I have a Delta 6″ jointer and a Delta 12 1/2 planner. On both, I get knicks in the blade shortly after replacing. Just about all the wood I joint or plane is either Oak, Pine, Birch, Poplar, and Walnut. Why am I getting the nicks in the knives?
Also, I am considering buying carbide knives for my jointer but would be terribly dissapointed(given the price) if shortly after using the carbide, I developed the nicks.
What to do???
Replies
The nicks can be caused by knots or sand grains or gravel embedded in the wood.
Try to eliminate as many knots as possible before you start planing, no point in beating up you blades on knots only to trim them out later. Knots by themselves can be very hard and can trap sand and grit in them.
Clean up rough sawn wood by sweeping it down with a wire brush before you plane the stock. Cut a bit off the ends of the boards before you start, this will eliminate grit and hardware driven into the end grain of the board. Also take a close look at chipped and scarred areas of the wood, and areas where there are boot prints, often you will find sand and small stones driven deep into the wood.
Carbide knives are fairly brittle, they can also be damaged by junk in the wood. They're main advantage is that they hold an edge longer when planing tough tropical woods and they can be used to on laminations and plywoods where the glue lines would very quickly damage steel blades.
John W.
John, thanks for your reply.
I have been doing a lot of things wrong. I have not given thought to knots damaging the blades and I have worked with a lot of rough lumber and have never given much thought to sand and grit if it does not jump out at me. Now I know!!
Thanks
Carbide jointer knives is what I use. Means I can clean up edges of MCP without worryin about trashing HSS knives . They (carbide knives) seem to last a very long time, and their cost is expensive, but not prohibitive.
I have not been able to afford carbide planer knives (makita 2040) and was once advised that HSS blades are actually keener when they are sharp. . Manmade wood doesn't often get fed into the planer, so I;m sticking to HSS knives there for now. .
Just my thoughts.
Eric
in Cowtown
My jointer/planer takes Tersa blades so I normally use carbide for everyday materials and when I need a really fine surface on figured or other tough material I throw a set of sharp HSS blades into the spindle. HSS is best for very highly figured wood. Unfortunately, HSS just doesn't hold a good edge for long._________________________________
Michael in San Jose
"In all affairs it's a healthy thing now and then to hang a question mark on the things you have long taken for granted." Bertrand Russell
There is something else you could try if you sharpen your own knives, try putting less of an angle on them so that they have more body towards the cutting edge this will strengthen the cutting edge. If I am cutting extremely hard timbers I find the blade will stay sharp longer if I lower the angle of sharpening, and for softer timbers I use the normal sharpening angle.
This of course depends on the amount of timber you are planing and whether or not you have the necessary equipment to sharpen the blades yourself.
Carbide lasts maybe 10x longer than HSS. In my view, nicks in HSS steel show up in the first 30 minutes of use or sooner. So expect carbide to show some dings inside of 4 or 5 hours or less. Longer service? Yes but if its dings you want to avoid the Tersa or Insta-blades HSS blade systems are the more practical solution.
Face jointing is not so critical since the planer will clean up the cut lines from dinged blades. Edges are another matter; a raised nick line will spoil an edge to edge glue up. I gave up on this merry-go-round. Made the router do the edges.
Thanks to all who replied. Looks like I am going to get the nicks which shows up as a small line. I don't worry about the finished jointed surface as the planner will cut over that and leave its own line(s). A little work with sandpaper or scraper takes care of that, but I would have liked to have found out that there is a way to avoid the nicks.
Is this a good forum or what!!
You can deal with nicked blades two ways. First, loosen one knife and move it either left or right a tad. The offset will cause one of the knives to cut off the raised track.
Second, you can easily remove the tracks with a scraper and/or sanding. The finish preparation will remove the tracks without any problem. They are really not worth worring about.
In addition to the other good replies, one of those handheld metal detectors isn't a bad investment either. They're even cheaper/better now than when I bought mine 5 or 6 years ago. When you figure what it costs to replace a couple sets of jointer or planer knives, the cost starts looking even better. Some of that stuff just isn't visible to the naked eye. I'm often finding one leg of a staple broke off just beneath the surface - presumably from someone upstream removing a shipping or lumber grading tag.
I love the smell of sawdust in the morning.
Cost of sharpening is also very expensive.
When I got my used DJ20 I though that it had carbide knives, thought this as great, until I heard that sharpening them was going to be near $100! My sharpening shop wanted well over $3 per inch for carbide vs $.60 for steel.
Turned out that the knives had a brazed HSS on a less expensive body.
This forum post is now archived. Commenting has been disabled