# Epoxy Tearout on New Planer



## BoilerUp21 (Apr 19, 2016)

A friend brought over an epoxy river table he is working on to get planned on my new Oliver 20" Helical Head planer. I have run hundreds of bf of lumber through it without much issue. We were getting uniform tearout in the epoxy and i was wondering if anyone else has had this experience specific to a HH planer on epoxy? I am thinking it has something to do with the epoxy, although it seemed just as hard/cured as other epoxy that i had previously put through my old Dewalt planer without issues…


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## John Smith_inFL (Dec 15, 2017)

I would go out on a limb here - thinking that the epoxy is 50% at fault.
it could be the brand, the age, the way it was mixed, atmospheric conditions
when it was poured and cured, etc.
the other % is the cutter head may have generated enough heat to pull out
pieces of the epoxy.
no real way to tell from just a photo - we would have to know all there is to know
about the whole project from start to finish.
but, from the photo, that is just my guess.

.


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## RichT (Oct 14, 2016)

From the looks of it, those could be trapped bubbles that got planed open. Also, what is that in the epoxy making all those specks? That surface should be dead flat and pure black. Final sanding will give you a surface you can apply finish to and it'll look like a million bucks.

If it's not bubbles, but chips, then something's wrong with the epoxy, or your blades are dull (which doesn't sound likely). It shouldn't look like that.


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## Unknowncraftsman (Jun 23, 2013)

I think it has more to do with how a insert head cuts. 
Or I should say scraps it has very little forward rake. If your not understanding look at it like this the insert has a 30 degree facebevel. It is acts just like a chip breaker and curls up the chip.


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## BoilerUp21 (Apr 19, 2016)

> From the looks of it, those could be trapped bubbles that got planed open. Also, what is that in the epoxy making all those specks? That surface should be dead flat and pure black. Final sanding will give you a surface you can apply finish to and it ll look like a million bucks.
> 
> If it s not bubbles, but chips, then something s wrong with the epoxy, or your blades are dull (which doesn t sound likely). It shouldn t look like that.
> 
> - Rich


There were not any bubbles in the epoxy so i can rule that out…Now I'm just wondering if it was the type of epoxy/curing/proportions he used etc… or something with the helical head (which i doubt). Going to make a small test piece and run it through after it cures with the epoxy i normally use. Really hoping it was the epoxy and not the expensive planer i bought haha


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## Unknowncraftsman (Jun 23, 2013)

Port orford cedar is a soft wood but kinda on the brittle side. 
My hh head doesn't do as well as my jointer knives. The tops of the ridges do well but the tips of the inserts where all the cut starts and ends not good.








Helical bryd head








Jointer knives


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## diverlloyd (Apr 25, 2013)

How long did the epoxy get to cure before it went through the planer?


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## CaptainKlutz (Apr 23, 2014)

+1 The helical head geometry is not an asset cutting soft materials.

Looks like typical soft wood helical head cutting issue? Known fact helical heads are not greatest on soft woods. 
If the epoxy was not hard enough, would create same effect.

+1 How long was it cured?

FWIW - Casting (river) epoxies are extremely slow curing to avoid heat generation and yellowing typical with large mass of resin. Casting epoxy typically requires 30 days at room temperature to reach 95-98% cure point. If temp is lower, then add several weeks to cure time.

The extra small uneven divots in the groove(s) is excessive tear out. Shows the epoxy was weak or soft in those areas, which could be due the pigments or pearl additives?

Also see wood fibers and epoxy residue stuck into epoxy surface. Would have to either: not be cured, or be heated too high; for resin to get sticky and hold particles.

+1 Not to entirely blame the state of cure and/or the machine, it could be the epoxy used was 'flexible' resin system; that may never get rock hard? 
Would need epoxy brand, mix ratios, time since mixing; to draw any hard conclusions?

Apologies for more questions, than answers/help.

Cheers!


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## david2011 (Apr 1, 2008)

If the cutters are getting hot that could contribute to the problem. Most epoxies, the exceptions being the heat resistant varieties, start breaking down around 400°F. Some epoxies never get truly hard so that is also a potential cause of the chipping.


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## Davevand (Feb 10, 2016)

I had the same type thing happen to me with an epoxy pour that I was trying to turn on my lathe. I tried fast, slow, carbide, HHS and nothing worked. I just assumed it was the wrong type of epoxy, maybe??


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## avsmusic1 (Jul 10, 2016)

Did he do the epoxy pour as 1 pour? 
I wonder if it's layered and the top was thinner/not cured


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## Unknowncraftsman (Jun 23, 2013)

> +1 The helical head geometry is not an asset cutting soft materials.
> 
> Looks like typical soft wood helical head cutting issue? Known fact helical heads are not greatest on soft woods.
> If the epoxy was not hard enough, would create same effect.
> ...


I disagree with your analysis. The reason is this. Inserts cutting head rely on curling a chip out of wood. It does not scoop out wood in the same fashion as a simple knife head planer or jointer.
The hard brittle epoxy doesn't bend the way a wood fiber.
Now if the op had a Oliver with a itch head he might have been successful. 
Let look at the difference between a Oliver itch head with no face bevel on the knife.
And a bryd head with a facebevel. And very little forward rake.

















Clearly we can see the 30 degree face bevel on the bryd head that scraps out wood if it didn't have the slightest tilt Im betting the power factor would be up up and away.


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## CaptainKlutz (Apr 23, 2014)

AJ2 - Disagreement is OK. Have formulated and dealt with machining issues on polymers for decades.
But I am not a machinist, and more than likely am not describing this accurately; which makes it easy to disagree?

What bothers me is your base assumption


> The hard brittle epoxy doesn't bend the way a wood fiber. - Aj2


Based on pictures and my experience, I think the epoxy was not hard, but SOFT.

Let me explain why this is problem:

A polymer is not metal or wood. Any polymer mixture as bowl of mixed sized objects (example: Popsicle sticks, gravel, grass, string, and paperclips). The ingredients have different densities, sizes, and strength. These are attached to each other tightly on the 'ends', and occasionally on sides. There are many areas not attached to each other, which is part of what makes a polymer softer/harder; and defines how the polymer chains move against each other. Hard rigid polymer have short chains, with many more cross links. Soft polymer has lower cross link density, and usually much longer object lengths.

When machining a soft polymer: A wide area in front of the machine cut moves slightly, and cutting edge lifts the polymer vertically instead of cutting it. The long soft chains also may not cut at contact point, they stretch and tear at weakest point; unless you exceed the heat capability of polymer during tearing and melt it apart. Due to the movement, the cut is not straight across the (hopefully flat) surface, but goes below the surface.
That is why I called the divots, tear out.

The best method for machining soft polymers is to make short stroke cuts with zero rake angle and larger relief angle, removing smallest width bite possible per cut, while taking a deep enough cut to force cut and not surface tear. Usually adjusting the speed to ensure minimal self heating. Any time you use steep rake angles or long angular cuts you exaggerate the polymer movement/tearing, and increase tear out. Best version of this method is grinding with small abrasives.

Personally, would never use helical head planer to machine a SOFT polymer. A hard polymer might can work, but not soft one.

IMHO - the best tool for flattening river table is router sled with fly cutter/spoil board cutter, or wide belt sander with large grit to avoid clogging the paper.

The issue for this entire discussion is we have no data on 'softness' of epoxy polymer as cured to know if it was source of tear out? Which makes all of this typing simply an educational exercise. 

Cheers!


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## Unknowncraftsman (Jun 23, 2013)

Darn it I already know your probably right.
One of these days I'm going to be right and appear smarter. 

Next time I mix up some epoxy systems 3 I'll mix some extra and do some testing. I actually have no scientific proof to when it comes to machining epoxies. Zero experience 
But I do have a good understanding of machining difficult woods and easy timbers.
Trying to apply my experience to man made chemistry I probably fall short. 
Good Luck always


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## logboy73 (Jul 23, 2009)

I do a fair bit of work with epoxy in my woodworking business. It doesnt matter what brand or formula I'm using, it pretty much always tears out like that with my 20" Grizzly spiral head. Dont beat yourself up over it as it just seems to be the nature of epoxy. Run it through your planer just enough to get it flat, then run it through a Timesaver to finish. I never use my planer for stuff like that unless I have a lot to hog off and want to save time running it through my Timesaver.


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## Joners (10 mo ago)

I've been trying out different cutterheads for my planer. First one I bought was a helical, taking chunks out of the surface similar to the OP. I spoke with the company who made it and they said that helical doesn't work well with epoxy so they made up a custom "hogging" cutterhead for my planer, unfortunately that didn't work either which surprised them. They have offered me a full refund on the new one and will do some R&D to come up with something else that hopefully works well with epoxy.


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## WadeP (Mar 10, 2008)

Just had the same result with epoxy that had plenty of cure time and product support told me that would happen when ever I ran it through a planer, so back to the drawing board!


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## wildwoodbybrianjohns (Aug 22, 2019)

I would have used a belt sander instead.


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## tomsteve (Jan 23, 2015)

imo, and a bit of experience, it is a combination of epoxy and feed rate. if it were possible to slow the feed rate of the planer down, you would see a noticeable difference in the outcome.


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## WadeP (Mar 10, 2008)

Thanks!


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