GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: AustinBinTX on May 24, 2019, 09:48:50 AM
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I’ve been messing around with making breeches for QBs for a while now, but I can’t seem to get enough time to devote to running the mill to make enough for all of my rifles.
I have a couple decent 3D printers, and I’m decent with CAD, so I figured why not give it a shot. It’s not like the QB breech sees any real pressure. It’s all contained in the transfer port, and that can be easily reinforced.
My ultimate goal is to make multi shot breeches for all of my QBs that are tall enough that I can shroud the rifles for backyard pesting. I don’t need any more power than CO2 provides, but I would like to be as stealthy as possible.
I printed a few tests over the last few days to test dimensions and fit. I ended up with a perfect fit on the fifth print. At 4.5 hours a print, it was definitely a sigh of relief.
A modified barrel band had to be printed as well to keep any extra stress off of the breech.
Everything went together perfectly and worked perfectly with no leaks. The dovetail holds the scope fine, and I had no issues zeroing. I’ll have to continue testing to see how well it will hold zero though. I imagine since I’m printing from PETG, it should be fine.
I plan on testing this single shot version for a couple weeks. If everything works as I’m expecting, I’ll chuck up the barrel and turn it down to fit a Marauder magazine. I’ll turn down the bolt if needed, and I’ll print off the multishot version of the breech I drew up. I’ll slap it all together, and have myself a poor mans multishot QB.
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Very cool!
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very nice , what % infill?? you could also extend the front for more barrel interaction
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very nice , what % infill?? you could also extend the front for more barrel interaction
Rob,
I’m printing them with 0.6mm nozzles at 0.3mm layer height. They have 4.2mm walls with 50% infill. I’m printing with PETG at 250C and a bed temp of 90C. Everything is fused together almost perfectly. No flex whatsoever.
It took a bench vise, a 3# sledge, and some serious muscle to crack the first test ones.
As far as extending the front, I had printed one tester that had an extended front, but it didn’t really make any difference. A good fitting barrel band did more for rigidity than extending the breech. A 15mm barrel hanging off the end of the metal QB breech will flex down just as much as these, so I’m not overly concerned about it. I would however, like to protect it from any extra added stress caused by hitting an unsupported barrel on things.
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Rob,
One thing I forgot to add was that the multishot version may need to be printed with 100% infill.
The cutout for the Marauder magazine will make the breech more prone to flexing, so it would definitely benefit from all the extra material that can be fit in there.
I’m off work tomorrow. I may start the multishot breech print(5.5ish hrs) and put the collet chuck on the lathe so I can turn the barrel and bolt down for the Marauder mag.
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awesome.. ive seen this attempted before but in lackluster fashion.. You may have cornered an entire market here if you spread the knowledge to discoveries and so on..
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awesome.. ive seen this attempted before but in lackluster fashion.. You may have cornered an entire market here if you spread the knowledge to discoveries and so on..
Rob,
I know there are some downsides to printing parts like this.
Longevity is one. A metal bolt cycling enough times will eventually wear the fused material.
Strength is probably the biggest concern for me. PETG is strong, but PEEK would be a much better option, that is, until you look at the cost for a half kilo of PEEK filament and the requirements to print it.
I’ll probably make a few of these to put on CO2 only rifles. If anyone wanted to test one of the single shot breeches, have a couple extra. I could print off matching barrel bands for whichever version QB you had.
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never printed in petg... I wonder if nylon would be better for surface friction durability ?? Youd need a volunteer who puts down a tin a week in a QB.. this way you get accelerated wear results. If i had to guess id think it would last quite some time so long as the bolt is polished etc
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Rob,
One thing I forgot to add was that the multishot version may need to be printed with 100% infill.
The cutout for the Marauder magazine will make the breech more prone to flexing, so it would definitely benefit from all the extra material that can be fit in there.
I’m off work tomorrow. I may start the multishot breech print(5.5ish hrs) and put the collet chuck on the lathe so I can turn the barrel and bolt down for the Marauder mag.
The mag cutout flexes in the aluminum versions, but not much of an issue <25fpe. For my lower powered repeaters I never ran a barrel band. Once you get up in the 25fpe+ range recoil/barrel harmonics come into play and breech flex is a real problem..
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The mag cutout flexes in the aluminum versions, but not much of an issue <25fpe. For my lower powered repeaters I never ran a barrel band. Once you get up in the 25fpe+ range recoil/barrel harmonics come into play and breech flex is a real problem..
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I may try printing from some CF reinforced Polycarbonate I have here. It’s by far the strongest filament my little Prusas can print. I just need to work on a better enclosure to keep the ambient temp up high enough to prevent warping.
Since the aluminum breeches flex as well, I’ll just roll with it. I’m sure if it would help, I could print the breeches off with internal slots on each side for an aluminum dowel rod on that would run the entire of the breech to stiffen it up more.
Too many ideas and not enough time to work through them all it feels like.
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I am seriously impressed and amazed at what technology has brought us. Couldn't you solve the durability problem by sleaving the bolt probe area?
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Even if the 3D print doesn't work out, you would still have the 3d file for the multishot breech that could be cut out of metal. As far as I can tell, nobody sells them new anymore.
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I am seriously impressed and amazed at what technology has brought us. Couldn't you solve the durability problem by sleaving the bolt probe area?
Sleeving it would definitely work. I had given thought to actually using the entire original QB breech as the sleeve, but I decided against it. Now that you asked the question though, I could turn the entire steel QB breech down in the lathe and press a lightweight version of it in a modified printed breech. It would save me the time of having to do all of the machine work from scratch. I don’t believe it would take more than 5 minutes to modify my CAD file for a sleeve either.
Thank you all for the questions, suggestions, and insight. Please keep them coming.
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Even if the 3D print doesn't work out, you would still have the 3d file for the multishot breech that could be cut out of metal. As far as I can tell, nobody sells them new anymore.
True, but I don’t see myself replacing my manual mill with a CNC mill, and I really don’t think I could get a good enough deal to have a run of them machined somewhere.
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The mag cutout flexes in the aluminum versions, but not much of an issue <25fpe. For my lower powered repeaters I never ran a barrel band. Once you get up in the 25fpe+ range recoil/barrel harmonics come into play and breech flex is a real problem..
I may try printing from some CF reinforced Polycarbonate I have here. It’s by far the strongest filament my little Prusas can print. I just need to work on a better enclosure to keep the ambient temp up high enough to prevent warping.
Since the aluminum breeches flex as well, I’ll just roll with it. I’m sure if it would help, I could print the breeches off with internal slots on each side for an aluminum dowel rod on that would run the entire of the breech to stiffen it up more.
Too many ideas and not enough time to work through them all it feels like.
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Or design so that the mag inserts into a mag well vs a slot----bridge the dovetail gap. This would mean a slightly higher dovetail, but I think the rigidity would be worth it.
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The mag cutout flexes in the aluminum versions, but not much of an issue <25fpe. For my lower powered repeaters I never ran a barrel band. Once you get up in the 25fpe+ range recoil/barrel harmonics come into play and breech flex is a real problem..
I may try printing from some CF reinforced Polycarbonate I have here. It’s by far the strongest filament my little Prusas can print. I just need to work on a better enclosure to keep the ambient temp up high enough to prevent warping.
Since the aluminum breeches flex as well, I’ll just roll with it. I’m sure if it would help, I could print the breeches off with internal slots on each side for an aluminum dowel rod on that would run the entire of the breech to stiffen it up more.
Too many ideas and not enough time to work through them all it feels like.
Or design so that the mag inserts into a mag well vs a slot----bridge the dovetail gap. This would mean a slightly higher dovetail, but I think the rigidity would be worth it.
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That’s a great idea for sure. I wonder about scope height with it though. I’ll have to draw everything up and see what it ends up looking like.
I’ll probably print the original design I have for the multishot breech tonight. It’ll give me time to machine my backplate for my new Pratt and Burnerd KC25 multisize collet chuck. I’ve been like a kid on Christmas morning waiting to use it, but I keep getting side tracked with the 3D printers.
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Whoops, I’ll print the design I have in hand, and then make changes as needed.
It’s hard for me to visualize revisions without having a prior version or two in my hand.
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Whoops, I’ll print the design I have in hand, and then make changes as needed.
It’s hard for me to visualize revisions without having a prior version or two in my hand.
at co2 pressures i think it will be fine .. especially with the internal sleeve suggested above. A small section of brass tube inserted where the bolt rides would cure wear and friction at once.
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Definitely need a good barrel band to prevent the barrel from leveraging on the front of the receiver and breaking it off, IMO.... I can't imagine any plastic not reinforced with continuous carbon fibres (which you can't print) being anything like as stiff as aluminum, let alone the original, which was steel.... I have always hated the short barrel inset in QBs.... The barrel wobbles around something fierce unless additional setscrews are added from the sides at the back of the loading tray....
Don't forget that the forward force on the barrel and the rearwards force on the bolt both are equal to the pressure times the area of the front of the bolt.... For a .22 cal bolt, that is 0.038 sq.in., so at 850 psi it is 32 lbs. but at 2000 psi it is 80 lbs.... Increase it to a .25 cal (0.049 sq.in) and it goes up to about 100 lbs.... If you are holding the barrel in with a setscrew, consider the loads on the plastic at the threaded hole....
Bob
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Intrested in durability.
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Definitely need a good barrel band to prevent the barrel from leveraging on the front of the receiver and breaking it off, IMO.... I can't imagine any plastic not reinforced with continuous carbon fibres (which you can't print) being anything like as stiff as aluminum, let alone the original, which was steel.... I have always hated the short barrel inset in QBs.... The barrel wobbles around something fierce unless additional setscrews are added from the sides at the back of the loading tray....
Don't forget that the forward force on the barrel and the rearwards force on the bolt both are equal to the pressure times the area of the front of the bolt.... For a .22 cal bolt, that is 0.038 sq.in., so at 850 psi it is 32 lbs. but at 2000 psi it is 80 lbs.... Increase it to a .25 cal (0.049 sq.in) and it goes up to about 100 lbs.... If you are holding the barrel in with a setscrew, consider the loads on the plastic at the threaded hole....
Bob
Bob,
I appreciate the insight.
I agree with everything you say, and I appreciate your concerns about the force on the bolt and the barrel set screw. I thought about the bolt, but I didn’t give any thought to the barrel set screw.
I do have to point out though, continuous carbon fiber reinforced plastic printing is now being done. It’s not exactly cost effective, but given some more time, I’d expect it to get into the price realm of us hobby guys.
https://markforged.com/materials/carbon-fiber/
I don’t believe that page specifies that it is continuous, but it is under their continuous composites section.
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I suppose I should add that printing continuous fibers requires special slicing software as well. I’m sure they don’t let that go cheap either.
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I suppose I should add that printing continuous fibers requires special slicing software as well. I’m sure they don’t let that go cheap either.
I thought cura had several specialty filament profiles that include metal wood and fiber.
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I suppose I should add that printing continuous fibers requires special slicing software as well. I’m sure they don’t let that go cheap either.
I thought cura had several specialty filament profiles that include metal wood and fiber.
I believe it does, but I don’t think it’s for continuous fiber. I can’t say for sure though. I haven’t used Cura ever since I switched to these Prusas and Slic3r PE.
I thought I had read that continuous fiber printing was still fairly new and that the slicing algorithms and software were still proprietary.
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Ya fiber fortified vs continuous probably is very different. I used repetier on my hacked davinci and using cura with my ender 3. So far I am quite impressed with the ender 3 it is hammering out parts at a resolution I thought I had to spend a lot more on to get.
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Well, the multishot version was a failure.
All the dimensions are correct, but as expected, and as pointed out, the flex on the mag cutout was too much.
New design printing now. This one is using the full mag well that was suggested. It is also 28mm longer on the barrel end to increase engagement and allow extra barrel set screws. I’ve added one on top, and two on each side.
I went ahead and sliced this one with 100% infill instead of 50%. I expect it should do the trick. Print time is 6.5hrs, so I’ll check it out and post a photo in the morning.
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I wonder if this would be a good opportunity to try lost PLA and cast a metal version? It would certainly cut down on machining time. Not saying you, but maybe someone...
I wish I had my forge made.
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Woke up this morning to a finished hunchback of Notre Dame print. Looks like the very bottom had some cooked filament from a roll change yesterday, but otherwise, it turned out as expected. No chamfering on the drawing yet as it’s a pain to go back and edit any dimensions without having to delete all the previous chamfering anyways.
I had to put my own supports in the mag well instead of auto generating. It looks rough, but it’s really not bad. I see where I forgot to add two supports as well. It should all clean up with a small file anyways.
This one is much stronger, and much uglier. It will work, but jeez does it hurt to look at.
I made it so the barrel will need to have the loading sled turned off, and then and extra 2mm. Instead of doing an internal o-ring, I’ll just do one on the end of the barrel similar to the Diana Chaser.
I apologize for the bad photos. I was in a rush to get out the door and on my way to work.
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I wonder if this would be a good opportunity to try lost PLA and cast a metal version? It would certainly cut down on machining time. Not saying you, but maybe someone...
I wish I had my forge made.
Would definitely cut machining time.
I’d be willing to send one off if someone wanted to give it a go.
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I wonder if this would be a good opportunity to try lost PLA and cast a metal version? It would certainly cut down on machining time. Not saying you, but maybe someone...
I wish I had my forge made.
Would definitely cut machining time.
I’d be willing to send one off if someone wanted to give it a go.
Ugh. Now I really wish I had my forge built... :(
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that looks pretty good Austin.. Yes some chamfering here and there.. Maybe your insignia on the side or something to break up the blockyness but it looks good.. Really your 98 % there.
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that looks pretty good Austin.. Yes some chamfering here and there.. Maybe your insignia on the side or something to break up the blockyness but it looks good.. Really your 98 % there.
I had thought about doing something on the side, but I’m printing these standing up with a .6 nozzle. It’s pretty hard to get any real detail on the sides when they’re printing vertically. I’d try printing horizontally, but I’m afraid it would mush the bolt and barrel bores out of round too much. On a side note, I should have taken a picture of the breech on the print surface. I’ve got 210mm of build height on my Z axis, the breech is 200mm. On the final layer with a 2mm Z hop, there isn't much left. Was definitely some picker factor the first time I watched it.
I’ve got an enclosure I can put one of the Prusas in. I may give CF reinforced polycarbonate another shot. Last time I tried it without an enclosure and I had terrible warping issues. It’s gotta print hot, and stay fairly hot to prevent it.
So far this has been a fun experiment. I think there’s more potential for FDM in the airgun world. Hopefully some of the industry technologies will drop in price so is hobby guys can afford them and prove it.
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yes.. breeches are incredibly hard to make.. The amount of machining involved justifies that.. 3d printed breeches could reduce the cost by a large factor , and possibly the overhead also. If your printing vertically, a weaver rail on the top surface instead of a 11mm would really break up the lines.. and thingiverse has some rails that print perfectly vertically.
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" justifies the price is what i meant to say.. ( edit is gone for some reason
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yes.. breeches are incredibly hard to make.. The amount of machining involved justifies that.. 3d printed breeches could reduce the cost by a large factor , and possibly the overhead also. If your printing vertically, a weaver rail on the top surface instead of a 11mm would really break up the lines.. and thingiverse has some rails that print perfectly vertically.
When I machined them on the mill I did picatinny rails, but that’s a lot of overhangs for printing. It’s only a few thousands under 1/8”, but it’s a whole lot of chances for the printer to mess up.
I noticed the edit feature was fine too. Why is that?
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yes.. breeches are incredibly hard to make.. The amount of machining involved justifies that.. 3d printed breeches could reduce the cost by a large factor , and possibly the overhead also. If your printing vertically, a weaver rail on the top surface instead of a 11mm would really break up the lines.. and thingiverse has some rails that print perfectly vertically.
When I machined them on the mill I did picatinny rails, but that’s a lot of overhangs for printing. It’s only a few thousands under 1/8”, but it’s a whole lot of chances for the printer to mess up.
I noticed the edit feature was fine too. Why is that?
I assumed the edit feature was just missing because of the new phone and Safari. All of the other random stuff in my posts is because I can’t seem to get iPhones autocorrect to stop fixing things that don’t need to be fixed.
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yea.. maybe just get it fully operational and later on worry about the fine details.. another way to approach it is to print the 2 sections of rail seeperately horizontally and attach em after the fact.. Still the same cosmetic affect but more work sadly.
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I suspect that when you machine one out of metal you could take some of quasimodo hump off.
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I suspect that when you machine one out of metal you could take some of quasimodo hump off.
I actually have never had the hump on them when I mill them. They end up looking basically like the Gauntlets breech, give or take a few millimeters here or there.
I’ve used 7075 the two times I’ve done it. The extra rigidity probably wouldn’t offset the extra cost of a larger drop of 7075 and the extra time to machine it.
I’ve been fighting the urge to just make a new one from aluminum on one of my nights off, but I’ve got my mill up for sale and I’m too lazy to keep recleaning it so it’s inspection ready. I got caught up in bigger is better, and now a huge chunk of my little shop is taken up by a mill I only use once every 3 months or so.
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I suspect that when you machine one out of metal you could take some of quasimodo hump off.
I actually have never had the hump on them when I mill them. They end up looking basically like the Gauntlets breech, give or take a few millimeters here or there.
I’ve used 7075 the two times I’ve done it. The extra rigidity probably wouldn’t offset the extra cost of a larger drop of 7075 and the extra time to machine it.
I’ve been fighting the urge to just make a new one from aluminum on one of my nights off, but I’ve got my mill up for sale and I’m too lazy to keep recleaning it so it’s inspection ready. I got caught up in bigger is better, and now a huge chunk of my little shop is taken up by a mill I only use once every 3 months or so.
You also have to double the cost and time for me to machine one. It never fails that I’ll mess something up on one of the last revolutions and trash the whole breech the first go round. It’s usually a powerfeed going in the wrong direction, or an incorrect tool diameter punched into the DRO.
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Id like to get a small mill and lathe like the bench top ones for what little I want to do it would be perfect. I have the luck too if its going too smooth I stop because Murphey comes by during the final stretch lol.
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having machined a few breeches myself , theyre a PITA>> too time consuming , too many operations.. too many setups.. Theres no margin in selling machined breeches unless you happen to have a 4 axis cnc and all the g-code already panned out..
The 3d breech , if done correctly and posssibly sleeved could be a huge loophole in these otherwise large obstacles. Especailly for lower power guns , once we start dealing in hpa this assumption goes out the window,.. I myself had thought extensively about mass producing breeches at one time , even with a 3 axis cnc in the shop, one mill and one lathe it made no sense .. This was in part due to fixturing and offsets.. The ideal way to do it would either be 4th axis on a rigid machine or multiple machines ( i.e having 2-3 mills set up for dedicated operations , where the breech only stops at each mill one and there is no tear down of the indexing set ups and offsets on the mill table )
EVEN then there is the challenge of longer drilling , sounds simple i know.. The problem with smaller diameter drills is they tend to wonder based on the diameter / depth of the cut.. So when dealing with 7/16 or even 15 mm holes that are long , this presents its own challenge irregardless of set up or reaming.. Yes , boring would be accurate but now we have a tool stickout issue.. The issues go on.. Can it be done ?? yes.. Guys a few yrs ago were cranking out manually machined breeches that were awesome and a good price.. But i suspect they had the machining and mutiple operational setups well planned or a ton of spare time (-'
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now conversely ( i apologize if im rambing ) with 3 d printing there are a seperate set of challenges.. Conveniently theyre all Up front.. In other words, 99.9 % of the labor intensive stuff is getting to point where the g-code and slicing is perfected.. ( this often includes orientation of the part based on surface finish or mechanical toughness ) .. Once you have the perfect file and its relaible , youre kinda good to go.. Its intellectual property as opposed to sweating on a hand crank..This sounds like a nice segway but oftentimes overcoming the limitations of the printer or the materials make this an uphill battle.. Ive been through designs where after 10 iterations it was simply never going to work. One idea I shared with a friend recently was insert voids.. Basically when you have a longer part where there may be bridging stress on the part, id draw in 2 long voids 1/8 th diameter each.. when the print was done , install 2 steel rods in the voids ( interference fit + jb weld or whatever ) to give the part massive spine strength without any visual inperfections to the part.. I dont have a great example of this but for the breech idea this may offset any flex tremendously
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I’m hoping the hunchback has eliminated most of the flex, but it’s not ideal.
Since it’s printed vertically, there isn’t near as much strength in the span as there would be printing it horizontally. No real good way to go about it if I keep the hunch other than making it a tongue and groove fit. Print the hunch as a second piece, but print it horizontally so it has more strength. It would have to either be filament welded or CA glued, or both.
I’m also not even sure how how the scope is actually going to sit, or have to sit to clear the hunch at this point. It could all be a wash other than the practice in CAD.
Dowels for stiffening are a good idea. 1/8” sounds a little small and flexy. There’s a decent amount of material left in the breech on either side of the centerline to go bigger I think. I was thinking at least 3/16 to 1/4” round.
I’m not sure I’m going to actually worry about stiffening anything up anymore if it works as is. I do plan on chamfering all the edges and streamlining some of the blockiness if possible.
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I’m hoping the hunchback has eliminated most of the flex, but it’s not ideal.
Since it’s printed vertically, there isn’t near as much strength in the span as there would be printing it horizontally. No real good way to go about it if I keep the hunch other than making it a tongue and groove fit. Print the hunch as a second piece, but print it horizontally so it has more strength. It would have to either be filament welded or CA glued, or both.
I’m also not even sure how how the scope is actually going to sit, or have to sit to clear the hunch at this point. It could all be a wash other than the practice in CAD.
Dowels for stiffening are a good idea. 1/8” sounds a little small and flexy. There’s a decent amount of material left in the breech on either side of the centerline to go bigger I think. I was thinking at least 3/16 to 1/4” round.
I’m not sure I’m going to actually worry about stiffening anything up anymore if it works as is. I do plan on chamfering all the edges and streamlining some of the blockiness if possible.
yea 1/8 was just an example.. 1/4 would be super stiff and possible eliminate the overhead hunch solving a few issues.
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Woke up this morning to a finished hunchback of Notre Dame print. Looks like the very bottom had some cooked filament from a roll change yesterday, but otherwise, it turned out as expected. No chamfering on the drawing yet as it’s a pain to go back and edit any dimensions without having to delete all the previous chamfering anyways.
I had to put my own supports in the mag well instead of auto generating. It looks rough, but it’s really not bad. I see where I forgot to add two supports as well. It should all clean up with a small file anyways.
This one is much stronger, and much uglier. It will work, but jeez does it hurt to look at.
I made it so the barrel will need to have the loading sled turned off, and then and extra 2mm. Instead of doing an internal o-ring, I’ll just do one on the end of the barrel similar to the Diana Chaser.
I apologize for the bad photos. I was in a rush to get out the door and on my way to work.
Very nice design, I like it. I would like it even more in aluminum and on one of my guns.
Great job!
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How has the breech printing gone? Any improvements? I am very interested?
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How has the breech printing gone? Any improvements? I am very interested?
I ended up dropping the idea of printing them.
No matter which filament I could print with, the strength and safety was never there. I printed with all of the toughest most exotic filaments aside from PEEK, and they all eventually showed stress failures.
The .step files have been proven to be good, but it’s still cheaper to order one from Umarex than it is to buy the drop and mill it.