets way too carried away with sharpening his blades but it is legal and cheeper than crack.
And finally finally I don't buy it that this will run cool enough not to remove hardness from the blade right at the last fraction of a millimeter of steel near the edge which is the only part of the blade that really needs to be hard.
Hi roc
I agree with all your comments bar this one.
Grinding on a belt sander is far superior to grinding on a dry grinder for speed and coolness. Of course the flat section will not produce a hollow grind, but the wheel end could be set up to do so.
Most belt sanders (such as mine, illustrated above earlier on) run at half the speed of a dry grinder. Mine runs at 1400 rpm. Faster than this and you would burn wood (never mind steel). The length and width of the belt absorbs and dissipates the heat. I have re-ground thick plane blades from wo-to-go without affecting the hardness.
The rule is, as with a dry grinder, the coarser the grit, the cooler the grind. I use 80 grit belts to create a primary bevel for BU plane blades. I have used 60 grit, but found that these did not necessarily grind any faster and left very deep scratches.
I have, in fact, used the belt sander as a complete grinder-sharpener. I have belts that hone steel to 2000 grit/1 micron, then use the disk sander as a powered strop (leather disk with green rouge - .5 micron), and the result is frighteningly sharp! But the down side is that that the process is a pain in the wotsit as you need to change several belts.
Overall the idea of a grinder-through-sharpener has merit. The OP deserves a pat on the back for his efforts.
Regards from Perth
Derek
Hello Derek,I have been mulling. While i got a hair cut. I am used to metal working belt sanders and finer grit that does heat things up a bit. Sorry to be ignorant on the wood working sander.I didn't have anything intelligent to say so did not respond. I wanted to ask then "can you hold your finger on the end of the blade while it is being sanded with 80 grit ?But besides that question I feel I now have something to contribute. Perhaps you have tried it already. Can you take say three inch wide sections of belt in various grits and slide them all onto the machine next to each other and so have your grits without dismantling to change grits ? Could brush or dress to get rid of last loosened grit.It would be nice to be able to sharpen this way.I should go back and read the articles but it looks like in the pics that you do not run the blade backs on the running belt. Do you always flatten backs on a long strip of the blue grit stationary only. Do I have this right or can you flatten backs on the running belt with 80 grit?
Edited 1/15/2009 5:47 pm by roc
Let me preface this stating that I don’t use sharpening jigs since I do it freehand. That said I think the magnets would be a fine idea. One question is how do you keep those wheels from getting worn down by the belt sander? Even with them rolling the belt will take off metal and change the alignment.
Hi Bob
I was one to respond on WoodNet, but not in regard to the use of magnets, rather a query in regard to blade angles.
On magnets, I consider a magnetised blade very undesirable. Trying to wipe swarf off a affected blade is a bugger. In a recent thread here, an article of mine was praised for the use of a magnet to aid in flattening the back of a blade. The difference is that that particular magnet was switchable and did not appear to magnetise the blades it came into contact with. Have you experienced much in the way your blades becoming magnetised? Of course a clamp would circumvent all this.
On design, I see a few flaws in your sled.
The first is that it runs on 4 wheels. Wear will develope and it will develope unevenly, which means that the blade will no longer be presented evenly/squarely to the belt. It will wear unevenly simply from downward hand pressure. Even if you reduced the wheels to 2, you would have the same problem.
The second is that I assume that your design requires that the blade be movable forwards to keep grinding. Hence the magnets? Or does it work some other way? If the blade is locked at an angle, and the blade is immovable, I cannot imagine how else it can work. An alternative to a magnet is a clamp+slide. This is not really viable because there is the danger of the blade lifting up as you adjust its projection (on a moving belt).
A third is that a potential buyer will want more range in their guide, that is, variable angles.
A fourth comment is that the use of a belt sander in the manner you envisage is - frankly - scary! I know as I have used a belt sander to grind (in a less scary fashion) for some years (FWW mag even published my guide for this) ...
Mk II
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And holder ..
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This type of jig provides a great deal of support for the blade as the belt moves. In fact I recommend that you grind into the turning belt as, in a similar way to a dry grinder, it will pull the bevel down. This is user friendly, and I know as I have feedback from many that have copied it.
The bevel angle is set by blade projection, but importantly with your jig in mind, the blade pivots over the bar (ala Tormek) and the grind is always going to be even (or adjustable to be even).
A better design (in my opinion) for running on a belt sander is one I came up with a few years ago (but I am sure is not original - what is?), and this uses the Eclipse honing guide ..
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If there is wear to the wheel - and there will be, even if it is small - then the single wheel will spread the wear evenly. A 3-point contact is also more controllable that your 6-point. Still, as I said earlier, this is not a method for the faint-hearted. You need to find a way to remove this issue from the equation.
Regards from Perth
Derek
Edited 1/14/2009 7:51 pm ET by derekcohen
Derek,
I don't like that use of an Eclipse type guide at all. It would be far better to rest the chisel on that cross bar or even to rig a suitable tool rest across that sander-if one had to use a sander.The grinding angle for chisels is not crucial so anyone can easily eye gauge the angle and compare it with a known 25 degree or whatever.
In fact, it is better to have any tool registered on a fixed guide, rather than a moving guide, especially one with wheel(s) that run on the abrasive. Apart from anything else the little wheel(s) would be moving at a hellish speed...
I think that many people have trouble with grinding because they hand hold everything too rigidly- assuming the right stone/means to grind are present it is a gentle touch which succeeds.Philip Marcou
Hi Philip
My use of the Eclipse here was not meant to indicate support for this method. I was just illustrating a different method of the sharpening idea originally presented. As I said earlier, it is a scary procedure. I do not recommend it in this format.
The reason I came up with the Eclipse for grinding - and it does work very satisfactorally, scariness aside - was some experimentation I was doing on creating a system that could take one from grinding through sharpening without having to reset the blade in the jig. For example, running the blade on the belt sander to grind a primary bevel, then continuing directly onto sandpaper or waterstones. All current systems require separate grinding and sharpening processes.
A friend brought in 8 derelict and cheap block and bench planes with an even more derelict blades. He wanted to tune them up for a woodworking class he ran. I used the belt sander to flatten each plane's sole (120 grit and 240 grit belts). This only required about 60 seconds per plane. The blades were too much work to flatten, so I ran the primary bevels on the Eclipse-and-belt-sander (25 degrees), then took the blade-and-Eclipse directly to 600 grit sand paper and honed a microbevel (26 degrees), and finished this on green rouge on MDF (still in the Eclipse). The blade was finished with the Ruler Trick (micro back bevel) to circumvent the unflat backs. The honing took about 1 minute for each blade.
All the block planes worked very well at the end. I did spent extra time adjusting and tuning the bench planes.
This is documented in part here.
Regards from Perth
Derek
one guestion , where is that sucker going to go if it slips out of your hand , also I'm with forest girl , magnets are a pain to clean and re magnets are prone to breaking if you "tap "them together
Thanks for all the responses. I guess the "dirty" magnets are out..lol.
I don't plan to use the sled on the belt sander every time I want to sharpen or hone. I'm collecting a set of type 11 Baileys and a few of them arrived with badly configured irons. I have not learned the finer points of grinder use.
My thinking about the four wheels started when I noticed that one of my chisel bevels looked curved (convex). I though it was a trick of the light until I thought about it. I have been using either an Eclipse or General honing jig. I do not believe either of these capable of delivering a flat bevel surface. As metal is removed, the subject is shortened. The single pivot point of the jig will cause the shorter subject to address the sharpening media at a different angle. As the shortening continues, the angle change continues.
As has been mentioned, theory and practical application are often at odds. I appreciate the comments.
Oh, the sled as shown is intended for use with sandpaper sharpening/honing. I intend to provide a model that straddles stones.Please Pray For Our Troops
Semper Fi!
Bob Ross
WalnutAcreWoodworking.com
Bob,My feeling with your jig and other honing guides is that they do only the simple easy tools and they cause one to focus on the bevel. The bevel is the easy part, accurately flattening the face or back of a plane iron or chisel is where the difficulty lies and probably the source of almost all the problems in sharpening. I don't think the woodworking world needs another tinker-toy, if you want to contribute something find a fast accurate way to flatten. I'm looking for something quick and that I can easily repeat on well maintained stones when I hone. You should only need to flatten tools that are new to you, after that it's merely a touch-up on the stones each honing to take care of wear at the edge.
>model that straddles stones.OK I am going to use " THE PHRASE "Nah dude nahthey are out there and not much use see :Sharpening Sled SS1 and the Pinnacle Honing Guidehttp://www.taunton.com/finewoodworking/ToolGuide/ToolGuideProduct.aspx?id=25689http://www.woodcraft.com/family.aspx?familyid=20080&ProductID=147763are already out there and I must say are fraught with problemsassuming one uses it with a stone it seems infinitely tedious to try to compensate for stones that are not only of vastly different thicknesses but they are not evenly "thicknessed". It is highly unlikely the two faces of the stone will remain parallel over the life of the stone.I loved to look at the Pinnacle when it came out ! I admit to being drawn in. It is just when the old brain starts evaluating it that things get, as brit dudes say, dodgy. And the tracks. Stuff is bound to get on the tracks and the little rollers are going to be bump bumping over that or else clean the guide and the stone every grit change. This is even too much for me and I enjoy a bit of dinking with sharpening stuff. OK allot of dinking with sharpening stuff.It stops cutting and one presses harder and the rails sag and now we have the edge rounding going on in two directions !If rollers on the table surface you are sharpening on then it must be clean and flat besides how to compensate for stone irregularities.Nope nope.>Eclipse or General honing jig. I do not believe either of these capable of delivering a flat bevel surface. As metal is removed, the subject is shortened. The single pivot point of the jig will cause the shorter subject to address the sharpening media at a different angle. As the shortening continues, the angle change continues.In practice once one has removed the wear and achieved a wire edge this is not a problem. One can change to a micro bevel and then the angle change is so minute as to be irrelevant. I have not measured it but my experience tells me it must be on the order of a few minutes of a degree.Interesting thought though. I had never heard why in the world one would bother with four wheels until now. Makes the free hand/hollow grind method more and more attractive. My problem with that is when one gets into the steep sharpening angles, say 47°, it is too easy to "stub your toe" and round over the edge if it catches on the stone a bit. Skew it I know. Awkward. With the guides I can run back and forth faster and get a bit mindless about it. Free hand takes more attention and cramps up the fingers if I have six or so blades to sharpen in a session.Free hand sharpening and using hand scrapers all in one day could put a guy in the hospital with paws that don't work. : )Still . . . I am going to ponder that at bit.On a microscopic level the trick is not so much a flat bevel as it is adequate clearance behind the blade for surface penetration. Set angle for MORE THAN ENOUGH clearance on the initial wear removal then ENOUGH clearance on the final two extra fine grits with light pressure. Hardly any material is removed; just from nearly invisible scratches to the bottom of invisible scratches. This can not change the angle much.>As metal is removed, the subject is shortened.You may be removing more metal than needed to remove the wear area. I know I was in the beginning.keep up the brain work though who knows where it all will end up.Edited 1/15/2009 3:11 pm by roc
Edited 1/15/2009 3:14 pm by roc
roc,
Maybe I can help with the scrapers...lol
http://i20.photobucket.com/albums/b202/bacsibob/CardScraperSled-1-13-09004.jpg Please Pray For Our Troops
Semper Fi!
Bob Ross
WalnutAcreWoodworking.com
Friends,
As I perused this thread, I came up with yet another way to make millions in woodworking. The others have not panned out, but this one will.I remember when I was growing up, there were lots of ads for a book entitled something like "How to pick up girls". I'll bet the guy who wrote that book made a lot of money. I am planning to write a book for woodworkers entitled something like,
"How to make millions by designing and making sharpening jigs".Part of my advice will be to purposely fail to do a lot of testing of your sharpening jig. The sooner people get sick of it, the sooner you will be able to come out with "Mark II".One thing is true in woodworking: woodworkers will always be looking for the easy way to sharpen things without learning any sharpening skills. THE DREAM WILL NOT DIE! I believe I will sell my book "How to make millions by designing and making sharpening jigs" for only $1.95 plus the usual $20 for shipping and handling. I am hoping that within six months of publication of my book, I will be able to afford a few of Philip's planes.The first 1000 people who order my book will get it FREE. You only need to send the $20 for shipping and handling. I was thinking of writing a book called "how to make millions by making sharpening jigs and also to be 100% successful with women, and how to predict weather using only a forked stick.", but it would take too long to write that book -- the weather prediction stuff is quite difficult.Have fun.
Mel
Measure your output in smiles per board foot.
>help with the scrapers<NOW THAT looks useful !roc
If you'd be willing to test/review it for me, I'll send you one.
If you use a stone after filing, let me know what the height of the frame and the width of the wheels need to be to clear.
Email your name and address and I'll get it out tomorrow.
Please Pray For Our Troops
Semper Fi!
Bob Ross
WalnutAcreWoodworking.com
Bob,
All these problems of metal filings are going to go away once we get away from the use of steel in our blades.
MelMeasure your output in smiles per board foot.
FWIW, I never said I had a problem with the metal filings. It was the spoutings of the pros and experts that made me curious. They offered opinions and comment without explaining why. I thought maybe a magnetized plane iron would reverse tough wood grain or something.
Hmmmm, I wonder what kind of edge I can get on a rare earth magnet.Please Pray For Our Troops
Semper Fi!
Bob Ross
WalnutAcreWoodworking.com
Bob - Well, from a marketing perspective, there are lots and lots of WWs out there that continue to buy power sharpening systems and new sharpening jigs, so potentially you could sell quite a few.
But I would leave the magnets out. While a clever idea to prevent the slipping/skewing that seems to happen with clamp-type jigs, magnetized tools in the shop is a major PITA, and de-magnetizing them is also a PITA.
What i think you might find more marketable (to give you a "hook") is a micro-advance gizmo with your jig. Not only will it make it more functional, it's also fairly unique. One of the more annoying things about sharpening jigs, and why I do it freehand, is getting the projection set correctly. Generally, this is a process of setting a square on the side of the blade/chisel, pushing the blade up to the right projection, then tightening two screws to lock it down. All of this can be managed with 2 hands, but 4 would be better. Since that sort of genetic engineering is a fair number of years away, you should be able to sell a few sharpening jigs in the meantime.
Thank you for the encouraging words.
I've come up with a couple work-arounds for the magnets and I agree about the micro advance. It's on my list of things to do.Please Pray For Our Troops
Semper Fi!
Bob Ross
WalnutAcreWoodworking.com
http://i20.photobucket.com/albums/b202/bacsibob/PlaneIronSledwAdjuster-1-17-09.jpgPlease Pray For Our Troops
Semper Fi!
Bob Ross
WalnutAcreWoodworking.com
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