Is my cylinder too small?

I recently started pumping with a homemade device. The cylinder is a gravel cleaner from petstore sized

2” x 10”. My base girth is 6”. When I remove the cylinder after pumping (no higher than 5Hg) I have a groove at the base of my dick and it is quite purple and it hurts a little. After massaging and applying heat it goes away, but I’m still wondering what may be causing this? Even though the cylinder claims to be 2” in diameter it actually measures 1 13/16” ID. Any thoughts?

Yes. Your cylinder is too small. The 2” probably refers to the outer diameter. If you bought from Lapdist (for example), the specified diameter would refer coincide with the inner diameter of the tube.

1.8125” diameter will fit a girth of 5.7” and lower.

Sounds like the cylinder you bought is a 2” OD. With an ID of only 1.8125, yes, that cylinder is too small with an inner circumference of 5.7”. If you find a cylinder with a 2” ID, it will fit correctly although you are close to being able to use a 2.25” ID also.

If the bottom of your cylinder is not flared and softened someway then it could be that it pressing into the pubic area. If it is not flared, you can wrap many rounds of electrical tape around it—say building another 1/4” or so then covering it with the motor cycle tube then there would be more surface area and not that thin edge but maybe you’re doing that anyway. I do not think just dipping into a gel would help a whole lot….Steve