I’m not really happy with it either
unistrut to arm is adjustable (a nut riding inside the unistrut, tightened down from below to the arm)
I’m not picturing what you are meaning
we run into trouble if the unistrut/arm sticks out far enough to interfere with the chain.
I forgot about the lack of the plunge capability.
For the bolt that attaches to the unistrut, all that matters is the top hole in the arm be in the right place, it doesn’t matter if the angle is off by quite a bit.
if we can drill a 3/8 or 1/2 hole through the arm and use a 1/4" bolt, there is an incredible amount of room for bad angles. If we drill a 1/4" hole, it can still be off by quite a bit and still clamp the strut to the top arm solidly
Ah. You are gripping to the channel and not the top. What if the you pass it all the way through the slots in the “bottom” of the unistrut. Do you need infinite adjustability?
https://www.homedepot.com/p/Everbilt-1-4-in-20-TPI-x-4-in-Brass-Hanger-Bolt-808608/204274971
If all its doing is clamping the unistrut to the arm, acceptable tolerance would be that the bolt pass out the bottom of the 2x4 and not the side. Even I managed to accomplish that. For adjusting it, do you have to put a wrench on the bolt head in the unistrut or is it captured?
Edit: I’ll answer my own question. The nut in the unistrut would be captured.
Hey Bar,
I was thinking about your design again, with wood spacers and long bolts connecting the top bar. Looking at the photo in the weekly update, I thought there might be some modifications which make it better, regardless of whether or not it is used. Orient the spacers vertically, so that they are parallel with the vertical 2x4. Make them as long as necessary to achieve rigidity, and to prevent the wood from splitting from all the screws. Rather than use one long bolt, use standard wood screws. Fasten the first spacer (2x4, oriented vertically) onto the vertical 2x4 using standard screws. Fasten the second spacer (2x4, oriented vertically) onto the first spacer using wood screws. Fasten the third spacer (2x4, oriented vertically) onto the second spacer using wood screws. Then, fasten the 10’ horizontal beam using standard wood screws or a larger lag-bolt.
How about doing away with the wood bracket, lag screwing one of these L brackets to the front and back of the top of the front leg (2 L brackets per leg). And then running 2 bolts into the unistrut arm (one front, one back).
Just an idea. I really like how easily adjustable it would be to use unistrut for the arm.
Considering that this is what people use to build their unistrut frames (I believe) then I don’t know why it wouldn’t be strong enough to hold up the arms.
the holes in the unistrut have a couple inches of solid material between them. We can’t afford to be that far off (more below)
That or a lag bolt will work just fine for something that only needs an inch or so of adjustment (suitable for someone who doesn’t plan to move things much), but the slots/holes on the unistrut are only so long (a couple inches on some version, 4 inches on others).
so that works just fine as the default basic version, and people who want it to move more can deal with either removing the lag bolt and putting it in another hole, or drilling for a bolt from below
that could work. you would need to go with longer unistrut (10-12" instead of the short 6" piece I posted the link to) a quick look found 16" and 24" pieces that would have to be cut in half, or cut pieces off of 10’ lengths.
Also, you need to be very sure that you mount the angles at the right place. If there are Ts available, we could have one side of the T be on top of the leg.
There are a lot of unistrut fittings availalbe, we’ll need to look through catelogs and see what we can find
P2343 looks like a solution. Wrap it around the edge of the 2x4.
Edit: Ouch, $17
I like it, matching it up against the edge of the 2x4 should have it start off straight, and while there is a potential for the horizontal arm to bend the bracket, they are pretty strong brackets (if there was one that had a gusset on the part sticking out it would be ideal)
hunt around on price, single prices, especially from big box stores are expensive
P2484EG may work, here’s a source for ~$6 each http://www.globalindustrial.com/p/storage/struts-and-framing/unistrut/unistrut-1-58-90-gusseted-fitting-p2484eg-7-hole-electro-galvanized?gclid=EAIaIQobChMIpaTAzfaH2QIVyF5-Ch27FADzEAAYASAAEgJDsfD_BwE
A mere $50. I think I’m going to start a new business…
With that, you have to align it parallel with the leg edge to use.
I think the frame is becoming a bit too complicated and I don’t like the free floating ends.
I’m going for a simple design close to the original. the top bar will provide a solid distance between the motors,the diagonal supports prevent sagging and warping of the top bar and you can add some wood to the ends of the top bar to align the sprockets and the sled attachement points, or even put the motors on a adjustable plate on top. lower support for the springy cords are optional.
I agree that we are losing sight of the simple frame goal
Edit: But I think we are exploring a lot of valuable and interesting ideas
correct, but a slight twist probably won’t matter much
while the machine is on it’s face, put the unistrut on top of the legs (even with the top of the leg), put the top beam on top of the unistrut. mark it and then drive a lag bolt through the unistrut into the top beam (established distance)
later (after the machine is up)
attach the angles to the unistrut, so that the top beam is over the angle (probably near the back of the angle). Place the assembly on top of the legs (this should make it balanced enough to stay in place)
drive lag screws through the bracket into the leg.
loosen the bolt clamping the unistrut to the angle and extend it out. you could use a 6" piece of unistrut with the P2484EG as it is gusseted and extends out 4" and 6" out from the face of the leg to the face of the top beam is about perfect
You designed something like this already and called it a monstrosity but I don’t agree.
Yep… … … … . …
in your design the plywood is part of your structure (but you really don’t need the angled pieces)
spacing the motors out from the top beam gives them leverage to bend the top beam (curving the ends forward), which the frame doesn’t prevent.
And you are going to need a lot of plywood gussets for your leg joints
you have a point about the forward curve.
I don’t mind the plywood being a part of it because I put 4mm mdf on top as replaceable spoil board
