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Cylinder Mount Finder

Every hole you could anchor a cylinder to, sorted into the ones that work and the ones that fail — with the reason each one fails.

Inputs

The mechanism

in

Along the arm from the pivot. This is also on a hole, so it moves in half inches.

°
°
lb·in

Worst case, which for an arm is level. The lift torque tool works this out.

The cylinder

lbf

One VEX cylinder at 100 psi gives 12.17 lbf. Two on the same arm give twice that.

The hard limit on how far the rod can travel.

×

How much more than the bare requirement, at the weakest point in the sweep. 1.0 accepts a mechanism that only just moves.

Results

Mounting holes that work

—

Best of them, across and up

—in

Its torque at the weakest angle

—lb·in

How much the torque varies

—×

Stroke it uses

—in

Widest sweep this can drive

—°

Where the cylinder can anchor

A map of every mounting hole around the pivot, coloured by whether a cylinder anchored there drives the mechanism, and if not, why not.
  • works
  • not enough torque somewhere in the sweep
  • needs more stroke than the cylinder has
  • passes dead centre — no torque at all there

The pivot is the dark dot at the centre and the two faint lines are the arm at each end of its travel. Squares are half an inch apart because that is the VEX hole spacing, so each one is a hole you could actually bolt to.

How this is calculated

There is no formula that hands you a mounting position. What there is instead is a small number of hard constraints, and a search over the places you could actually put a bolt.

The three ways a mounting fails

They are separate problems with separate fixes, which is why the map keeps them apart rather than colouring everything that fails the same.

  • Dead centre. The cylinder's line passes through the pivot somewhere in the sweep. The moment arm is zero there, so the torque is zero, and the mechanism stops no matter what pressure you give it. Moving the anchor further off the pivot line is the only fix.
  • Not enough torque. The geometry works but the weakest point in the sweep does not clear the load. More force helps here — a second cylinder, or a bigger bore.
  • Not enough stroke. The geometry and the torque are both fine but the rod cannot travel far enough to complete the sweep. More force does nothing at all for this one. A longer cylinder, a shorter attachment radius, or a narrower sweep.

Why so many mountings fail on stroke

Because torque and travel are drawn from the same account. The rate the cylinder lengthens as the arm turns is the moment arm, so:

stroke used = average moment arm × sweep angle in radians

Torque wants a large moment arm. Range wants a large angle. Their product is stroke, and stroke is a small fixed number. Push either one up and the other has to come down.

This is why the last result on the page is the widest sweep your setup can drive at all. When the map comes back empty, that number tells you what you would have to settle for — and if it is far below what you need, a cylinder is the wrong actuator and a motor is the right one.

What the search does not know

  • Whether the robot is in the way. A hole can be geometrically perfect and have a battery bolted to it. The map is a shortlist to check, not an instruction.
  • The cylinder's own length. It reports the travel needed, not whether the body plus rod physically fits between those two points. Measure before you drill.
  • Retract. Everything here uses the extend force, which is the stronger direction. If the load is on the way back, use the retract figure from the cylinder force tool instead.

Save this as evidence

Collects what you entered, what came out, how it was worked out, and anything the tool flagged, with a timestamp and a version so someone else can reproduce it.

This is evidence, not a notebook entry. It deliberately does not write your problem statement, your reasoning, or your conclusion, because under RECF rules an Engineering Notebook has to be the students' own work and no tool may generate or organise its content. Take the numbers, decide what matters, and write it yourself.

Save this run, and compare

Keeps what is on screen so you can change something and see both sides of the change. Saved in this browser only, never uploaded.

Sources & assumptions

The 0.5" grid is the VEX hole spacing, the same one that decides which gears mesh. Stroke lengths are the sizes VEX sells.

The geometry is the same as the pivot force page, and was checked the same way: torque from the cross product of the attachment vector with the cylinder direction, verified against virtual work across the sweep to about one part in a million.

The widest-sweep figure is a search, not a formula. It narrows the sweep until at least one mounting works. That is only meaningful because viability grows as the sweep narrows — checked across sweeps from 90° down to 15°, where the count of workable holes rose without reversing at any step.