Molds For Pvc Lures

[Bbob]

If you have seen my topic on swim bait joints, you can gather I'm in the process of making a swim bait. It's time consuming so I was thinking of making it a mold master. What kind of mold material should I use and what kind of PVC should I use to do this on somewhat of a budget?

[Vodkaman]

You have two choices of materials; resin with micro-balloons or foam.

The resin, even with micro-balloons to lighten it, still has a specific gravity of at least 0.7 which leaves you very little ballast room. Without sufficient ballast, stability will be a problem.

The heaviest expanding foam that you can find will give you rock hard material and still be light enough for plenty of ballast, but it is harder to work with. The mold will need to be RTV.

You will also have to figure out the ballast all over again.

Dave

[Travis]

RTV is the way to go for sure but you can save money by using Plaster of Paris, Durhams Rock puddy, and bondo body filler can all be used to make molds.  They won't work if the design has detail that will work to lock the lure in place but if not then no issues.  Also you can use both halves of the prototype mold to hold the lure and mold the first half using RTV.  

 

I use 16 lb foam but think that seams to not be the norm.

 

Simple topwater using a rock puddy mold.  No major undercuts so no issues.

 

RTV mold once I worked everything out on a simple crank design. I use the rock puddy mold as described above as a holder to mold with the RTV.

[Vodkaman]

I have seen foam advertised as 26Lb. Even this density is only SG 0.41 which is compatible with cedar and slightly lighter than pine. The hardness of 26Lb must be amazing.

My choice would be the same as Travis, 16Lb foam. This is an SG 0.25 which is between a heavy balsa and a basswood. Perhaps a bit light for a swimbait, requiring rather a lot of ballast, but still my choice, I can live with all that lovely stability.

Dave

[Bbob]

So if I was to use the puffy stuff and the 26 lb foam how much are we talking?

[DingerBaits]

the foam is usually a 2 part mix, which you can figure out the ratio of how much you need per bait by doing some simple algebra. as for the mold, I when ever I make a cast of anything i use the two part silicone. Smooth On makes a great kit for starters. Here is a kit I bought once http://www.smooth-on.com/index.php?cPath=1217 , pretty good minus the 6 hour cure time. I have used it on a few hard baits, but mainly on soft plastics that aren't in production any more. 

[Vodkaman]

Not sure what you mean by puffy stuff, the 26Lb foam expands 2:1.

For a 1.9Lb pak costs around $30 (Google 'foam-it')and will deliver 130cu-ins of foam. For a 6" trout lure, that should deliver 25 - 30 bodies, so around $1 per lure.

Foam problems - you have to judge the amount, to account for the expansion. Too much and you may have pressure build up if your venting is not good enough. You will probably need to experiment with the venting to get it right or ask for advice.

Mixing is critical. For consistency, you have to mix the same each time. I would suggest counting the stirring strokes. Temperature affects things too, so best try and keep this consistent, or make notes of the temperature and effect for future reference, in fact, keep notes of the whole process at least until you have it all sorted out.

There is a learning curve when using foam for the first time. Lots of reading, try to anticipate the problems and don't give up too soon.

Dave

[Bbob]

Is it called durhams rock hard water puddy?

[Bbob]

And should I mold the pieces separate or can I cut the joints after the lure is molded?

[Vodkaman]

I am doing CAD for a swimbait mold for a customer at the moment. He wants it in one piece to cut in post and that is fine.

With foam, you will have to pour the foam into each section anyway and each section will require its own venting, so my choice would be to make the sections separate and save a bit of post work. Either will work though.

Dave

[mark poulson]

It's called putty.

[jonister]

It's called putty.

 Smartba$$. hahaha   

 

i have used FeatherLite by smooth-on and if is very straight forward and simple. it expands a bit but not to much. Their trial size is 2.5 pounds and 25$ so pretty well priced too. 

[Bbob]

It's called putty.

I don't mean to be smart but not just any putty would work, right?

[mark poulson]

I don't mean to be smart but not just any putty would work, right?

 

I don't know about any other putty.  All I know is some people here use Durham's Rock Hard Putty successfully.  Years ago we used to use it as a filler on construction projects, but I have never tried to make a mold from it.

Here's a link to where it's sold:

 

http://www.homedepot.com/p/Durham-s-Rock-Hard-DU-1-1-lb-Water-Putty-1-CAN/100184116

[Bbob]

Thanks Mark

[Bbob]

I am doing CAD for a swimbait mold for a customer at the moment. He wants it in one piece to cut in post and that is fine.

With foam, you will have to pour the foam into each section anyway and each section will require its own venting, so my choice would be to make the sections separate and save a bit of post work. Either will work though.

Dave

What do you mean by post work?

[Vodkaman]

Bbob - 'Post' refers to 'after'. So in this case it means after the molding work. I guess it is short for 'Post Process'. The term gets used a lot in engineering, it just slipped through this time.

Dave

[Travis]

I must be lucky.... I use a spoon (as the same type I used to eat cereal with) and poured into  spoon and then just dumped it into a dixie cup.  Spoonfuls of then mixed for about 20 seconds, it doesn't take that many lures before you visually can tell it is mixed well.  The 16 lb foam I filled the mold about 1/3 full pouring direct from the dixie cup.  For my purposes I usually could fill 4 molds with out any issue at a time.  The dixie cup is left with a little in it and once it was set (12 minutes or so) I would demold.  I typically would use two sets of 3 or 4 molds and just kept it moving.  So while waiting for one set I was mixing, pouring, and clamping the next set.    I have always stuck with US Composites stuff and never had any issues.  

 

I would mold the joints as doesn't make much sense (time wise) to have to cut.  Also do it right the first time and every bait  you make from that mold is dead on correct.  Once you start trying to cut you bring in some variability and screw ups if you don't have jigs, or take careful measurements, or just aren't paying attention when cutting.  Same reason I molded in the lip slot on cranks.  

 

http://www.uscomposites.com/foam.html

Edited September 9, 2015 by Travis

[JRammit]

My best question here is... What is the advantage of carving every lure by hand when you can do it once and copy it infinantly with the foam???

Besides the satisfaction and demonstration of craftsmanship.... Is there any advantage to a hand carved lure vs foam molded???

[mark poulson]

Being able to hand carve a lure gives you the ability to experiment.  By using PVC, waterbased airbrush paints, and UV cured resin, you can conceive, shape, ballast, test, paint, topcoat, and fish a lure in one day.

I think molding is for when you've got one that really works well, and want to go into production.

For some, it's the destination.  For others, it's the journey.

Edited September 9, 2015 by mark poulson

[Travis]

What I don't like about foam was it just never felt like I was crafting something.   It became much more about stamping out widgets sort of thing and not so much about enjoyment in the making process.   I also still like the "feel" of fishing wooden bait.

Edited September 9, 2015 by Travis

[Vodkaman]

JR - Mark nailed it; 'For some, it's the destination. For others, it's the journey.'

But, developing the lure to perfection by carving still leaves you with more setting up work with the casting, as the body density changes. You just have to design your mold so that you can accommodate these changes.

For me, it is the journey.

Dave

[Bbob]

My best question here is... What is the advantage of carving every lure by hand when you can do it once and copy it infinantly with the foam???

Besides the satisfaction and demonstration of craftsmanship.... Is there any advantage to a hand carved lure vs foam molded???

I'm a better painter than a carver so I would like to save the really good lure to make more of. Also I'm a junior in high school with a job so I don't have a lot of time

[woodieb8]

we have used the 16lb and 26lb foams. .. in a well vented mold the hardness is as stated. back pressure on vents will create even harder cast,s

[JRammit]

I like the journey too... But when i complete the journey, im ready to go on another one!

I finish a project and want to move on to the next, but one lure doesnt fill the tackle box... So im torn between building more, or starting a new one...... Thats whats great about soft baits, i can do both!