Using 3D printing to make soft plastic fishing lures (My Way)

[TCBtacklebox]

Hey everybody! I want to make a little post today detailing what I've learned and what I do to make 3D printed soft plastic molds. I looked on the forum and I know there have been 3D printed lure threads in the past but I just kinda wanted the throw my hat into the ring on this topic. But I apologize in advance if I repeat what is commonly already known.

Instead of resin 3D printing I use FDM printers which are 3D printers that use spools of plastic filament instead of liquid resin. Kinda like a fancy advanced hot glue gun. Resin printers are great but it's simply not the path I went down. 

 

Software:

-AutoDesk Fusion 360 (you can use a program like FreeCAD but I think it's harder and good tutorials are harder to find for it) Fusion 360 is free under a hobby license but you can subscribe to higher versions if you feel the need to.

-Ultimaker Cura (This is the slicing software that turns the 3D mold model into printable code for the 3D printer) Cura is also a free to use software that works well in my opinion.

The 3D printer itself:

-I used to use an Ender 3 V2 but it was finicky and I hated adjusting the spring knobs to level the bed all the time and the included bed surface was pretty unreliable. 

-I now use an Elegoo Neptune 3 which has become my favorite budget printer for less than $200. That being said, you must be prepared to change a few things on this cheap printer because there's less quality control because they're so cheap. I ended up having to replace my stock bowden tube and z-Axis aluminum extrusions so the printer could work right. though, after my adjustments my prints turn out great. The printer comes with auto bed leveling, a touch screen with phone cord, and can print multiple kinds of materials.

The bed surface for the printer:

-I have found that a magnetic PEI coated bed surface works great for me. The Neptune 3 comes with a bed like this and I've been very happy with it and had very little bed related failures when printing. I wipe the bed down with 70% isopropyl alcohol and occasionally Acetone when I feel the bed is too dirty for the iso.

 

Materials:

PLA: Yes, PLA can work in molds contrary to what some people may say. It works in a pinch and that's what matters to some people. PLA is great for making prototype molds that only have a few uses in them after they warp too much or fail in some other way. It helps to inject a PLA mold with 300-320 degree F plastisol. Also making sure the inside of the mold has lots of solid top layers when printing. With PLA I recommend 8 to 12 solid top layers and with 25%-50% infill on the inside. You can get away with higher infills in PLA without much warping and the higher internal density of plastic will make the mold slightly stronger. 

PETG: I've worked with this material and it's great for prototyping hard body baits but it doesn't work well for soft plastic molds. The plastisol sticks very well to the inside of the mold even with oil. It is not usable to me.

ABS/ASA: I primarily make my molds using ABS. It withstands higher temps but also warps more so you need good clamps as you use the mold more. ASA is like ABS but I find it sticks to plastisol slightly more than ABS so I don't use it anymore. Of course you need an enclosure to print ABS to give it the best chance of turning out and being strong. ABS molds will last longer than a PLA mold but will warp over time but with good clamps it's not a huge deal. My ABS molds are still 25%-50% infill but the solid top layers are about 6-8 layers on top.

Vent holes: 

-I also design my molds in a way that makes it so they require minimal pressure to inject so there is hopefully less chance of injury. I include small vent channels in the mold so that plastisol can slightly ooze out of the ends letting you know it's been fully injected. So far this has worked well for me and I've had no injection incidents. 

 

I Think that's most of what I know. If anyone has any questions or tips of their own please feel free to chime in!

[Les Young]

Great info. I've been wanting to get a printer & make my own molds but haven't yet. You gave some very good info  for sure.  Please come back & share more info & pics of your results. Thanks

[alsworms]

1 hour ago, Les Young said:

Great info. I've been wanting to get a printer & make my own molds but haven't yet. You gave some very good info  for sure.  Please come back & share more info & pics of your results. Thanks

+1

Good stuff.......thanks for sharing!! 

[TCBtacklebox]

Thanks, you two! I appreciate the replies! I'll be sure to give you all updates once things warm up in my area or if I make anything new.

[Hand Crafted Angling]

Good write up. I never tried pla but I used petg and abs before. In my experience petg deforms on larger molds and the abs molds get cracks in then over time. The abs still works but it makes surface defects in the lures. I found this new plastic that’s a blend of polycarbonate and petg. I’ve never had any issues with the mold deforming or warping since I started using it. It’s also much stronger so I use it for all of my hardbaits as well. It needs an enclosure but prints at abs temps. https://a.co/d/iQQQXW7

[TCBtacklebox]

This is pretty interesting. Thank you so much for sharing that! I know you said it prints at abs temps, can you print it lower than 245 C? 

[Hand Crafted Angling]

11 minutes ago, TCBtacklebox said:

This is pretty interesting. Thank you so much for sharing that! I know you said it prints at abs temps, can you print it lower than 245 C? 

My temp tower came out good on that if I remember correctly I print hotter for the better layer adhesion. I don’t think that matter much for the molds though.

[KStix]

This is awesome. Would love to see how they turn out. Keep is updated!

[Vodkaman]

My suggestion would be to design in 'bolt on' backing plates with recessed bolt heads. This will help keep the shape of the mold halves, and simplify assembly with permanently fixed backing plates.

Make the printed halves identical, so you can print extra halves if problems arise.

I have to make more of an effort to source a 3D printer here in Indonesia. I have been lazy. I will be printing hard-baits rather than molding. This gives me the opportunity to improve the shape beyond 'mold-able', and with the added benefit of making my printed lures difficult to copy.

Dave

[Hand Crafted Angling]

On 2/6/2023 at 11:02 AM, Vodkaman said:

My suggestion would be to design in 'bolt on' backing plates with recessed bolt heads. This will help keep the shape of the mold halves, and simplify assembly with permanently fixed backing plates.

Make the printed halves identical, so you can print extra halves if problems arise.

I have to make more of an effort to source a 3D printer here in Indonesia. I have been lazy. I will be printing hard-baits rather than molding. This gives me the opportunity to improve the shape beyond 'mold-able', and with the added benefit of making my printed lures difficult to copy.

Dave

I tried something similar to this although not  affixed to the actual mold. In my experience it does save some time putting all the bolts together. It would save even more time if it was attached perminitly like you mentioned but I was too cheap to buy bolts for every mold. I don’t think it’s going to help with the rigidity of the mold because fdm prints flex too much. In my experience I don’t really think it’s needed. To be fair I put a ton of bolt holes in my molds. When I put enough in I get zero flashing whatsoever. I think the best thing to figure out would be a way to use a vise and some clamps. I haven’t figured out a way to do that yet every time I get a bunch of flashing but it would save a ton of time

[Les Young]

What about a piece of aluminum or board or something  like that on each side of the mold tightened down in a vise?

[Hand Crafted Angling]

15 hours ago, Les Young said:

What about a piece of aluminum or board or something  like that on each side of the mold tightened down in a vise?

I tried wood board it didn’t work maybe aluminum would work. I wonder how thick it would need to be to make sure the mood gets clamped down evenly. 

Edited February 19, 2023 by Hand Crafted Angling

[SlowFISH]

Couple suggestions since I've used quite a few "alternatives to aluminum" mold materials in my time here on TU.... plaster, silicone, FDM/ABS, HDPE urethane.... 

1. Everything deflects (warps) under temp - some just deflect more than others.  Even aluminum deflects with enough heat - we usually don't get them hot enough with plastic - but pour some lead sinkers in a thinner mold and you'll see.

2. Bolts and clamps work - the more the merrier - but at some point the molds just holds too much heat after repeated injections and aside from using a hydraulic press that would likely crush the rapid prototype molds to some degree - you'll need to wait and cool the molds.  I use urethane - and on hot days after repeated shots - I have to just let them sit with a fan on them to "undeflect" or I get flash as well.  Even aluminum will deflect - that's why production company's use big presses so the can fill those molds with a lot of cavities (that contain alot of heat).

3. The size of your bait vs size of the mold is a HUGE - HUGE - HUGE factor... the size/amount of baits vs molds size is a factor you can control - and can really help.  Most of my molds are 5" x 8" to fit in my CNC mill.  That mold size with little 2" craw baits will NOT deflect noticeably.... but the same mold size with 4-5 fat swimbaits jammed in there starts deflecting after a few shots.  So monitor how many cavities / size of bait you use vs your mold size and you can really help your cause.

4. Related to above - at first I was a cheap guy trying to minimize every square inch of my mold material. It works - but after years of doing that I now have dozens of molds that are all different sizes.... 3x5, 3.5x6, 4x4, 5x8, 6x10 - you name it - I got - LOL.  So while I saved a few bucks here and there on my small molds.... clamping is now a pain in the a$$.  Being all different sizes I have to use multiple clamps, some I have to just bolt together on their own.  Since I altered my thinking to making nearly every mold 5"x8" unless it needs to be bigger - I can put 5-6 molds in a couple bar clamps and crank them down.... so with 2-3 clamps I can hold a bunch of molds nice and tight.... that's a alot faster than bolting/clamping every mold together on its own.  Wish I wasn't so cheap to start as some molds I don't even use because  of the hassle.  So come up with 1 or 2 common mold sizes and stick to them.... in long run it will be helpful.

5.  I've found Bench Wood working vises are also helpful.... because they usually provide for a 4"x6" faceplate from and back - they keep things help evenly and are friendly to use.

Hope that helps.

J.

Edited February 19, 2023 by SlowFISH

[Les Young]

Yep i have to let my aluminum cnc molds cool when i get on a roll & make a bunch of baits in a hurry. I have put half of another mold on each side of the mold i was injecting. If injecting several i will put a half on each side of them all & clamp down tight. It's enough of a heat sync that i  haven't had any problems like this. 

Edited February 19, 2023 by Les Young

[SlowFISH]

Pouring in the winter before the season starts up here in NY helps alot too!  Except this winter has been really warm - so not sure i can count on that anymore!!

   J.