Rebuild a 3M Taper

[John Allen]

I have a broken 3M taper does anyone know who can rebuild them or where I could get parts if I rebuild it myself? Thanks

[MikeAurelius]

What are the symptoms? I've rebuilt mine a couple of times now, and 99% of the problem is a jammed large piston (moves the lens up and down). This is from dirt and dust getting down into the nylon sleeve.

Take the whole piston assembly apart but carefully. Directly under the nylon piston head is a group of steel bearings that help to spread the pressure evenly across the top of the piston. Don't loose any of those!

Clean the piston and the sleeve with solvent, scraping off any hard accumulations of debris. Reassemble, and when you slide the piston into the sleeve, use light machine oil (sewing machine oil or equivalent) to lubricate.

Another problem we've had is the vacuum generator. It can get gummed up from not using a filter/oiler on the air line. If it is too badly gunked up to be cleaned, they can be replaced, I think either Grainger or McMaster Carr has replacement generators.

[John Allen]

The piston does not go up, it will go down if manual raise it. You can see the tape push up from the air, but the piston does not rise. I will take it apart and see what I can do. Thanks for all the help.

[John Allen]

I took the cylinder machine off the frame but the three phillip screws were partially stripped out and they are on tight to take apart the piston. Do I need to heat them, is there lock tight on those screws? I plan on heating them up and use a impact screw driver and if that does not work and they strip out I can drill the heads out. But, before I do that I wanted to get anyones opinion on the best way to remove them? Also, can I buy a new plastic piston for it anywhere, it looks really worn out, big gap between piston and cyl.

[MakeOptics]

The plastic disc the lens sits on is dupont delrin. Easily machinable and stable. You can order a sheet and have a local maker space machine it for you. If you having a hard time sourcing delrin a white plastic cutting board is usually made from delrin.

[MikeAurelius]

The piston does not go up, it will go down if manual raise it. You can see the tape push up from the air, but the piston does not rise. I will take it apart and see what I can do. Thanks for all the help.

The tape should be pulling down from the partial vacuum that the vacuum generator causes. This might be part of the problem.

The unit uses a venturi style generator. If the "polarity" of the generator is reversed, you get pressure instead of vacuum.

[Don Gilman]

At some point might be cheaper to buy another. I have several used from OWC similar to the 3M at $250.00 EM me if interested don@superoptical.com
or call 1-800-543-7376

[John Allen]

It does push the tape up how do i reverse polartity

[MikeAurelius]

I will post a picture of the air pressure "guts".

[John Allen]

I took the fitting off that holds the jar before it goes into the cyl and it is blowing air, I assume this should have a vacuum instead of a positive pressure. So does this mean the generator is bad or can I repair it?

[MikeAurelius]

AA is the vacuum generator.
BB is the pressure switch.

Pressing down on the red lever activates the pressure switch, allowing air pressure to flow into the venturi (vacuum generator) AA. Air flows over the venturi exiting through the muffler (the gold tube) and creating a partial vacuum through the filter (the white tube on top) then routed into the the cylinder housing through the black tubing on top.

[MikeAurelius]

The partial vacuum pulls the tape down and the piston up. Be sure your air pressure is at least 80 PSI entering the taper.

[John Allen]

I just checked one at another shop and theirs has a vacuum, mine blows on the hose going to the piston. Does anyone have a part number for the generator where I could buy a replacement one?

Also how do you clean the generator?

[MikeAurelius]

AVR093H

http://www.airvacpumps.com/AVpump.html

[John Allen]

I really appreciate all the help on this, got the part ordered.

[MikeAurelius]

Not a problem, glad to help. These things can be a ******, sort of counter-intuitive. Took me 3 days the first time LOL

[John Allen]

Thanks for all expert help. The taper is working but now the polycarb water trap bowl is leaking it has a few cracks by the valve. Does anyone know where i can get a replacement?

[MikeAurelius]

Best thing to do is to just replace the entire regulator assembly. The bowls get old and crack as you've found.

[John Allen]

Do you know where i could find one? I was going to order the same one as the 2g edger's

[MikeAurelius]

Anywhere that sells pneumatic tools and supplies. Take the old one off and bring it with you.