SP o-ring insertion tool

[Bluey]

Does anyone have the exact dimensions of the mk25 o-ring insertion tool?
I want to machine one up prior to servicing my reg.
Plans for making any other handy reg tools would also be great.

Thanks
bluey

 

[rstofer]

I don't have any dimensions or related information but you can try Scuba Tools

Perhaps these: Scuba Tools - Scubapro®

Richard

 

[Couv]

Hi Bluey,

I do not have a MK25 o-ring tool, but below is a link to a thread where others have posted some helpful DIY tools and ideas.

Edit: You may want to ask your question in the DIY section.

Couv


http://www.scubaboard.com/forums/repairing-your-own-gear/264505-tips-tricks-tools-techniques.html

 

[redacted]

I don't have the necessary measuring devices but I do have the tool and, using this illustration, http://www.scubatools.com/images/PRODUCT/large/20-150-200.jpg, we should be able to reverse engineer it.

The bushing installation end has two steps. The length of the first step is 13 to 14 mm and the diameter is enough to loosely hold the 2 bushings and the o-ring. The intermediate step is about 15 mm in length and is of a diameter to fit inside the body of the Mk20 through the area where the air inlet from the tank is located. The full diameter of the tool need to fit inside the opening for the HP seat retainer. This end on the tool simply holds the 2 bushings and the o-ring in place as they are inserted all the way up to the spot in the body that the piston is inserted through. After insertion, a little twisting of the tool as it is withdrawn should leave the bushings and o-rings sitting in place.

The piston installation end is probably a little trickier and might best be done as a separate piece of tubing The inner diameter of the tube must allow the piston to be placed inside. The outer diameter must allow the tube to be placed inside the body of the Mk20 to hold the bushings and o-ring in place as the piston is installed through it. The length of that section to the shoulder is 15 mm. The wall of the tube has to be less than the thickness of the 2-010 o-ring it is retaining so something right about 1 mm should do it.

 

[tfsails]

With Mk 20/25s, you can also install the HP seat and spring and retainer and they will keep the two bushings and o'ring in place while you install the piston. There is probably a higher chance of nicking the o'ring this way, but if done carefully with a well-lubricated piston stem (lube the o'ring too) it should work just fine.

 

[halocline]

tfsails beat me to it.

 

[pescador775]

The tool is made of delrin and is double ended, primary and secondary. The primary end is stepped with two diameters and two ledges. Smaller diameter of the primary end is 0.217, length is 0.540. Larger diameter of the primary end is 0.380, length is 0.590.

The secondary end has a single step. Diameter is 0.380, length is 0.600. The secondary end has an internal bore of 0.250 and 2.00 depth.

Large diameter of the tool is 0.500

Overall length is 4.00

All dimensions in inches

 

[Mr Carcharodon]

Initially I tried to do everything "by the book". So I went down to the local LDS and asked them if they had the bullets and other special tools that the manual says you absolutely must have. Turns out the LDS just drops the piston o-ring and bushings over the end the piston and works them in place with the wooden end of a cotton swab. And then holds them in place with the spring. That is the way they have been doing it for past 45 years to apparent success. It has been working for me too. Of course your mileage may vary.

 

[pescador775]

Yeah, got it, simpler is better. I fry eggs the old fashioned way, squash the egg in the pan and pick out the bits with my teeth.

 

[Bluey]

You guys rock!
Thanks for the detailed descriptions and pescador for those exact dimensions.
Sounds like I need not be too concerned over having the specialty tools, but it would only take a few minutes to machine one up.