Carbide tip planer knives?

[Allan Speers]

In about a month, I will be embarking on a fairly large planing task: I have around 4 - 5,000 BF of rough-sawn lumber that I want to skip-plane & clean up.

Last year I picked up a 12" Powermatic PM100, and got it running well, but it still has the regular knives, and they are in bad shape. my original plan was to add a shelix head, but I can't afford that right now (over $1,000 with the bearings) so I'm considering getting carbide-tipped blades instead. The price per BF cut would likely end up about the same, maybe even less.

Would you do this, or get lots of HSS blades?



note: As of right now I don't even have a sharpening system. I'm looking into that now. (Any recommendations?)
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MY THOUGHTS:

The carbide-tipped are not nearly as robust as solid-carbide, being made of softer material. They actually are more prone to chipping than good HSS knives.

The carbide-tipped would still last much longer than HSS, so less hassles sharpening or changing them.

The carbide-tipped supposedly don't give as good a finish. - but maybe I shouldn't worry about this for the task at hand?

The carbide-tipped would be much harder to sharpen. - Can you even sharpen them?

The carbide-tipped would cost a LOT more if I hit a bunch of knots or embedded stones, etc.



All thought welcome. Thanks.

[David Kumm]

Have you looked at the Kanefusa knives. A compromise between carbide and HSS. I've not used but have heard good things about them. Dave

[Andrew Hughes]

You didn't say what you plan useing the Ct knives on.If it's a soft wood you may not be happy.But since your only blanking them maybe it won't matter.
What a poor comment on my part.Sorry

[Wayne Lomman]

The best planer blade material depends on the job but for me carbide is the default option. I am not sure where the idea comes from that carbide gives a lower standard finish because it is the reverse that is true. The exception is for multi tip cutterheads that are either poor quality or not cleaned when setting the tips - simple considerations for any woodworking tool/machine.
Carbide blades remain true overall even if you nick them. Knots won't worry carbide but stones and metal will. It is worth taking the short time to check and clean each board as you go. It the boards are dusty, carbide will hold its edge much longer than HSS. Carbide will also last much longer on inherently abrasive timbers such as teak.
I always have a spare set for each machine. This way I can send the blades away for professional sharpening with minimal down time. I don't attempt sharpening carbide tips as the professionals are so quick and cheap and accurate. You can hone them with a diamond stone but you will sacrifice accuracy.
If you can't get the boards clean enough, HSS may be a better option. Stones will still nick them, but if you have spare sets and change/sharpen regularly, you won't lose accuracy to any great degree.
I'm not familiar with the Kanefusa brand, but good HSS is an alloy of steel and tungsten anyway. Compromises that offer the best of both worlds sounds like slick marketing.

[Allan Speers]

Wayne, that's great info, but are you maybe talking about SOLID carbide knives? Those are made of a much harder carbide than can be used on carbide-tipped knives, hence they can be sharper and give excellent results. (The same goes for shelix-head inserts, which are solid carbide.) EVERYONE I've talked to says carbide-tipped knives give an inferior cut to good HSS.

I hope you can clarify, because your comment about knots is critical. Carbide-tipped knives are also more prone to chipping than HSS or solid-carbide, and I will likely it a TON of knots & pithy areas.
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David, I looked at those Kaneusa ST-1 knives. If their claims are true, (lasting 5X as long as HSS) then they make a lot of sense, as a 12" set is only ~ $80. - But their claim that they are "self-sharpening" seems a little far-fetched.

Do you actually know of someone that has used these?

[Mel Fulks]

The knives that I have seen in Powermatics marked "powermatic" were not high speed steel ,and we're not marked as such. I could tell by their color ,feel ,and the way they cut that they were " semi high speed". I would buy T-1. Last longer and give better finish. Much less tear out. Perhaps Powermatic also sells some kind of premium knife ,don't know,but I'm sure I have not used any.

[Chris Fournier]

I used to use the knives that you are asking about and they were not chip prone. They crushed HSS performance everyday and were no lesser than solid carbide knives. The grade of carbide tells the tale. Fresh HSS will always give a better surface than carbide but you are only skip dressing so who cares?

[Mark Wooden]

I have the same machine and keep a set of carbide tipped knives for when I have to plane abrasive stuff like teak, ipe or sometimes painted lumber. They are pricey and I think that as long as your RS lumber is new, just get a few sets of T1 like Mel says. I use them and easily run over a few thousand feet before I change them. I keep three sets and the moment one dulls it goes to the sharpening shop. I always have two sets waiting that way.

FWIW, if the knives are still sharp. most knicks can be cancelled out by moving one knife right or left a little. Keeps you running.

[Rick Lizek]

Over thinking it and you left out what kind of wood!

Typically you skip face on the jointer then plane.

Why would you skip face on the planer? Are you leaving something out? Where is this wood going next...resale, construction?

2 extra sets of HSS would be plenty.

Send them out for sharpening. Not cost effective to sharpen yourself.you can plane a couple thousand feet before you need to change them. Changing sooner will minimize how much they have to grind. I can bring them to my local sharpener and wait. They have a long grinder for paper knives and can mount 4 paper knives and in minutes they are done.

Carbide requires diamond to sharpen.

HSS can bow after a few sharpening. I have my sharpener check for this and they straighten them. For years the guys in our shop struggled with this and when I got there I had the sharpener fix this. I can install bowed knives with some extra fiddling.

When changing knives the first thing I do is get rid of the blade height adjusters. Useless! I always install them higher and tap down with a block of wood or special faced dead blow hammer. Ip ut a little tension on the first, last and middle gib screws. For 24" heads I do four gib screws. I get it to .010" above the head then bring it a few thousandths at a time to zero. When I tighten the gib screws the knives stay exactly where I want them unlike when you use adjusters. I can set knives on 24" jointers and planers in 1/2 in a leisurely half hour.

http://www.northfieldwoodworking.com/gauges/gauges.htm Buy an indicator from Enco and you can make a straddle base from from wood or steel aluminum channel. For jointers I use the same jig on larger heads. For smaller jointers I use a design similar to the Oneway but home made. DSCN0771_2.jpg



Even if you the planer mounted grinder it's still easier to swap the knives. With this set up you have to fiddle with the adjustments of pressure bar etc.

Only use carbide for resinous woods like teak. I know the helical one use carbide.

If you hit something with solid carbide you can destroy the whole knife as the fracture can go deeper.

Why do you say carbide tipped are softer?

IMG_0328.jpgDon't know why it's sideways. Bought this for $250 thirty years when I was doing lager machines commercially. It does everything on a planer from setting knives, rollers, pressure bar and jointer knives and adjustable lock edge shaper knives. Have made several since then from scrap metal for $0. Have scaled it down for heads under 3" The original one was for heads 3" and bigger.

You cannot buy this gauge!

[Bradley Gray]

I use only HSS knives, 2 sets and typically get about 2K BF before changing. I would expect more just skip planing as I usually run a 3rd pass. 4-5 years ago, I bought a pair of magnetic knife holders for setting knives on my old iron 24"planer. Set up time went from 2 1/2 hours to 20 minutes!

[Wayne Lomman]

Allan

If this post shows up twice, I'm blaming the wife who rang halfway through and I can't remember what I was doing. I'm working away from home restoring a Georgian style house at the moment, so I only get to talk to her once a day.

About the knives, I am talking about carbide tipped knives.

There is no question that if a carbide edge hits a hard enough object, it will chip rather than deform as is the case with HSS. However, I cannot recall blade damage caused by anything other than very hard foreign objects. As well as Australian hardwoods,I frequently machine framing grade softwoods from North America eg spruce, douglas fir, and Monterey pine. I get it rough, knotty and well seasoned, old and new and the carbide knives outperform the HSS every time.

I have to admit that this is the first time in 40 years that I have heard that carbide has an inferior cut. I would be interested to hear an explanation as to why. My experience is the exact opposite. Cheers

[Mel Fulks]

Running the skip planing on the highest speed is easier on the knives. I've always used PLANER for skip planing and only as an aid to cutting rough lengths for grain matching.

[Robert Willing]

I did not read all of this post but try these people for CT planer blades http://globaltooling.bizhosting.com/...nife-sets.html. I bought their CTB for my Dewalt 735 and they are very good. No complaints since I installed them and they are more reasonable than others. I tried others who claim they are the best HSS but still underperform.

[Mel Fulks]

Allan, you have two of us reccomending T-1. Please try them . It was the first high speed steel and the most used for years. The junk did not start coming out til WW2 tungsten shortages. I like Powermatic machines, but their knives are just low quality SEMI high speed steel sold at a higher price than places like global get .And I notice they don't sell T1. You don't have try them long to see the difference. The first board or two run with the cheap stuff will show striations in the adequately smooth areas that don't have tear out. First boards run with T-1 will actually have a sheen and less tearout. And maybe it will help to point out that machines generally ran at lower speeds when T1 first came out,so if you use an older machine now with cheap steel the tear out is close to what you would get with a wood chipper.

[Allan Speers]

Allan, you have two of us reccomending T-1. Please try them . It was the first high speed steel and the most used for years. The junk did not start coming out til WW2 tungsten shortages. I like Powermatic machines, but their knives are just low quality SEMI high speed steel sold at a higher price than places like global get .And I notice they don't sell T1. You don't have try them long to see the difference. The first board or two run with the cheap stuff will show striations in the adequately smooth areas that don't have tear out. First boards run with T-1 will actually have a sheen and less tearout. And maybe it will help to point out that machines generally ran at lower speeds when T1 first came out,so if you use an older machine now with cheap steel the tear out is close to what you would get with a wood chipper.

Good point about the speed. I purposely got a 3-ph Baldor for my PM100, with a VFD. I can't change the ratio of rpm to feed rate, (CPI) but I CAN slow them both down together.

The older PM100's (the "green" era and earlier) did indeed run more slowly than the "gold" era and later. 4400 rpm vs 5047 rpm. I assume that's due to improved bearings, but who knows? I set up my pulleys to give the "gold era" arbor speed at 100% motor speed, so I can easily slow it down as desired. If nothing else, lower speed = lower heat, and less noise to bug my neighbors.

I'm still not sure about the knives. I've pretty much decided against the carbide-tipped knives, based on this thread.
T-1 is easy to get and CHEAP. I like cheap. - but those ST-1 knives from Kaneusa are intriguing. I wish I could find a few folks that have actually used them.