OK, I’ll admit it, I’m just slightly younger than dirt. When I was a student, learning woodworking, one of the first things we were instructed on was the proper way to sharpen our own (steel) blades. This was in the late ’50’s when carbide blades were not commonly found in most shops. This knowlege has come in handy on many occasions while out ‘in the field’ A saw sharpening file is always in my kit of tools.
In order for the blade to fit properly onto the arbor, there has to be a slight bit of play between the arbor and the hole in the blade, otherwise it would be a force fit on some arbors, while being a ‘proper’ fit on others, so all blades have a slightly oversized hole in them.. To ‘compensate’ for this, the blade was always placed on the arbor with the label (name) at the top. This way, the blade ALWAYS dropped down onto the arbor and all jointing and then sharpening was done with this allignment. If the blade was put onto another saw, the allignment (blade to arbor) would be correct and would not have an ecentric motion. or vibration as it turned. I’ve mentioned this to other woodworkers and they have never heard of this proceedure. Has anyone else heard of this, or am I perpetuating a myth from my instructor?? With modern saw sharpening machinery, is this proceedure still followed??
SawdustSteve Long Island, NY (E of NYC)
Replies
hi steve,
in my daily work i use mostly hss saw blades. this is because the district sharpeners will not sharpen carbide. there are two old saws in the shop. the 5hp olly has an 1" arbor and the northfield has an 1 1/8". not trying to argue with you but the blades on both don't seem to have any play in 'em. what's more, most of these blades had any etched labelling worn off long ago, so no reference point. when the tool sharpener mounts his blade for gumming would he not want it perfectly centered? i hope others will also comment, you've got me curious...
eef
Here is some good info on DIY blade sharpening:
http://www.toolcrib.com/blog/2008/07/31/diy-carbide-saw-blade-sharpening-4-blade-sharpening-services/
You might also want to call Scott Whiting and ask him your questions. Also, you can call or e-mail Forrest Saw Blades at: www.forrestblades.com/
I was taught to install the blade label on top as well
SawdustSteve:
In 1969 my high school shop teacher gave the same instruction to us that you received. He went so far as to recommend using a small punch to mark top dead center about an inch up from the arbor hole to use as a permanent reference point. I don't remember him saying anything about the arbor hole intentionally being oversized however. The reason he gave was so that the blade would stay true to the saw as it wore down.
In terms of sharpening a steel blade, I was taught to install the blade backwards on the saw, drop it down below the top of the table, and then slowly raise the running blade until it just kissed the surface of a large oil stone clamped down to the table. I always thought of sharpening tablesaw blades as being more of a honing operation, sort of a maintenance issue. Very little metal was removed. If a blade was nicked or really dull I always sent it out for true sharpening.
gdblake
Interesting...
Hi gd,
I have to admit it's been a LONG time since I saw a steel blade, so I can't remember how my last one was configured. Seems like the sharpening method you describe would only work with flat-ground tops - not ATB or TCG types. Seems like it would work pretty well on the flat ones, though.
I wonder what the lawyers in the recent Ryobi lawsuit would think of this method. On a related note, I wonder if the oil-stone would be conductive enough to trigger a SawStop when the lawyers force all of us to buy one, whether we want it or not.
Mike
We did a lot of crazy stuff back in the day
Mike:
Not every blade design lent itself to being trued up by running the blade reversed on the saw. Rip blades were easy to touch up this way. Many crosscut blades could easily be ruined with this approach to honing. I haven't sharpened by own plane in twenty years.My first carbide blade spoiled me. Once you use a Forrester Woodworker II there's no going back.
gdblake
I'm with you on the carbide
I thought there might be some limitations...
My first official tool was a 12" Craftsman Industrial radial arm saw my dad wasn't using anymore. He had the original steel blade with it and I wasn't patient enough to take it the guy in town that sharpened blades - went right from setup to "gotta try it out". The blade was pretty dull, lots of chipout - I almost thought I could do better with a hand saw.
Not long after that I got my first carbide blade, and haven't even seen the steel blade in about 20 years. Still waiting on my wife to find the Forrester ads I keep leaving around prior to birthday, anniversary, Arbor Day. So far no luck.
Mike
Yes, and Hi-Tech developments
I've heard of setting the blade as you say, although I admit I don't practice it and can't say that I notice any difference in how I place the blade on the arbor.
Just a bit of machine trivia for those who like this stuff-
The Weinig company, who makes top-of-the-line molding machines has developed several innovations on their highspeed units, because the tolerances are much tighter than we are used to working with. After the cutter is locked on the shaft, pressured oil flows through passageways in the arbor and hydraulically tightens the fit uniformly between cutter bore and shaft. On these machines you also have the option of running the head in the opposite direction and sharpening on the spot with an integral sharpening attachment. Makes for perfectly concentric cutters. This is not home shop stuff, but thought someone might be interested...
Not me
Probably not a surprise, but I've never heard of it.
The tolerance, even on my cheepy Delta is quite a good fit (and in addition run out was nil). I wouldn't worry about it.
(so where are all the people who used to bang the bench and say who cares about a thousandth of an inch THIS IS WOOD WORKING after all. . )
We are talking about less than a thousandth here
That being said I will say more :
When the teeth bang into that eight quarter plank of sumpin really great and expensive it is going to shift under that slick washer that is not held all that tight by that nut that one doesn't want to over tighten.
So
IT DOES NOT MATTER
I still sharpen most of my own tools
Like you, I started my carpentry career back when carbide blades were really expensive, and I would sharpen my blade right on the saw during break-time without taking it off of the saw, usually daily. After a lot of sharpening, they would need truing, so I did the jointing without taking the blade off. It really didn't make any difference if the teeth were forward or backwards to that stone.
Follow that by sharpening until the shine was gone. When more set was needed, I did that with a crescent wrench, then touch the same stone to the side while the blade was running, would true that up, and reduce splintering.
Now, the only time that I bother with the careful placement of the blade on the arbor, it on the larger machines, like my radial saw, which has a 16" blade. I have found that by using a dial indicator against the side of the blade, I can usually find a sweet spot which might be .004" better, which makes it a lot quieter when it is spinning.
I suspect that the automatic machines making todays blades probably have a collet type arbor that centers the blade so the teeth are concentric with the arbor hole rather than off by a few thou.
I don't have a new blade, but it would be easy to test your theory by using a dial indicator set to just touch the teeth while spinning backwards by hand, with the blade mounted label up then down. If you don't have a D I, you can send me a new blade and I will test it for you.
Blade lore
Hi Guys... I'd like to close this discussion by saying THANK YOU for the comments. Just like EEF, the saw I REALLY learned to do woodworking on was an ancient Oliver. It took a 14 or 16 inch blade and was a tilting TABLE saw. Since it was 50 plus years ago, I don't remember if it had a sliding table or not. Power was from a HUGE DC motor, the size of a 30 gallon garbage can, laying on its side and turning a 3 or 4 belt wide pulley. It was probably built in the late 30's or early 40's. I guess industrial tolerences have greatly improved over all these years and the placement of the blade on the arbor is not critical any more. It just seems strange that guys will carp about a saw table being .003 out of flat across a 30 inch span, or that they are not getting an absolutely perfect cut from a glue-line blade, yet will 'throw' a blade onto a saw and not worry about concentricity to the shaft, even if they are running dados. I must surmise that SOME processes have got to be perfect while others can be 'whatever' the saw gives them.
As for 'jointing the blade with a stone, yes, it worked on rip blades with a flat top, but on cross-cuts, the light 'kiss' to the stone showed us exactly how far to file the blade to get all the teeth sharp again. Today. if you show up to an event in a Ferrari or a Saleen, guys will be in awe of you. 50 + years ago if you showed up on the jobsite with a carbide blade, you were greeted with the same awe and envy.
SawdustSteve Long Island, NY (E of NYC)
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