Cut comparison - straight knives, Tersa, and Shelix on nasty curly maple, with pix

Finally got around to some planing tests. Material was heavily figured hard maple, .280 thick x 3" wide, took .010 - .015 cut

First ran thru my old SCM S50 w/ 4 hss knives, kinda sharp. Got what I expected, a fair amount of tear out no matter which direction I sent it thru.

Then off to Will Tracey's shop and his modern SCM with Tersa head, digital read-out, GPS, and WiFi. Knives had some use on them, but seemed fine. Got about the same amount of tear out. Will generously volunteered to swap the knives out for fresh ones (took about 3 minutes - nice!) Sent the maple thru, results once again comparable to my planer. Hmmm…. Was disappointed, but not really surprised. I'd always felt my machine worked really well with thin and curly material.

Got back to my shop, decided to run it over my 6" jointer w/ Shelix head. Kinda hairy running something so thin and fluttery, don't try this at home. Was surprised by the result - no tear out! I bought the machine used, haven't swapped or turned inserts, you can see a raised line where the knives are chipped. I suspect that's how these deteriorate, chipping rather than dulling.

Pix show the Tersa and Shelix cut, same place on the lam, same lighting, same direction feed.

I'm convinced now that the Shelix or similar shear cutting insert head is what I need for planing thin curly stuff, just have to figure out what machine it should be in. Still not inclined to spend $3K to retrofit the 20" SCM just to plane 3" wie stock.

I'm surprised Richard- I never see tear out like that in figured maple.
I will see if I still have a stick of highly figured stuff in the shop and show a pic or two of results.

I'm sort of a hack too- none too careful or messing around with blades- the planer just works.
Maybe the lack of GPS on mine helps...

I wish my planer had GPS, I hear that's really good for figured stock. Maybe if I had sprung for a Martin it would have been better, but then the head would still be a Tersa. I think straight knives and really curly maple just don't play well together. The pics of the surface from the Shelix do look clean. Maybe you could add a few more powered rolls to your resaw feeder and rig it up to run stock past your Shelix head on the shaper?

Will

Just out of curiosity, what is the effective face angle on a shelix head?

I've used that type insert to make stackable shaper cutters for close to 30 years, but was always afraid to mount them the way planer head manufacturers do. Thinking about it, they may have fairly moderate rake. Or maybe not. But if the effective face angle is down in the 5 -12° range, that would explain a lot of the reduced, or free from tear-out.

smt

Tr - Part of the issue may be the thinness of the stock. My planer did very well with the 5/4 blanks before resawing, not so well with the thinner stuff. Also, as Will noted during our test, his machine, and mine too are happier taking heavier cuts. I remember finding long ago that a .020" cut was ideal. Lastly, it may be that there is a difference between cutting on a planer versus a jointer, but I doubt it. If anything I'd expect the planer to do better with the heavily controlled cut. But, no proof of that (yet)

Will- your machine may not really have GPS, but it is a great fortune teller, sealed my fate. At first I thought you were kidding with the shaper idea, but then I realized it would probably work great. Damn, last thing I need is to make another feed gizmo. Was really hoping to just stick a Shelix in a used Grizzly and get right to work. There's a G1021 on CL, tempted to take a look.

Will, when you get your bench finished you gotta start a "show us your bench" thread. Your "sumo" bench will blow everyone away!

Stephen - I have no idea what the effective rake angle on that head is, especially with the shear cut. It looks drastic, but we're so used to seeing knives with the bevel out, maybe it's not at all. If I have a few free moments maybe I'll take a closer look.

Going in this morning to fire up the sander and be done with it all. Stephen pretty much called it in his reply to my last thread, it's the best option for me right now. But I'm really impressed with those shelix heads, after being very skeptical about them for a long time. Old dogs….

Unrelated, but not really - I've been using exkenna's polished CCGT inserts for turning wood on my pattern maker's lathe with incredible results. Once again I was rally surprised, didn't think they could come close to hss or tantung, but wow! I'll post on this when I have more experience, making some custom tool holders, trying some other shapes. But those babys are SHARP!

I have a 15-year old 24" SCMI S630 planer with Tersa, and so long as the knives are sharp, I don't see that degree of tear out ever, and I regularly run curly bubinga and cocobolo through the machine. That said, I've found the Tersa HSS knives are best for softwoods- they dull quickly otherwise, and in both my planer and jointer I've switched to Tersa carbide, which lasts seemingly forever. Tried the Tersa M42 knives and they don't seem much better than the HSS.

Also, given the size of the SCM's 4-knife cutterhead, there is a fair amount of distance between the infeed roller and outfeed rollers - I think the minimum piece than can be fed into the machine is 12" long - and thin boards can get chewed up a bit because the cutterhead can lift them slightly, especially with curly grain. Whenever I want to plane stock that is in the 1/4" thickness range or less, I use my Makita 2012 portable for the task, which has a much smaller cutterhead and only about 6 inches or so distance between the infeed and outfeed rollers. That does a great job with sharp knives, however it struggles of course on anything wide and has limited capacities in general.

I have a Shelix head on my shaper and it works well.

Richard, I was half joking when I mentioned your feeder, but as soon as I had the thought I figured it might actually be a good way to go. There's got to be a simple way to use the components or even just modify it as is to feed your shaper. Probably a project best left until after you get through the current round of work... I will start a thread about my bench, it should be finished pretty soon.

Chris, I agree, the plain HSS does dull pretty quickly. I have been running the M42 knives for a while and have had good results with it on domestic stock. I don't plane enough exotics to justify the extra expense for the carbide, though I am curious how it performs. My S520 manual does list a minimum length of 12" I think, but the actual distance between the feed rolls is something like 9-3/4" or 10", and it will feed stock that short. Thin stock is tricky, and as Richard mentioned a heavier cut does seem to mitigate the problems somewhat, but it's not perfect. I find that I most often try to take cuts of about .050". I've never had great results from portable planers, and I think that for all but the really fussy stuff that the S520 does the job.

That maple of Richard's is pretty ornery; I don't think the pics quite capture the extent of the curl. Something about the combination of thickness and figure is just right to make it misbehave.

Will

This curly maple is real ornery stuff - very hard and intensely curled. I've worked with all sorts of figured and exotic stuff over my 45 years in this biz, and nothing has been more difficult to plane than really intense curly hard maple (and birdseye). This batch of lams included a lots of super curly red maple - no problem, or at least nothing that wouldn't disappear with a cleanup cut on the lathe. And some other nicely figured hard maple too. But this one board with the tight, intensely undulating curls is a whole different animal. And of course that's the stuff I like best.

I'm also sure that as some of you have noted, the thinner stock is just not as stable going thru the machine, and that is a big factor in the quality of the cut. Needs to be very well held down just in front and behind the cutterhead. That's why I wound up with my machine - they had one at RIT in the 70's and it impressed me with it's abilities with thin stock.

I remember going to look at a 24" SCM back then, had been completely rebuilt with entire new top end as a result of hitting a knot and blowing up. Must have made quite a noise! Anyway, I call the tech guys at SCM to ask if I could expect comparable performance to the 20", and they told me that the design had been changed and had increased the distance between chipbreaker, pressure bar and the knives. Maybe a lot of these were blowing up! The one I looked at had the new version up top, so I passed on it and wound up with the S50, which has been an excellent machine for me.

The chipout is ahead of the knife- on a deep cut, the wood itself acts like a chipbreaker. What I am trying to say is, the wood still chips, but the depth of cut is deep enough to cut away the chipping, which occurs on the surface. huge difference on my shaper between taking a skim cut, and taking .030 or more.

Is your plan to glue right after planing with no sanding? There is talk about the shelix heads leaving longitudinal scalloping- I don't know if it is a problem or not.

I wonder if a vacuum platen could be made up to hold and back thin stock as it went through the planer.

Thanks for that Richard.
I was busy today so could not look into this on my setup.
Also- my snip at the Terminus gear is probably unfounded.
My only experience was on a small planer which is not as solid of machine as this Tersa head MiniMax I have now.
I attribute that as the difference I had between the two machines.
I have seen good results with this gear but perhaps not broad enough.
My workaday world is teak teak teak and just occasional forays into exotics for one off projects.

For me- carbide pretty much lives in the planer/joiner and I keep fresh m42 blades around and swap out if I need to cut really thin or figured wood.
As above- the carbide lasts forever..
I needed to cut something thin and only had a set of HHS in brand new condition and got a ding in the first pass.
To the poster above- it is probably worth it to buy the carbide as they offset so many sets of anything else, even if you do not specifically have tough woods to process.

I understand the value in carbide but what about the cut quality? Do those of you that are running it in Tersa heads notice a difference between it and HSS/M42

Will

I've had no issue in regards to cut quality with carbide Tersa. Not quite as sharp as new HSS, but hold their edge for an extended period. I've been working nothing by teak and hard ass exotics for the past year or two, and the carbide just keeps on ticking. So long as the surface is not torn out or fuzzy or knife beaten, or showing blade nicks, how important is the cut quality from a machine that is simply dimensioning stock? The final surface is created by another tool after the planing, etc., is complete.

Thanks Chris that's kind of what I thought. Cut quality is important, your description is pretty much how I look at it. I'm happy with the M42 for the most part, I'm just curious how the carbide compares. The longevity factor of the carbide does seem like it would be worth it, though I don't go through more than a set or two of the M42 blades in a year.

Will

Will- this is a teak part run with a set of beater carbide blades which have been in the shop for a few years:



A fast pass with 320 on a DA and the stock is glassy smooth and ready for finish:



They work like a champ and just keep on cutting..

Hmmm there's curly maple and then there is curly maple. I have run this class of curly maple up to 10" wide through a Shelix planer with great results. I have Shelix heads in both my planer and jointer.

Coolidge - nice amp! Is that hard or red maple? That bigleaf stuff you guys have out there gets some crazy figure, but sugar is still my favorite.

Stoneaxe makes some good points about taking a heavier cut. My resaw gizmo is so accurate that I only have to take a buzz cut, and I'm sure that's part of the problem. But I'm trying to maximize the yield from this expensive stuff, so I'd like not to have to saw oversize.

I tried a vac platen way back for planing 1/16" veneers. Didn't work, all went up the dust chute. Even if it did, it would be a slow process.

My shelix heads do leave longitudinal scallops. Only .001" for the jointer, which is not a problem for me. In my banjo rims, one surface is turned on the lathe, the other would be from the planer. But the shaper head leaves .005 deep, 1" wide "furrows", which would seem to be unacceptable. That is on my scarf joint, but it's hardly if at all visible, maybe I get so much pressure it irons out. But if I put a shelix in a planer I'd want the .001 version.

Coolidge - Do you get scallops from your shelix heads? Are they a problem?

Richard that's east coast maple from my figured maple supplier in PA, these crack smokers on the west coast think their maple is infused with gold or something price wise. I have zero problem with scallops from either my jointer or planer. But type/density of wood maybe that's a factor in whether it scallops or not. My Powermatic planer for example does not snipe at all on Sapele but snipes bad on oak, go figure.

Richard,
The tearout is going to be much reduced with the helical head in any machine.
I have noticed that my jointer (16" EMA 4 knife) will joint the boards with less tearout than the planer (SCM S50 4 knife).
Not sure why, probably the hand feeding and a slightly different angle.
The planer does have a built in knife sharpener and with sharp knives the cut is impressive, however it is still a crapshoot with certain types of figure.
Does your machine have the analog style digital indicator? Mine is in metric and it is really accurate, down to a tenth of a mm.
Have you ever tried wetting the surface just before planing?

Michael

ps, nice writeup in the FS Book.

Richard, I was half joking when I mentioned your feeder, but as soon as I had the thought I figured it might actually be a good way to go.

Click to expand...

Yes, but the shaper is not a convenient orientation to feed, and it has no chipbreaker or presser foot.

So, if a "shaper type set up" were deemed sufficient, that is where the genesis of my Belsaw/RBI type planer comes in. The original head can be reomved and replaced with a heavy shaft. Mount a shaper head on the shaft, of sufficient width for the work. This would be the same as, but a whole lot easier than modding a shaper.

The tearout is going to be much reduced with the helical head in any machine.

Click to expand...

I find this too, on the Diehl lumber jointer. I haven't fit the knife jointer to it, so i don't consider the cut quality (scallops) to be adequate for other than run of the mill glue up. However, the way it will joint most figured and brash wood, with reversing grain, is, well, so to speak several cuts above my well tuned F & E jointers. The Diehl has skew knives, which translates to a helix when sharpened.

My guess is that a Shellix type would be even better due to the broken cut across the width.



smt

I will second the "nice amp!" That is some sweet work, coolidge! Tell us more!