Author Topic: Sanding Hardwood Plywood  (Read 5467 times)

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Offline Michael Kellough

  • Posts: 3534
Re: Sanding Hardwood Plywood
« Reply #30 on: November 21, 2017, 08:19 PM »
I managed to sand through the veneer on walnut ply with an ets 150.  Maybe it was low quality ply, but although the plywood looked really flat to me it actually had high spots that burned right through.  Maybe a sander with a smaller or softer pad that would not try to flatten everything. I would not be confident using a belt sander.

In that case a soft pad and a fine abrasive (180 or more) is about all you can do with a machine.

Hand sanding is a last resort.

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Offline Steven Owen

  • Posts: 409
Re: Sanding Hardwood Plywood
« Reply #31 on: November 21, 2017, 09:12 PM »


I find it interesting you would consider using a random orbital on sheet plywood.  Most people reccomend orbital sheet sanders for the job.  My biggest concern with using a random orbital on such a thin veneer would be a higher potential for swirl marks even with a light touch.

Really?  I can't imagine wanting to use orbital over random orbital unless a delta or non-round pad is needed. I have always felt the swirl marks were more likely with orbital than random orbital. Interesting.

In any case when I use an ETS150/5 or /3 on thin veneer plywood (really thin) one pass with 180 does the job and no marks and no sanding through.

Seth

I was thinking more about human error when sanding veneers.  The rectangular shape of larger sheet sanders force you to stay with the grain when sanding. 
Festool CT Midi, Festool ETS 125, DF 700 Domino Coming Soon

Offline Cheese

  • Posts: 4944
Re: Sanding Hardwood Plywood
« Reply #32 on: November 21, 2017, 11:03 PM »
I find it interesting you would consider using a random orbital on sheet plywood.  Most people reccomend orbital sheet sanders for the job.  My biggest concern with using a random orbital on such a thin veneer would be a higher potential for swirl marks even with a light touch.
I was thinking more about human error when sanding veneers.  The rectangular shape of larger sheet sanders force you to stay with the grain when sanding.

Large 1/2 sheet sanders are great for keeping a large surface flat when you have a lot of resawing/planer marks to remove. However, when the surface is already flat they really don't offer any additional magic that any 125/150 sized ETS EC type sander can provide. Using fine grit papers, the dwell time over any specific spot is really minimal because the area is already flat and the surface is already relatively smooth. The veneered ply you're purchasing doesn't have a 40-80 grit surface finish, if it did you probably wouldn't purchase it in the first place.

Per the random orbital swirl mark observation, a random orbital sander in woodworking vernacular, is also known as a DA (dual action) sander in the automotive finish trade. I purchased my first pneumatic, National Detroit DA version in the late 60's or early 70's and still own it. The DA sander has been the go to sander for the automotive/motorcycle paint restoration business for the last 50+ years. As far as I know it may still be...unless laser surface treatment techniques suddenly became more popular when I walked away from the computer and took the dog for a walk.  If so...that'd be cool.  [cool]

What other, more highly defined surface, is offered to the general public than the painted surface of a new automobile?  Be it a Suburu or a Mercedes, what surface is smoother, has virtually no orange peel and exhibits no swirl marks than a new automobile?  These surfaces were probably prepped using DA sanders.

In wood working semantics we refer to them as "piano finishes" or "polished lacquer" finishes, when in reality we are really trying to replicate automotive type finishes on wooden materials.  [tongue]  And we are using random orbital sanders to produce that finish.

Whoops...I forgot to include these photos. Maple ply, purchased from the cheapest-of-the-cheap big boxes, Menards. Sanded with a ETS EC 125 wearing a 150 sized pad, using 240 Granat and finished with 3 coats of GF water based clear poly, hand sanded between coats with Festool 400 grit foam backed squares.     
« Last Edit: November 22, 2017, 12:34 AM by Cheese »

Offline Steven Owen

  • Posts: 409
Re: Sanding Hardwood Plywood
« Reply #33 on: November 22, 2017, 01:07 AM »
I find it interesting you would consider using a random orbital on sheet plywood.  Most people reccomend orbital sheet sanders for the job.  My biggest concern with using a random orbital on such a thin veneer would be a higher potential for swirl marks even with a light touch.
I was thinking more about human error when sanding veneers.  The rectangular shape of larger sheet sanders force you to stay with the grain when sanding.

Large 1/2 sheet sanders are great for keeping a large surface flat when you have a lot of resawing/planer marks to remove. However, when the surface is already flat they really don't offer any additional magic that any 125/150 sized ETS EC type sander can provide. Using fine grit papers, the dwell time over any specific spot is really minimal because the area is already flat and the surface is already relatively smooth. The veneered ply you're purchasing doesn't have a 40-80 grit surface finish, if it did you probably wouldn't purchase it in the first place.

Per the random orbital swirl mark observation, a random orbital sander in woodworking vernacular, is also known as a DA (dual action) sander in the automotive finish trade. I purchased my first pneumatic, National Detroit DA version in the late 60's or early 70's and still own it. The DA sander has been the go to sander for the automotive/motorcycle paint restoration business for the last 50+ years. As far as I know it may still be...unless laser surface treatment techniques suddenly became more popular when I walked away from the computer and took the dog for a walk.  If so...that'd be cool.  [cool]

What other, more highly defined surface, is offered to the general public than the painted surface of a new automobile?  Be it a Suburu or a Mercedes, what surface is smoother, has virtually no orange peel and exhibits no swirl marks than a new automobile?  These surfaces were probably prepped using DA sanders.

In wood working semantics we refer to them as "piano finishes" or "polished lacquer" finishes, when in reality we are really trying to replicate automotive type finishes on wooden materials.  [tongue]  And we are using random orbital sanders to produce that finish.

Whoops...I forgot to include these photos. Maple ply, purchased from the cheapest-of-the-cheap big boxes, Menards. Sanded with a ETS EC 125 wearing a 150 sized pad, using 240 Granat and finished with 3 coats of GF water based clear poly, hand sanded between coats with Festool 400 grit foam backed squares.   

All good points.  I’ve always tried to understand the purpose of sheet sanders and where they fit in.  If you had a Rotex with a hard pad, would it not erase the need for sheet sander?

The goal many of us have with hardwood plywood is not making it look like it’s plywood for a laugh. You want to stain hardwood plywood to blend seamlessly with the solid wood elements in a product.  You don’t want the client to look at a finish thinking it looks like plywood.

Festool CT Midi, Festool ETS 125, DF 700 Domino Coming Soon

Offline Holmz

  • Posts: 4010
Re: Sanding Hardwood Plywood
« Reply #34 on: November 22, 2017, 02:48 AM »
Personally I think that a belt sander , even with depth control frame, is just asking to sand through the veneer.

In general it just doesn't need much sanding.

Seth

It does seem counter intuitive.
Which is where some factual evidence is worthwhile. (which I do not have).


Hey Holmz, I wouldn’t let a belt sander get within 20’ of the veneered ply. The maple ply I’m using now has a veneer that is less than .020” thick, that is under .5mm. It doesn’t take much of a whoops moment to suffer a catastrophic result.

As others have said, the ply is very smooth in the as-purchased condition and only needs a quick “kiss and a promise” to prepare it for finishing. I own a RS 2 and I wouldn’t even consider breaking it out for sanding ply. The ETS EC or the Mirka of your choice would also be my choice. Maximum material removal is probably in the .001”-.002” range, likely much less than that. We’re not trying to remove planer blade marks.

However if you’re trying to remove an applied finish from the ply, then that’s a different story.

Well how is plywood made?
And how are veneers made? and how are their surfaces prepared?
Whether or not knowing that has any bearing, I am not sure.

As the frame can be adjust to not even touch the belt to the wood means that the only place for possible trouble is at the edges.


...
All good points.  I’ve always tried to understand the purpose of sheet sanders and where they fit in.  If you had a Rotex with a hard pad, would it not erase the need for sheet sander?
....

A >4" by >8" surface with the mass over the top of it... is less prone to wavyness than a5" circle with a handle hanging off the back.

I will often use 80 or 120 to flatten with a 1\2-sheet, and then bust out the DEROS (180/240) to make it smooth when on solid wood .

Offline McNally Family

  • Posts: 614
  • Festool Atomic Phaser Particle Blaster (APPB Set)
Re: Sanding Hardwood Plywood
« Reply #35 on: November 22, 2017, 07:35 AM »
I managed to sand through the veneer on walnut ply with an ets 150.  Maybe it was low quality ply, but although the plywood looked really flat to me it actually had high spots that burned right through.  Maybe a sander with a smaller or softer pad that would not try to flatten everything. I would not be confident using a belt sander.

Here are the hand sanding block products I like to use, particularly between coats of finish.  No electricity required, other than what is needed to run my CT26.  It also helps that I own the correct size sandpaper for these tools:

Festool 496963 115mm X 226mm Hand Sanding Block
http://www.bobmarinosbesttools.com/hand-sanding-block-115mm-x-226mm/p/496963/

Festool 496962 80mm X 130mm Hand Sanding Block
https://www.festoolproducts.com/festool-496962-hand-sanding-block-80mm-x-130mm.html

Festool 495019 Hose HSK D21.5 5m
https://www.festoolproducts.com/festool-495019-hose-hsk-d21-5-5m.html

Festool 498527 Plastic Universal Brush Nozzle
https://www.festoolproducts.com/festool-498527-universal-brush-nozzle.html
GREEN: In order of purchase = | CT26  |  RS 2 E | Hose w/ Sleeve 3.5m | 115mm X 226mm Hand Sanding Block | 80mm X 133mm Hand Sanding Block | HSK D21.5 5m hose | CT Boom Arm Bundle Set | 1080 Plate for custom MFT | OF 1400 EQ Router (metric) w/accessories | SYS-Rock BR10 | Cordless Sander RTSC 400 Set |  Cordless Delta Sander DTSC 400 Basic | Linear Sander LS 130 | PDC 18/4 set | CXS  2.6Ah Set | Installer Cleaning Set (2018 version) |  New style Festool hose D 27/32 x 3,5m AS/CT | Replacement Hose Garage | Remote control CT-F I/M-Set | MFH1000 work stool | Next purchase: TBD

RED: // Mafell P1cc  //  MT55cc  // Next purchase: TBD

Offline kcufstoidi

  • Posts: 768
Re: Sanding Hardwood Plywood
« Reply #36 on: November 22, 2017, 07:43 AM »
Personally I think that a belt sander , even with depth control frame, is just asking to sand through the veneer.

In general it just doesn't need much sanding.

Seth

I’d also think increase caution in handling and storing the plywood plays Big roll too.  I was thinking of keeping a roll of thin packing styrofoam to protect the sheets to prevent adding problems and scratches through mishandling.

If I plan to make a side business building wall mounted TV stands, I have to consider clever ways of reducing the weight for wall mounting to make the stand easier to lift and mount.  A combination of solid hardwood top and Hardwood plywood seems the way to go. 

I wonder how restistant an MDF core would be to warping under wieght.  High end audio equipment can add 250-400 lbs to a stand depending the set-up. MDF on it’s own can warp when a heavy load is not balanced well.  You see MDF warps in around the lift system Router tables all the time when the MDF cannot be reinforced.

 In my experience building custom units for the last 15 years proper design and construction methods are essential when using any material. Any veneer with a core material will sag whether its hardwood or not. For what you just said about the units you're going to build off the shelf material is going to be disappointing. Custom laid veneers matched to the hardwood components on an FX, classic or MDF sandwich core would give the best results. Again in my experience your goto sander would be something with similar specs to an ETS 150/3, its an easy to use relatively light unit that does not give swirls if used properly.