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Assembly/outfeed table design

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Forum topic by JakeK posted 10-14-2016 03:05 PM 827 views 0 times favorited 33 replies Add to Favorites Watch
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JakeK

26 posts in 145 days


10-14-2016 03:05 PM

Topic tags/keywords: torsion assembly table casters racking

I am thinking of building a new assembly table based somewhat on the wood whisperer’s design with a torsion box top, but i wanted to make it mobile. For the cabinet area i wanted to have mostly drawers. I dont think i’ll put in any doors. In my plan i have leveling casters on all 4 corners but to avoid sagging i think i’ll put 2 in the middle as well. To prevent racking i put vertical pieces of plywood attaching each bay as well as a full sheet on the bottom. I’m looking for feedback on this design, which is currently pretty simple. As well, if there are any features you would recommend i add to this simple design, that is welcome as well. Any help is appreciated. Thanks


33 replies so far

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JBrow

818 posts in 384 days


#1 posted 10-16-2016 03:16 AM

JakeK,

If I understand your design, the cabinet will be 96” long and 48” wide with a ¾” sheet of plywood for a bottom. A vertical ¾” plywood spline centered on the bottom running from one end to the other provides center support of the bottom. Drawers would be located on each face of the cabinet (six drawer bays in all). I am guessing that the drawers will be on drawer slides mounted to the drawer bay dividing plywood panels. The leveling castors will afford mobility and can be adjusted to ensure that all four corners of the cabinet will rest firmly on an uneven floor when in stationary mode.

Based on this understanding, yours looks like a good well thought out design. The only potential issue I could foresee is that the bottom could possibly sag a bit putting strain the joinery used to connect the dividers to the bottom and the center spine, especially with drawers loaded down with contents. Any sagging of the front and back faces of the cabinet could add some stress to the long sides of the torsion box. If a face frame is added, support to the bottom and dividers would be added and center castors could be avoided. Otherwise the center supporting leveling castors would add center the support needed and would be a good idea.

I would also think that when shopping for castors, ensuring together they will support up to a 1000 pounds could avoid headaches down the road. I figure that with the weight of the cabinet and torsion box top, drawer contents, and a pile of lumber or a project setting on the top could approach 1000 pounds. Lighter duty castors whose load rating is exceeded can develop a flat spot on the tires. Light duty castors can also make a heavy table difficult to roll around.

If you build the torsion box top so that it features an overhang over the base, workpieces could be clamped to the top. I would think an overhang of perhaps an 1-1/2” would offer sufficient bite for the clamps while still allowing good access to drawer contents.

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Harry

71 posts in 644 days


#2 posted 10-16-2016 06:50 AM

I built a table a while back and was going to make removable cabinets but have since decided that the space underneath comes in handy when changing projects. Here is what I ended up with.

-- Harry - Professional amateur

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muleskinner

881 posts in 1901 days


#3 posted 10-16-2016 02:06 PM

I would think if you use a single piece of plywood down the middle for the divider between the front and back, you shouldn’t have any concern over sagging.

-- Visualize whirled peas

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JakeK

26 posts in 145 days


#4 posted 10-16-2016 08:32 PM

Thanks for the replies guys. These are the casters i was thinking of using. They would rest on pads when stationary. http://www.woodcraft.com/product/149511/woodriver-machine-leveling-caster-plate-mounted-4-pack.aspx. i’m thinking 6 will be the way to go.

Not sure if you can tell from the pictures, but my design had the 4 short panels as a single panel an the one that goes the long way dado’d into each of those. So in other words there isnt a single long divider going the long way. My thought was for building purposes it’d be easier to have 4 identical panels that go the short way and with glue and screws it’d be just as strong this way. let me know if you disagree.

Harry, i like how you made your torsion box. I was thinking of doing the same thing with lap joints. What did you mean when you said that the underneath was handy when changing projects? My thinking was with drawers down there i could keep the tools for layout and assembly. Nail guns, nails, squares, glue, screws, tape measures, double stick tape, cordless tools, domino/biscuit joiner, hammers, etc. I am a bit worried though about how heavy this thing will be.

I was kind of hoping to get the best of all worlds with this thing and incorporate dog holes and some sort of vice but maybe i’m better off building a separate work bench for those things.

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Harry

71 posts in 644 days


#5 posted 10-16-2016 09:30 PM



Harry, i like how you made your torsion box. I was thinking of doing the same thing with lap joints. What did you mean when you said that the underneath was handy when changing projects? My thinking was with drawers down there i could keep the tools for layout and assembly. Nail guns, nails, squares, glue, screws, tape measures, double stick tape, cordless tools, domino/biscuit joiner, hammers, etc. I am a bit worried though about how heavy this thing will be.

I was kind of hoping to get the best of all worlds with this thing and incorporate dog holes and some sort of vice but maybe i m better off building a separate work bench for those things.

- JakeK

Jake, I fully intended to make storage cabinets for my table but I have two reasons why I am not going too. First off, this thing weighs in at right around 700lbs, with cabinets that would put it at 1000 or so. I like having the open room for parts as I am building or whatever underneath in one place. All my tools are on wheels as I tend to jump around to different projects in our studio. When I get back to it, most everything is in one place on or under the table. Works really well for a guy that can make a real mess of the shop. Good luck with your build!

-- Harry - Professional amateur

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JakeK

26 posts in 145 days


#6 posted 10-18-2016 03:44 AM

Harry, on your torsion box, what size did you make the grids? as in each square’s dimensions. Also what method did you use for creating the dado’s in the slats? Did you gang up a bunch and run them through together? Did you use an indexing pin of some sort on a sled or miter gauge?

Are the outside rails of the torsion box also 1/2” MDF or are they 3/4”?

I’m thinking of putting in 3/4” dog holes centered in the grids so I can use the festool or bessey quick clamps to hold things down. Also considering making the cabinet smaller so the torsion box can hang over the edge enough to accommodate a face vise. If I would put in a face vise I would beef up the torsion box in the area where the vise would mount. Anybody have any thoughts about either of those ideas?

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DirtyMike

460 posts in 366 days


#7 posted 10-18-2016 03:50 AM

109 dollars for casters huh? For an outfeed table?

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JakeK

26 posts in 145 days


#8 posted 10-18-2016 04:01 AM

Yeah they’re a bit spendy and i wouldnt buy them to go onto my current outfeed table that is constructed of 2×4’s and CDX plywood but this is more than an outfeed table. This is a rolling cabinet that also serves as an assembly table and outfeed table. I posted this here for feedback so if you know of a cheaper alternative that can support this weight and the wheels wont develop flat spots, i’d be interested.

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Harry

71 posts in 644 days


#9 posted 10-18-2016 04:28 AM

Jake, the grids are 6” x 6” and the outer rails were 3/4” just because I had extra. Bottom is the 1/2” MDF that was used to build the box on and the top is 3/4”. I cut the dado’s with a simple jig with an indexing pin attached to my miter gauge. Just did one at a time, real easy. I was thinking of also adding a few dog holes in mine as well. I traced the grid on the bottom so I could find the center of the grids. I think my top hangs over about 4”.

-- Harry - Professional amateur

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daddywoofdawg

1010 posts in 1039 days


#10 posted 10-18-2016 05:21 AM

something I want to put into my next out feed table,is crosscut sled,jig and accessory storage.and a bin to store cut-offs.

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clin

514 posts in 460 days


#11 posted 10-18-2016 05:43 AM

Concerning the basic design, I think it is sound. If you look at it, with the internal panel running the length and the cross panels, the entire thing is forming a torsion box. The key to that being strong and rigid is the panels being well attached to the “skins” (bottom panel and top pieces).

In this case the bottom is a full skin. The key to it not sagging is making sure the joint between the internal panels and the bottom are very secure. A simple glue in a dado may not be enough. The joint is actually in shear and compression (which is helpful). It’s just my concern that there may not be enough glue surface. If you could glue some addition strips into the corner formed by the internal panel and the bottom. Especially the full length panel, that would help. Effectively making for a much deeper dado. I’m thinking perhaps 1/2” square stock.

It is equally important to have a good joint on that top panel running in the center. As is, I think you would want the top of the table to add support, so you want it to be securely attached to the case in multiple places. That way it will act as a the top skin of the torsion box formed by the case. But in all cases, you need good joints on all the panels.

A face frame is critical too. Since there are not full front and back edges (because of the drawers), the face frame sort of functions like this. So this frame should be as large as possible and very well attached.

Bottom line, generally looks good, just make sure the joints are really solid. And I think adding some extra material to the joints of all the panels would help a lot and not interfere with the overall design.

I don’t think typical cabinet construction is good enough since, typical cabinets are not self supporting over a long span like that.

Also, use the best darn plywood you can get. I’d use Baltic Birch, though that comes in 60”x60” panels, so I’m not sure what the best thing is you can get in 4’x8’ sheets. But you want the best you can get.

-- Clin

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JBrow

818 posts in 384 days


#12 posted 10-18-2016 01:02 PM

JakeK,

One other thought occurred to me. The assembly/outfeed table could interfere with the travel of sleds and the mitre gauge. While the lifting castors make the table mobile, I suspect moving the table out of the way of the mitre gauge bar would become an unwelcome and frequent chore. Of course slots that align with the table saw mitre slots could be incorporated into the top of the torsion box, but I would think the slots would weaken the assembly table and potentially introduce some unwanted flex in the torsion box top. A thicker top layer of the torsion box or perhaps a two layer torsion box top could solve this problem. A thicker top will affect the height dimension of the supporting lower cabinet.

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tmasondarnell

23 posts in 1254 days


#13 posted 10-18-2016 01:37 PM

JakeK

Looks like a good plan.

I do have experience with those castors. At my company, we use them on equipment we manufacture to facilitate move in. They are great, but they are not easy to raise or lower. So f you plan on moving the table around frequently, they would be frustrating.

Good luck

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JakeK

26 posts in 145 days


#14 posted 10-18-2016 04:11 PM

Clin, thanks for your response. I haven’t thought of it as a torsion box but that makes sense. I thought about a face frame but i’m wondering how much strength it will really add if the pieces are only 3/4” wide x 3/4” thick. I had originally planned on either edge banding the plywood or just leaving it natural since it is shop furniture.

Regarding the joints, there are several places where plywood is dado’d in on both the front and back side. 1/4” dado on each side only leaves 1/4” of meat in the middle. I’ve never tried doing this before. Do you see this as a weakness? should i make 3 separate cabinets and screw them together instead?

I’m now considering maybe making a rectangular metal tube frame to go between the cabinet and the casters. Maybe that would be the strongest way to go.

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JakeK

26 posts in 145 days


#15 posted 10-18-2016 04:16 PM

JBrow, i had considered this. I’m thinking of just putting the outfeed table right below the height of the table saw miter slots so they wont get hit by the miter gauge. That’s how my current crappy outfeed table is. It’s only really there to catch large pieces. I also thought about maybe making a small attached outfeed table, say 8-10” deep that attaches to the back support angle iron on the saw and height wise is just above the outfeed table. That might not be the best idea though, not sure.

I’m not crazy about adding another sheet of MDF to the top of this thing. At some point this thing is going to get unbearably heavy.

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