Where Do I Find the Serious Mechanical Problem Solvers
February 1, 2021 8:14 PM   Subscribe

I am trying to remove the gas cylinder from the bottom of an office chair without scratching or harming the cylinder. I've tried most every suggestion I've found online. I will explain in detail below, and I welcome Mefite comments, but I think I could use ideas from the world of serious mechanical problem solvers. My question is, where do I find them online?

The one inch diameter, smooth, stainless steel cylinder attaches to the chair by a friction fit in a recess in the steel bottom of the chair that's about an inch deep. There is no mechanical attachment. In a perfect world, tapping on the steel chair bottom with a plastic dead blow hammer while pulling on the cylinder will release it. It's not a perfect world. No amount of repeated doses of WD40 / PB Blaster around the joint and repeated hammering over a period of days has had any effect. I tried using vise grips and pipe wrenches over a protective leather sleeve on the cylinder, but the leather shreds before the tools ever get a firm grip. I've tried repeated heating with a high temperature heat gun. I've looked at strap wrenches, but I doubt they can get a good grip on the smooth stainless steel. I've thought of trying to shrink the cylinder slightly by cooling with dry ice but don't have a good idea of how to do that. I'm out of ideas, so I'm looking for places to ask for help.
posted by Jackson to Technology (25 answers total) 4 users marked this as a favorite
Try actual lubricating oil. When I had to do this, I believe dripping in some oil that was intended for lubricating my paper shredder was what finally freed the cylinder from the taper on the bottom. Along the way, I also removed the spring clip from the bottom of the cylinder (which allowed me to separate the top + gas strut and bottom of the chair with the outer cylinders still in their tapers), but that didn't end up being all that helpful so I'm loathe to recommend it when you want to re-use the cylinder.
posted by Alterscape at 8:24 PM on February 1, 2021 [2 favorites]

I'd try a rubber jar opener. They get a good grip on slick items - I've used the one from my kitchen multiple times for things such as plumbing or bolt removal.
posted by ShooBoo at 8:33 PM on February 1, 2021

Can you us a hydraulic bottle jack with some chain around the bottom of the jack and the chair base legs to press the cylinder out from the bottom?
posted by Short End Of A Wishbone at 8:45 PM on February 1, 2021

Have you tried a "technical drop", from approximately 12" down onto a hard floor? Take the castors off before you do this.

And you're sure this wasn't welded in place?

Do you have a bench vice you could clamp the cylinder into with grooved wood to hold it in a V notch? Then apply a twist to the base.
posted by nickggully at 8:46 PM on February 1, 2021 [1 favorite]

If you look at videos from office furniture pros online, they’ll have a widget (PDF of instructions) that straps around the cylinder where it sockets into the seat assembly and provides a surface you can really whack with a hammer and not just tap with a mallet. I didn’t have that widget, but I had a scrap of wood. I put the scrap of wood in that spot and whacked it with a hammer, and the cylinder came loose (and was undamaged) after like two whacks. FWIW I had a worse time getting the cylinder out of the base. For that I had to tap opposite arms of the base with a mallet for what seemed like too long, but I did notice progress. Eventually it came loose. It took LOTS of taps.
posted by fedward at 8:58 PM on February 1, 2021 [5 favorites]

Canvas Strap Wrench?
posted by Raybun at 9:13 PM on February 1, 2021 [2 favorites]

If the end fits into a bracket bolted to the bottom of the chair, you should unbolt the bracket and drive the cylinder out of the bracket.

If it fits into a recess which is an integral part of the underside of the chair seat and cannot be removed, which is how it sounds from your description, I think you will need to remove the seat pad and drive the cylinder out from above the sitting surface. Not least because I wonder whether there could be some kind of set screw holding it in place which can't be detected from underneath.
posted by jamjam at 11:22 PM on February 1, 2021

I'm not a Serious Mechanical Problem Solver, but My Mechanics might be: instagram ; youtube.
posted by lulu68 at 11:58 PM on February 1, 2021

Some kids' bikes have a 1" seat tube, and the standard adult size is just a couple of mm more, so I'm imagining covering the SS cylinder with a sheet aluminum shim made from a pop or beer can to protect it, putting it with chair attached into the seat tube of a bicycle and tightening it down, then twisting the chair by its armrests in order to loosen the cylinder up.
posted by jamjam at 12:07 AM on February 2, 2021

Look on LinkedIn for a current or former engineer at Staples/etc and tweet or Insta. Same for the engineering dept at a university. A smaller, low-profile school might be more responsive.
posted by jojo and the benjamins at 12:46 AM on February 2, 2021

Maybe ifixit ? They have an Answers forum.
posted by ZeroDivides at 5:26 AM on February 2, 2021

The garage journal forum. Lots of mechanics, engineers, technicians and analysts are members.
posted by qsysopr at 5:50 AM on February 2, 2021

Best answer: A shaft collar may give you the purchase you need on the cylinder to rotate it with a wrench without gouging it up. Here's one with handy wrench flats machined in.


When asking questions like this, pictures are worth a thousand words. Mechanical minded people are often visual and kinesthetic learners, they may not do words good.

Practical Machinist is a good forum for mechanical questions, although it does skew toward people with large, specialized tool collections, not average joe DIY.
posted by dudemanlives at 5:53 AM on February 2, 2021 [1 favorite]

Are you able to access the top side of the chair frame? Maybe drill a small hole and push the cylinder nub out? Might require a puller.

Experience from detaching ball joints from steering spindles (also a taper fit) suggests the following:
-Pickle fork. The end of the cylinder steps down where the mating nub starts, right?
-Heat the chair base, multiple cycles. Tough to do if the fabric/sitting part of the chair can't be removed.
-Suspend the chair off the ground by the bottom of the seating surface. Suspend some weight from the caster legs so there is now some tension in the taper joint. Now: don't just whang on the chair base with a hammer - use a metal hammer (probably a ball-pein to fit into the inside corner of the chair base), and use another metal-faced hammer opposite where you're striking, to redirect the shockwave back into the chair base.

A dead-blow only is useful in the direction to pull the parts apart. For a taper fit, you need to get the two tapers to suddenly no longer mate up so nice. The only way to do that is to induce vibration in the mating surface, and the best way to do that is with a metal-faced hammer.
posted by notsnot at 7:30 AM on February 2, 2021

Best answer: Dudemanlives's suggestion of a collar may give you enough purchase for a pickle fork between the chair base and the collar.
posted by notsnot at 7:33 AM on February 2, 2021

I'n confused why you are worried about damaging the cylinder when you can buy a new one pretty cheaply. I'd have thought you'd be more concerned about damaging the chair? Are you trying to reuse the cylinder or the chair?

You can try warming the steel around where the cylinder sits with a propane torch or a heat gun (not a hair dryer) and then trying the dead blow hammer method. If it is a steel on steel interference fir you may need to get the interfacing collar pretty hit, pretty quickly to take advantage of expansion to remove the interference amount, but if you have tried it with aggressive heating already (too gradual just makes both parts expand) then I suspect there is more than an interference fit there. Are you absolutely sure there is no other attaching point? With a steel insert it'd be easy to put in a spring clip, in which case a steel hammer may be better to shock it loose.
posted by Brockles at 7:50 AM on February 2, 2021 [1 favorite]

In lieu of dry ice cooling/shrink, you may have a duster spray that can be used upside down to cool the cylinder.
posted by Muted Flugelhorn at 9:01 AM on February 2, 2021

These are pressurized gas cylinders, so random whacking/heating may have a non-optimal outcome. The office chair I just put together had huge "don't even think of ..." warnings around the gas strut.
posted by scruss at 9:06 AM on February 2, 2021 [1 favorite]

Have you used a rubber strap wrench?
posted by wenestvedt at 11:37 AM on February 2, 2021

Okay, how about using a car jack between the wheel base and the seat. One end or the other has gotta give. At least half the job is done.
posted by JackFlash at 12:21 PM on February 2, 2021

Got a pal who is one of these guys. He loiters on r/AskEngineers
posted by jessamyn at 1:22 PM on February 2, 2021

Response by poster: I very much appreciate the responses. Here is some additional information. And a photo of the bottom of the seat where the cylinder enters the mounting hole.

The chair is a Haworth X99 task chair about 18 years old. Haworth says the cylinder is a friction fit in a hole about 1 inch deep. There are no fasteners. I assume some sort of taper is involved, but there is no taper visible on the cylinder outside the hole.

My intent has been to replace the cylinder with a longer one. I am tall and the seat doesn’t adjust high enough. I need my knees well below my hips due to back problems. The current cylinder has 5 inches of adjustment and 9 inches would be ideal. Haworth has nothing to offer except the original. One replacement cylinder manufacturer has a cylinder with 10 inches of travel, but before guaranteeing a fit, they want to see a picture of the seat end of the existing cylinder. Oddly, I can’t get a complete photo of the existing cylinder from Haworth or anyone else – can you? I’d like to remove the cylinder without damage in case nothing works out and I stay with the existing cylinder.

As a responder noted, there are special tools from some chair manufacturers that supposedly make quick work of this removal. The one I priced from Steelcase was $140, which is way more than a replacement cylinder.

Of all the ideas so far, the ones that seem to hold the most promise for my skills and tools involve shaft collars (dudemanlives, notsnot), which could be used as either a purchase for a pipe wrench or a pry point for a pickle fork. If used with a pipe wrench, a shaft collar manufacturer has told me that even if the shaft collar spins under the pipe wrench torque, it will not harm the surface of the cylinder. I assume the same would be true if it slides longitudinally under prying. When pricing the correct Climax shaft collar with bore size 1 1/8 inch on Amazon, I see that many people buy them to permanently attach to older office chair cylinders to keep the seats from sagging.

What with all the Mefite input, I haven’t even gotten to the suggested sites yet for other ideas.

Just a side note. I used a rope with an icicle hitch tied to the cylinder to suspend the chair upside down from an overhead beam while I beat on the chair bottom. I had always wanted to try this hitch on a smooth cylinder and it really worked. I think it would have supported me and the chair without slipping.
posted by Jackson at 4:38 PM on February 2, 2021 [1 favorite]

Another method, perhaps more along the lines of "offer the barometer to the building superintendent" (if you are familiar with that story) than a mechanical method: call around to furniture repair or office furniture places and ask if removing the cylinder is a service they offer. Someone who does mechanic work out of their garage might be another thing to try.
posted by yohko at 10:39 PM on February 2, 2021

Response by poster: Discovered that Office Oasis sells replacement chair cylinders with a "replacement tool" that consists of two shaft collars that force the cylinder out of the seat. Pretty clever. The collars are not sold separately. LInk to written instructions; instruction video is available on their website.
posted by Jackson at 3:22 PM on February 3, 2021

Interesting. Jacking screws like that are common on race car parts for removing bearing seats and the like (usually integrated into the parts). Those ones look very similar to Kart split locking collars:


I wonder if the diameter is close? You'd need to tap (and possibly helicoil) some threads into the side of it, but you could Heath it up without too much trouble if you have the equipment. If the replacement cylinder is reasonable price, though, you may as well buy that anyway just to get the collars!
posted by Brockles at 5:21 AM on February 4, 2021

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