Recently decided I needed to know more about sharpening my tools (more would be easy as I learned I didn’t know squat). So I bought Leonard Lee’s Fine Woodworking Book “The Complete Guide to Sharpening”, I read the Fine Woodworking Artilcle written by Jefferson Kolle, and I was horrified at the price of the water cooled Tormex variable speed grinder. Well in NONE of these sources (and several more I have not mentioned, they don’t give a hint at how to use a electrical bench grinder – these things are high speed and can quickly take the temper off of most any thing one wishes to sharpen. Shouldn’t a bench grinder be running much slower to properly sharpen a plane’s knife or a chisel? That is, not to sharpen, but to shape the tools cutting edge preliminary to final sharpening on a stone, sandpaper, whatever??? Am I wrong here that the speed needs to be cut back alot, OR is this a matter of operator responsibility to know enough to use a slow hand and to make sure the heat build up in the tool is carefully controlled by extreme care?
I am perfectly willing to be told to do my sharpening by hand (stone, sandpaper, etc) but I have then so fouled up that they truely do need correcting (getting the cutting edge straight, the nicks out, etc. I have a very small grinder wheel on a WEN water cooled grinder, but Leonard Lee says these things are just too small and put to much of a sharp concavity to the chisel that it weakens the cutting edge so it can’t hold a edge for long.
In short —– HELP for some you guys/gals who know a whole lot more about this than I. (I understand I can put a rheostat on my SEARS bench grinder if it has removeable brushes – havn’t checked the brushes status yet, but can anyone venture an opinion on the accuracy of this statement – the statement about being able to adjust motor speed if the motor has brushes.) Thanks a bunch. (Really, any other ideas on sharpening my tools would be appreciated.)
Replies
Geezee peezee, JB. Do you mean that you burned the edges blue on all you chisels and plane irons? Let's hope not. When I use a bench grinder ( which I really don't much do unless I'm hogging metal off a new tool I've just been forging) I keep a can of water beside the grinder and dip the edge tool in...OFTEN. That helps control the temp so the steel isn't burned.
If you have reached the point where you have to do some major grinding on your edge tools before you start hand sharpening you might try using your belt grinder. I clamp my BG by the handle between the jaws of a wooden clamp. Close the switch and take care not to crush the switch lock button. I clamp the thing to the bench and use a normally open foot switch to turn it on and off. The BS will move metal fairly quickly without heating the steel. When in doubt, quench. Yes, and be a doubter.
This is not an ideal setup, but ya run whatcha brung, right? If you have the belt grinder it will help get you there.
BJ
JB,
Yes, you're better off using a larger diameter wheel for grinding chisels, plane irons and such. More steel will be left "behind" the cutting edge for the needed support. As for using a "speed dial" on your grinder, you should be ok, if it's not a "soft start" motor.
JB,
Under the catagory of other ideas...
I have a professional sharpen my blades maybe once a year and then I do the honing the rest of the time. Having the professional do it provides a nice benchmark for sharpness as well as an outstanding foundation for honing. I hone frequently with stroping and compound... and when necessary backing up to 1000 grit and 4000 grit waterstones....they seem to be getting sharper and sharper...which tells me my free hand techniques are getting better too.
Hand chisels I'm less concerned with...if they are a little less sharp no big deal. Scary sharp and honing keeps them fine. I only use the grinder for turning tools....there its different because your shooting for a specific profile...
Here's a link: http://www.planemaker.com/articles/grinding2.html
I have to tell you I disagree with some of what Leonard Lee has in his sharpening book.
Larry
The edge should be established with the edge pointing directly toward the arbor.
Looking at the small picture with these tired eyes, I cannot see exactly what is meant. It looks as thought the edge is skewed sitting on the rest? Is this correct and can you elobarate a little so I can pick up this technique. I understand about the second stage, but the initial edge kind of lost me. I also understand and agree about the heat less likely to build after the edge is established.
I'm just confused (dumb) about how you got the initial edge. I don't like to assume anything with pricey irons or chisels at stake.
Thanks...
sarge..jtProud member of the : "I Rocked With ToolDoc Club" .... :>)
Sarge,
Grind like you're trying to flatten the end of the chisel. This removes any damage, straightens what will be the future edge and gives you a clean starting point. If you try to do these by grinding the bevel, you'll end up over-heating the edge. After you have a crisp starting point then bring the bevel to it.
This is only necessary when you're first tuning up the tool, there's been some damage, or you're changing the bevel angle. If you do this every time you grind, you'll end up shorting the tool life because of the amount of steel you use each time.
The Tormek is great except it's real s-l-o-o-o-w. I could sharpen a whole set of chisels in the time it takes to do one on the Tormek. I teach a few hours a week at a local high school and they have an 8" 1800 rpm grinder with a fine white wheel. I hate that sucker and can't use it without over-heating tools. I finally took in an old grinder I had and just give it to them so I could sharpen their tools. I can grind all day on a real grinder with a properly dressed coarse wheel and never damage a tool.
Larry
Thanks.. I understand the point now with that explanation. I have to agree about the using a regular grinder. I don't or haven't used a slow speed, but a good 8" has always got the job done. I dress the wheels with a daimond wheel dresser. I take my time and let it cool on a cast iron top to help dissapate the heat if it even gets warm in my hand. I don't get in a hurry as I set aside time for sharpening each week. One of the advantages of being a hobbyiest. I think burning on a regular grinder is due to being to aggressive or impatience.
I ocassionally use a 1" belt sander to round over corners on smoothing irons or the bevel-face contact point on mortice chisels. Just a light touch gets in done quickly.
Thanks again...
sarge..jtProud member of the : "I Rocked With ToolDoc Club" .... :>)
A flat diamond 'stone' (more exactly a flat steel plate impregnated with diamond grit) in course grit will do the initital grinding pretty quick. You will need to make a holder for the stone and a jig to hold the blade being sharpened. DMT is one company that makes these. Expect to use lots of 'elbow' grease.
When using a bench grinder type stone, I find that 100 surface inches per second is about as fast as you can go with a dry grey stone. 2x faster if the stone is wet. Those speeds would equate to about 250 RPM / 500 RPM for an 8" diameter stone. You can go faster with white stones. Anything less than 8" diameter will put a radius on the surface that might be greater than desired. 10" diameter stones might be more desirable, but rpm's must be dropped accordingly.
The combination of a slow speed circular stone for the initial grinding and the 'scary sharp' sandpaper method for the final honing is hard to beat.
Instead of doing the initial grinding yourself, you can always send your blades out to a commercial sharpening service. MVP Sharpeners here in Houston does mail order sharpening and are very good. They're presently moving north up to Cypress TX. They will charge more to straignten out the edge on severely mangled blades. For the price of one Tormex system and all the attachments, you probably could send out more than 100 blades to a sharpening service.
PlaneWood by Mike_in_Katy (maker of fine sawdust!)
PlaneWood
Thanks so much for ya'lls input. I am not on many forums, but the folks, by dent of their comments, on the Taunton press forums (Knots and Breaktime) certainly are the most thoughtful, well spoken, and knowleable of any that I see. I am sure there are exceptions - but I really havn't seen any. Again, thank you.
I use a $49.00 6" Delta import grinder and it is a high speed model. Just make a new tool rest out of 1/2" conduit at the center line and go slow, the white wheels also help a lot. The hollow grind is just right, then you only hone the edge.
JB, Deep six that Wen! You are embarassing all of us.
Get a 6" bench grinder and get a recessed or cup wheel That way you can sharpen on the outside edge, which presents a flat surface.
Also a deep can of water to drop the chisels in. Another adjunct, is a permanent magic marker (blue) or a can of Dykem Blue spray. By 'Bluing' around the area needing dressing, you, (with a square,) can scribe a reference line perpendicular to the iron and dress up the tool using the line as a guage so as not to remove more material than is needed.
The 'Trick' to good sharpening, is to keep the tool always moving side to side on the wheel to remove equal amounts of material. Also, by moving it a bit beyond the wheel's edge while moving side to side, the wheel will wear evenly and not develop a 'Rut'After you master this 'drill' I'll show you how to dress the wheel when it's worn or 'glazed' Stein.
Another tip, sharpen a few chisels at a session, so when #1 gets hot you can drop it in the water and work on #2 and 3, 4, 5, etc, etc. G'Luck ED.
Edited 12/1/2003 12:02:19 PM ET by steinmetz
Edited 12/1/2003 12:08:40 PM ET by steinmetz
I'm a strong advocate of wet grinding as being the best sharpening system around. You can use a dry wheel and keep a can of water nearby but I have never been a fan of this system. A cutting edge is only a few microns thick and it doesn't take much friction to heat up the edge and remove its temper. The Tormek machine is very expensive but a more econmomical alternative is the Delta wet grinder model 23-710, http://www.deltawoodworking.com/index.asp?e=136&p=844
I've worked with it a lot and I love the results. You can make a nice hollow grind on chisels or plane irons and finish up on a water stone with an angle jig, the veritas model works nicely. I even use it on carving gouges. I would not recommend the Delta model 23-710 horizontal wheel wet grinder, you have no control on the tool and it is complicated to true the wheel surface once it gets worn. I occasionally use a dry wheel grinder to remove bad nicks on a tool edge but I try to avoid it. I read in an article on sharpening that it is better to put more pressure on the tool and grind for a short amount of time (1-2 seconds) than to put less pressure and grind for a longer interval, the tool heats up less and has a lower chance of losing its temper, and of course dip it in water often and immediately, within a fraction of a second. Practice a lot, you'll become proficient and you'll love sharpening and how much it makes your cutting easier.
8" wheels are better than 6". 1725 rpms is better than 3450 rpms. That being said I have a 6" craftsmen with 3450 rpms. First get a friable wheel and a dresser. When getting close to edge or when a light grinding is all you need, turn on grinder until it reaches full speed. Then turn off grinder and grind until you stop the wheel, repeat as many times as necessary. This method is especially good for turning gouges.
You are correct in all your assumptions.
mike
I do use the Tormek water cooled grinder for my chisels, plane blades etc. It's horribly expensive but I don't have a single complaint about it thus far. I've even made a few bucks re-sharpening things for other people with a couple of the jigs they have for the grinder. Before the Tormek I used a plain old oil stone and leather strop to sharpen chisels, planes etc...
I use a small 6" Delta bench grinder if I damage the end of a plane blade or chisel to take out the "knicks." Depending on how bad the knick is you could be at the Tormek forever getting it repared. I also use the bench grinder for all my Sorby turning tools.
The key to not over heating the chisels or blades on a bench grinder is to frequently dip the end into a glass of water. I always have a rag or towel to just dab the excess of on before I return to sharpening. Another thing to consider is to the kind of stone you use on the bench grinder. I personally use the Norton white stones. I beleive their Aluminum Oxide (someone correct me if I'm wrong) which is suppose to keep the tool from over heating too quickly. Even with the use of the Norton white stone I still dip the tip of the tool in water frequently to keep the steel from overheating.
Not sure if any of this helps you...I hope so!
Sincerely,
E. Anderson
This forum post is now archived. Commenting has been disabled