Concern about white Delrin for muzzle

Strange.

Hmmm. It might be that the white Delrin has less UV resistance. Or it could be completely unrelated to the color. For example, maybe there was an undetected manufacturing defect when I drilled the hole, or inserted the spike. Do you still have your black one?

LunkerBuster---I have the same white 2 hole Tin Man muzzle with spike on my RA 120 Carbon.
I just pulled it off the rack and looked. It is not cracked or rusted as in your picture.
I have seriously abused my white one by stabbing a shark or two AND a 6ft moray and firing at least two .357 rounds while testing the Pursuit PPDs.
IMO, I now realize that white may NOT the best color for a muzzle BECAUSE white shows every imperfection as your pictures illustrate
Unless I am mistaken, we REQUESTED Tin Man to manufacture white muzzles for us to test.
I like you am not the least concerned about the structural intergrety of our white muzzles
(By the way, those are some very high quality pictures, thank you)

Tin Man--is the Delrin or nylon available in clear ?
I would love to have several Tin Man 2 and now 3 band clear muzzles with spikes.
Thanks Jeff

Hau - I have never seen Delrin or Nylon available in clear, though Polycarbonate material is available. However, it won't stay clear after I machine it. The machining, even if it feels smooth, will leave microscopic scratches that leave the surface opaque. The only way to get it clear would be an extremely fine polishing, which I can't do. Most clear materials are cast, which avoids the scratches.

Lunkerbuster - I'll hook you up with a replacement the next time I do a batch of muzzles. If Hau's white muzzle is holding up, then I think maybe the crack might be due to a defect, rather than an inherent difference with the white material. Just let me know what color you want.

On a side note, how did you guys find the white vs. black muzzle comparison? Any clear favorite?

Jeff,

Was the pilot hole and spike the same sizes for both white muzzles? Is it possible pressing the spike into Lunkerbuster's muzzle causes a very tiny (and unnoticeable) crack that then propagated until it was visible?

That's been quite some time ago, so I can't be certain. The way I do it now, is to drill the hole for the spike about 7-8 thousandths undersized for a press fit. Then I counterbore the beginning of the hole to 9/32" diameter, so that there is no stress due to the interference fit right there at the beginning of the hole where the edge is thin (underneath). But I don't remember if I was doing it that way in the beginning. It may have been press fit all the way, with no counterbore.

I got a muzzle from Tin Man for 3 5/8 bands for a JBL gun. I doesn't show any stress cracks, and I installed 2 much smaller spikes on it (3mm diameter, 5mm length outside the delrin) that I use for shooting line routing.

I'm posting this as to suggest a different way to insert the spike - instead of a press-fit, the small pins I used are threaded and I screwed them into pilot holes in the muzzle. It might be a better holding system without stressing too much the delrin with the stress-fit.

Stefan

Tin man, try this test.... leave test samples of black and white Delrin from the same suppler exposed to the same cycle of sun/ UV index. After 90 days rub the white test sample with a black cloth and the black sample with a wht cloth. You may find the white Delrin takes on a chalky surface .The carbon particulate in the black sample may provide a better UV filtering ability limiting the depth of UV penetration.

Small micro crystals of salt and minerals forming in any non water proof joints of the metal-Delrin interface of the shark probe may be adding to the materials loss of elasticity at this slightly stressed area.

The interference fit of LunkerBuster's shark probe boring along with UV could be limited to only his early prototype part.

Cheers, Don

i'm not sure whats going on with muzzle in question but i had one made out of delrin that broke into several pieces when the loading pin from a ray odor shaft hit it as the shaft was leaving the barrel (i suspect). i though delrin was indestructible but it's really not, i switched to uhmw which is a bit softer but wont shatter.

Quote from LunkerBuster

that is good info steve although based on the design of Jeff's muzzle it is ompossible that anything would hit it as it is soo open.

it is possible that the brittleness you described is what is causing the small crack, just from a few eel pokes and fish jabs damn eels

it's really hard to say but "brittle" is a good word in describing delrin. i'm not sure how the material got to be so popular among gun makers, bill kitto used it as a track way back when so everyone asumed it was the way to go. i thinks it's a good material for some applications, it low friction so it works well for tracks and it finishes well but it's expensive. uhmw is much cheaper and i think is a much better choice for muzzles although it's softer and doesn't finish as well.

btw, nicely smoothed corners like the ones jeff puts on his muzzle is the way to go in preventing the shaft from bumping into the muzzle as it's fired.

I think that Steve summed it up. Delrin is strong, and finishes well, but it doesn't stretch at all. So I have learned to use it in applications that are in compression (like muzzles) and to avoid stress concentrations like sharp corners that can initiate cracks. For example, where my muzzles are necked down to insert into the barrel, I machine a radius to avoid a sharp corner. Likewise, it works fine for shapelock handle frames, which have a very large radius inside the grip area, but I do not use it for the AR-15 style because sharp corners are unavoidable. For cosmetic applications like pushrod covers and such, it works great.

No material is perfect. Part of our never ending education is learning which ones work in which applications, and with what critical limitations.

I have played with UHMW Polyethelene. Crazy tough impact strength, but almost impossible to get an attractive finish on a part that requires multiple machining operations. I'll have to play with some HD (High Density) polyethylene and see how it cuts.

im on with don paul about salt crystal build up causing stress at the joint. I am a marine mechanic by trade and i know what kind of stress a little salt buildup can put on something. saltwater has an incredible tendency for getting into the tighest of areas and causing issues. just got done torching a few water pump bolts to remove due to salt.