Flattening cupped & twisted boards on thicknesser with shims

[Graham Orm]

A method I've not seen before. Anyone else tried this?

http://www.youtube.com/watch?v=S0AL3GdKfxw

 

[marcros]

No I looked at it- there is an article in one of the fine woodworking mags. The thing that put me off was the storage of the sled. There is a bit of discussion on a thread of mine somewhere, and the suggestion of a couple of alternatives. In the end- I used a router And sled for the once that I needed to flatten a wide board.

 

[Random Orbital Bob]

??? He doesn't use a sled....just paper shims and masking tape. Confused?

 

[marcros]

sorry, i didnt look at the video- i was viewing on my phone. I had assumed it was something else.

 

[Eric The Viking]

If you've got beautiful machines like those, you can do that!

I assume that nice cast iron table runs right through the thicknesser, all flat, slippery and wonderful. For the rest of us mere mortals, a sled of some sort will have to suffice :-(

I couldn't easily work to the accuracy in that video, not least because the rollers in my P/T wouldn't let me take that thin a cut. I assume that Jet has a rubber-faced feed roller (or something similarly magic). Doing cupping that way might work, but his procedure for correcting wind is rubbish for all sorts of good reasons:

• The correction needs to feather to zero in the middle, and that's assuming the wind is even along the board.
  
• It won't address lengthwise warping, as the rollers will still push the board flat against any spring.
  
• I wasn't listening to the commentary, but it *looked* like he didn't account for the thickness of the masking tape, so was over-correcting in the second part (wind).
  
• assuming decent downward pressure applied by the feed rollers, on a board that thin it would squash it down just after it ran off the tape, giving a bump in the middle. You'd have to take off more stock to eliminate that, too.

I've chocked a big oak board to flatten it on the bench with a router+trammel+surfacing cutter. It worked pretty well within the limitations of the procedure, cleanup with #5 and #7 then sent out for drum sanding. It lets you choose where in the board you get the squared final piece from - to optimise the thickness. That's similar to the advantage you'd get with a sled.

The biggest issue is that his thicknesser (planer) probably costs 20x or 30x what mine did. Not that I'm jealous or anything...

E.

PS: Is that some sort of 'special' thicknesser for cabinetmakers? If it has got rubber feed rollers, roughsawn stock might be 'interesting' in the wrong sort of way.

 

[carlb40]

Axi used to sell something very similar i think. Could be this one
http://www.jettools.com/us/en/p/jwp-15h ... ead/708543

Axi version had rollers instead of solid in/outfeed tables.

 

[Jacob]

You don't need shims to get rid of wind.
If a board is twisted fairly evenly then the middle of the board will be in the plane of the best (retaining max thickness) flat face you can get from the board.
So you start your planing in the middle of the convex side by floating it over your planer with downwards pressure in the middle, not at the ends. You thereby extend the flat centre of the board and ideally will be left with two opposite corners identically unplaned just before your last pass.

 

[Eric The Viking]

Axi used to sell something very similar i think. Could be this one
http://www.jettools.com/us/en/p/jwp-15h ... ead/708543
Axi version had rollers instead of solid in/outfeed tables.

Ah - helical head. That'll be why he can take a thinner cut - the feed rollers can use far less pressure as the actual cutting length at any one time isn't much more than a 3/8" chisel.

I saw a Hammer P/T demonstrated at Peter Sefton's open day last summer with a helical block - really elegant idea in so many ways, and the finish was outstanding.

Jacob, I see what you mean, sort-of, but it's a bit hit-miss, and it depends on the wind being even, and you *might* not choose the board from the middle (although I agree that's the most likely scenario).

E.

PS: The Jet doesn't seem to be over here, but the US price is $2,750 (plus tax and shipping), so I wasn't far off - around 20x the price of my s/h Kity if you do the typical 1:1 for the exchange rate. And the Powermatic 1791315 209HH looks oddly similar (but 20" and yellow).

 

[Jacob]

....
Jacob, I see what you mean, sort-of, but it's a bit hit-miss, and it depends on the wind being even, and you *might* not choose the board from the middle (although I agree that's the most likely scenario).....

With practice it can be spot on. Start in the middle and see how the un-planed bits are shaping up. If one end has more taken off than the other you shift the downwards pressure away from it, on the next pass. You should end up with two identical triangles at opposite corners, un-planed, which come off with the last pass.
Takes a bit of practice, as with everything.

 

[Graham Orm]

You don't need shims to get rid of wind.
If a board is twisted fairly evenly then the middle of the board will be in the plane of the best (retaining max thickness) flat face you can get from the board.
So you start your planing in the middle of the convex side by floating it over your planer with downwards pressure in the middle, not at the ends. You thereby extend the flat centre of the board and ideally will be left with two opposite corners identically unplaned just before your last pass.

Jacob are you taking planer or thicknesser? The guy in the video used a thicknesser.

 

[Jacob]

You don't need shims to get rid of wind.
If a board is twisted fairly evenly then the middle of the board will be in the plane of the best (retaining max thickness) flat face you can get from the board.
So you start your planing in the middle of the convex side by floating it over your planer with downwards pressure in the middle, not at the ends. You thereby extend the flat centre of the board and ideally will be left with two opposite corners identically unplaned just before your last pass.

Jacob are you talking planer or thicknesser? The guy in the video used a thicknesser.

Planer. The guy in the vid has one too.

 

[carlb40]

Flattening cupped & twisted boards on thicknesser with shims

Jacob are you taking planer or thicknesser? The guy in the video used a thicknesser.

Planer. The guy in the vid has one too.

](*,) ](*,) ](*,)

This was about either not having a planer or boards too wide for your planer, hence the guy only using the thicknesser.

 

[Jacob]

Flattening cupped & twisted boards on thicknesser with shims

Jacob are you taking planer or thicknesser? The guy in the video used a thicknesser.

Planer. The guy in the vid has one too.

](*,) ](*,) ](*,)

This was about either not having a planer or boards too wide for your planer, hence the guy only using the thicknesser.

My method is about using a planer over the top. The chap's planer was wide enough for the board he demo'd. Does it matter at all?

 

[Random Orbital Bob]

LOL....are you deliberately trying to confuse the issue Jacob? I don't think the US/UK terminology helps here to be honest....planar in US = thicknesser in UK.

Jointer in US = planar in UK

 

[Jacob]

:roll: OK.
He uses both machines in his demo.
He shows how to flatten a narrow board on his planar(?)/thicknesser, which he could do a lot more easily on his jointer/planer, using the method I describe.
Personally I couldn't give a f|g what he does. Carbo is easily confused isn't he! :lol:

planar in UK? News to me. Its a "planer" in the UK as far as I know. "Planar" has another meaning.

 

[Graham Orm]

The method appeals to me as I only have a little planer. I intend to try the method in the vid, for some reason I never feel comfortable sliding my hands over the planer. I've used it loads, just still wonder if this will be the time I lose some skin.

 

[Jacob]

...I never feel comfortable sliding my hands over the planer. I've used it loads, just still wonder if this will be the time I lose some skin.

I always use 2 push sticks as a matter of course. You get used to it, you feel exposed without them and they also increase your reach, dexterity and finish quality - you can pass a longer piece over the top without stopping to change hands etc.

 

[Graham Orm]

...I never feel comfortable sliding my hands over the planer. I've used it loads, just still wonder if this will be the time I lose some skin.

I always use 2 push sticks as a matter of course. You get used to it, you feel exposed without them and they also increase your reach, dexterity and finish quality - you can pass a longer piece over the top without stopping to change hands etc.

I use the pads with plastic handles like the guy in the vid. It's the potential to slip I think.

 

[carlb40]

...I never feel comfortable sliding my hands over the planer. I've used it loads, just still wonder if this will be the time I lose some skin.

I always use 2 push sticks as a matter of course. You get used to it, you feel exposed without them and they also increase your reach, dexterity and finish quality - you can pass a longer piece over the top without stopping to change hands etc.

I use the pads with plastic handles like the guy in the vid. It's the potential to slip I think.

I saw some modified ones on youtube the other week. Designed to give better grip. The guy fixed timber repair plates to the underside to give a better grip.

 

[Jacob]

...I never feel comfortable sliding my hands over the planer. I've used it loads, just still wonder if this will be the time I lose some skin.

I always use 2 push sticks as a matter of course. You get used to it, you feel exposed without them and they also increase your reach, dexterity and finish quality - you can pass a longer piece over the top without stopping to change hands etc.

I use the pads with plastic handles like the guy in the vid. It's the potential to slip I think.

I don't think they are a good idea - as you say there is the potential slip, and you have to reach past the cutters, or the saw blade on a TS. With push sticks you don't go anywhere near them with your hands, but you may keep getting the push stick ends nibbled at. Best made of wood; plastic shatters - save the plastic one as a pattern and copy it in 1/2" ply. Make half a dozen while you are at it and keep them near the machine