"The Good Blades": when do you switch?

[Narayan Nayar]

Hi.

Well, as some of you read, I took delivery of a Hammer A3-31 Jointer/Planer a few weeks ago. Among other accessories, I ordered their super-special "cobalt" knives.

Quick question to those of you who have a good set of blades--for whatever machines you may own. Do you always use the good set? Do you use the "lesser" set for most work and switch to the good blades when using highly figured stock? Do you just always use the good set? Obviously, on the TS and BS, I switch blades when a cut requires a different blade, but that's not quite the same thing as swapping blades which do the same thing but which are of different quality. The blades in the Hammer swap out very easily, so swapping won't be much of an inconvenience.

My initial thoughts: use the cobalts all the time. A new set is $60 or so--not something I'll want to replace every month, but not terrible. Keep the normal blades around for questionable material or for backup.

So far the normal blades have been working very well, but I can't say I've run much challenging wood through them. An argument could easily be made to just use the normals until they're no good then swap to the cobalts and at that time order a backup set.

Yeah, I'm thinking through this too much...in the end it probably doesn't matter too much. Just wanting to glean some experience off y'all and see what you've established as best practice.

[Joe Chritz]

I wouldn't ever change planer or jointer blades unless they needed it. If the operation is to damaging I wouldn't do it.

Unless that unit has quick change blades it isn't a 30 second operation to change them like a saw blade.

I "heard" that running a board with a drywall screw it in is bad on brand new (under 250 BF) planer blades. :o

Joe

[Narayan Nayar]

You heard right, Joe. And I'm guessing you heard it in person :)

Yes, the Hammer has quick change blades. Probably 1-2 minutes tops for all blades.

But I suppose my question applies not only to jointer blades, but to other pieces of equipment as well.

[David Romano]

I don't think the decision should be based on whether or not the wood you put through the jointer/planer is "challenging" as much as it should the risk level of the wood. Unless you go to carbide, the sharpness of the different blades will be essentially the same, carbide being a little less sharp. The sharpness is the only important blade factor when milling wood that might tear out (if this is what is meant by "challenging". The other important factor of course being cut angle, which is fixed.

On the other hand, if the wood is known to or suspected to have dirt or other grit embedded in it, then switching to a lesser set of blades would be a good idea. Chips can be a burden to grind out.

The "good" set of blades you are referring to are probably just a better type of high speed steel, M42 since they are advertuised to have cobalt. The sharpness is probably no better than the M2 steel, but it does offer better durability. So, they last longer.

TS/MS blades are just about always carbide tipped these days, so for me, a "good" blade would be one that gives the best quality cut. And I would use that blade for everything except if I were building a deck, or cutting alot of not so precise lumber.

David

[Travis Gauger]

Hi.

Well, as some of you read, I took delivery of a Hammer A3-31 Jointer/Planer a few weeks ago. Among other accessories, I ordered their super-special "cobalt" knives.

Quick question to those of you who have a good set of blades--for whatever machines you may own. Do you always use the good set? Do you use the "lesser" set for most work and switch to the good blades when using highly figured stock? Do you just always use the good set? Obviously, on the TS and BS, I switch blades when a cut requires a different blade, but that's not quite the same thing as swapping blades which do the same thing but which are of different quality. The blades in the Hammer swap out very easily, so swapping won't be much of an inconvenience.

My initial thoughts: use the cobalts all the time. A new set is $60 or so--not something I'll want to replace every month, but not terrible. Keep the normal blades around for questionable material or for backup.

So far the normal blades have been working very well, but I can't say I've run much challenging wood through them. An argument could easily be made to just use the normals until they're no good then swap to the cobalts and at that time order a backup set.

Yeah, I'm thinking through this too much...in the end it probably doesn't matter too much. Just wanting to glean some experience off y'all and see what you've established as best practice.



I have carbide blades in my planer. It came with HSS and when they needed to be sharpened I just put the good ones in. I now have two sets of the carbides and just stay with those all the time. Like you said, I don't think it will really matter. I don't notice a difference between the HSS and the carbides when they are new or just sharpened. No difference in the cut quality. It's just that the HSS ones needed to be pulled out for sharpening about once a month depending on load. The carbides are lasting way longer. I actually just changed them last month after having them in there for about three months and they didn't look bad at all. Don't know how much longer they would have held out but they aren't really in need of sharpening yet. Hope this helped a little.

[Rye Crane]

Hi Narayan,

I see that you are also in the SF Bay Area. I have all my sharpening, purchase Tersa style knives for my 520mm J/P from Bay Area Carbide, 1843 East St., Concord, Ca. 94520 925-687-7543. If you are interested call Doug McAdoo their President. Great guy and has been know to give discounts. So far he has done excellent work on my t/s blades, will make up bands for your bandsaw any length and handles several lines of tooling.

I would suggest you use your M42 knives until you see their quality decline then change out and keep them for nasty jobs or just rough work since they change easily.

Rye Crane
Pittsburg, Ca.