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IN, USA
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Posted: 8/28/2023 11:48:29 AM EDT
I am new to 3d printing (and 40mm) and have printed some, but they seem slightly large for the printed nose cones. I have to really force them in the nose cones or in the case. Looking for the actual size to see where I am off.
Is there any decent forums for 40mm questions? Grogs seems to be VERY slow. Reddit sparse. It seems to have a lot of replies here. |
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MT, USA
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Posted: 8/28/2023 12:12:33 PM EDT
[#1]
Seems easy enough! I'll measure one tonight if I have the time to.
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OH, USA
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Posted: 8/28/2023 12:18:53 PM EDT
[#2]
In case you didn't see, there is a new reddit sub just for 40mm. It's growing still but showing promise
https://reddit.com/r/40_mm/s/xPBxbZOgjs |
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IN, USA
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Posted: 8/28/2023 3:25:39 PM EDT
[#3]
Quote HistoryOriginally Posted By SGT-Fish: In case you didn't see, there is a new reddit sub just for 40mm. It's growing still but showing promise https://reddit.com/r/40_mm/s/xPBxbZOgjs I am new to reddit, but will look it over. Thx BTW I sent you a couple emails, not sure if you know of any places for blanks new or used. My email usually gets sent to a spam folder. |
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WI, USA
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Posted: 8/29/2023 1:43:44 PM EDT
[Last Edit: NAM]
[#4]
Mine's been fired, so dimensions may be a bit squished up
Base: 1.485 ~1.490 Driving band lip: ~1.615 Driving band: ~1.58 Nose cone side: ~1.51 Note: The nose cone side has a small ramp down to the driving band. The nose is a hair more blunt, but it's hard to get a good measurement because the projectile is covered in RTV. I have a buddy who can get buckets of wheel weights for free. I've been experimenting with casting a slug the size of the washer pocket in the 3D printed models. Seems to work better than washers in my limited tinkering, but I have yet to fire any (waiting on DD paperwork). |
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OR, USA
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Posted: 8/29/2023 3:03:36 PM EDT
[#5]
Quote HistoryOriginally Posted By NAM: Mine's been fired, so dimensions may be a bit squished up Base: 1.485 ~1.490 Driving band lip: ~1.615 Driving band: ~1.58 Nose cone side: ~1.51 Note: The nose cone side has a small ramp down to the driving band. The nose is a hair more blunt, but it's hard to get a good measurement because the projectile is covered in RTV. I have a buddy who can get buckets of wheel weights for free. I've been experimenting with casting a slug the size of the washer pocket in the 3D printed models. Seems to work better than washers in my limited tinkering, but I have yet to fire any (waiting on DD paperwork). I didn't even think about that. Being able to cast led pucks you can drop in would be significantly heavier than the washer solution, albeit more hazardous and laborious. |
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WI, USA
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Posted: 8/29/2023 3:10:14 PM EDT
[Last Edit: NAM]
[#6]
Quote HistoryOriginally Posted By homemadeammo42: I didn't even think about that. Being able to cast led pucks you can drop in would be significantly heavier than the washer solution, albeit more hazardous and laborious. Lots of the wheel weights these days are zinc too, so you could do either or. It's quite simply a case of "pissing with the cock you've got". I had lead on hand, figured it was worth trying. Like I said, I haven't actually fired any yet, but in theory, it should work. As soon as I get approved paperwork in my hands and get everything assembled, I'll try it out and report back.   (Credit to SGT-Fish; I'm 99% sure that's his 3D printed pusher design) |
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WI, USA
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Posted: 8/29/2023 3:24:12 PM EDT
[Last Edit: NAM]
[#7]
On second glance, I think I may have the measurements backwards. I was assuming the domed section was forward, but after looking at it a bit, I'm pretty sure I've got it backwards. lol...That would make sense that there's a bit of a recess on that side, for the casing to be slightly roll crimped into place.
My zinc pusher also looks a little different than others I'm seeing online; I wonder if this is from an older lot. I'll have to defer to the 40mm experts.  ETA: based on the deformation of the driving bands, I definitely had my pusher measurements backwards. |
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IN, USA
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Posted: 8/29/2023 6:56:18 PM EDT
[#8]
Quote HistoryOriginally Posted By NAM: Mine's been fired, so dimensions may be a bit squished up Base: 1.485 ~1.490 Driving band lip: ~1.615 Driving band: ~1.58 Nose cone side: ~1.51 Note: The nose cone side has a small ramp down to the driving band. The nose is a hair more blunt, but it's hard to get a good measurement because the projectile is covered in RTV. I have a buddy who can get buckets of wheel weights for free. I've been experimenting with casting a slug the size of the washer pocket in the 3D printed models. Seems to work better than washers in my limited tinkering, but I have yet to fire any (waiting on DD paperwork). Thanks for the info... It looks like mine is printing over size. base size (the part that fits in the case) is close to 1.52X. I was also thinking of either casting a lead weigh to fit in the printed plastic pusher, or seeing if I can cast some zinc pushers myself. I think I can make a casting block. Just the price of the Zinc is pretty high especially after shipping. I have not ran across any zinc pushers yet... Just getting into the 40 mm world. |
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IN, USA
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Posted: 8/29/2023 7:06:30 PM EDT
[#9]
Quote HistoryOriginally Posted By NAM: On second glance, I think I may have the measurements backwards. I was assuming the domed section was forward, but after looking at it a bit, I'm pretty sure I've got it backwards. lol...That would make sense that there's a bit of a recess on that side, for the casing to be slightly roll crimped into place. ETA: based on the deformation of the driving bands, I definitely had my pusher measurements backwards. I have a buddy who can get buckets of wheel weights for free. I've been experimenting with casting a slug the size of the washer pocket in the 3D printed models. Seems to work better than washers in my limited tinkering, but I have yet to fire any (waiting on DD paperwork). I think so on the measurement... Form the 3D printed one I made (Thanks SGT Fish) the nose cone side was slightly smaller than the case side. I had to really push to get the nose cone on mine, for a test fit. I had to put it in a vise and tap it off with a screwdriver. I need to find a buddy who can get me some wheel weights. Too bad you are not closer. Hint hint |
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IN, USA
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Posted: 8/29/2023 7:16:25 PM EDT
[#10]
Quote HistoryOriginally Posted By NAM: Lots of the wheel weights these days are zinc too, so you could do either or. It's quite simply a case of "pissing with the cock you've got". I had lead on hand, figured it was worth trying. Like I said, I haven't actually fired any yet, but in theory, it should work. As soon as I get approved paperwork in my hands and get everything assembled, I'll try it out and report back. (Credit to SGT-Fish; I'm 99% sure that's his 3D printed pusher design) Did you try to weigh your plastic printed pusher with the lead?? SGT Fish had a video with the weights of the 3D one and an original. Not sure how much of a lead puck you would need to get the weight close to an OEM round. |
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WI, USA
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Posted: 8/29/2023 9:27:30 PM EDT
[#11]
Some images:
Zinc pusher  Pusher with lead  Pusher with washers  Lead slug  Zinc with nose  Lead with nose  Washers with nose  So, lead pusher assembly is less than an ounce lighter. If the cavity in the plastic pusher were a little deeper (or more stuck out the end) to accommodate a ~33% larger slug, a weight identical to the zinc pusher should be doable. |
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Posted: 8/30/2023 11:54:30 AM EDT
[#12]
I've got some brand new zinc pushers if anyone need more precise measurements.
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WI, USA
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Posted: 8/30/2023 1:56:16 PM EDT
[#13]
Quote HistoryOriginally Posted By brazos609: I've got some brand new zinc pushers if anyone need more precise measurements. What's the weight? and length? Curious if the ones with the recess in the middle are longer and/or lighter. |
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TX, USA
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Posted: 8/30/2023 3:13:42 PM EDT
[#14]
Quote HistorySo, lead pusher assembly is less than an ounce lighter. If the cavity in the plastic pusher were a little deeper (or more stuck out the end) to accommodate a ~33% larger slug, a weight identical to the zinc pusher should be doable. I'd thought about that when looking at the pusher I printed. Going to have to start playing around and learning 3d cad |
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WI, USA
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Posted: 8/30/2023 3:36:42 PM EDT
[#15]
Quote HistoryOriginally Posted By usmcagg02: I'd thought about that when looking at the pusher I printed. Going to have to start playing around and learning 3d cad Doing so would be rather trivial in tinkercad. Upload to tinkercad, create an empty cylinder the same diameter as the opening, but sink it down in a bit (making the hole deeper). Merge, export as .stl, ????, Profit.   (just a demonstration of how to do it. Tinkercad is free and pretty easy to use. I need to measure how big the slug would need to be, then size the hole appropriately). |
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WI, USA
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Posted: 10/2/2023 3:21:43 PM EDT
[#16]
Picked up a bunch of pushers this weekend. Will post dimensions tonight (if I remember). Also going to try 3/4x10 rod for ballast; easy to find...just screw it into a modified PLA pusher.
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WI, USA
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Posted: 10/3/2023 11:32:27 AM EDT
[Last Edit: NAM]
[#17]
Got sidetracked. :-D
Pulled out a box of 15 pushers, here's the averages/relative standard deviation: Pusher weight: 5.517 oz, RSD .656 Length: 1.321 in, RSD .435 Top (chalk side) width: 1.491 in, RSD .207 Band width (widest): 1.618 in, RSD .176 I haven't been able to get a reliable measure of the tapered bottom side. All of mine are pretty caked with RTV/adhesive, so the measurements will be all over the place. |
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WI, USA
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Posted: 10/3/2023 9:07:59 PM EDT
[#18]
Here's an updated pusher design I'm working on. It uses Sgt Fish's .stl, with a 3/4x10 hole in the middle. 3/4x10 nut and rod inserted; weighs 5.2 oz (standard M781 pusher is 5.6 oz). Still tinkering to find the perfect length to come out to equal weight.
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USA
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Posted: 10/31/2023 6:39:15 PM EDT
[#19]
If we could figure out how much zinc shrinks, we could cast them in green sand. The lost wax method would be possible if the print was thin and would burn out.
Say six per charge? No more roadblock on legit pushers. Casting is really actually easy but laborious. Pouring molten metal is always fun. |
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USA
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Posted: 11/1/2023 3:10:43 AM EDT
[#20]
Quote HistoryOriginally Posted By FADALdude: If we could figure out how much zinc shrinks, we could cast them in green sand. The lost wax method would be possible if the print was thin and would burn out. Say six per charge? No more roadblock on legit pushers. Casting is really actually easy but laborious. Pouring molten metal is always fun. Polycast + Zamak |
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TX, USA
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Posted: 11/10/2023 2:57:16 PM EDT
[#21]
Does someone have the weight of a complete factory M781 chalk round? Or preferably, the weight of projectile (zinc pusher, nose cone, and chalk)
Seems like trying to match the weight of the pusher is only part of what should be consistently the same weight for best accuracy results. |
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WI, USA
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Posted: 11/11/2023 2:22:32 AM EDT
[#22]
If I recall, it was right around 6oz. I can try to measure one in the next day or two if I remember.
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WI, USA
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Posted: 11/13/2023 2:18:53 PM EDT
[#23]
Loaded, ready to fire M781: 7.6 oz
Pusher/nosecone/chalk: 6.7 oz Empty case: 1.1 oz Primed case: 1.2 oz As you can see, the numbers vary slightly, most likely due to chalk load and variance in the components. |
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Posted: 11/18/2023 1:41:10 AM EDT
[#24]
Quote HistoryOriginally Posted By NAM: Here's an updated pusher design I'm working on. It uses Sgt Fish's .stl, with a 3/4x10 hole in the middle. 3/4x10 nut and rod inserted; weighs 5.2 oz (standard M781 pusher is 5.6 oz). Still tinkering to find the perfect length to come out to equal weight. https://i.imgur.com/2Ka9n1s.png Really curious how this is working for you...? |
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TX, USA
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Posted: 11/20/2023 3:27:19 PM EDT
[#25]
Quote HistoryOriginally Posted By NAM: Loaded, ready to fire M781: 7.6 oz Pusher/nosecone/chalk: 6.7 oz Empty case: 1.1 oz Primed case: 1.2 oz As you can see, the numbers vary slightly, most likely due to chalk load and variance in the components. 
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WI, USA
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Posted: 11/20/2023 10:32:48 PM EDT
[Last Edit: NAM]
[#26]
Quote HistoryOriginally Posted By MauserMatt: Really curious how this is working for you...? Honestly, project has sat. I found a bunch of pushers locally, so my immediate needs are met. Furthermore, it looks like KAK may be selling new mfg pushers in the near future. https://kakindustry.com/zinc-pusher-for-40mm/ My biggest issue was getting a thread to print properly. They all looked perfect, but bound up when the rod was threaded. I downloaded the proper thread files from McMaster Carr, and calibrated the printer, but it still doesn't seem to mesh properly. I decided to pick up a 3/4x10 tap and just cut threads instead. |
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IN, USA
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Posted: 1/13/2024 12:17:49 AM EDT
[#27]
Quote HistoryOriginally Posted By FADALdude: If we could figure out how much zinc shrinks, we could cast them in green sand. The lost wax method would be possible if the print was thin and would burn out. Say six per charge? No more roadblock on legit pushers. Casting is really actually easy but laborious. Pouring molten metal is always fun. Now that I figured out how to make sure I am subscribed to the thread.... I am finally getting a little caught up around here and back to kicking over ideas. Why are the pushers made of Zinc?? Why not lead? I think they are close in weight? Zinc costs quite a bit more. I am thinking that lead may be more malleable, but the military was not going to reuse or recover the pushers anyway. I am game to learning how to make a mold. But looks like Lead pushers would be cheaper to make. Unless there is some reason that Zinc is better? Used Lead is about a buck a lb. Zinc is about $7 a lb. I think that comes out to be about 3 pushers per lb. |
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WI, USA
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Posted: 1/13/2024 12:29:13 AM EDT
[#28]
Zinc is harder; might hold up to the rifling better? Just a guess. Lead is a little denser as well. I considered homebrew lead pushers, but haven't had the time or the need recently.
Check with your local tire shop. Wheel weights are a good source of lead. Can't use zing for casting all that well, but for a larger projectile maybe it's not a big of an issue? Lots of the newer weights are zinc, so maybe a win/win. |
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USA
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Posted: 1/17/2024 12:27:48 AM EDT
[#29]
Quote HistoryOriginally Posted By FADALdude: If we could figure out how much zinc shrinks, we could cast them in green sand. The lost wax method would be possible if the print was thin and would burn out. Say six per charge? No more roadblock on legit pushers. Casting is really actually easy but laborious. Pouring molten metal is always fun. Look into polymaker polycast filament You can print it like PLA, then encase in sand or plaster , then burn out with minimal ash Pour in whatever you want Boom done With ZAMAK-3 im getting enough resolution in plaster to see individual layer lines. |
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IN, USA
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Posted: 1/17/2024 9:50:52 PM EDT
[#30]
Quote HistoryOriginally Posted By 7insert: Look into polymaker polycast filament You can print it like PLA, then encase in sand or plaster , then burn out with minimal ash Pour in whatever you want Boom done With ZAMAK-3 im getting enough resolution in plaster to see individual layer lines. Hmm. I am still not getting alerts on new posts. What are you paying for Zamak? At 3 pushers per lb it can add up. Knowing my luck, I will be losing a bunch. |
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IN, USA
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Posted: 1/25/2024 3:10:20 PM EDT
[#31]
Quote HistoryOriginally Posted By NAM: Zinc is harder; might hold up to the rifling better? Just a guess. Lead is a little denser as well. I considered homebrew lead pushers, but haven't had the time or the need recently. Well, A quick look and Lead is about 50% heavier than Zinc. Zinc weighs 4.123 oz per cubic inch and Lead weighs 6.556 Oz per CI. So if you use Lead you will have to redesign the pusher to be lighter. I wonder if it is worth the effort to try the Lead. Saving 80% of the cost going with lead. Has anyone made a bullet mold for a pusher? |
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USA
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Posted: 1/26/2024 5:03:41 PM EDT
[Last Edit: 7insert]
[#32]
Quote HistoryOriginally Posted By BrianSki: Hmm. I am still not getting alerts on new posts. What are you paying for Zamak? At 3 pushers per lb it can add up. Knowing my luck, I will be losing a bunch. https://www.rotometals.com/zamak-3-ingot-aluminum-4-zinc-96/ $5/lb 3 pushers per pound $1.60 per "mil spec" pusher I just use the washers as originally specced, Im not so much worried about mimicking HE rounds I dont have access to. 55gr M193 vs 62gr 855a1 for plinking in my mind.  That being said, you can just pour lead via polycast as well or trash metals its not like this is a load bearing rocket component. Youre shooting it into dirt. |
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IN, USA
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Posted: 1/29/2024 8:25:09 PM EDT
[#33]
Quote HistoryOriginally Posted By 7insert: That being said, you can just pour lead via polycast as well or trash metals its not like this is a load bearing rocket component. Youre shooting it into dirt. There you go!! |
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