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Force exertion when packed

Force exertion when packed

I’m looking for a little visualisation help here.

If your base for about 2” is packing the tube, and your glans is packing the tube, leaving a big gap inbetween the packed base and glans, where is most of the pressure focussing on?

I feel the length pull more than I do the width pull (can’t really feel that at all). You see, my base for 2” packs the tube and my glans packs it completely, does this create more of a length pull? I would have imagined so, as if the glans wasn’t packing so tightly I imagine the shaft would be more inclined to pack the tube.

Does this sound right? I’m only using a 1.75” tube, and in my time pumping I’m now about 1/4” longer at max than I was when I started, but the base isn’t packing a whole lot more. I’m not bothered by this, and I’m just going to stay the course and stick to my routine, but the physics of this evaded me which I don’t like much!

Back off on your pressure and increase your time. That way, you will slowly expand and be more equal. Just go slow on the pressure and I think it wil make a difference,


I’ve upped the time recently, but I was wondering more about the actual physics of it, is the glans packing creating more length-wise force than width-wise?

If your glans is totally packing the tube - that is, completely blocking off the top of the cylinder (that’s hard to do because of the shape of a glans, but possible - then most of the pull is going to be on the surface of your glans, pulling the shaft up. This is good, and bad. Good for length, but not necessarily good for the glans if you were to bump up your pressure a bit or lengthen your time in vacuum for too long. The glans has the most sensitive skin area of the entire penis, frenulum aside. Just watch for blistering, or any discoloration.

My bet is that at the area of the frenulum, on your ventral side which you cannot see, there is a pocket of space through which you are pulling vacuum and this will keep influencing the portion of your shaft which is not yet packing.

Hint to pumpers: When your glans starts to pack a tube, it is especially important to lube that area heavily. You don’t want that part of you abraided against the dry, acryllic side walls. Major “owie.”



Thanks Avocet.

I get some darkening around the glans afterwards because it gets squished so much. This goes away though.

Hey ICM,

As for the physics, I think what’s happening when you pack the base is that you effectively shorten the cylinder, so that the vacuum acts only upon the portion of your penis above the packed base. Especially if your penis is well lubed, the packed base will form a plug and the vacuum will not extend further toward your body.

I doubt that your packed glans really forms an effective plug. I’m guessing it’s only your corona that’s packed. The corona is fairly soft and will only weakly resist airflow top to bottom. This means the pressure above and below (i.e., distally and proximally) your glans will be about equal—at whatever your gauge is reading. So, any non-packed area distal to your base is probably getting a good girth stretch.

I responded to a thread awhile back about length stretch in a tube. Check it out: Pump vaccum expressed as weight

With a 1.75” diameter tube fully packed, you get a length pull of about 1.8 lbs per inch Hg. That’s 5.88 lbs for 5 in Hg.


For the past several years I have been using a mushroom head tube. The shaft of the tube is only slightly bigger than I am so I quickly pack it. This puts all of the pressure on the head. I have found that if I lube up right, I get a great lateral pull along the length of the shaft in addition to the general expansion of the glans. I am able to reach a length of slightly over 6 3/4 inches in length, which is a lot for me. I think I got the mushroom head tube at It is a little pricey, but very worth it.


What if my glans really was making a good seal? Over 50% length-wise packs the tube eventually, which I think is a lot.


I had thought about one of those, but due to the price I’d only get it once I was done with length.


It’s certainly possible that packing 50% your glans’ length in the tube forms a plug. Check to see whether you’re really packed all around. The bottom of the glans (ventral part) often tapers upwardly. This may create an air passage.

Another thing to consider is that your glans only gets packed after being in the tube for a while. So the vacuum probably reaches the unpacked part of your shaft at least initially. The formation of the plug when your glans get fully packed will close off the shaft from the vacuum source, much the way the tube as a whole gets closed off from the source when you disconnect the pump (if your system works that way. With my LA pump, you can disconnect the hand pump and gauge and walk around.). But that won’t cause the vacuum around your shaft to dissipate entirely.

You can try a simple experiment. Next time you get coffee, pick up one of those narrow red straws. Cut it to about 2 or 3” long. The next time you pump, place it in the tube with your penis, so that it extends both above and below the glans, thus bridging the length formed by the glans “plug.” I think the straw is rigid enough not to collapse under the pressure.

See if it feels any different.

Interesting idea Modesto.

I’m certainly not bothered by the effect, and might not experiment as it was purely to see if there was a definate answer and to get a better feel for how negative pressure affects things. I think I have a good enough idea now.

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