I’ve read everything I can find on the forums, and I see lots of people using unistrut as well as folks using wood for their Lowrider tables.
I’m building a table shortly, and am trying to decide what’s the best way. My current table design is be based on the tension box style and surfaced with 3/4 MDF, and will be a full 4x8 usable cutting space. The MDF is to be supported not only by the plywood (tension box), but also by a 2x4 frame using 10’ 2x4’s on the outside perimeter. This design is not using unistrut, but now I’m wondering if i should change the design to use unistrut on the edges? Here is my current design (not yet finished, but the concept is the center 4x8 sheet is fully supported on the edges by an inner 2x4 frame, to keep it flat / secured), and will be CNC cut (yes, by the Lowrider itself, a “mostly-printed table”!):
[attachment file=74387]
[attachment file=74386]
So my questions:
Anybody have experience on if superstrut is flatter/better than MDF on ply / tension box frame?
I see some cool designs where the table is only 8 feet and the superstrut goes the extra few feet to give a true cutting space of 8'. Does this work well, or is it better to have the table surface extend the full ~10 feet?
My LR build uses a torsion box/superstrut configuration, and I was really surprised how much flatter my frame was than the unistrut. Both pieces had slight twists across the entire length. After bolting it to my table, everything straightened out.
If I had to do it again, I would still use unistrut. I was worried that over time the side wheels would make uneven grooves in wood, and my bolting strategy allowed me to fine-tune the exact level/squareness of the strut, whereas if the frame is crooked you’re kinda screwed.
I attached a picture mid-build where you can see the structure. The angle makes it look a little crooked, but it’s almost perfectly square.
Thanks, and for the pic… So the unistrut/superstrut was bowed, but clamping it to your (flat) table “fixed” it. So then why not just stay with wood? Does seem like it would be a lot of use before any true wear steps in? Is that the main reason? I’ve often wondered how smooth/even the strut will be, compared to MDF. However, in my design, I have two cuts in the mdf where the rollers will run and that worries me… And I don’t trust 2x4’s to be flat (hence the MDF on top).
From the pic, it looks like your table is 8’ (or at least shorter than the strut), and you use the strut to extend it further out. Are you happy with that, or did you make the final top the same length as the strut? Seems like it is “wasted space” in that you could use that space for clamps (holes drilled into the top) or to hold parts/pieces/tools, but does bring down the price (less sheet goods).
Longer unistrut here as well. This way it’s a single piece for the surface. My unistrut was straight from the store. Sometimes you get warped pieces, I check them with the floor at the store. Unless there’s a floor drain in that isle, the concrete floor at floes or home despot will be flat enough for this check. It waaaaaay flatter than the floor of my barn! My unistrut is attached to two pieces of plywood that’s bolted to the sides of my table, so I just make sure the top edges are parallel to each other.
My unistrut wasn’t super twisted, I probably could have been more careful when I bought it, but it was pretty close to straight. My frame just ended up being more square because I was very careful with my wood and cuts. My surprise was mostly just my assumption that the metal would be near-perfectly square, and it wasn’t.
My table is only 6’ long (8+’ wouldn’t fit in my shop). I was originally going to cut the unistrut even with the table, but someone on the forums (maybe Jeff?) mentioned that adding an extra 6” to the rail lets you cut all the way over the edge of the table, which seemed useful. I’m not 100% sure it’s worth the hassle, but it’s a lot easier to cut it shorter later than buy all new unistrut.
My $0.02, if you’re going to use plywood for the torsion box, don’t have the 2x4 in there. The plywood will be flatter, and very strong. The plywood is more stable.
I think it would be great to have 6" of table at the end that didn’t have any spoil board on it, so you could mill on the ends on boards. I don’t have a good way to clamp stuff to the end, otherwise, I would have tried this already.
Dimensional lumber will always warp, even if kiln dried. It might take a couple years, but it will move. As for clamping, if you have access to the inside of your table drill some 3/4" holes across the end every couple inches. Then you can use quick grip clamps after passing the bar through and reattaching the end.
I agree wrt 2x4 warping, though was thinking that securing it to the MDF top and ply frame would basically eliminate that problem. So why the 2x4 frame at all? A (maybe silly, over-engineered?) thing I was trying to do… build a simple 2x4 frame and using that hold the Lowrider so it can cut that rest of the table. Then assemble the table around the frame, so you wouldn’t need to reinstall the Lowrider. I’m thinking now that I’ll skip that, and just build a table… Less cost, likely better - just not as “cool”!
I’m still unclear if Superstrut/Unistrut is actually better than MDF over a plywood tension table. Do you find the metal to be as smooth/smoother than an MDF top? I do see how you can force it into something close to flat with leverage, though MDF over clean cut ply starts off pretty darn flat!
I don’t think there are any secret features. Unistrit is stable, easy to attach, stiff, and about the perfect size. Wood would require cutting it, and a lot of the remaining features depend on the tools you have available to cut. Mdf, cut with a good table saw would be just as smooth and stable.
One other advantage of unistrut is that your table can be any thickness you want. If your LR rides directly on the table, your max table thickness is less than 4” — any more and the hardware won’t fit.
I’d lean more toward not using a 4x8 sheet in the center with pieces added to the outside to make it large enough. You’re going to be using two sheets of MDF anyway, cut so the outside has the largest pieces to help hold everything square and flat.
Heath, here’s a picture of the bottom of the right side of my LR2. The plastic and bearings holding the bottom of the Z tube hang out to the left of the tube, and would just barely fit under the bottom edge of my table (which is 4” thick) if I didn’t have the unistrut.
You guys rock! Thanks so much for all the advice. I’m going to redesign my table, and will share the next iteration for your awesome feedback. I’m heading offshore on a boat tomorrow for the next 7-10 days, so it will be a bit before the next update (when will Satellite bandwidth be affordable and fast???) - but hope to design it while out on the blue water…
No doubt. I’m using the Iridium Go! … which is at best (rare) 2400 baud. Remember those days? Dial-up, 2400 baud? That was back in the days when web sites barely existed (CompuServe/AOL anyone?) and everything was text? Try it these days - CNN home page is 1MB!
Boy, I remember the day I switched from the 300 baud modem to a 2400 (skipped 1200 entirely). Gawd but that thing was fast, I had a hard time keeping up with text scrolling past while I read it.
