Tooling for Teak

Teak is hard and abrasive, and takes its toll on knives and blades. This long, informative thread delves into the heavy-duty tooling choices for handling extra-hard woods, and also touches on useful techniques for working with teak. December 1, 2005

Question
I just started my first project with teak, and am getting my initiation the hard way. I know teak can present challenges. It is sometimes difficult to bond and its hard/abrasive nature wears tools. However, I am getting a terrible surface finish after planing about 1/4" off of 3 or 4 boards and there is a fair amount of heat in the boards as they come out of the planer. And these are with brand new knives on a Powermatic 15S. Does it really dull knives that fast or am I missing something simple? There are deep grooves that follow the grain of the wood. And sanding it down is a fiasco, as the oil gums up my sandpaper.

Forum Responses
(Solid Wood Machining Forum)
From Dave Rankin, forum technical advisor:
Teak will dull steel knives fast. You need to use either DGK coated knives or carbide. The abrasive nature of teak will produce heat and nick knives quickly.


From contributor F:
It could be the grain direction of the boards. .25" is a lot to remove from any species. I have a re-saw and usually will remove most of a large thickness reduction with it before I plane to save time and wear on knives. Before I had the re-saw I would use the table saw to re-saw, but I could only do up to about 6" wide by using two passes. The only other trick I have is that I reserve an area of my planer knives for light, final passes.

From the original questioner:
I’m not sure I know what DGK stands for. Also, are there any tips on where I might find these upgrade knives? I know it’s easy to find anyone that will sell you parts, but knowing which ones are reputable or competitively priced is important.

From contributor F:
To the original questioner: Did you say you were getting grooves in your planned boards? A nick in a knife causes a raised spot on the wood, not a depression.

From contributor J:
With teak I would suggest using carbide. You will still fight with it somewhat. As far as glue joints - rub it down with acetone first and then let it evaporate and apply the glue.

From the original questioner:
To contributor F: Yes, grooves. Or perhaps widespread tear-out that is more pronounced along the grain lines is a more accurate way of stating it?

I took the cover off and cleaned a lot of pitch off the back of the blade and the cove in front/underneath. Pardon my understanding of the terminology, but would that be the gullet? I don't have an especially trained eye, but I did not see any real nicks and the back bevel was still present and the grind marks visible.

Can anyone tell me a more scientific way of determining what is an unacceptable amount of wear besides firing it up and trying another board? In the meanwhile I still welcome any tips on the best place to find a carbide blade.

Contributor F - I don’t know if I misled when I said I took off 1/4". I didn't mean in one pass. I had 4/4 rough stock that I milled down to 0.750", taking about 0.020-0.030" per pass.


From Dave Rankin, forum technical advisor:
Let me present a few questions:

Are you running high production? 25,000 lineal feet or more? Are you a small shop that will run teak occasionally, but oak, maple and poplar more often? Are you on a budget?

If you are running high production then carbide is the way to go without a doubt. If you are a small shop and going to run only 2 or 3 thousand lineal feet then DGK is a less expensive option.

DGK is a heat reflective coating that is harder than carbide. It is only 7 microns thick so it does not flack. With it being this thin it also allows you to grind and joint the knives with standard ceramic or vitrified abrasives. In the field, DGK has proven to work well on long runs of maple, medium to short runs of teak and even MDF. It is simply an option.

A simple cost comparison:
HSS planer blades about $2 per inch
DGK planer blades about $4.50 per inch
Carbide planer blades $8 up per inch

As the user, you are the only one that knows your production requirements.


From the original questioner:
I am a small (one man) shop. You made a correct assessment of my species usage. This is the first teak job and mostly I'll stick to cherry, oak, maple, birch, etc. I don't know if you meant monthly usage or annual, but I probably haven’t milled 25,000 lineal feet in my life. I am on a budget, but am willing to spend a few extra bucks if it pays off in the long run and produces quality results. With that said, I'll look into the DGK coated first.

From contributor A:
I would suggest going with carbide on a small planer for teak. On a regular HSS you can only expect to run about 50-100 linear feet of product before your knives are totally dull.

From contributor F:
To contributor C: I was not misled. That is why I recommend re-sawing first. To plane 4/4 rough down to .75" takes about 6 passes. If you re-saw first then you have fewer passes dulling your knives. Men worked teak with hand planes and then high speed steel long before carbide was invented. It sounds like you were running against the grain. I like to run stock over the jointer first and while doing so, I determine the boards grain direction. This simply means the board will get less tear-out when one end of a face is feed into the jointer first as opposed to the other end of that same face. I make a mark on the end grain near that face to keep track of the grain/feed direction per board. I find that if the jointer likes a feed/grain direction, the planer loves it.

From the original questioner:
I recently spoke to WHM Group's (parent company of Powermatic) Technical Service Department. I am normally very skeptical and disappointed when I speak with many customer service departments, but I must say I was impressed with this department’s apparent knowledge of their product.

According to Powermatic, these blades are carbide tipped. They did not believe that that amount of teak should have dulled my blade. I didn’t ask the department to qualify if that were so for steel or just the carbide tipped.

He was not sure why the advertising people don't point this out as it would be a selling point. In addition to cleaning the pitch off the blades, they recommended that I make sure the chip breaker was as close as possible to the cutterhead. In addition to allowing buildup behind the blade, they said this could allow chips to accumulate in the serrated infeed roller and embed into the surface of the wood just ahead of the cutterhead.

Finally, these blades are straight when they come out of the box. They are flexed as they are fastened to the head. Pardon me if I am restating the obvious to all who have more experience with spiral knives.

I don't know if the aftermarket knives that various people offer are solid carbide, but this mounting method would probably preclude that. Perhaps they are carbide tipped as well.
Finally, there is no recommended adjustment on the serrated infeed roller. I should plan my work so that I avoid the desire/need for making a 0.001" cleanup cut and the subsequent licorice look.


From contributor J:
In theory, chip removal is what keeps your knives cool. Is it possible that taking .020-.030" is to light of a pass thus overheating your knives and causing premature dulling?

From the original questioner:
To contributor J: Your point is closely related to another recommendation that Powermatic made that I think I failed to pass along in my last post. Even though they say that you can use it without dust collection by simply removing the chute, a dust collector would have helped my problem and made the performance of the chip breaker less critical. Of course we always think of the health and housekeeping reasons when we employ dust collection, but blade cooling and chip removal are added benefits.

From contributor R:
I think Contributor J has a good point. Too light a cut or too slow a feed speed will create premature dulling and finish problems. It sounds like the grooves could be chip dent, usually caused by poor suction. I have planed small runs of teak for various jobs over the years with high speed steel. One board will leave an impression, but you can run a fair amount prior to sharpening the knives, honing in the head with an oil or diamond stone is possible maybe a few times prior to changing them and may get you through the job.

You can count on changing the knives after running, even one piece. Buying carbide is generally not practical for a small custom shop using teak on an occasional basis. You also might consider paying someone with carbide to do the milling for you. I would be skeptical of the claims being made regarding DGK. WI Knife makes what appears to be an identical product called Optisteel, I don't know if its available in thin planer blades.


From Dave Rankin, forum technical advisor:
To clarify the different types of knives discussed:

Solid Carbide: Normally most expensive and last well.

Carbide Tipped or Inlay: Normally less expensive and last almost as long. They are areat choice for medium runs in teak.

DGK Coated: 7 micron thin heat reflective coating that is applied in a high technology vaporization process that takes several hours. They grind very easily.

Opti-Knife: A specially heat treated knife from WKW that works well in many applications.

HSS: There are many different HSS. Some will only run a few feet in teak while others will run a few hundred feet.

The length of the teak run should be considered and the frequency of running teak and maple should also be considered. Carbide will not produce as good of finish as the HSS, Opti or DGK.
Carbide will last longer.

There are many tool products on the market, T1 is another option. One thing that we do here at MSI is test every product that we can. As techs with over 40 years between us, we have tested or run in production most every type of cutting tool product available at this time. The reason for so many options is to provide the end user with the most cost effective product that will work.


From contributor A:
Most people are familiar with Titanium nitride milling cutters like drill bits and endmills. The metalworking industry has been using surface coated high speed steel for over 20 plus years. By coating HSS you can easily gain 500% longer cutting times. More importantly they tend to stay very sharp until they dull versus a steady dulling of regular HSS.

Basically DGK is a newer coating that is harder and has a lower coefficient of friction. There is also another process which can be thought of as surface heat treatment. Plasma nitriding will penetrate M2 HSS up to .005". It brings the surface of M2 from RC62+/- to RC72+/-. Some companies’ offer a dual coating in which they will first surface harden and then surface coat.
NorthEast Coatings in Maine has coated several of my custom moulding cutters. The cutters come back sharper and harder.


From the original questioner:
Contrary to what the first WHM tech rep told me, the next WHM rep told me that my knives are not carbide tipped. As someone here mentioned, these are disposable steel blades. For those not familiar, it is one long skinny flexible blade with about 5 tabs attached like a sprue. These tabs go under the gibs and the blade is bent/flexed around the cutter head. Before I resigned myself to pulling the blades, I cleaned them up real good and hooked up my dust collection system, to no avail. The cut was just as poor, and as another respondent said, the skinny is my knives were just simply dull.

One respondent suggested I refrain from planing and re-saw as close to final thickness as I can with the bandsaw, then reserve the planer for final cleanup passes. The dealer that sold me the planer further suggested that I use a drum sander for that instead of ever involving a planer. From my own experience I agree that sanding was a lot more effective than planing, and I managed to salvage the project this way. Someone else suggested wet sanding as a way to get around the oil gum up issues with sandpaper.

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