Assembly Table questions

[Graham Hutchinson]

I'm planning an assembly table and after some research I've come up with the following design.

Approximately 34"x68"
5/8" MDF core and skins
core members 2.75" high, so total thickness 4"
8" center to center core grid
Halved joints at each core grid intersection (cut with dado blade on table saw)
3/4" x 4" trim around the outside
4 legs with leveling casters (I have an uneven basement floor)

Any comments on the above design?

I read on one site where the MDF with the half joint cuts had expanded when the glue was applied, and the joint could no longer be made. Has anyone else experienced this?

Not sure whether to add a hardboard top. What are the pros and cons?

Also considering some 3/4" holes for bench dogs and clamps but I have not seen any assembly tables with them. Has anyone found them useful on an assembly table? I would reinforce the cell on the inside that contained the hole.

thanks in advance for your input

Graham

[Chris Fournier]

I've made alot of torsion boxes over the years, given your application I would not bother with the lap joints - there is simply no need.

IMG_00000156.jpg

This is my current assembly table and the top is a torsion box like you propose and the core is simply butt jointed (glue and stapled), it is like granite and extremely flat. I welded up the base and took great care to keep it square and flat then I built the top on the base (3/4" MDF faces and 13/16" particle board core with laminate on all external surfaces). This table is worth every moment and $ that it took to build and I know that you will feel the same way about your assembly table too. Make your table as large as you can for your work space, you won't regret it.

Show us your table when you're done!

[tom coleman]

i made a 65 inch table, top was 3 layers of mdf topped w hardboard then banded w hardwood. I mounted a vise on one end and drilled a series of dog holes in line with with vise. Served me well. Next step is to add auxilliary top with Kreg Track for pocket hole jpoindery

[Sam Babbage]

I agree with Chris, glued butt joints are fine. Space them far enough apart to get your brad gun (and hose) in between. Lap joints are massive overkill and can even lead to problems, as you mention.

[Kevin Jenness]

The scantlings are fine, but the top will be heavy. If you want to move it around by yourself, make the top of thinner material and use thinner core stock spaced more closely. I work on a 4x8 p-lam clad assembly table made with 5/16" basswood core strips about 3 1/2" o.c. with 1/4" lauan skins. It's 25 years old and still going strong. I am 25 years older and can still pick it up and slide it around easily.

I have built quite a few torsion boxes, and I find the half lap method faster and easier than butt-jointing myriad small pieces and keeping them aligned for glueup. I gang the full length strips together and cut the half laps with a dado head on a sliding table saw, then the frame practically assembles itself.

[Kevin Jenness]

Looking back at the original question I see that some have had trouble assembling glue-swollen half lap joints. There is no need to glue these joints- they add nothing to the box's strength which comes from the glued joints between the core and skins Whether half lapped or stapled, the core joints are merely a way of holding the core strips in position for gluing the skins on.

I also note that the description of my table left out it's depth, which is 4". I think that is about right for a 4'x8' table with minimal base framing.. I have a 3 1/2'x8' x2 1/2" torsion box that I use as an auxiliary table. It is plenty strong in bending, but I have to take care in setting it up to avoid twist if I need it perfectly flat. The 4" thick box takes a lot of force to twist out of plane.

My top sits on two 20"x28"x42" hollow boxes made with 3/4"x4" pine frames on 4 sides and 1/4" lauan skins on the last two faces. Normally they rest on the 20"x42" faces on the floor, giving a net table height of 32". For assembling and working on deeper cabinets,I slide the torsion box aside and rotate the supports onto their wider faces, giving a net height of 24". I find this makes hanging drawers and doors a lot easier. The lightness of the parts makes this an easy process, and they can be readily moved right out of the way to give unobstructed floor space, always at a premium in a small shop.

Be sure to put solid blocking anywhere you intend to mount a vise or other hardware.

[Graham Hutchinson]

Thanks everyone, good suggestions. Weight is an issue for me. If I every want to get it out of the basement, the table will have to be carried out on its edge.

[Chris Fournier]

Weight is always your friend until you have to move it. The top I posted takes two guys to move. If you intend to bash about on your table then heavy is good. Personally I wouldn't consider a 1/4" face and I would dispense with any solid wood components and use sheet goods for stabilities sake. I pound on my table like mad and it sucks it up.

[Loren DeShon]

<<Also considering some 3/4" holes for bench dogs and clamps but I have not seen any assembly tables with them. Has anyone found them useful on an assembly table?>>

I put Rockler T-Track in the top of my assembly table and I don't know how I ever did without it. I'm going to add it to the tops of my workbenches that don't yet have it.

[Jim Andrew]

I'm also in the process of building an assembly table. Am using a harbor freight motorcycle lift as the base to make it a variable height table. Picked it up a couple days ago on their blowout sale for 299. My plan is to use some oak strips to fill under the 3/4" offset on the edges, and around the outside to make the table wider, then a sheet of 3/4" ply for the table top. Am shopping for some clamp track now, as I would like to add the track to one side and end. Appears that just regular T track is not heavy enough to stand up to the Kreg clamps, looking for a lower cost alternative to the Kreg klamp trak.

[Ruhi Arslan]

Am using a harbor freight motorcycle lift as the base to make it a variable height table. Picked it up a couple days ago on their blowout sale for 299. My plan is to use some oak strips to fill under the 3/4" offset on the edges, and around the outside to make the table wider.

Unless you use auxiliary legs on the perimeters, it will be dangerously unstable. As big as it is, even if when the weight is positioned right in the middle, it is very easy to tip front to back (yes, in the long direction) and very shaky side to side. Like to hear how it works out.

[Chris Fournier]

I'm also in the process of building an assembly table. Am using a harbor freight motorcycle lift as the base to make it a variable height table. Picked it up a couple days ago on their blowout sale for 299. My plan is to use some oak strips to fill under the 3/4" offset on the edges, and around the outside to make the table wider, then a sheet of 3/4" ply for the table top. Am shopping for some clamp track now, as I would like to add the track to one side and end. Appears that just regular T track is not heavy enough to stand up to the Kreg clamps, looking for a lower cost alternative to the Kreg klamp trak.

We had one of these lifts kicking around at work, it was very unstable as has been pointed out. Perhaps you will be able to modify it!

[Michael W. Clark]

Appears that just regular T track is not heavy enough to stand up to the Kreg clamps, looking for a lower cost alternative to the Kreg klamp trak.

I saw some 3/8" T-track at ttrackusa. It looks heavier, but I haven't used any. You could also rout a t-track in hard maple and use lots of screws/bolts to attach.

[Jim Andrew]

You might look at the harbor freight website and see the lift I'm using. It is not the small lift table, it is the large one built to drive a motorcycle onto and lift the entire machine up. The platform is 26 3/4 wide by 86 5/8 long, and the wheels are 21 wide and about 51 length wise. Figure if you can drive a Harley onto it, and it is stable, should be pretty stable for a work table. My big deal is the clamp track, have to wait to get some ordered before I can build the top. On tops I have used for gluing, if they were finished the glue came off easily, unfinished it has to be scraped, so think I will give it a couple coats of finish. The melamine is pretty brittle, just pb with the melamine coating, so think I will go with ply.

[Ruhi Arslan]

This one is instructional and not painful at all like many other amateur "youtube star" instructional videos.
http://www.finewoodworking.com/woodw...bly-table.aspx