Sacrificial Workbench Top?

[Bill Adamsen]

What is a good sacrificial workbench top (Masonite, 1/4" mdf) and how do you attach it? Thinking something that would last six months and then be replaced.

[glenn bradley]

Sacrificial in regard to physical damage, finish slop or what? I made a work table almost 15 years ago with a replaceable hardboard top; it has never required replacing :o. Having learned the durability of tempered hardboard, on a recent outfeed table I just laminated the hardboard top to a plywood substrate. Do you want something to chop into when doing dovetails? Something like that? For this I use a bench hook; am I getting close?

[Prashun Patel]

my experience mirrors Glen's. I replace my temporary tops as often as I build brand new benches.

My sacrificial top is constrained by aprons that rise above the surface of the bench top.

Stuff gets in between the edges of the top and the apron and it's a constant pain to keep clean if you're a sweeper; if you vacuum it's a non-issue.

If I were to do it again, instead of using aprons, I'd just screw or brad nail it to the top.

[Mike Ontko]

My bench top, covered with 1/4" hardboard on top of two layers of 3/4" MDF and wrapped with a maple edging is pictured here (below) beneath a previous bookcase project. I had expected to replace the top at least once before I build a more solid workbench, so I used screws around the perimeter spaced at about 8". The two additional holes shown in the lower left are for the vise. It's about two-years old now and still has a long way to go before needing replacement.

http://www.sawmillcreek.org/attachment.php?attachmentid=331688&d=1455517178

[John TenEyck]

I use 1/8" double tempered Masonite attached with brads around the perimeter. When it gets all dinged up or slopped on more than I can stand, I flip it over. Each side lasts me a couple of years. This one has been on less than a year, but you can already see it's seen some abuse.

https://lh3.googleusercontent.com/xWjp92fEBvqzRAgl3eJgXPQGYg4BP2K3Hqlj13rEnMCr10BmRQ TJNnHcWdqG2m0h0e_S-WU7fwL3qcCz-BLCfAywYEQYH0usqlNeCWidjpscsWxTl2NTjSJCKQPB0gyxLxV T98JCqMF5M485OVksD82R3_uMzjOh9Q1Yqo9sCjiyIBr-vKatJbFzWSqza2eoTVZJ-9haeVw5x-QT8PyiduSsnIhqIqnK8vyfHu9LvNmK6J_LvhvN8GxwpKFHuJfJ zDsae0uAEOM15cO4sKqrpc2aJoAqDuM2V2MX86AIWgThUpRqqs mwfFeItsWwrT_pX0cvNW8WkSHhZwIcllVK18O6va7xbluZI0u_ yYuYK97QVipZSbSxllCFZ80hytOGwu2GKXiMEVZU93LI0OKJi_ E7wDRtcaxue5c9b26N5p_EEvwhvmUVehaCdg-XEJqaw5ykeIpMIT96u8beBjzefExLQx4FO6Uc7OivrwzLEu6QJ VDEp83maaBqzIfFe0NNCCvehH48DOvOJHKVO5wjenrlhbENpdB uJt1XeMViITR4RRuwr9ltyeWq3_qIeFWS1ZUHscxRtZWgujDCZ DJo1uTBeNjVf64U2elh-34kqovjn5LcsJmHnoKAMRJRH1JiD-xy8_lhu9CK8t6jI7UYs8tNmHezhhcJMABY6aSX-4M=w838-h628-no

John

[David Eisenhauer]

Masonite covering some type of sheet goods will last a long time/forever, but be aware of the fact that it is slippery and work clamping (for hand tool work) on a Masonite surface requires more effort. Short brads to fasten the Masonite top down to something can loosen over time and come back up, which can scratch your work if not re driven down from time to time. Easier to use the 1/4" Masonite and countersink small screws or perhaps use longer barbed type brads in the 1/8" stuff.

[Art Moore]

My benches are 20-odd years old and are topped with 1/4 Masonite as well, and were secured to 1-1/2 inch MDF by carpet tape for easy replacement. Apparently I could have used anything to secure them because they still have no damage to speak of. Masonite must be like cockroaches... ya just can't kill it off. :D

[andy bessette]

Tempered Masonite! :)

I just use a few very small brads to keep it from sliding around. Tough as hell. Unlikely to ever need replacing.

[John C Cox]

Dad uses some sort of 1/2" thick soft paperboard stuff with the texture of cork. Works great for sticking push pins/brads into when you need to fixture stuff. Its also awesome for not dinging up edge tools. Very soft and squishy. I think he called it "Norbord" but I am not totally sure.

[Bill Adamsen]

Glenn: Primarily glue-up and finish slop. Current top is just plywood that I sand smooth when necessary. But I keep wondering when I will cut through the top veneer. Reality is I probably don't need to worry about it. And if I do remove part of the veneer I can just vacuum bag on another layer.

[Dan Henry]

My work bench top is 2 layers of 3/4 partial board topped with 1/4 MDF held in place with 5/8. Brads, when it is time to replace simply remove the old MDF and cut new one rough size, nail in place and run a router trim bite around the edge and you have new top

[Dan Hulbert]

Dad uses some sort of 1/2" thick soft paperboard stuff with the texture of cork. Works great for sticking push pins/brads into when you need to fixture stuff. Its also awesome for not dinging up edge tools. Very soft and squishy. I think he called it "Norbord" but I am not totally sure.

Sounds like Homasote. We used it for model train layouts. Never thought of using it for a bench top but it does sound like an interesting option.
My bench has 1/4 hardboard top coated with leftover shellac. Helps keep the slops from sticking although I occasionally have to go over it with a cabinet scraper.

[Bill Adamsen]

Folks ... original poster here ... should have asked the question differently. My plan is to use the table for assembly but also for vacuum bag work. So one of the key attributes is that it needs to be flat and with no twist. Flatness - I've been using a table that has no twist, but about 3/32nds of an inch of sag over 8 feet. When assembling I deal with the sag by using wedges, shims and/or jacks. It is really annoying. Over the weekend I welded up a new table base using a laser to make sure the four table supports were in one plane. My first thought was to make the new top as a torsion box. I've made several in the past and they usually work out great. But then they also take a full day to make. Would simply gluing up layers of MDF work just as well?

[Prashun Patel]

I wouldn't glue up layers of MDF. My experience is that it ultimately sags. You may get lucky, but given your experience and ability, I would make a torsion box.

[Bill Adamsen]

I would make a torsion box.
Thanks Prashun .. not necessarily what I wanted to hear, but what I knew deep down to be the right solution. For the torsion box I would probably do 3/8" or 1/2" 4X8 Baltic Birch (my suppliers now refer to it as Russian Birch ... interesting branding shift!). Used 3/8" on a recent project and found that in full sheets it is remarkably unstable. So even though it weighs 1/3 more, I'll likely use the 1/2". The core I typically use is eastern white pine which glues well.

[John TenEyck]

Bill, you didn't say how large the table needs to be. The bench I showed above is a piece of lab bench top under the Masonite, 32" wide x 8' long. It has stayed flat for 25 years, and is the bench I use for vacuum bagging. A solid core door would do just as well if large enough to meet your needs and you would be done yesterday. Nothing wrong with a torsion box, just that it takes time to build. And FWIW, I had my RAS bench top out of two layers of particle board, skinned with Masonite, over 20 years ago, and it is still flat and true. If you have adequate support under them composite panels are fine. If you welded a couple of additional cross bars to your frame I'd have no hesitation using it with a layered composite top.

John

[andy bessette]

You don't need a torsion box. But you do need to add some cross members to that bench support.

[John Sanford]

What Andy said. Add 1 or 2 cross members. The cross members would also make using MDF more practical. Doubled MDF, and then some Masonite on top that can be replaced.
You'll likely find yourself using the bench for more than just vacuum bagging.

Fine looking bench frame btw.