Rough finish round knots when planing? Avoidable?

[julianf]

Hello,

I probably need to take a photo to explain better, but im trying to get a better finish around knots etc when planing.

Im only using rough wood for practice, which may be the issue, but i want to be sure.

It looks like the surface has been roughed up around the knots, rather than planed. As if the blades have scuffed at the surface, rather than sliced it. There are also points where it looks like the wood has caught, and the blades pulled out small chunks, rather than sliced.

This is on a thicknesser, and the blades seem sharp enough, so im wondering if its just low quality wood (im just using scrap whilst learning)


Is this something that can be resolved by taking off more and more material, or am i cutting too deep, or is it just the wood, and its unresolvable?

Ill see if i cant take some photos and post them up tomorrow.


(im new to woodworking - im more used to metal - cnc engraving mainly)

Thank you,
Julian

 

[MikeG.]

Welcome, Julian.

That's tear-out, and it can occur whenever the grain is in the wrong direction in relation to the plane (or planer, or thicknesser) blade. You may just have learnt an important lesson with woodworking: it's never just as simple as pushing the wood into a machine!!

There are lots of ways around this issue, including judging grain direction or using sharp well-tuned handtools, but at the beginner stage you may just be better off making sure that you don't use wood with knots or problematic grain.

PS I don't think you will be able to post photos until you have a certain (small) number of posts here. It's a bot and spammer defense thing, apparently. But don't worry, every single woodworker here is extremely familiar with the issue you raise, I promise. We've all done it.

 

[dzj]

Slower feedrate, sharp blades and light passes.
Not much else you can do.
Following-up with a sharp, properly set up smoothing plane will deal with tear-out.
Some people prefer using a belt or random orbital sander.

 

[julianf]

Thank you both.

It seems that you both know exactly what im talking about, so no need of photos.

I have no hand plane (as i say, im just starting) but will try taking as shallow a cut as possible with the thicknesser - it is a basic unit, so no feed rate control. I do have Mirka DA sander, so i will see if cant finish up with that when i get it close enough.

Im not specifically trying to make anything yet, but more experimenting with technique.

Thank you.

 

[Yojevol]

It reminds me of the first lesson in the furniture making course many years ago. The lecturer likened it to stroking a cat. You always stroke it in the right direction otherwise you end up with a scraggy looking cat.

 

[ED65]

Slower feedrate, sharp blades and light passes.
Not much else you can do.

There is one other thing you can try and that's to dampen the wood right before sending it through. This trick is also useful when hand planing for the knots themselves, because knots can be very hard and brittle they crack or crumble easily even with a just-sharpened iron in the plane.

I do have Mirka DA sander, so i will see if cant finish up with that when i get it close enough.

In case you haven't read this yet you should expect to have to sand after you run the wood through a planer, even a much better one. Additionally, after power sanding you should finish sanding by hand in the direction of the grain with the paper backed by a sanding block.

As an alternative to sanding you can use a scraper, and scraping is something well worth learning to do early on and not later after you've become accustomed to sanding. Getting into scraping early you'll save yourself buckets on sandpaper and your working area will be quieter and much less dusty, the way God intended

 

[Bodgers]

With cheap SPF in my experience, it is never going to be fantastic. Pine knots are just ugly IMO.

I have just built some workshop cabinets and I did the face frames and door frames from pine. I basically just worked all the knots out by resawing all the pine down the middle rotating and laminating back together again so you end up with a straight grained quarter sawn look with virtually no knots. What knots were left I cut out.

It is the same trade off - spend time or spend money. More money - spend it on better wood, more time - spend it working you way around defects.



Sent from my MI 3W using Tapatalk

 

[julianf]

I will try the wetting thing.

Where im at at present is that ive tried to make a laminate from a number of 15mm ish sheets. The sort of thing that people do when they're starting off end grain chopping boards (but that's not what im trying to do - im not really trying to do anything yet, except learn)

Like a beach block kitchen counter sort of thing, but starting with rough old hardwood (and much smaller).

I did not sand the inner boards before gluing.

It does not look so bad, but the boards, after re-planning, have dirty looking lines where the joints are.

Im doing this like a total heathen, and there are a number of things i know are wrong, but im wondering which is affecting it most -

a) boards not having a great finish before gluing - i thought id put the worst in the center, and i think that may be most of my issue
b) glue was whatever i had about the place (ie some pva more suited to sealing plaster)
c) short overnight clamping
d) incorrect clamping procedure (a couple of g lamps and a vice)

Please forgive me - like i say, im normally doing industrial engraving, so i do understand that you cant bodge things and hope for a good finish, but im just trying stuff at the moment really.

Obviously all the points above would need addressing, but where would i get the greatest gains?

 

[julianf]

Hey, i think ive made enough posts for photos now, so here are a couple (you will have to hit the links, given the photobucket situation)

These are just bits of hardwood pallet. I know you cant make a silk purse from a sows ear (without a lot of effort) but i dont really want to make a mess of nicer wood just yet.

Besides, i actually like the visuals of the knots and nail holes, but i know it makes things more awkward -

http://i1277.photobucket.com/albums.../IMG_20171121_100909_zpsxmpavghf.jpg~original

http://i1277.photobucket.com/albums.../IMG_20171121_100817_zpstuvsqdws.jpg~original

 

[Bodgers]

Hey, i think ive made enough posts for photos now, so here are a couple (you will have to hit the links, given the photobucket situation)

These are just bits of hardwood pallet. I know you cant make a silk purse from a sows ear (without a lot of effort) but i dont really want to make a mess of nicer wood just yet.

Besides, i actually like the visuals of the knots and nail holes, but i know it makes things more awkward -

http://i1277.photobucket.com/albums.../IMG_20171121_100909_zpsxmpavghf.jpg~original

http://i1277.photobucket.com/albums.../IMG_20171121_100817_zpstuvsqdws.jpg~original

Pallet wood is even worse than carcassing SPF. Not to mention the fact that a lot of it is heavily treated and toxic.

If you have large glue lines then it's one or both of:

- your glued edges are not straight and smooth enough.

- not enough and/or uneven clamping pressure.

Make sure the faces you are laminating together are smooth and can be placed against each other with zero gaps before glueing. Plane the edges you are glueing together to get them consistent.

Clamp evenly and firmly across each lamination.

If after that it is still bad then ditch the pallet wood!


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[julianf]

Thank you.

Ill give it another go. I have some nice wood stashed away, but id rather learn on something thats both disposable, and brings out the issues quicker. Im a fan of the "previous life" look, in moderation, too.

eg -
http://i1277.photobucket.com/albums...loor boards/DSCF7582_zps33d2eb1e.jpg~original
http://i1277.photobucket.com/albums...loor boards/DSCF7579_zps5ee9786d.jpg~original

(one day ill re-finish them in something more durable than wax - they look nice when just done, but dont stay shiny for long)

Ill try again later if i can find some more hardwood strips.

 

[DBT85]

Julian, have a look at Paul Sellers on Youtube. He has a plethora of videos that will really help. Even just his latest video about making a laminate for a workbench will cover what you want for your laminations.

I think he'd probably say try a cabinet scraper for the nasty bits of grain as it apparently can always cope where even the finest set sharp plane won't.

 

[ED65]

a) boards not having a great finish before gluing - i thought id put the worst in the center, and i think that may be most of my issue

Yes, never do this. Apart from leaving ugly dark lines only clean wood glues properly.

A badly compromised glue joint can open up on its own just from natural movement in the wood over time.

b) glue was whatever i had about the place (ie some pva more suited to sealing plaster)

That might actually be all right since white PVAs are mostly very similar at heart, just watered down to varying degrees. But probably advisable to pick up some purpose-made woodworking glue fairly soon.

c) short overnight clamping

Short and overnight... does not compute :lol: If the temp isn't too low overnight is fine for clamps to stay on. Much better to wait too long than to take clamps off too early, so if you want to err one side or the other then don't have any qualms about waiting a bit longer.

d) incorrect clamping procedure (a couple of g lamps and a vice)

This may also be an issue if max joint strength is desired since PVAs need high clamping pressures to work well (and that's even with dead-smooth surfaces).

G-clamps are capable of exerting very very high clamping pressures indeed so they are perfectly fine to use, but you need a fair few of them to apply sufficient clamping force across longer pieces.

 

[ED65]

Not to mention the fact that a lot of [pallet wood] is heavily treated and toxic.

It is good to be cautious with pallets but most over here are untreated.

I think he'd probably say try a cabinet scraper for the nasty bits of grain as it apparently can always cope where even the finest set sharp plane won't.

He would indeed but he's copping out There are many things Paul Sellers won't plane that are easily planable, if the plane is set up the right way.

That's not to say every piece of wood can be planed 100% tearout-free without any regard to grain direction, but you can get darned close if you use the cap iron the way it's intended to be used.

 

[MikeG.]

..... if you use the cap iron the way it's intended to be used.

You've said this twice now. Could you expand?

 

[DBT85]

I think he'd probably say try a cabinet scraper for the nasty bits of grain as it apparently can always cope where even the finest set sharp plane won't.

He would indeed but he's copping out There are many things Paul Sellers won't plane that are easily planable, if the plane is set up the right way.

That's not to say every piece of wood can be planed 100% tearout-free without any regard to grain direction, but you can get darned close if you use the cap iron the way it's intended to be used.

haha. I'll let you tell him

I assume the reason a scraper does so well is the angle of the blade? I know nothing, let it be known.

Also could you elaborate?

 

[Woody2Shoes]

..... if you use the cap iron the way it's intended to be used.

You've said this twice now. Could you expand?

I think this video illustrates what ED65 is alluding to:

https://www.youtube.com/watch?v=1bhh6kxXZOQ

Cheers, W2S

Also: http://www.smallworkshop.co.uk/2016/02/ ... -cap-iron/

 

[dzj]

Slower feedrate, sharp blades and light passes.
Not much else you can do.

There is one other thing you can try and that's to dampen the wood right before sending it through. This trick is also useful when hand planing for the knots themselves, because knots can be very hard and brittle they crack or crumble easily even with a just-sharpened iron in the plane.

Yes, a trick also used by carvers when working on end grain. Some use alcohol or paint thinner as it evaporates more quickly.
Still, it's always a bit of a toss-up when machining wood.
If one is particularly enamored with a knotty board and a bit of tear out is out of the question, use a hand plane.
Or a drum sander.

 

[DBT85]

..... if you use the cap iron the way it's intended to be used.

You've said this twice now. Could you expand?

I think this video illustrates what ED65 is alluding to:

https://www.youtube.com/watch?v=1bhh6kxXZOQ

Cheers, W2S

Also: http://www.smallworkshop.co.uk/2016/02/ ... -cap-iron/

Ahh excellent. Thanks!

Also answers my earlier question about a cabinet scraper, it does indeed look like having that high angle is what deals with the fiddly grain.

 

[ED65]

..... if you use the cap iron the way it's intended to be used.

You've said this twice now. Could you expand?

The cap iron's main role is to prevent tearout when set close enough to the cutting edge for the job at hand. The grain largely determines how close it needs to be set, the hardness of the wood and the strength of the user determine how close it can be set because it increases planing resistance.

With easy-planing mild wood you can set the cap iron well back and take thick shavings without any problems, with difficult wood e.g. where there's reversing or emerging grain it needs to be set close or very close to work as intended and the shavings get thinner. Occasionally though there's no option but to plane the surface as well as you can using fine shavings and then use a scraper or sanding to complete the surface sans tearout.

How close is "very close" is one thing that's been discussed to death in threads all over, while it's fairly easy to experiment with and find out what works and doesn't (as you set it closer step by step and take successive passes the tearout gets visibly less and less until it disappears 98-100%) to give a basic starting point:

• "set well back" is roughly 3mm or 1/8" in old money, no point in setting it any further back than this and many times the range of adjustment on a metal bench plane won't allow much more than this anyway
• close is in the region of 1mm, less than 1/16"
• very close is under 1mm, 1/32"
• "as close as possible" is 0.3mm, approx. 1/64", and under

There's loads of previous discussion over the past two years on this in the Hand Tools forum if anyone wants more depth and some historical perspective.

An interesting sideline to this is trying to discover when (not if as some contend) the proper use of the cap iron fell out of general knowledge. Despite clear instructions being given in numerous written sources it was not universal practice to use the cap iron this way, as clearly illustrated by some old hands like Paul Sellers not using it so.

What's more odd is it didn't become less well known in the distant past, books and booklets published through the 70s had some clear instructions and very clear guidelines are written in plain English in one of Robert Wearing's books first published in the 80s I think. But it's clear that some time before this it wasn't universally known and that by the Internet age the knowledge of it was largely lost.