This page shows the working. It is a calculation from the CAD geometry, not a measurement — no force has ever been measured on a pump or on this part, by us or by anyone we can find. Where a number is calculated it says so; where it is cited it says where from; and where nobody knows, it says that too.
The headline, and it is not a flattering one: the PALM's mechanical advantage is exactly 1. It has no lever and no pivot. It does not make a stiff pump any lighter, not by a single newton. What it changes is how wide the surface is — 62 mm instead of 13.5 to 28.1 mm — and therefore which part of your body can press it. Whether that helps you is a question about your hands, and one only you can answer.
Every dimension below is transcribed from handl's own engineering files — RANGE_SPEC.md and the parametric CAD source the parts are built from. The arithmetic is in a script anyone can run, and it reproduces the engineering notes' own figures to 0.1 mm, which is the only reason to believe the rest of the table.
On this page
1. Mechanical advantage: exactly 1
A lever multiplies force. This is not a lever.
The engineering source states the load path in one line: “Press load runs disc → top of the head; the walls only locate and retain.” There is no pivot, no fulcrum, no linkage and no elastic element in the load path. It is a rigid plate sitting on top of the pump head.
A rigid body transmitting a coaxial load has a mechanical advantage of 1.00. Force in equals force out. Calculated, by inspection of the load path.
So if your pump needs 15 newtons, it still needs 15 newtons. If it is too stiff for you, this part does not fix that, and a foaming dispenser or a wall-mounted lever will — both of which we do not sell, and both of which are set out on the comparison page.
2. What does change: area, and therefore pressure
The disc is 62.0 mm across and 3.5 mm thick. The pump tops it is built to fit are 13.5 to 28.1 mm across the narrow way.
Subtracting the sixteen radial grooves and the debossed logo — a deliberately conservative floor, since a hand bridges both — leaves about 2,510 mm² of face against a gross 3,019 mm².
| Pump head across | Head area | Disc ÷ head, by area | By width |
|---|---|---|---|
| 13.5 mm | 143 mm² | ~17× | 4.6× |
| 18.9 mm | 281 mm² | ~9× | 3.3× |
| 20.6 mm | 333 mm² | ~7.5× | 3.0× |
| 23.7 mm | 441 mm² | ~5.7× | 2.6× |
| 28.1 mm | 620 mm² | ~4× | 2.2× |
Pressure is force divided by area: P = F / A. So for the same push, the average pressure over the available surface falls by the same factor — roughly 4× to 17× depending on the head.
That reduction is only realised if a larger part of your body actually does the pressing. Press a 62 mm disc with one fingertip and the contact patch is the same fingertip it always was, and so is the pressure on it. The area is an opportunity to use a palm, a fist or a forearm — it is not an effect that happens by itself.
We have not measured the contact patch of a real hand on the disc. We would be making it up.
3. Where the head sits — a real limitation
Standard and Wide are tapered slots. A head wedges at the point where the channel width equals the head width, and because the channel narrows from one rim to the other, that point moves with the size of the head.
Solving the taper for the wedge position: a 20.6 mm head on Standard sits 12.2 mm off the disc centre. The engineering notes independently state 12.2 mm, which is the cross-check that makes this model worth trusting.
| Head across | Offset from disc centre | What that means |
|---|---|---|
| 13.5 mm | 31 mm | At the far rim — the extreme of the range |
| 18.6 mm | 0 mm | Dead centre. The best case |
| 20.6 mm | 12.2 mm | Noticeably off centre |
| 23.7 mm | 31 mm | At the entry rim |
The consequence, stated as the limitation it is: for most head sizes the disc is not centred over the pump. Press near the far rim and you apply a turning moment about the head rather than a straight push — which is less efficient, and at the extremes can cock the disc. Press over the head, not out at the edge. Wide is centred at 23.5 mm, which is why the engineering notes say its taper should not be changed.
Retention is a separate question and the geometry is comfortable there: the half-wedge angles are 4.70° (Standard) and 4.24° (Wide), both well inside the 10–16° band at which plastic self-locks on plastic, so pressing wedges it on rather than driving it off. Dome works differently again — a split ring closing past the widest point of a round top, on a 27.20 mm lip circle. All calculated; the fit itself was tested by hand, on a handful of bottles, at home.
4. What a pump actually needs — and the honest gap
This is the number everything else hangs on, and it does not exist.
We searched for published actuation forces for domestic soap pumps. What we found: figures inside patent applications, which are design targets rather than measurements of things you can buy; and numbers in manufacturers' own marketing. Nothing independent, nothing peer-reviewed, nothing comparable across brands, and nothing at all for the supermarket bottles people actually own.
We have not measured it either. Until somebody does, any sentence of the form “a soap pump needs X newtons” on this site or anywhere else is worth exactly what it cost to write.
That gap is the single most useful thing this business could close, and closing it needs a kitchen scale and an afternoon rather than a laboratory. The method is written up in handl's own notes and the results will be published here with the raw table, whichever way they come out.
5. What published data says about hands
Cited, not ours, and about people in general rather than about this product.
The standard reference for adult hand strength is Mathiowetz et al. (1985), Grip and pinch strength: normative data for adults, Archives of Physical Medicine and Rehabilitation 66(2):69–74 — 310 men and 328 women aged 20 to 94, measured with a dynamometer for grip and a pinch gauge for tip, key and palmar pinch. It is the dataset occupational therapists have used for forty years.
Two things in it are relevant here, and we are quoting the findings rather than the tables, because we could not obtain the tables in a form we could verify:
- Grip and pinch are measured separately because they are different capacities. The study reports them on different instruments and they do not track each other — grip correlates strongly with age, pinch only weakly to moderately.
- They decline on different schedules. Grip peaks between 25 and 39. Tip, key and palmar pinch stay relatively stable from 20 to 59 and then decline gradually from 60 to 79.
What follows from that is a question rather than a claim: if your whole-hand capacity is greater than your fingertip capacity, a wider surface lets you use the larger one. Whether that is true of your hands, and whether the difference is enough to matter for your bottle, is something you are far better placed to judge than we are. Press the pump with your palm before buying anything — the bottle in your bathroom will tell you more than this page can.
We have deliberately not quoted specific kilogram figures from that paper. We could not obtain the tables in a verifiable form, and a normative value repeated from a secondary source is exactly the kind of number that gets quoted back at you later.
6. What it is made of
Bambu Lab PLA Pure, white. A plant-based filament made from renewable corn and sugarcane.
The precise position on certification, because the difference matters:
- The filament's ingredients are individually certified against EU 10/2011, the European food-contact materials regulation, and EN 71-3, the toy safety standard for the migration of certain elements. That is a fact about the raw material, published by its manufacturer.
- The finished printed part is not certified as anything. A certified material is not a certified part. Printed layer lines hold moisture and soap residue, the process is not controlled to a food-contact standard, and nothing has been tested. So PALM is not food safe, food grade, medical grade, antibacterial or sterile, and none of those words belong on it.
- It is hand wash only. The material softens above 60 °C, so warm water, never hot, and never the dishwasher.
On “vegan”: PLA is made from plant starch rather than anything animal-derived, which is why the material is described here as plant-based. We have not been able to verify a formal vegan certification for this specific filament from its manufacturer, so that word is not used. If a supplier statement exists it will be cited here and the wording changed; until then, plant-based is what the evidence supports.
7. Status of every number on this page
| Figure | Status |
|---|---|
| Disc 62.0 mm, channel widths, lip, wedge angles, lip circle | Design values, from handl's CAD source |
| Mechanical advantage = 1 | Calculated from the load path |
| Areas, area ratios, wedge offsets | Calculated — rigid body, ideal contact, friction ignored, circular approximation for the head |
| Self-locking band 10–16° | Cited from handl's own design rules |
| Hand strength findings | Cited — Mathiowetz et al. 1985 |
| Material certifications | Cited — the filament manufacturer, for the filament only |
| Force any pump needs | Unknown. Not measured by us; no independent published data found |
| Contact patch of a real hand | Unknown. Not measured |
| Fit on real bottles | Measured informally — by one person, on his own bottles, at home. Three confirmed: Baylis & Harding Signature, PZ Cussons hand wash, one decorative dispenser |
PALM was designed by one person for his own use, because he could not press the pump in his own bathroom. It has not been through any trial, test programme or certification, and no clinician has assessed it. It is offered on the reasoning that a mechanism which helps one pair of hands may help others with similar difficulty, even where the underlying reason is completely different. That is the whole claim, and we would rather make that one honestly than a bigger one we cannot support.
Where to get proper help, most of it free
Nothing on this website is a substitute for any of the following, and all of it is better than a website.
- A pharmacist. No appointment, no referral, and they will talk to you about hand pain and about what is worth trying. The most under-used free advice in the country.
- Your GP. Particularly if the difficulty is new, getting worse, worse in the morning, or in both hands at once.
- An occupational therapist. This is the profession whose actual job is the problem this page is about — they look at your hands and your kitchen, not at a category page. In England you can ask your council for a needs assessment for equipment and adaptations, and much of what they recommend is provided at no cost. Ask your GP, or your council's adult social care team directly.
- Arthritis UK — the charity that was Versus Arthritis until its 2026 rebrand — and NRAS both run free helplines staffed by people who know this subject properly.
- Living Made Easy, run by the Disabled Living Foundation, is an impartial database of daily-living equipment. It lists products from everyone, including our competitors and including things that would replace PALM entirely. If you want to compare options without being sold to, start there.
PALM is a daily-living aid, not a medical device. It makes a soap pump easier to press. It does not treat, prevent or improve any condition, and nothing here is medical advice or a diagnosis. If your hands hurt, the people in the list above are the ones to ask.