I built a sturdy work bench about 3 years ago with two layers of 3/4″ MDF, set up nice and flat and well glued together.
I’ve recently noticed that my planes seem to only work near the ends of long boards – zounds! the bench is no longer flat. My straight edge confirms it – the benchtop has settled somewhat (dang!).
All the “flatten your workbench” articles feature handplanes being used to level traditional wooden topped workbenches. Were this monster outside, or even in my garage, I’d flatten it with my big belt sander with a leveling tray attached. But not in my basement workshop!! Dust like you can’t even imagine.
I’m pretty sure that I already know the answer, but rather than find out myself through experience, does anyone already know if MDF takes the edge off a plane iron so fast that it’s just not a practical solution to try leveling the beast with a jack and then a jointer plane? I’m really not looking forward to re-topping this bench with glued up 2x’s at present.
Mike D
Replies
I don't use this stuff much but it is my understanding and experience using it in jigs, that it is precise in its thickness but will change shape due to moisture absorption from the atmosphere. Then laminating it the glue may seal one side of each layer so they could be fighting each other. Heck I don't know but chances are it will change with the weather. Perhaps you can just shim the underside and get it to screw down flat again.
Yes it should be full of grit from the stuff it is made of. I would put a layer of wood on top and plane that. Or use this bench to make your next bench.
I would think since this stuff won't come off as curls but like fuzzy dust you will have dust in any case and definitely unhealthy and even dangerous to breath ! ! ! especially while huffing and puffing at a big planing job like this.
I like purple heart for a bench top. That is what I used in my Klausz bench. No regrets. It does smell like dirty feet while working it. No smell after. It is hard and dulls tools. Glad I stuck it out.
Although I can't tell you what MDF will do to a plane iron, I can say that it isn't something I'd try. I suppose you can always resharpen, but if your bench top is sagging, leveling it the way you propose will only satisfy you for a while before you have trouble again. In fact, if it's bowed, it probably means that it has room to move and any time you put preassure on it, the surface is likely to give a little, so flattening it won't really solve anything.
I'd recommend a different approach if you're intent upon saving the bench top. You could bolt a pair of stiff, strait cleats lengthwise on the underside to take the bow out and stiffen it up a bit.
Another way would be to make an adjustable harness with light wire and small turnbuckles that run end to end over a couple of cleats under the mid section -- increasing the tension on the harness would straighten the top. Move over Rube Goldberg!
Verne
Fill the low areas with bondo.. level off and sand flat.. add a 1/4" or 1/2" sheet of new MDF on top.
Sarge..
Hey Sarge, I LIKE that idea. I can even use the Bondo 'cheese grater' plane on it before it completely sets up to knock the worst of the high spots off.As an alternative, you've gotten me thinking about a product for leveling floors (like when you've got to retile an old bathroom floor) that you mix, pour on like thick soup (being sure that there's no holes for it to flow through), watch it level itself and then harden like rock. Then I could add another layer of something to it. Nah! on second thought, I suspect that it would not accept a drill bit through it for new dog holes.I like your idea, though. Thanks.Mike D
You're welcome Mike but... I see in a latter post you are going to address the real problem which I believed you originally stated you did not want too. The Bondo will work just as a band-aid to stop the bleeding but it doesn't address the real problem where stitches are required. That is the support frame under-neath not being adequate enough to keep the MDF flat.
I have a double laminated router top that has remained extremely flat for 7 years. Why.. because under the top there is a angle iron support frame that won't allow sag even with my heavy 3 1/2 HP router hanging on it. I have built around 24 work-benches.. all have had 3" thick tops.. laminated together and glued face to face. I flattened the .030 the southern yellow pine had moved over 14 months the other day with a #7 jointer in 8 minutes. The 3" thickness and all the glue surface is not goint to allow a tremendous amount of movement.
BTW... if you do go solid wood as you mentioned, I have built the last 5 WB tops with SYP for around $25. Cheap.. stable if you use dry.. straight stock from the git-go. Not exotic but.... IMO a work-bench top doesn't need to be exotic.. simply flat and stable. But even more important is the foundation it sits on. Solid.. stable.. won't rack.. then you put any flat top on it and it will work. I simply use Doug fir for bases with all through tenons and bridle joints.
Sarge..
Edited 12/26/2008 1:32 pm ET by SARGEgrinder47
Edited 12/26/2008 1:33 pm ET by SARGEgrinder47
Very nice bench Sarge,Hi Mike,
I have a massive MDF bench topped with a layer of 3/4 Birch about 12yrs old and I have not noticed any movement. God only knows what mine weighs, but folks in China should watch out if this thing ever sinks.
I think the fellows here who mention that the base is key are right. My bench has two torsion box layers. The bottom is the first torsion and the area immediatly under the top is also a torsion box. The area between has drawers or cupboards. If the first base is not rock firm and sags even a hair, I think the sag will transmit up to the top. If the legs are not carrying an equal amount of the weight, gravity will slowly work it's way and distort the top.
If I were in your position and wanted to go through the effort of flatening my existing benchtop, I know I would start from scratch, not just repair the top. Especially as you want to use special wood for the top.
It's a lot of work, but with a bit of research and reading forums like this, it's a rewarding task.
Hi Sledge,
I had to get on with it so I flattened it. It'll last through this project and then I can look at a more permanent fix.
Mike
add a 1/4" or 1/2" sheet of new MDF on top..
I'd go with 1/4 inch tempered hardboard (or is 1/8 inch the standard thickness?).
Very reasonable in price and tough!. All that is needed is a level base (as in Bondo or whatever to level the base) and some trim around the parameter to keep it from moving.
One poster stated purpleheart. A wood I use alot of. I made a very pretty bench from Jatoba (trim) and the legs and top of purpleheart.
When finished, the top was about 5 inches thick. It never warped. My first 'build' was laminated 'sticks' with threaded rod holding it all together. No glue. The top was edge grain not face grain. BIG MISTAKE in my opinion. Not the choice of wood but using edge grain. It tears/chips? out very easily.
I made a new top (to place onto the existing top) using not the edge but the face.. Tough as nails!
I realize this has nothing to do with the original post. Sorry to the original poster for my yapping' away...
I for one am not above using MDF for templates or whatever. I never use it in the actual object that is made. OK, so I have several router table tops made from it. Edges sealed with glue of shellac and wax on the top and bottom.. None have warped to anything that made them unusable.
I HAVE used my planes on MDF but my planes are not by any stretch of the imagination, museum pieces or even stand out in a junk pile!
I for one, never had much success planning MDF. Best left to saws and sandpaper.. Hand scrapers seem OK.
If you like your bench other than you current problem.. I would go with the other posters that wanted you to 'beef up' or otherwise try to straighten/correct the bottom.. As in the basic structure.
Just me though.
Nice tip about using face grain rather than end grain with the jatoba. Pretty hard stuff. What'd it cost aprox. ? I very curious about the cost it would take to build a workbench out of similar hard woods. I really never thought about it till now. Thanks for this thread honestly if i where going to try an exotic work top I'd have used end grain also. And chipped and gouged away. Thanks for bringing up the mdf problem Wish I had more to offer, but maybe you're saving me some frustration in my future. I've worked only crooked tops not figuring out what I was doing wrong through way too much good wood and ended up with a sweet pile of shavings and venner.Some folks carve their whole lives never to realize it's not the sculpture they're after but the process. Enjoy the process. (woodchuck the wise woodrodent)
Nice tip about using face grain rather than end grain with the jatoba.
Sorry for misleading you.
I meant that I found that the Purpleheart would tear-out on edge grain. I used Jatoba for trim and Purpleheart for the top.
I used Purpleheart because I like the look of it and at one time it was widely used for flooring in trucks and train box/flat cars. At least that is what I have read.
And besides, the Purpleheart was about half the price of hard maple when I made that bench. That was many years ago though.
Never thought of using Jatoba for a top. I'll think on it a bit for a router table replacement I plan to do this summer..
Edited 12/27/2008 6:11 am by WillGeorge
My mistake, Happy I read this it'll push me to grow outside my box a bit. I totally must have gotten ripped off on the purple heart i have :( Oh well I'll research it a bit more. Thanks for the reply. Happy new years and keep chippin away ! :)Some folks carve their whole lives never to realize it's not the sculpture they're after but the process. Enjoy the process. (woodchuck the wise woodrodent)
Tempered hardboard will also work, Will. And I keep 1/4" and 1/2" MDF on hand to use for making templates for router pattern bits to transfer to wood stock. Cheap... easy to use and if you mess up a template.. easy to re-do with cheap MDF. It has some great uses.
BTW... both my small and large assembly tables have 1 1/2" laminated MDF tops but... both are heavily re-enforced under the MDF with a SYP cross-work frame. Both stay flat.
Regards...
Sarge..
Mike,
1)How is the mdf top attached? Can you take it off , turn it over and reattach after making sure the framework is straight? (And not going to carry on sagging).
2)If the top has sagged as you say is there no way to jack up the middle off the floor and then brace it so it stays that way? (My bench has detachable feet in the middle of each lower long rail which I can use to stop sag).
Bondo! Good Call. and wow purple heart work bench top *(&^% holy molie I really did enter the fine woodworking site! I'd go with bondo too until you can afford that bubinga or rather lignum V. workbench. I can't imagine how much it would cost to laminate a bench top w purpleheart.? Cool discussion.
Ah, don't make fun of Bondo. It's fast, available, if you time it right, can be easily worked before it hardens, it actually hardens completely through, and grips like a monkey. It can make a great permanent repair if you plan to paint it.Others point out what I've completely missed, however - that MDF has no long term stiffness - it slowly conforms to what ever shape is supporting it.I've gone back over the top with my straight edge and discovered that it has actually dished around the support frame for the top, including the middle braces both across and lengthwise. I would have never guessed that it was possible for something 1.5" thick to do that.It hasn't dished much - about 1/16" across 3' x 1.5' - the area between the braces - but that's apparently plenty enough to screw up planing something 3/4" thick.A replacement dimensional construction lumber top is beginning to look better and better.Mike D
Edited 12/26/2008 8:11 am ET by Mike_D
Purple heart is relatively plentiful and not that expensive IMOP. Besides you are going to be looking at it for a great deal of your shop time. This is where I should not mention my original idea of putting a layer of zebra wood on top of the purple heart. You know. So it wouldn't be boring.I chose the purple heart because it was heavy, hard and strong.I suspect i have read one too many articles by Wendell Castle. The interior designer I welded for was a bit out there as well. I probably have some residual influence from her. She would like the zebra top ! Now that was pricy. Still might do it. Don't push me ! I will do it !At that same studio we had a woman who would show up after her classes to help with the metal work. She would wear a short chartreuse skirt, thigh high white boots and red hair. She would then slip into her camies and logging boots and spend about four hours with a plasma cutter. She probably contributed to my twisted aesthetic tastes. She was haaaaat ! Steady roc old boy ! Steady on.Did you read my rant about how the owner of the local WoodCraft said purple heart is no big deal. That in the countries it is harvested in they use it like we do two by four woods. They make homes and stuff out of it. HE SAID !as I said then "Now you know why I am as happy (?) as I am with my local WoodCraft store !"Don't be afraid to spend some bucks on your bench.roc
Edited 12/26/2008 6:53 pm by roc
Cool, I spent some years in a fine arts shop as well and was a welder also. I'll look into purple heart again. Maybe I got ripped off pretty good. One day I' will afford my guacium officinal or sanctum aka jamaican ironwood aka Lignum V. OH one must dare to dream!
I still only have one log but may take another lignum vacation and stock up big. I suppose I was too used to the forums on L.J. 's Ya just don't see the money and thinking outside the box there. Glad I'm here, if it makes ya happy how much is it worth. Oh yea . Happines isn't always cheap. I'd love to see those homes built out of purple heart. Would be a cool article. Thank for the input.Some folks carve their whole lives never to realize it's not the sculpture they're after but the process. Enjoy the process. (woodchuck the wise woodrodent)
I spent some years in a fine arts shop as well and was a welder also.. I could do some wonderful welding on Army Vehicles but never tried to weld wood or a painting!
Just funnin ya abit.. No hate here...
Maybe I got ripped off pretty good. .. Maybe but not probably.. Wood is wood.. No supplier can guarantee the outcome of ANY wood when it is cut!
Edited 12/28/2008 7:43 am by WillGeorge
Paddyboy,>Happiness isn't always cheapWell happiness as in "don't worry be happy" is cheep. But cool stuff tends to cost a bit, quite a bit, more.I think the purple heart homes only exist in his mind. Any knot dudes or dudets seen any in the countries the wood comes from?At first I read your post when I got up before coffee. I thought that you were asking how much my purple heart cost for the bench. Now that I have had a touch of coffee. It occurs that I miss read but have looked up in the mean time.A few years ago (still not awake enough to get closer than that ) I paid $ 7.69 a board foot. for 8/4 rough.Price goes up if you bought surfaced and thinner from say a Woodcraft rack.For comparison Zebra local in 8/4 was ~ $22 a board foot and as I recall Kingwood was around $50.Yep shows how groggy I am. Here is the date right bellow the price 6-14-06 ( Too much sour cream on the burritos last night. Sure were good though. Excuse me while I slip into a little revery . . . )I bought aprox 60 board feet. How much you buy effects the price as well. This was at a local mom and pop who sponsors the local New Yankee /Norm broadcast.>New Yankee /Norm broadcast. AND LOCAL. A pleasant bicycle ride from my house. Ya see ya gotta consider ALL the factors when buying wood.I checked back in the Eastern lumber suppliers when I bought. They had purple heart for $5.50 but they had a minimum I could not meet and shipping and handling was $175.00 plus residential delivery of $30The owner of my local store dropped it by my shop on his way home. Can't beat that !Isn't that some thing though. A person can get one of the very hardest. strongest woods in the world for not that much money ! One of the reasons I chose PH.roc
Roc, Thanks for the wood Intel. I write here when in need of much coffee myself.
And I think your right, someone else wrote about the indigenous people "using P.heart like we use 2x4's to build homes" Well let's just say they'd need cordless portable hip plasma cutters, to frame and build homes with that stuff. I can't see it . Not commonly anyways.
So we're way off mdm now, but I like that. Very cool about ya workin up in yankee land, I'm sadly still stuck in brooklyn 'a tough place for one who loves his trees/fishin/and shops. Me ma has a farm up near mystic though and 'will' one day escape from NY. I'd love to some day see a pic of the workbench. I myself STILL, am in need of completing a "real' workbench
and am so envious of anyone that's finished a nice one. As of now I'm still working in renovations mostly thank god, finish carpentry, moulding, cabinets, and just getting into some custom wood counter tops. I have a few idea's to break free one day and be able to use nothing but hardwoods and a bit o creativity. But that's still classified intel. See I went to school for a BFA so really it qualifies us to teach or work in construction. Ha at least that's everyone I went to school with. 35 now and still floundering around doing Needing to keep working with my hands, It's something I was born with rather than born into. Not many around me understand it and just figure i have a few too many knots on my head. But I LOVE IT. Sounds like I need to get outta yc huh. Well now that was a 530 am RANT!
Sorry If I flew way off course but it feels good sometimes. Keep makin sawdust. Your pal in wood. Paddy .Some folks carve their whole lives never to realize it's not the sculpture they're after but the process. Enjoy the process. (woodchuck the wise woodrodent)
Final report on this subject:While a new wood top is somewhere in the future, I really needed this darn thing flat now. So, what the heck - nothing ventured, etc. I decided to flatten it.An old Stanley #4 converted to a scrub plane takes the big lumps off an MDF sheet in no time at all.
It's so aggressive, I didn't even have to resharpen it before I'd finished with the rough leveling.
Next, since I have the Spinning Thing 3000 sharpening system (with the new large blade sharpening platform that puts an "acceptably sharp" edge on a plane blade, likity-split), I committed my BU jointer to final leveling. That worked well, also. I had to sharpen that blade about 3 times to finish flattening a 3' x 5' surface. I found that setting the blade to take an aggressive shaving worked while attempting to "shave" the top didn't work worth beans - made powder.Finally, when done, I cleaned up the shop - MDF dust everywhere - and shellacked the top with Bulls Eye until it would accept no more.Voila! Flat MDF bench top, didn't ruin the planes, and because it also has a 3/4" sheet of BC plywood under it, I'm hoping that it will stay flat until I'm finished with my current project. Next step is the grinder where I'll clean up the bevel of both planes and resharpen them for real wood.Thanks for all the chatter.Mike D
MDF has zero stiffness over long spans. The secret to using it in as bench top is to have a stong wood frame below it, if the frame is straight the top will be also.
MDF is built in layers, the outer fibers are saturated with resin which makes the surface hard, the inner 75 percent has much less resin, if you sand or plane through the surface you'll end up with a soft nappy surface.
The way to fix your top is to stiffen the frame supporting it and, if needed, shim between the frame and the underside of the top.
John White
Good to see you still checking in here now and again John! Hows the new life treating you?
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Men will never be free until the last king is strangled with the entrails of the last priest.~ Denis Diderot
Life is OK, but the tough economic times are stressful for my family and a lot of the businesses up here.John W.
i often plane small patches of mdf. if there is corner damage or something before i laminate (i work in an industrial millwork shop....lotsa laminate..) i will patch it and plane it instead of beltsanding. its rough on the blade, but i have one reserved for it. on small things its ok, but it goes from shaving hair to dull pretty fast. if you decide to plane your whole top, you will find that once you remove the paper facing, the mdf gets quite weak.you are better off shimming your base . once its nice and level your top will be too.considering the price of mdf, you may want to get new stuff.as for laminating, i dont find a problem only laminating one side of mdf.plywood yes, but mdf and melamine dont have a problem.i know many might disagree, but i deal with 1000's of sheets a year.you will have more problems glueing a 1/2" mdf to a 3/4" mdf. have seen those warp like a banana. i made an island for my own kitchen and the top is mdf ....plain on the bottom , lam on top...flat as a pancake....good luck on the bench..
MIKE
Couldn't you use a self leveling floor filler and then cover with hardboard or thin MDF?
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