Planer Moulding Cutter material

I run a small 1" wide moulding cutters (HSS) along with the planer blades in one of my planers, to make a Shiplap siding profile.
When I am working with nice clear old growth Redwood, the blades hold up ok, but when I am running knotty second growth, the moulding/shiplap cutters take quite a beating, planer blades are fine.
My question is, I would like to have these shiplap cutters made out of carbide, but don't know if solid carbide would stand up to the beating these take, as they are only 1/8" thick and stick out from the head almost an inch. I don't see any of the laminated carbide/steel material that the carbide blades are made of, that have a full lamination of carbide that would cover the whole profile, usually it's only about 3/8" along the cutting edge.
I could go to 1/4" thick blades, any suggestions?

Thanks

janc

I ran Redwood patterns by the truckload through a Weinig moulder. Hi-Carbon Hi-Chrome was the knife material of choice as the tannin's in the Redwood would not etch the material. HSS would etch and was overkill for this softwood. Properly sharpened these pattern knives would last for thousands of board feet. Any sort of carbide wasn't even considered for this application.

Stuart

You can extend the life of your cutters by resharpening. Just grind the face back on a surface grinder. Grind all the cutters in the set together so they will be a matched set. Be sure not grind on the part of the cutter that fits into the holder.

As has been noted, carbide, in the past did not play well with softwoods because the acids erode the binders. Cutters dull from cutting wood due to chemical erosion, not abrasion, though that would not seem obvious. However, modern inserts might be your best option both because they are now formulated to run pretty well with any wood matrix, and because it is easy to change them when dull. I have replaced solid cutters like you show with insert cutters and they run multiple times longer. I have always wondered if those Sears/Corob cutter really were HSS, what grade, and how well hardened.

I used to run a fair amount of redwood for jobs in DC, still do some WRC occasionally. It takes sharp tooling. I made all these cutters to accept off the shelf inserts, except the slotters and noser which i brazed.







The point of this is: If you make some smaller gibs for your planer to take a thicker shank, you could make bits that take off-the-shelf inserts for the cutting edges. It's really easy to make this tyle pocket; though an angle end mill is needed to make the 2 reference edges to locate the insert. I made mine (angle cutting EM) but something close can be purchased.

This insert cutter body is made for metal, but the principle is the same.
Mill the pocket with an over-run on one corner to clear the insert corner. The end mill should have the same angle as the side of the insert:



Then drill & tap for the retaining screw. Bias the tapped hole a few .001's toward the corner, so as the head enters the insert, it pulls it tight toward the corner.
Do not over-do the bias, about .003" from x & Y toward the corner is enough. Certainly not more than .005" with small-shank screws. Metal inserts are tough; but wood-whacking inserts are thin and can snap if the bias is too great.



The cutter body is still over-size in this photo, will be cleaned up for clearance to the insert in a later op.



Making flat, insert cutters is dead easy. This is one for a metal planer, but the principle would be the same for spikes for a wood moulder:



It would be advisable to either use 4140 pre-hardened steel for the shank; or use something like S7 and harden after machining, to maybe 40 or low 40's Rc, to get the strength for your app. "mild" or unhardened steel could be apt to bend.

smt

Thanks for the input and ideas on these cutters, Stephen, I really like your suggestion and use of inserts, these little cutters just wear so much faster than the long planer blades, a quickly changeable edge would be nice in several ways.

janc said:

I run a small 1" wide moulding cutters (HSS) along with the planer blades in one of my planers, to make a Shiplap siding profile.
When I am working with nice clear old growth Redwood, the blades hold up ok, but when I am running knotty second growth, the moulding/shiplap cutters take quite a beating, planer blades are fine.
My question is, I would like to have these shiplap cutters made out of carbide, but don't know if solid carbide would stand up to the beating these take, as they are only 1/8" thick and stick out from the head almost an inch. I don't see any of the laminated carbide/steel material that the carbide blades are made of, that have a full lamination of carbide that would cover the whole profile, usually it's only about 3/8" along the cutting edge.
I could go to 1/4" thick blades, any suggestions?

Thanks

janc

Click to expand...

Please don't put carbide knifes into a standard head... Better to braze a carbide face to a mild steel backer (a la wadkin) or braze onto a full profile head.
Leitz makes a carbide knife head but the system uses a close patterned backer with the profile knife as well as a separate chip limiter.

When you say planer moulder I assume a Belsaw/Woodmaster type machine. First and foremost I would question the quality of that steel. There are many factors that weigh into getting good surface finish. High speed steel is the preferred for a molder because it can actually be honed much sharper than carbide and is much more impact resistant (knots). The down side is it does dull more rapidly and is subject to high heat issues. That being said there are many grades of HSS that can be suited to the material being run. Some withstand knots better by being less brittle but dull quicker, others very hard and stay sharp longer but knick very easily.

The next part to consider is relief angle and maybe a factor in your problems. Old growth lumber and most clears are dried differently from #2 or knotty materials and require different relief angles as do softwoods versus hardwoods.

Lastly, as I look at your picture, you're plunging fairly deep and if you go single knife like lots of those machines do you will naturally dull quicker. If you can get a way with it a slight taper to those vertical edges will also help to last longer.

I think I would get a hold of one of the moulder knife grinding services and ask for recommendations and if they can grind for your machine try several different types of steel. That's a small knife so wouldn't be too expensive.

Yes it's a Woodmaster

MikeAa said:

When you say planer moulder I assume a Belsaw/Woodmaster type machine. First and foremost I would question the quality of that steel. There are many factors that weigh into getting good surface finish. High speed steel is the preferred for a molder because it can actually be honed much sharper than carbide and is much more impact resistant (knots). The down side is it does dull more rapidly and is subject to high heat issues. That being said there are many grades of HSS that can be suited to the material being run. Some withstand knots better by being less brittle but dull quicker, others very hard and stay sharp longer but knick very easily.


The next part to consider is relief angle and maybe a factor in your problems. Old growth lumber and most clears are dried differently from #2 or knotty materials and require different relief angles as do softwoods versus hardwoods.

A regrind with attention to that detail is a good idea.
Lastly, as I look at your picture, you're plunging fairly deep and if you go single knife like lots of those machines do you will naturally dull quicker. If you can get a way with it a slight taper to those vertical edges will also help to last longer.


I think I would get a hold of one of the moulder knife grinding services and ask for recommendations and if they can grind for your machine try several different types of steel. That's a small knife so wouldn't be too expensive.

Click to expand...

You are correct in your assumption on the machine, it is a Woodmaster that I purchased new more than thirty years ago, not the best machine or my only planer, but it does the job. These blades were a couple sets of blanks that came with the machine that I had cut to this profile at my local machine shop.

A regrind with attention to the relief detail is a good idea.

This machine holds three knives in the head, it works, but takes every bit of the five horsepower to make a cut of both the planer and moulding blades.

I should take it back to the person who first cut them, my closest cutter grinding service didn't like the little bevel ground into the side, said their machine couldn't do it.