Sliding Dart Door
Posted 23 March 2012 - 09:20 PM
Here's the fitting we'll start with. Saw away the threads first.
File the top flat. I removed material from the bottom of the fitting for weight. I started a slot with a fine ceramic disc. The slot needs to be even across and at the right depth.
Here's the depth it should be at from the inside.
Now let's cut out the door. I used a coping saw and went slowly.
Start the fitting by dremeling or filing the edge of the door smooth. Be careful not to remove too much material or you will need to make another. It has to fit across the inside of the coupler tightly. Try it's fit in the slot and adjust the slot's height so that the door starts to fit. The corners of the slot needed the most attention. Eventually the dart door will fit in the slot about halfway. Then just file the corners carefully, keeping the file parallel with the other side. Trimming a bit with a razor knife saved time and was precise.
Here's the finished slot from the front.
I quickly added a hole and a band to secure the door to the clip. Now let's add a seal. I used an old phone cover. Oh how times have changed. I pushed the cap into the material with some force to mark it. I then used a fine point marker to mark the cut. I used small, sharp scissors to cut out the seal.
I scuffed & dusted the cap and seal. I have found this material to be tricky to glue so I want to get some surface area. I used gel superglue. I laid a bead of glue above where the seal would rest so that the seal would (hopefully) pull the glue down into the gap. I pushed the seal against the door at the edges carefully with a piece of cpvc. Pull the door out and wipe off the glue that gets on it.
I added a filet of thin superglue around the seal.
Let it dry and then put the door in the slot. I eyeballed my punch into the center of the bottom of the seal. I twirled it a bit just to mark the rubber and see if it was centered. I adjusted and then spun the punch through the seal until I felt it start to bite into the door. Make sure to cut all the way around remove the punch. That'll do it!
Here it is mounted to a homemade wye with a small clip. I tested it by clearing out the darts, pumping it up, holding my finger over the muzzle & firing. It seals perfectly. I added a little white lithium grease to the seal. Don't push the cap on too tight over the clip or it will impair the door's movement. It stays open when pulled out by the tension from the band. Perhaps not as ergo as other designs but it performs well and seems sturdy so far.
Posted 23 March 2012 - 09:47 PM
Posted 23 March 2012 - 09:53 PM
Posted 23 March 2012 - 10:00 PM
Yeah a roll pin was my first idea and was the way I was going at first. Then I got lazy, lol. That could make this really nice!
Edited by iamthatcat, 23 March 2012 - 10:20 PM.
Posted 24 March 2012 - 02:41 PM
Posted 25 March 2012 - 09:37 AM
Nice work, I wil have to put on of these on my sgn. Have you had any problems with the cap falling off?
I've been using one of these for well over a year, and I think they are great. Although mine (I didn't make them, I contracted them) do not seal 100% whatever small amount that's lost is easily made up for it in ROF. Mine is made from two bushings nested inside of each other though, not cut up pieces.
Posted 25 March 2012 - 05:43 PM
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