Sharpening Jointer and Planer Knives In-House
Machines with built-in knife grinders can be a good investment. October 30, 2005
Question
I want to sharpen our jointer and planer knives in-house and I want to find a used, low cost machine. Does anyone have any information on types, brands, costs, etc?
Forum Responses
(Solid Wood Machining Forum)
From contributor A:
You might look into a planer that has a built in knife grinder. I have seen this feature on a Powermatic planer and I am sure there are others. Keep in mind that it isn't easy to grind a planer or jointer knife accurately. I send mine out, and even the sharpening shops with the proper equipment seem to have a hard time making the edge perfectly straight.
From the original questioner:
I was thinking that a surface grinder would work. Has any one tried this? Used grinders are not too hard to find.
From contributor B:
There is no better way to sharpen these than to do it in place on the machine. You will get what you pay for in a machine to do them in-house and out of the machine. I don't believe there is a machine that a woodworker can afford to do this. Try to find a Powermatic with a built-on grinder. I have a model 180 and only recently changed out the knives for the first time in about 12 years because I developed some damage I didn't want to take the time to grind out myself. It was quicker to change out and send in the damaged set. It may take some looking but you may be able to find a used set up like the Powermatic and install it on a jointer. I know that Northfield machinery makes a setup for their big jointers. Maybe you could look into retrofitting their grinder on your machine. Remember that if you change to a spiral insert type head, they don't normally consider the finished wood surface to be truly a finished surface and it would need to be widebelt sanded after.
From contributor C:
I can change the knives faster than setting up a knife grinder. I think it would be cost effective to go with insert type tooling - a Tersa head or Esta knives.
From contributor D:
I agree with contributor C - if you nick a knife, put in a new one and you're up and running
From contributor E:
If you nick the knives and they are still sharp, simply move one knife over about 1/8" and reset it with a magnetic knife setter.
From contributor F:
Another advantage with grinding knives in place is the option of jointing. It really speeds things up. Also, small nicks can often be jointed out.
From the original questioner:
We don’t run our planer and jointers all day so the need for quick change is not an issue. The grinder is a good idea. The Powermatic planer we have does have this. They don’t make the model 100 anymore. We are out in the country and have to send out our items and it takes time to do this, besides the cost for shipping and the service. I thought that it would not take many years to cover the cost of the machine. We use insert on our door sets because the set up is a lot easier for the guys. We can order on phone and receive the order in two days. I had a guy who sharpened our items on an old machine - he clamped the knife to the angled holder. The motor and grinding wheel - cup style - was above, and moved back and forth on some steel rods. This did a great job and it was not a home made rig. I would like to find a machine like that or a surface grinder. I have seen them for under 1K and that wouldn’t take too long to pay for.
From contributor G:
You can't go wrong with a built in or knife grinding attachment. It is impossible to set knives as true as a grinder will make them. Another option you might try is Dispozablade. The blade holder is held in place with rare earth magnets. You use paper shims under the magnets to fine tune the height. I put a set on my 8" Oliver. The initial setup was pricey but the setup for a 16" or 24" machine is not double or triple the price of the 8". A replacement set of 8" double edge knives is $25. That's $12.50 per knife change. You can't sharpen a set of knives for that price.
From the original questioner:
Insert is a good option when compared to sending out our knives. But is it as cost efficient as in-house? What system of inserts is best - Tersa, Esta, Dispozablade?
From contributor G:
If you want to sharpen in house, I think a built-in sharpener or grinding attachment is best. It requires less downtime and less equipment and will yield a better finish. Since it requires less downtime you will tend to keep your knives sharper. As far as inserts, I only have experience with Dispozablade. The blades stay sharp longer than my machines using a grinder and factory knives, but the knives are less forgiving when encountering a knot, or an embedded nail or foreign object. Repositioning blades after a minor nick is quicker, however. Setup cost - about $250 for my 8" jointer - was reasonable. I think I was quoted about $500 for a 24" 3 knife head.
You should be able to find a used grinder for your Powermatic if a new one is not available. Are grinding attachments available for your other machines? How many grinders will you need? My surfacer and large jointer are both Oliver and share the same grinder and rail. I just got a short grinding rail so I can use the head to grind the knives on the 8" jointer and get rid of Dispozablade. If money is not a problem I would buy an ITCH (Insert Tooth Carbide Head) machine with a built in grinder. I'm looking for an Oliver. I have a 24" Delta RC-63-N - it has a Newman quiet spiral head. It is a beautiful machine. I don’t have a Grinder for it so it costs about $600 with shipping to have Newman sharpen it. I'm looking for a used auxiliary grinder for it. A new one is about $4000. The head is a true spiral and unlike the spiral head contributor B mentioned, the finish is very smooth and flat. The only downside is, as the knives dull you will have some tear out along the right side of the board.
From contributor H:
We have a grinding and jointing setup on a Crescent P36 36" planer and I wouldn’t trade it for the all the tea in China. If you have a larger machine I think the grinder is the way to go.
From contributor I:
Can a Powermatic 180 be used as a molder?
From contributor B:
To contributor I: Maybe for very shallow profiles at or less that 1/4" but I think it would be so time consuming to set up that you would be better off with a Williams and Hussey.
