Author Topic: Workbench undercarriage design  (Read 3629 times)

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Offline Upcoaster

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Workbench undercarriage design
« on: January 03, 2020, 11:56 PM »
I'm building a new workbench and I'm sold on a torsion box surface.
Here are a few thoughts that went into the attached draft (image).

Today, it'll be a stand alone work bench but I'm making it the same height as my table saw (36.25") just in case I decide to re-arrange the shop one day.
  • This will be a fairly sizable work top as I want this station to accommodate the task of sizing down 4x8 sheets into smaller pieces.
  • The bench will have a wood vice and I may also mount my metals vice at one corner of the top (still thinking about that though).
  • The depth of the torsion box might be a few inches too generous and may get slimmed down an inch or two. I don't want to be restricted on what tools and such I can store in the cubbies to keep the work surface clear.

My concerns:
  • With the torsion box design, I'm not concerned about rigidity of the surface but I'm a little apprehensive about the undercarriage racking back and forth.
  • Given the vice features of it, I'll be whacking, sawing, planing and the like so I want it to be sturdy.
  • I'm trying to balance that need with also maximizing access to the lower shelf (located even with the 2x6 horizontal stretcher shown in the "side view") and the items I'll store there.


I was thinking that the grid to support that shelf would be 2x4 material unless y'all think that going 2x6 would enhance the stability of the undercarriage and somehow contribute to anti-racking along the long axis.
On the end view, you'll notice plywood panel instead of a skinny stretcher. I figure that'll take out the racking for that axis of the undercarriage but does anyone have predictions about performance on the long axis?
The one nice thing about the deep torsion box is all of that vertical contact between the legs and the box. I'm hoping the rigidity stemming from that element makes up for other possible shortcomings of the rest of the design.

Thoughts and suggestions pretty please?

TIA,
David in Washington

« Last Edit: January 04, 2020, 12:47 AM by Upcoaster »

Offline demographic

  • Posts: 741
Re: Workbench undercarriage design
« Reply #1 on: January 04, 2020, 08:18 AM »
You can mount a metalworking vice on a board with a cleat on tthe underside so it can be held in a woodworking vice.
Then the board the vice is on can also have a raised lip round its sides so filings don't get on the woodworking bench so much.

Offline RustE

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Re: Workbench undercarriage design
« Reply #2 on: January 05, 2020, 11:14 AM »
Have you considered making a box structure from 2x6 for the bottom shelf?  I made a workbench with two frames like the sketch below that were joined with the plastic legs from a 2x4 Basics kit.  I would not use the 2x4 Basics legs for a bench like you describe, but for certain applications and environments these are a good option.

* frame_sketch.pdf (11.49 kB - downloaded 231 times.)

Another consideration about the legs:  I would probably use a 2x8 joined to a 2x6.  This would give each 'face' of the leg about the same contact surface with the torsion box (top) and frame (bottom).  Attach the legs to the frame with carriage bolts or another fastener that has a large head on it.
« Last Edit: January 05, 2020, 11:22 AM by RustE »

Offline xedos

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Re: Workbench undercarriage design
« Reply #3 on: January 05, 2020, 12:03 PM »
Your design should be plenty stiff enoug to resist racking.

For me though , 4+ Ft. width is a bit too much. I'd go 42" max and prob 36".

Offline jeffinsgf

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Re: Workbench undercarriage design
« Reply #4 on: January 05, 2020, 04:27 PM »
I'm with Xedos... a full 48-inch table sounds like a good idea, until you're using it for more normal use and can't reach from one side to the other. I'm in a similar planning stage personally and just built something similar at our model shop. 3 wide by 5 long seems very convenient Then throw a full sheet on top of that when you're breaking down full sheets.

Offline tomp

  • Posts: 119
Re: Workbench undercarriage design
« Reply #5 on: January 06, 2020, 11:37 AM »
If you plan to do some heavy-duty "whacking" on the top, you might consider having the top supported other than by the screws as shown - add a second layer of plywood to the legs underneath the top so that any vertical force is transmitted down to the floor, essentially having the top sit inside a dado in the legs.

Offline Upcoaster

  • Posts: 19
Re: Workbench undercarriage design
« Reply #6 on: January 28, 2020, 08:40 PM »
Crisis averted.



If I add a "box" for drawers (with some intentional design for anti-racking) that joins the lower stretchers/shelf grid with the under-side of the torsion box, that'll add some significant rigidity AND give me some great storage utility.  The mix of open cubby and drawers will actually be a really nice upgrade to the initial design.

Offline Upcoaster

  • Posts: 19
Re: Workbench undercarriage design
« Reply #7 on: January 28, 2020, 08:45 PM »
Another consideration about the legs:  I would probably use a 2x8 joined to a 2x6.  This would give each 'face' of the leg about the same contact surface with the torsion box (top) and frame (bottom).  Attach the legs to the frame with carriage bolts or another fastener that has a large head on it.

Excellent call regarding the 2x6 married with 2x8 for the legs.  I would have smacked my forehead after the fact if I hadn't thought of this in advance.  As for the hardware, I hadn't gotten that far in terms of specifics. Carriage bolts sounds like a winner as well.

Offline Upcoaster

  • Posts: 19
Re: Workbench undercarriage design
« Reply #8 on: January 28, 2020, 08:58 PM »
I'm with Xedos... a full 48-inch table sounds like a good idea, until you're using it for more normal use and can't reach from one side to the other. I'm in a similar planning stage personally and just built something similar at our model shop. 3 wide by 5 long seems very convenient Then throw a full sheet on top of that when you're breaking down full sheets.
It's a worthwhile caution to consider. I'll mull that over.
I'll have access to 3 out of the 4 sides vs. having it backed into a corner and only have access to 2 sides.  If I can't reach across the surface, I can easily go around to the other side. I think this'll be nice for an assembly table.  Plenty of space to lay out parts, clamps, etc.  A portion of the top will have dog holes so it'll be nice to have different zones of the surface to accommodate different types of work.