MDF or Baltic Birch torsion box top?

[Jon Steffen]

I'm building a 4x8 torsion box top for my assembly table. I'm going to be drilling 20mm holes with a Parf Mark 2 system.

The inside grid will be baltic birch.



Should I make the top and bottom out of mdf for super flatness, or should I go with Baltic Birch that's lighter, less noxious dust?

[Jon Steffen]

I forgot to mention I'll glue and pocket hole screw is together.

[Jon Steffen]

What do you think of just screwing the top down, and no glue so the top can be replaced?

The rest would still be glued and screwed.

[Eric Arnsdorff]

My choice is the Birch. I actually used Birch and oak to build up a thicker top then put an 1/8” sheet of hardboard on top. I waxed it and I’m very happy with it. I’ve done that for my work table and my table saw extension table which also supports my router table.
I can see either but I’m not a fan of working with the MDF and it is heavy if weight is an issue. I’ve used it before and it does have some benefits. So either isn’t a bad choice.

[Jim Matthews]

If you already have stock, either material will do.

If not, Plywood is more resistant to abuse and can be assembled with only glue and pin nails.

Plywood will also readily accept the occasional screw for clamping fixtures, etc.

https://www.canusawood.com/premcore

[Kevin Jenness]

For maximum strength and torsional rigidity, glue both sides to the core. You can add a sacrificial top layer.

If the plywood is reasonably flat to start with and held down to a flat surface when glued up the torsion box should come out as flat as if made with mdf.

[ChrisA Edwards]

If you plan on using clamps that go through the bench dogs holes, your top is pretty much limited to 3/4" or the clamps will not fit through, so be careful with the idea of a sacrificial top as an add on layer.

When I redo my bench, I will make the top a torsion box with the lower flat glued to the inner skeleton, but will screw the top on as it will be sacrificial with bench dog holes.

Using either plywood or MDF, at 4' x 8', with either material, that torsion box will be heavy. I might be inclined to use a sheet of melamine for the top as it's easy to clean glue and other spills off.

With a removable/replaceable top, if you use one material and don't like it, it relatively cheap to replace it.

[Jim Becker]

MDF for me.

[Mark Carlson]

I'm planning to do the same. Its 3/4 in mdf for me. Planning on biscuits for outside for alignment and glue and 18 gauge brads. Thinned down poly for the top. My main goal is flat so mdf. If I wanted mobility I'd go with 1/2 ply.

[Jon Steffen]

If you plan on using clamps that go through the bench dogs holes, your top is pretty much limited to 3/4" or the clamps will not fit through, so be careful with the idea of a sacrificial top as an add on layer.

When I redo my bench, I will make the top a torsion box with the lower flat glued to the inner skeleton, but will screw the top on as it will be sacrificial with bench dog holes.

Using either plywood or MDF, at 4' x 8', with either material, that torsion box will be heavy. I might be inclined to use a sheet of melamine for the top as it's easy to clean glue and other spills off.

With a removable/replaceable top, if you use one material and don't like it, it relatively cheap to replace it.

life is a compromise, so I think i'm going to go the same route and do a glued bottom skin/inner skeleton setup, but the top will only be screwed down in MDF. if the skeleton frame isn't flat, glue and screws wont make the top flat.

If the skeleton frame is flat then an mdf top screwed down should be pretty darn flat, AND i can replace it.

Onto my next question. I'm going to wrap the box in maple I think. I want to drill 20mm dog holes around this perimeter.

1.How thick should I make the perimeter pieces so I don't worry about them splitting if some force is applied to the dog holes for clamping?

I'm thinking if the outside board is clamped inward towards the table, it doesn't need to be that thick, but if I ever applied pressure outward against a dog there, its possible it could split.

2 more questions.

I will be using through clamps on the table, like the Festool ones, but on the boarder I won't. I've read some people drill a hole all the way through the boarder board, this seems unessesary, but would help so wood dust/chips don't fill those holes.

2. Do you guys think I should drill all the way through the boarder board?
3. Does mdf come square from the factory, or do you still need to cut the edges to make sure its square?

[Dan Chouinard]

1/2" mdf on mine with plenty of glue. 1/8" hardboard sacrificial top that is 8 years ish old and still good as new

[ChrisA Edwards]

I would drill all the way through on both the top and the side boards.

I would use 3/4" Maple. You could use thicker, but I would hollow out the back to allow the Festool clamps to be used on the side as well.

Just plan where the bench dog holes need to go and draw out your skeleton placement to give you the maximum use of the through clamps.

[Jon Steffen]

I would drill all the way through on both the top and the side boards.

I would use 3/4" Maple. You could use thicker, but I would hollow out the back to allow the Festool clamps to be used on the side as well.

Just plan where the bench dog holes need to go and draw out your skeleton placement to give you the maximum use of the through clamps.
you think 3/4" maple with a 20mm hole drilled through it would be thick enough? I was thinking 1.5" of maple with the 20mm hole in the middle of it.

I like your idea on the hollow out back side idea.

[Jon Steffen]

1/2" mdf on mine with plenty of glue. 1/8" hardboard sacrificial top that is 8 years ish old and still good as new
Ha, so in all likelihood I don't need a sacrificial top, because if I get 8 years out of one side, I can just flip it over have a fresh top. If I design it right that is.

[Corey Pelton]

Double up the top with 3/4 BB. Add a 1/4” mdf overtop that if you need something replaceable.

[John M Wilson]

Just did this a couple of months ago for my new "Paulk style" workbench top. I used 3/4" birch ply for the top, screwed on for when I want to replace it. I also used the Parf system for drilling my holes in the top, which worked out great. I left the bottom (glued on) as a solid surface for an assembly table. One thing which I realized about 1/3 of the way through drilling all the holes in the top is the horrible blow-out when the drill went through the last layer of the ply -- I started using a clamped-on backer board, but still got mediocre results.

On my next top, I'm definitely going to drill the holes before attaching it, and use a proper backing board. MDF is probably more forgiving, since the ply I used just looks terrible when I have the thing flipped over in assembly table mode (even though I am the only one seeing it, and you have to look inside at an angle, it still bothers me.) With one sheet each of 3/4" birch ply for the top & bottom (and 1/2" for the webbing), the table is still light enough for me to pick up, maneuver around, and flip without too much difficulty. I'm not sure if the added weight of MDF would make it unwieldy. The top is flat enough for my purposes (I can't see a light underneath a 4' level, but it's not surface table flat.)

Hope you have much success!

[Jon Steffen]

Just did this a couple of months ago for my new "Paulk style" workbench top. I used 3/4" birch ply for the top, screwed on for when I want to replace it. I also used the Parf system for drilling my holes in the top, which worked out great. I left the bottom (glued on) as a solid surface for an assembly table. One thing which I realized about 1/3 of the way through drilling all the holes in the top is the horrible blow-out when the drill went through the last layer of the ply -- I started using a clamped-on backer board, but still got mediocre results.

On my next top, I'm definitely going to drill the holes before attaching it, and use a proper backing board. MDF is probably more forgiving, since the ply I used just looks terrible when I have the thing flipped over in assembly table mode (even though I am the only one seeing it, and you have to look inside at an angle, it still bothers me.) With one sheet each of 3/4" birch ply for the top & bottom (and 1/2" for the webbing), the table is still light enough for me to pick up, maneuver around, and flip without too much difficulty. I'm not sure if the added weight of MDF would make it unwieldy. The top is flat enough for my purposes (I can't see a light underneath a 4' level, but it's not surface table flat.)

Hope you have much success!
I'm glad to hear I'm not the only one that gets annoyed by minor mistakes that only I know about.

[Jon Steffen]

Have you ever heard of Xtira MDF? .
Looks like its made with an exterior moisture resistant glue. Would this make it resistant to wood glue? I'm calling them tomorrow.
https://miratecextira.com/extira-exterior-panels/
438100

Its $60 a sheet, but for my torsion box top, might be sweet.

[Jim Becker]

$60 for a sheet of Extera is a pretty good price, Jon. (.75") And yes, the benchtop inserts on my guitar bench as well as the top for my auxiliary bench are Extera. Yes, it's water resistant. No, it' not glue resistant. You sill will want to put a finish on it to help with that. Guitar bench has oil. Auxiliary bench has "left over oil based poly".

[Jon Steffen]

$60 for a sheet of Extera is a pretty good price, Jon. (.75") And yes, the benchtop inserts on my guitar bench as well as the top for my auxiliary bench are Extera. Yes, it's water resistant. No, it' not glue resistant. You sill will want to put a finish on it to help with that. Guitar bench has oil. Auxiliary bench has "left over oil based poly".
Bummer, perhaps the malamine mdf cored top with a finish on it will be best for glue resistance then?

[Jim Becker]

Melamine is inherently glue resistant, at least for PVA type glues, but it's still best to wipe it off at first opportunity.

[ChrisA Edwards]

Also, when I'm doing a glue up, where I know I'm going to get drips that I can't get to, I'll put a layer of parchment paper down. That keeps the mess off my work tops. This is especially true for cutting boards where you have a lot of glue lines, but really want to reference the flatness of the assembly table.

[Kevin Jenness]

With melamine and laminate work surfaces I find it easiest to keep them waxed and pop glue drips off with a scraper once cured.

[Will Blick]

some great input here... these projects require a lot of planning and foresight. i did the same, and it was no easy task... but maybe I did not think things through as well as you are. Starting here was a great idea.

To make the torsion 4x8 FLAT, how will u do this? long straight edge references? Straight on one plane is NOT FLAT over the entire surface. You can just imagine all the scenarios of square and straight, but NOT flat. Square is easy, Flat is not... I am big on FLAT surfaces. MDF will "give" or conform to the flatness of your torsion box. I would love to read a good article on how to build a large FLAT torsion box dead FLAT. Not sure what reference to use that is larger than the 4x8 to assure the torsion box is FLAT on top. a 5x10' Flat Granite surface would be NICE! ;)

When you build your torsion box, remember, to fine tune it to flat, you might be hand planing areas a few thou here and there...MDF does not plane... BB does with a sharp blade.

I went with 1/2" MDF top x 2, the top sheet being sacrificial. Only the Festool right angle clamps seem to require 3/4" max thickness top to insert, which I dont use, all other components, I have NO issues. So many great 20mm clamp accessories available today, many from UJK in the UK, which I order from. To replace the top sacrificial panel, I use the panel below as the new guide to drill holes for perfect alignment, so no need to return to the Parf II system (PITA) which I used to drill the original holes, i.e. both 1/2" sheets secured together to act as a 1" sheet. I nail the edges down mostly at the corners of the MDF to the torsion box, so I dont hit nails while using the Festool saw. it works pretty good... not much pull up. If you dont plan to use the top to cut with track saws, this is a non issue and I agree, secure it everywhere.

As for the finish, love that water resistant MDF shown above, never knew about that before, damnit, I would have used it. I went with a black matte dye mixed with water based poly.... many many coats, sand, re apply etc. Matte finish... the look is superb, however, water still seems to penetrate to the MDF...so next time, I would use the water resistant MDF and do the same.

Also.... The Parf II system is quite the novel invention. I had to return a few parts as they were not SPOT on which will throw off square. I finally ended up with what appeared to spot on sticks. I was meticulous in using the Parf system, took me forever... while the holes are damn good (as for square) considering the relatively low price of the Parf system, dont expect perfection, specially over 4x8'. Errors magnify over distance. Again, this assumes squareness of the holes matters to you... if only clamping, not an issue. But if you plan to use it as a fast cutting station, well then it does matter. After you are done, use the large Woodpeckers squres to check for square, if you are good at right angle math, you can easily determine how out of square you are... or use the 5 cut method, many videos on this, even by Peter Parf himself.

Another thing I learned after the fact was... a few companies make "lifters", prob. not the proper name... which allows all the tracks to lift up 5mm IIRC, to place a 5mm sacrificial cut sheet under your stock and cut lines, this prevents cutting through your Parf top and avoid drilling all those holes again and again.... I would re consider this next time for sure. I bought some of them to experiment from a company that 3d prints all these 20mm components.

The other lesson I learned is... 3/4" MDF is the material on the Festool tables... but remember, these are for field use, light weight fold-able, etc. But for fixed shop use, if you go with 3/4" use something super strong, such as ultra dense MDF or as u suggest BB Ply.... When mounting some bolted clamps in, i find a 1" top much more robust, it resist buckling. Of course, how tight your torsion box is, and how close the fasteners are that secure the top mattes here. AGain, if you plan to cut through the top, u must be careful with fastener locations, put them where you wont cut them, so less secure to the torsion box.

My other lesson learned... on my front apron, which I use waaay more than I thought for holding long boards for edge planning... USE 1" heavy duty BB ply for sure! 3/4" can get sloppy with all the holes you drill to have the ideal hole in the right place for fast and perfect board placement. I under estimated the value of the apron, I use it as much as the top.

Lots of improvements if I ever build my second table. Quite the project...

[Frank Pratt]

Just another plug for water resistant MDF. The brand I use is Medex. Superior to the standard stuff in every way. For the little bit of MDF I use, I only buy Medex anymore.

[Will Blick]

thx Frank
where do u buy this Medex?
Does it machine like MDF or more difficult I assume?
Does water bead off it?
Do u still finish it ?

[Frank Pratt]

thx Frank
where do u buy this Medex?
Does it machine like MDF or more difficult I assume?
Does water bead off it?
Do u still finish it ?

PJ White Hardwood or Windsor Plywood in Calgary. Water mostly beads up but with extended exposure, the surface will wet. The stuff isn't intended for prolonged submersion. I left a piece underwater for a week and there was some swelling at the very edges. For exterior use, they recommend sealing cut edges with something like epoxy before painting.

Glue bonds very well with it. It machines just like regular MDF. But edge delamination is not nearly as much of an issue. It's also a fair bit stronger.

[Don Stephan]

Perhaps I'm too old and uneducated, but for me an assembly table does not get holes drilled in it, which could get glue along their edges. When gluing I use clamping cauls and bar clamps, and check for square by measuring the diagonals. Planing faces and edges is done on a Klaus style workbench.

My assembly table is a torsion box, with a 1/4" x 4' x 8' melamine foil sheet lightly screwed to the top of the torsion box. I did wonder if the foil surface would be durable enough, but after about 6 or 8 years it is still in good condition.

[Kevin Jenness]

Ian Kirby wrote a how-to article on torsion boxes back in 1982 in FWW # 32, well worth looking up.

I worked for 25 years on a 4' x 8' table with a core of basswood 5/16" x 3 1/2" strips about 4" on center and skins of 1/4" luan plywood with hpl surfaces. It sits on supports within 16" of the ends and 8" from the edges. If your support is smaller you may need to add strongbacks or make the box a little thicker. Mine is a little shabby from errant sawcuts and mallet blows, but still serviceable and flat overall, and can be moved by one person easily, probably 70 lbs or so. I think about 4" thick is about right for a really stout work surface that will remain flat no matter what it is set on. If you are going to drill holes through it you should lay them out to avoid the core grid. Any spots that need more solidity for fastening can get a filler block.


I have found it a little easier to assemble a core of halflapped continuous strips than stapling numerous individual pieces. The hardest part is making the first table flat. Mine was second generation, clamped with cauls to a torsion box that was assembled on a 3x6 cast iron machinist's setup table. After that it is easy to breed more with the "beast with two backs" technique. If you want to screw to your worktop you will want thicker skins, in which case you can go with larger spacing in the core grid. The core merely transfers shear stresses to the skins, so tight joinery in the core is not important, just sufficient glue surface to keep the skins together.

I have a lighter worktop that I pull out of the plywood rack for occasional use about 42" x 90" x 2 1/4" thick with 1/4" lauan skins. It's not perfectly rigid torsionally but if the horses under it are level it is good for veneering or cabinet assembly.

The key to getting a flat surface is to start with one and clamp to it. You can make a carefully levelled base with freshly milled 2x4's or the like, but it is best to clamp the new assembly to the base no matter how you assemble it. Just laying one skin on the base and pocket screwing the core elements to it won't ensure that everything is in plane. A set of curved cauls is very useful for gluing up.

[Jon Steffen]

With melamine and laminate work surfaces I find it easiest to keep them waxed and pop glue drips off with a scraper once cured.
Do you mean that if something does drip onto it, you just leave it and then scrape it off later, rather than wipe it up right away?

[Jon Steffen]

Perhaps I'm too old and uneducated, but for me an assembly table does not get holes drilled in it, which could get glue along their edges. When gluing I use clamping cauls and bar clamps, and check for square by measuring the diagonals. Planing faces and edges is done on a Klaus style workbench.

My assembly table is a torsion box, with a 1/4" x 4' x 8' melamine foil sheet lightly screwed to the top of the torsion box. I did wonder if the foil surface would be durable enough, but after about 6 or 8 years it is still in good condition.
No idea Don, i'm a newb with a track saw, hoping to make an accurate repetitive cut mft type table to make a bunch of cabinet carcass and learn to make segmented bowls, that triples as an assembly table and work table.

I'm hoping to make a large portion of the table have no holes in it though, but if need be, i'll probably throw down a few sheets of rosin paper.

[Jon Steffen]

The key to getting a flat surface is to start with one and clamp to it. You can make a carefully levelled base with freshly milled 2x4's or the like, but it is best to clamp the new assembly to the base no matter how you assemble it. Just laying one skin on the base and pocket screwing the core elements to it won't ensure that everything is in plane. A set of curved cauls is very useful for gluing up.
I've seen several done in this way, milled 2x4s with shimmed saw horses, hot glued to the floor and measured for level at a ton of different ways....

So do you recommend clamping the ends of the MDF to the ends of the 2x4s, and many clamps along the long edge to the 2x4 under its edge?

[Jon Steffen]

life is a compromise, so I think i'm going to go the same route and do a glued bottom skin/inner skeleton setup, but the top will only be screwed down in MDF. if the skeleton frame isn't flat, glue and screws wont make the top flat.

If the skeleton frame is flat then an mdf top screwed down should be pretty darn flat, AND i can replace it.

Onto my next question. I'm going to wrap the box in maple I think. I want to drill 20mm dog holes around this perimeter.

1.How thick should I make the perimeter pieces so I don't worry about them splitting if some force is applied to the dog holes for clamping?

I'm thinking if the outside board is clamped inward towards the table, it doesn't need to be that thick, but if I ever applied pressure outward against a dog there, its possible it could split.

2 more questions.

I will be using through clamps on the table, like the Festool ones, but on the boarder I won't. I've read some people drill a hole all the way through the boarder board, this seems unessesary, but would help so wood dust/chips don't fill those holes.

2. Do you guys think I should drill all the way through the boarder board?
3. Does mdf come square from the factory, or do you still need to cut the edges to make sure its square?
I bought a 49x97 sheet of mdf today, its exactly 49x97 and corner to corner was spot on. SO....hopefully MDF 6-10 years from now will still be 49x97 and perfectly square.

[Kevin Jenness]

"So do you recommend clamping the ends of the MDF to the ends of the 2x4s, and many clamps along the long edge to the 2x4 under its edge? "

I would recommend clamping curved cauls under the base and over the torsion box. Lacking sufficient clamps and cauls for that, the assembly should be at least clamped down around the perimeter of the base and checked for contact in the center before gluing.

If you are drilling system holes around the edges at least 3/4" should be left between the hole edges and the outside of the rim.

If you are going to screw the top to the core, grid members should be at least 1/2" thick, and the screws will need to be laid out accurately to get a reliable purchase. The screws should be located to miss the holes and the holes, if you plan to insert Festool style f clamps, should be clear of the interior grid. If you want to get the full structural advantage of a torsion box both skins should be glued, or at least fastened very thoroughly. Be aware the screws in the top are always a risk for cutters set too deep.

[scott lipscomb]

I built mine with 3/4" ply. The lumber store called it "Russian Birch"-pretty much Baltic Birch as far as I can tell. I used the Perf Guide system, and drilled a full grid of the tiny pilot holes then drilled every other pilot hole with the the full 20mm holes. The other, every other grid, was the grid for the torsion box ribs. Then, I used the pilot holes to screw the whole thing together while the glue dried, then I took the screws out. It worked really well. The resultant cells, which are 192mm center to center, are the perfect size to fit the Festool clamps and still be able to rotate 360 degrees. It is my assembly bench. I also have a Roubo style woodworking bench, which I like, and use a lot, but I use this torsion aft for 85% of my work.

To answer the original question, I considered both mdf and ply, and I am very happy I chose ply. Its finished with Waterlox, which is what I had on hand and durability of the ply is a non-issue with my work. I think the top weighs about 180-190 lbs, and it floats on the base, which means I can move it around for flexibility.
438189

[Chris Fournier]

I have a 4' X 8' assembly table on a metal base. My torsion box top is MDF on top and Particle board on the bottom. A bit less weight and $$$. It is 5" deep and extremely heavy. I has supported woodwork, metalwork, motorcycles etc. Great shop addition. Good luck with yours. Oh yeah, I vacuum bagged mine no fasteners in the faces and I just throw a 1/8" HDF sheet on top when things get ugly.

[Jon Steffen]

"So do you recommend clamping the ends of the MDF to the ends of the 2x4s, and many clamps along the long edge to the 2x4 under its edge? "

I would recommend clamping curved cauls under the base and over the torsion box. Lacking sufficient clamps and cauls for that, the assembly should be at least clamped down around the perimeter of the base and checked for contact in the center before gluing.

If you are drilling system holes around the edges at least 3/4" should be left between the hole edges and the outside of the rim.

If you are going to screw the top to the core, grid members should be at least 1/2" thick, and the screws will need to be laid out accurately to get a reliable purchase. The screws should be located to miss the holes and the holes, if you plan to insert Festool style f clamps, should be clear of the interior grid. If you want to get the full structural advantage of a torsion box both skins should be glued, or at least fastened very thoroughly. Be aware the screws in the top are always a risk for cutters set too deep.
Thanks Kevin, i'll have to research what curved cauls are.

[Jim Dwight]

I do not use MDF for hardly anything. I hope it works out for you. It's dust is NASTY. It doesn't hold screws well. It swells from moisture very badly - even falling apart. It has very little strength - much less than plywood. So it sags at the slightest opportunity. Can you tell I do not like it?

The top of my outfeed/accessory/work table is 3/4 plywood with 20mm holes on 4 inch centers. Works very well. I usually use a sheet of foam board on top when cutting up sheet goods with the track saw. But I do crosscuts on the table using dogs. So I have one kerf from that that can be filled in if it starts to bug me. It is built paulk style with a second top 8 inches below and ribs with big holes separating the two tops. Frequently used tools go on the lower top (or underneith) for easy accessability. I just added a leg vise at one end.

I think you're worrying too much about replacing the top - but maybe not if you use MDF. I am pretty confident my table will never have to have the top replaced. But I don't worry about minor nicks and stains. It may not look pretty 10 or 20 years from now but I am confident it will still be structurally fine and able to serve it's purpose. If not, I guess I will build another. It's probably close to 10 years old already.

[Jon Steffen]

I do not use MDF for hardly anything. I hope it works out for you. It's dust is NASTY. It doesn't hold screws well. It swells from moisture very badly - even falling apart. It has very little strength - much less than plywood. So it sags at the slightest opportunity. Can you tell I do not like it?

The top of my outfeed/accessory/work table is 3/4 plywood with 20mm holes on 4 inch centers. Works very well. I usually use a sheet of foam board on top when cutting up sheet goods with the track saw. But I do crosscuts on the table using dogs. So I have one kerf from that that can be filled in if it starts to bug me. It is built paulk style with a second top 8 inches below and ribs with big holes separating the two tops. Frequently used tools go on the lower top (or underneith) for easy accessability. I just added a leg vise at one end.

I think you're worrying too much about replacing the top - but maybe not if you use MDF. I am pretty confident my table will never have to have the top replaced. But I don't worry about minor nicks and stains. It may not look pretty 10 or 20 years from now but I am confident it will still be structurally fine and able to serve it's purpose. If not, I guess I will build another. It's probably close to 10 years old already.
You could be right. I'll see how much time is invested in drilling the parf grid before I decide if i'm gluing the top and bottom or just the bottom.

[Jon Steffen]

"So do you recommend clamping the ends of the MDF to the ends of the 2x4s, and many clamps along the long edge to the 2x4 under its edge? "

I would recommend clamping curved cauls under the base and over the torsion box. Lacking sufficient clamps and cauls for that, the assembly should be at least clamped down around the perimeter of the base and checked for contact in the center before gluing.

If you are drilling system holes around the edges at least 3/4" should be left between the hole edges and the outside of the rim.

If you are going to screw the top to the core, grid members should be at least 1/2" thick, and the screws will need to be laid out accurately to get a reliable purchase. The screws should be located to miss the holes and the holes, if you plan to insert Festool style f clamps, should be clear of the interior grid. If you want to get the full structural advantage of a torsion box both skins should be glued, or at least fastened very thoroughly. Be aware the screws in the top are always a risk for cutters set too deep.
okay, i've read up on curved cauls a bit. When you do this, I can envision if you put too much clamp pressure on the ends of the curved caul, it could make the base actually bend and form to the curve.

Do you fine tune the clamping pressure to try and make the skin have consistent contact with the gridwork, so it doesn't bend?

[Ole Anderson]

I haven't done a torsion top, but I always think of the old David Marks video when he made one. IIRC you set up sawhorses perfectly level to each other to avoid twist in the surface. Most torsion top videos have that as one of the initial steps.

[Kevin Jenness]

Curved cauls are used in pairs- when clamped together they should meet in plane.

[Jon Steffen]

Its ben a busy few months for me. I just got my two laminated MDF panels from Alpine Plywood from Milwaukee, WI.


I don't know if I should be upset or shocked. Is this normal for panels you get "MADE" to have the laminate not cover the whole MDF panel below, for them to write with magic marker on the nice side of the panel? For the panel to be dented where they banded it to the two LDF panels? Is this normal that the buyer needs to trim the laminte flush to the MDF core? I would have figured the manufacturer would do that.


Is this normal or did I get hosed?
445566445567445568445569

[Jim Becker]

Um....I'd be pretty upset about what you show in those photos, Jon...

[Jon Steffen]

Um....I'd be pretty upset about what you show in those photos, Jon...
Thanks Jim. The company VP told me its industry standard to only have 32SF of good panel when you buy a laminate 49x97 MDF CORE. They are giving me a $50 refund from the $371 order total for 2 panels.........

Guess i won't be doing future business with Alpine Plywoods out of Milwaukee Wisconsin.

So Jim, are you saying this is not "industry standard"? I've never ordered a custom laminate panel, so i have zero reference.

[Jim Becker]

Jon, I have no idea what the standards are. I just know that what you showed in those photos would have "caused bad words" if I paid good money for custom panels...unless there was full disclosure in advance. I may have even uttered one or more of those words when first saw your pictures. :D Some places might say that the buyer "should know" but if the buyer isn't a regular, it sure would be courteous to mention the "Ground Rules" before the game commences.

[Frank Pratt]

I think the supplier has a valid point, as long as you can trim it & get a full 4x8 sheet out of it. But they should have made it clear when you ordered it. The $50 refund was a fair gesture.

[Jon Steffen]

Jon, I have no idea what the standards are. I just know that what you showed in those photos would have "caused bad words" if I paid good money for custom panels...unless there was full disclosure in advance. I may have even uttered one or more of those words when first saw your pictures. :D Some places might say that the buyer "should know" but if the buyer isn't a regular, it sure would be courteous to mention the "Ground Rules" before the game commences.
lol, there was no full disclosure, and the response after the sale was less than stellar from the veteran rep (vp's words, not mine). I read what the VP's name was on their about us and then guessed what her email was, swapped out adam@xyz with Laura@xyz, lmao.

Since i asked 20 questions prior to the sale, a good sales rep would have notified me of this (maybe i'm the first newb customer they ever had that was shocked by the quality, or they just don't care to learn from their mistakes).

Live and learn. now i just need to decide if I use these panels for the intended project or use them for something else.

[Jon Steffen]

I think the supplier has a valid point, as long as you can trim it & get a full 4x8 sheet out of it. But they should have made it clear when you ordered it. The $50 refund was a fair gesture.
I wonder if that's their work around for making inferior panels, or if that truly is an industry standard. When i start my own panel laminating business (HA!), they'll cover the whole core AND come pre flush trimmed! Winning over the woodworking community, 1 panel at a time. lol

Thanks for your input Frank and Jim.

[Frank Pratt]

This got me curious, so I just had a quick look online & both Formica & Wisonart come in standard sheet sizes in 12" increment, ie width: 36", 48", 60" & length: 96", 120", 144". So it wouldn't make sense to completely cover a 97" x 49" sheet of MDF.

So now we know.

[Jon Steffen]

well this company probably gets special sized ones because both sheets are definately not off by 1" on two edges.

Its almost flush on the 49" side (actually a bit wider than 49") and off by 1/8-1/4" on the long side. The same amount its overhanging on the other side.

[Frank Pratt]

well this company probably gets special sized ones because both sheets are definately not off by 1" on two edges.

Its almost flush on the 49" side (actually a bit wider than 49") and off by 1/8-1/4" on the long side. The same amount its overhanging on the other side.

Well, if that's the case, then it's just poor management on their part. Makes no sense.