🌞 New Stock Frame Design 🌞

[dlang]

@bar

I’m a little bit worried about this connection here:

I guess that the forces there won’t change as we move up or down, but joining lumber like that could be tough, right?

that point is a 12" piece of 2x4 that has the flat of the top 2x4 across the top, and the flat of the side 2x4 on the side.

With a couple screws (or lag bolts) through this from each direction, it would be pretty stable. There aren’t a lot of vertical forces here, it just needs to support the sled + top beam out to ~8" in front of the frame

If needed, it’s pretty easy to add a triangular brace below this. It would be toenailed into the 12" parts and then screws through it to the side of the frame.

[dlang]

Example with the added braces

[rjon17469]

@bar

Pictures would be great!

Here are a few that I quickly snapped just now. I’m not completely finished, but all the major pieces are there. I was going to make a separate thread that goes in more depth of why I did some things, but the short story is I just had time to kill before my kit gets here.

[dlang]

normally I hate toenailed joints, but in this case, they are merely providing vertical support to prevent the supports from twisting.

All fasteners are going into the face grain of the wood (no end grain joints). If I was building it, I would use lag bolts instead of screws, but I’ve been known to overbuild things

[bar]

What a gorgeous build! I really like how you did the angle 4x4s to push the motors forwards. It’s probably a little too advanced for the new stock design but love it!

[dlang]

@rjon17469 I second that, a beautiful build. I like massive overkill, which this is. But you won’t have problems with flex

[rjon17469]

Thank you guys! It’s definitely not a contender for a stock design, but it was still fun!

[dlang]

in my folding design, the height of the frame is a compromise to fit in 10’ 2x4s, if I used 12’ 2x4s I would make the frame wider (less unsupported plywood out to the sides) and if not using wheels, extend the sides down the ground.

I also worked to keep it under 80" (the standard height of a door in the US)

[Bee]

@rjon17469

this was what i was talking about in this post:

Alternate Temp Bracing

lets have a conversation about 2x4’s and fastening systems. For my non US peeps please alter to MM in your head. I’m going to toss a premise out. If anyone wishes to argue or dispute it I will be glad to participate as long as you create a new thread where we can debate it. For the sake of argument we are going ot say a 2 x 4 is resistant to bending more on the edge of the 2 x4 rather that the 4x2 edge due to bias. One of the figures below shows this - [2by4] Further when you introduce…

I sent the last post as PM thinking it was posting here, my bad.

I love your build.

Great work.

Thank you

[blurfl]

@dlang

If needed, it’s pretty easy to add a triangular brace below this

I think that some form of brace is needed there. rigidity is the goal.

Too, I’d advise spreading the verticals out to the ends of the workarea and adding one in the center, to better support the top bar. The closer the supports are to the motors, the more stable the frame is. The center support doesn’t need to go to the floor, but it should tie the bottom beam and the workare sheet and the top bar together.

[dlang]

@blurfl

Too, I’d advise spreading the verticals out to the ends of the workarea and adding one in the center, to better support the top bar. The closer the supports are to the motors, the more stable the frame is. The center support doesn’t need to go to the floor, but it should tie the bottom beam and the workare sheet and the top bar together.

The bending stress on the top bar is not that high. You have the weight of the sled (and a little pull from the motors if the bit has trouble cutting) pulling down on the ends. Using a 2x4 on edge, or a piece of unistrut gives you a lot of strength.

The current design has 54" between the edges of the verticals, so it only has 32" on each side from the supports out to the motors. I really don’t think that it would matter much to shrink it. The

The plywood hangs out on each side (72-54)/2 = 9" on each side, so that’s not much.

I would consider putting a tab/block on the back of the bottom beam (center and outer edges) to support the plywood. Also notice that there is a 2x4 across the top of the plywood to support it.

[blurfl]

@dlang

bending stress on the top bar

I’m more concerned with bow and twist. Three connection points determine a straight line, two just anchor the arc.

[madgrizzle]

My suggestion for the stock frame design is to make sure you can source all the parts from either HD or Lowes (as examples) and not be too intimidating or difficult to put together. It should be dimensional lumber but since 10-foot unistrut is readily available at both big box stores, it could be used as the top bar as in @dlang’s design. I wouldn’t use unistrut for the entire frame… too many nuts and bolts and is a bit intimidating to cut to length.

[Bee]

Good point. In my head for a few days I’ve been playing with a T design. 1 Unistrut at the top And 1 vertical 2 x 4 in the center. Then to support it an Easel folding design with 2 more 2x4s

The rest is either but some sort of vertical support to attach to. I want to figure out a method of cutting ( or drilling ) mounting holes, a jig that allows me to flip my work and cut a mirror pattern.

This has been rolling around my brain.

Thank you

[madgrizzle]

I think we need something people can use to keep the work piece flat. This weekend I put a sheet of 1/2-inch ply on my plywood “frame” and it was bowed rather badly and I used clamps on edges to flatten it out. My plywood frame isn’t perfectly flat, but I’ve got some boards stiffening it up some. So some considerations should go into ensuring there’s a flat plywood/mdf/whatever backing that work pieces can be clamped to, otherwise it will cause problems in cutting. It may not need to be “structural” but I think we need something.

I like @dlang’s design, but maybe with three A-frames (two near out edge and one in the middle)

Can I also suggest that we incorporate a place to mount the electronics? like a cut piece of plywood that the boards can get mounted to?

[Keith]

That is one BEEFY frame!

[lilimade]

with a unistrut frame i assume there is also no need for there to be plywood as structure? just wasteboard?

[Bee]

Here is a sketch of my basic idea. My representation is gorked on scale. David, perhaps you or anyone else could onshape this. if we could design a 2x4 to Unistrut mounting cap. It could be easy to put together and take apart quickly. The design is based on making the Skirt out of 9 inch boarders cut from a single 4 x 8 sheet first. Using 2x4 small pieces of 2x4 to hold the skirt edges together. This frame creates a negative space to mount the “working sheet”. The 2 2x4’s 46 inches apart create the “Working Sheet” main attachment. Two 46 inch braces between the uprights at the outer edges of the skirts. The Unistrut sits on top of that. A diagonal brace between the 2 upright 2x4’s support it’s not racking.

1 more 2x4 as a “leg” to tilt back on.

The motors are on a 12 foot long Unistrut 21 inches above the working top edge - ~7 foot 9 inches tall.

BOM

5 - 8ft 2x4’s
1 3/4 inch sheet of plywood
1 12 foot Unistrut

2 motor caps
2 unistut mountng caps

1 box of deck screws

Thoughts?

Thank you

[dlang]

That’s my feeling as well.

For the top beam, it’s about twice the weight as wood and 4x the price ($20ish
instead of $5ish), but I think it’s a valid option to have.

[dlang]

twist is an issue for chain alignment, but I’m not sure anchoring it is always
going to be enough.

bow doesn’t bother me, second worst case, just recalibrate (and if needed shim
one side), worst case, spend nother $6 and try a different board

wood can bow and twist badly enough that it doesn’t matter if you anchor it in
to places or three, it just won’t work.