question on sizing molds to your injector

[keakar]

im going to make a mold for 3" (80mm) paddle tail minnow swimbaits

i dont want to make too many or too little cavities per mold but im unsure how far the plastic goes

i have a 4 oz injector so that is realistically only going to hold 3.5 -3.75 oz of pouring plastic when full

so with that in mind what can that fill in one shot? 3 cavity, 4 cavity, 5 or 6 cavity?

i would like to do a 5 or 6 cavity mold but not if i cant fill it in one shot

thanks for your help

 

 

 

Edited August 24, 2019 by keakar

[mark poulson]

I usually make 6 cavities for smaller baits, with individual sprues.  That way, if I run out of plastic, there will still be some baits that are good.

If you're making  a one sprue/multi-cavity mold, I'd probably only do 4 cavities with a 4 oz. injector.

If it's still too much for your injector to fill, you can always block off one cavity at a time, until it pours right.

[keakar]

1 hour ago, mark poulson said:

I usually make 6 cavities for smaller baits, with individual sprues.  That way, if I run out of plastic, there will still be some baits that are good.

If you're making  a one sprue/multi-cavity mold, I'd probably only do 4 cavities with a 4 oz. injector.

If it's still too much for your injector to fill, you can always block off one cavity at a time, until it pours right.

thanks mark, im just doing it as a hobby for fun so im not in a position to have a lot of waste so im trying to keep things in sinc as far as not too big or too small

[mark poulson]

23 minutes ago, keakar said:

thanks mark, im just doing it as a hobby for fun so im not in a position to have a lot of waste so im trying to keep things in sinc as far as not too big or too small

I do it as a hobby, too.  I understand wanting to try to get as close as possible, so you don't waste either plastic or mold making material.

If you want to get close, weigh some similar baits, and then weigh 4 oz. of plastic.  Figure out how many similar baits it takes to weigh 4 oz.  You'll have to subtract some for the sprue, and there will be a little waste anyway, but that should get you close.

It is not an exact science.  Be prepared to fail.  We all do.  If you make a mold with too many cavities for your injector, you can always eliminate some cavities until you get it right.

Remember, perfect is the enemy of good.  

[Canga~]

i have the angling ai little hammer mold, which is a 2.75" swimbait, 4 cavity and a fairly large runner, with 4 individual sprues for each cavity (hard to explain, but it takes a decent amount of plastic, check the pics on the ai site) and it fills very easily with around 2oz of plastic. i would think with a normal sprue/runner, you would be fine with 6 or 8 cavities. the 3.75" version fills with about 2.5oz, just for reference.

[keakar]

21 hours ago, Canga~ said:

i have the angling ai little hammer mold, which is a 2.75" swimbait, 4 cavity and a fairly large runner, with 4 individual sprues for each cavity (hard to explain, but it takes a decent amount of plastic, check the pics on the ai site) and it fills very easily with around 2oz of plastic. i would think with a normal sprue/runner, you would be fine with 6 or 8 cavities. the 3.75" version fills with about 2.5oz, just for reference.

thanks, the most i would do is 5 or 6 cavity mold but im glad that 4oz is more then enough to fill it

i was thinking it would be ok but then we all know how assumptions go

 

Edited August 25, 2019 by keakar

[Troutfishing303]

On 8/24/2019 at 1:23 PM, keakar said:

im going to make a mold for 3" (80mm) paddle tail minnow swimbaits

i dont want to make too many or too little cavities per mold but im unsure how far the plastic goes

i have a 4 oz injector so that is realistically only going to hold 3.5 -3.75 oz of pouring plastic when full

so with that in mind what can that fill in one shot? 3 cavity, 4 cavity, 5 or 6 cavity?

i would like to do a 5 or 6 cavity mold but not if i cant fill it in one shot

thanks for your help

 

 

 

 Let's say, for one mold, your baits + sprue + runner = 100 grams.  Pour plastisol into a measuring cup until it reaches 100 grams too (or a little more for good measure).  Now you know how many fluid ounces that mold takes to fill. 

Since you haven't actually made the mold yet,  I would make one cavity and see how much that bait weighs and then multiply that by however many cavities you want and then use the same method above to see how many fluid ounces the mold would take to fill.  I'm new to soft plastics.  This is just what I would do so maybe the veterans can chime in too. 

[keakar]

5 hours ago, Troutfishing303 said:

 Let's say, for one mold, your baits + sprue + runner = 100 grams.  Pour plastisol into a measuring cup until it reaches 100 grams too (or a little more for good measure).  Now you know how many fluid ounces that mold takes to fill. 

Since you haven't actually made the mold yet,  I would make one cavity and see how much that bait weighs and then multiply that by however many cavities you want and then use the same method above to see how many fluid ounces the mold would take to fill.  I'm new to soft plastics.  This is just what I would do so maybe the veterans can chime in too. 

well im not making any creature baits, everything i make will be 3" long variations if this