All Springer/NP/PCP Air Gun Discussion General > 3D printing and files

Prototype PETG-CF Parts

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I decided it was about time to try making some airgun parts from carbon filled PETG to look at the quality.... I used up some of the Priline, because these are just trials and will not be subjected to the abuse of use....  ::) .... I printed a Picatinny rail sitting on a 1 degree wedge, and a spacer that would be used between two tubes, the lower one being the main tube, containing the valve, and the upper one the large diameter .183 cal match barrel, or the carbon sleeved LW .22 pellet barrel, that I will be using on my dual tank benchrest PCPs.... The transfer port passes through this part, as well as the bolts that hold the two tubes together.... The bolt runs inside the upper tube.... My plan is to use TPU95 to print the transfer port, probably transitioning from a round valve port to an oblong barrel port, like I have seen in this gate previously (sorry I can't remember the printer/author to credit you).... Anyways, here are the (rather rough) prints....

I think both parts will be strong enough for the intended use....


Bob what brand filament?
Was combing off?
Type and size nozzle?
That looks about like what I get with TPU.
I haven't had much luck with TPU seals.
I can't get a smooth enough surface finish to get a reliable seal.
I have never tried a transfer port seal.

Priline, which is the worst I have.... Combing was set to "Not in Skin".... Chinese hardened steel nozzle (seems to be holding up), 0.4mm diam., set to 0.25mm layers and 0.60mm (150%) extrusion width.... I was using 70mm/sec, with walls and top/bottom set to 40.... The TPU seals will be basically a 1/2" washer, about 1/2" high, with a 1/4" hole, and long enough to be in a bit of compression (the key to sealing a TP).... The bottom, against the bed, should be plenty flat, and I will use Concentric Ironing on the top, with thin layers and possibly a 100% infill, as I want it to work more like Delrin, which is what I use currently.... If it doesn't seal, I'll just machine a Delrin one....


Most of the time I use a larger nozzle with CF .5  or .6

I don't have any 0.5mm nozzles, but I did a lot of strength testing with 0.4mm and 0.6mm, and I found that two factors (other than a high temperature) were very important.... First, you must use at least a 0.25mm layer height (because of the carbon content), and secondly you get much improved layer-to-layer adhesion by using an extrusion width of 150% of nozzle diameter, and 2.5-3X the layer height, because of the increased nozzle pressure required.... This means optimally a 0.25mm height by 0.60mm width with a 0.4mm nozzle, or a 0.3mm height with a 0.9mm width with a 0.6mm nozzle.... I tried layer heights all the way up to nearly 0.5mm, and the appearance of anything over 0.36mm was dominated by the layer lines and surface imperfections.... For good appearance, I plan to use either a 0.25 or 0.30mm layer height, and those can be printed with a 0.4mm nozzle, although I think a 0.5mm nozzle might be optimum.... That assumes I do not find a better combination with a filament I have not yet tested (it's early in the game).... I have not tried it yet, but I am curious about using a 0.33mm height and 1.0mm width with a 0.6mm nozzle for fast printing....



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