Sign in to follow this  
Followers 0
KelpKritter

Last Minute Advice-rtv And Casting Resin

18 posts in this topic

Well I made my first order of RTV and Casting Resin from JGreer mostly because it was local and I saved the difference in shipping over the Dascar products.

I have been looking very intently at the recent posts about resin casting and did a lot of reading through old posts and exchanged a few PM's with a prominent poster of moldmaking topics to get as much help as possible.

I am confident but a little leary going into my first moldmaking adventure. I will be molding a four piece swimbait whose biggest piece is 2.25" long x 1.75" tall x .75" thick. The only real detail is the eye depression for the 3D recessed eye and the cutouts at the front of the final three sections that make up the hinge openings where the screw eyes sit.

Just looking for any last minute advice/encouragement as I delve into this new way of making my baits.

Thanks for all of the great advice here on TU.

DaveB.

KelpKritter

Share this post


Link to post
Share on other sites

Well I made my first order of RTV and Casting Resin from JGreer mostly because it was local and I saved the difference in shipping over the Dascar products.

I have been looking very intently at the recent posts about resin casting and did a lot of reading through old posts and exchanged a few PM's with a prominent poster of moldmaking topics to get as much help as possible.

I am confident but a little leary going into my first moldmaking adventure. I will be molding a four piece swimbait whose biggest piece is 2.25" long x 1.75" tall x .75" thick. The only real detail is the eye depression for the 3D recessed eye and the cutouts at the front of the final three sections that make up the hinge openings where the screw eyes sit.

Just looking for any last minute advice/encouragement as I delve into this new way of making my baits.

Thanks for all of the great advice here on TU.

DaveB.

KelpKritter

If you do a 2- piece mold with all the lure pieces in it be sure to arrange the pieces to allow air bubble to escape. If you see a spot where air "might" get trapped... It WILL get trapped there. So don't be afraid to have several vents... its way easier to trim a vent then it is to hassle with filling the holes. :twocents:

Share this post


Link to post
Share on other sites

Did you want to mention if it was a one or two piece mold. As I said in previous post a one piece mold with one piece in it will let you experiment a bit more. To cast all the parts at once is really hard especially if you have cut outs for hinge hardware. When I did one with the cuts I cast it with the cuts on the bottom so I would not get air bubbles. Anyways before you pour the part if you have any deep impressions I brush the rtv in those spots so I know there will be no bubbles at least not there. Mix the rtv real good so there is no streaking from the catalyst. Good luck for which ever way you do it. Oh and make sure your master is real good.

I see you are in so cal if you like take a drive up north and I will show you how I do it. I will be home all weekend. Frank

Share this post


Link to post
Share on other sites

You seem to have covered all the bases and improved your chances of getting it right first time.

If you do have a bubble/cavity problem consistently in the same place, you can always cut an extra vent, using a sharp knife.

Consider this post as encouragement. Time to get stuck in. Post some pics when you're done.

Dave

Share this post


Link to post
Share on other sites

Thanks for the words of advice/encouragement.

The first time around I will make two piece molds, primarily because I cannot see any way of casting the hardware into the bait with a one piece mold. I am leaning towards placing two pieces into two seperate molds to make the four pieces of the bait.

I will definately post pictures when I am finished with all of the parts of the process to hopefully help someone in the future.

I am not afraid to take the plunge into learning new techniques, but this one seems like it could be costly with the price of RTV if I make a lot of blunders during the learning curve :(

DaveB.

KelpKritter

Share this post


Link to post
Share on other sites

Dave,

The only thing I've ever poured is concrete, so I'm no expert.

But I'd suggest you mix up a small test batch, and pour it into a throw away mould made out of plaster of paris, to get a feel for the material, before you try your real mould.

Share this post


Link to post
Share on other sites

Thanks for the words of advice/encouragement.

The first time around I will make two piece molds, primarily because I cannot see any way of casting the hardware into the bait with a one piece mold. I am leaning towards placing two pieces into two seperate molds to make the four pieces of the bait.

I will definately post pictures when I am finished with all of the parts of the process to hopefully help someone in the future.

I am not afraid to take the plunge into learning new techniques, but this one seems like it could be costly with the price of RTV if I make a lot of blunders during the learning curve :(

DaveB.

KelpKritter

RTV facts.....

You need appx 20 gms of rtv for each cu in. Do the math and Just mix enough to cover the model by 1/4 - 3/8" That'll keep you from wasting it. After the mold is done, you can affix the mold to a sized piece of wood with silicone sealant to give it support. OR you could fill the remainder of the mold box with Walmart RTV sealant (Get their Mainstay white 100% silicone sealant $2.97 for 10 oz ) mixed with water. Apply it over the cured rtv and smooth it out. It will cure in 20 minutes and will adhere to the RTV, Then you will have a thicker mold w/o wasting the expensive RTV. These methods will stretch out your RTV allowing you to get more molds from your stash.

Use vaseline to keep the mold halves from sticking to each other.

If you follow that advice, you can get a few molds per pound of RTV. If they're small even more.

Use a digital scale to measure out the RTV. At a 10-1 ratio, there is no way you can do it by eye.

Edited by Husky
more stuff

Share this post


Link to post
Share on other sites

If you do get a bad mold dont throw it away cut it up and add it to future molds for fill. You know were it is thick.

Share this post


Link to post
Share on other sites

Frank,

Thanks for asking. Well it has taken me the last two weeks because of my schedule to produce the two molds and pour the four sections of the bait. The first swim test I did was with the first two sections molded attached to the back two sections of one of my previous PVC baits. The bait rolled on its side during the sink but swam great on the retrieve. I expected this because there was no ballast in the front two sections. I did this because I wanted to get an idea of how quickly the bait would sink without microballoons in the cast pieces and how it would swim with the density of the straight resin cast. I wanted to use this as somewhat of a guage to see if I needed any modifications to how I was going to ultimately cast the baits. I was happy with the results and I proceeded to make the second mold and have cast a whole bait but have yet to be able to test it.

Because the baits are used primarily in salt water I am confident that after I swim test the completed bait it will need about half the weight of my current PVC baits and still do everything the current baits do, but still maintain the same sink rate. I am confident the action will not change either because, although I do not make a slower sinking bait, I have used this same configuration in testing the previous model and it swam exactly the same but as a floater. I wanted to be able to make this bait without microballoons if possible and it appears I will be able to do so.

Saturday I will put the finished, i.e. weighted bait, in the pool and see exactly how much weight I will need.

The molds are ugly as sin, but the castings have come out clean as can be. I now have the ability to make about 5-6 baits in the same time it took me to make one hand shaping everything. Still very satisfying when you build something and see guys whacking nice fish on your creations.

DaveB.

KelpKritter

Share this post


Link to post
Share on other sites

That is great I am glad it worked for you. I have tried mine without mb but it does not do what I want without them. They want to roll, Maybe mine are to tall in profile. Looking forward to the next report.

Share this post


Link to post
Share on other sites

To perform sea water sink/float tests, you can always create your own sea water equivalent. Find a homebrew shop and purchase a hydrometer. Add plain salt to your bucket of water, until the spacific gravity reaches 1025.

Dave

Edited by Vodkaman

Share this post


Link to post
Share on other sites

Looks like I spoke a bit to soon. I tested the fully cast bait today with ballast and had a few issues. The minor issue is the bait jumps a little on certain retrieves. This is actually pretty cool as I think it adds a dimension to the realism of real fish when they are fleeing from a predator, but not sure if it is what the fisherman will want. The second more important problem is how the bait sinks. My previous PVC baits sank perfectly level in the position the joints were stopped at. It did not matter if the bait was flexed or straight. The new bait sinks belly down for the most part but, for lack of a better word, flutters as it sinks. It essentially sinks downwards with a slant to the right and then either stays in that position or kicks back and then sinks to the left. I like the sink rate and the swim action, but wonder if making the bait more bouyant with microballoons will help cure this problem. I still have plenty of room for more ballast to keep the sink rate the same. But I need to try and fix the way the bait sinks. Any suggestions?

Thanks,

DaveB.

KelpKritter

Share this post


Link to post
Share on other sites

Looks like I spoke a bit to soon. I tested the fully cast bait today with ballast and had a few issues. The minor issue is the bait jumps a little on certain retrieves. This is actually pretty cool as I think it adds a dimension to the realism of real fish when they are fleeing from a predator, but not sure if it is what the fisherman will want. The second more important problem is how the bait sinks. My previous PVC baits sank perfectly level in the position the joints were stopped at. It did not matter if the bait was flexed or straight. The new bait sinks belly down for the most part but, for lack of a better word, flutters as it sinks. It essentially sinks downwards with a slant to the right and then either stays in that position or kicks back and then sinks to the left. I like the sink rate and the swim action, but wonder if making the bait more bouyant with microballoons will help cure this problem. I still have plenty of room for more ballast to keep the sink rate the same. But I need to try and fix the way the bait sinks. Any suggestions?

Thanks,

DaveB.

KelpKritter

I am just guessing that it is sinking like a rudder, if it sinks right it goes to the right? If this is right that is a similar problem I had and MB did help alot. My wood ones sink like I want them to, but they have at least double the ballast as the resin. I have tried this with two methods. Hope you have a small scale. I weigh all my resin then add MB at the rate of 5%-10% buy weight this should give you what you want. Another thought that I have been throwing around is to cast foam in the top then add ballast.

Buy the way did you mention if your baits are wire through?

Share this post


Link to post
Share on other sites

Looks like I spoke a bit to soon. I tested the fully cast bait today with ballast and had a few issues. The minor issue is the bait jumps a little on certain retrieves. This is actually pretty cool as I think it adds a dimension to the realism of real fish when they are fleeing from a predator, but not sure if it is what the fisherman will want. The second more important problem is how the bait sinks. My previous PVC baits sank perfectly level in the position the joints were stopped at. It did not matter if the bait was flexed or straight. The new bait sinks belly down for the most part but, for lack of a better word, flutters as it sinks. It essentially sinks downwards with a slant to the right and then either stays in that position or kicks back and then sinks to the left. I like the sink rate and the swim action, but wonder if making the bait more bouyant with microballoons will help cure this problem. I still have plenty of room for more ballast to keep the sink rate the same. But I need to try and fix the way the bait sinks. Any suggestions?

Thanks,

DaveB.

KelpKritter

I am just guessing that it is sinking like a rudder, if it sinks right it goes to the right? If this is right that is a similar problem I had and MB did help alot. My wood ones sink like I want them to, but they have at least double the ballast as the resin. I have tried this with two methods. Hope you have a small scale. I weigh all my resin then add MB at the rate of 5%-10% buy weight this should give you what you want. Another thought that I have been throwing around is to cast foam in the top then add ballast.

Buy the way did you mention if your baits are wire through?

Share this post


Link to post
Share on other sites

In my four piece sinking lures, I put some of the ballast in the belly of the second section, and some in the third, if I need to, but never in the tail.

Could it be that your ballast is too high up in the lure?

I had that problem when I tried to put all the ballast in the head, since I use 1/4" lead wire jammed into 1/4" holes drilled up from the belly.

Since you've had such good luck with PVC, if I were you, I would make a test mould, rectangular, and cut a piece of PVC the same size. Then I'd play around with different mircro balloon mixtures until I cam up with one that matched the bouyancy of the PVC. It may take some experimenting, but, since you've already perfected the ballasting of PVC baits, why not eliminate all the reinvention with the resin, and just make it perform like PVC?

Once you get the right mix, you never have to worry about it again.

Share this post


Link to post
Share on other sites

Frank,

To better describe the sinking action imagine a falling leaf. As it falls it flutters back and forth in a vertical position. That is basically what the bait is doing now. It is not moving forward and to the right or left but it is just fluttering back and forth.

Mark,

I may just go that route. My hope was to eliminate some ballast because of the fact that the resin was going to sink already as it was cast. It would simply be a matter of perfecting the weights to get the right sink rate. I have created a mold that makes 1/8-3/16 oz. weights that are 1/8-1/4" thick so they sit in the absolute bottom of the bait, well below the centerline. The original PVC baits have 2 weights in the front section and one in each of the second and third sections. When I started weighting the new bait I started with one in the head and one in the second section. The fall profile got closest to the original bait when I had all four weights in the same places as the master.

DaveB.

KelpKritter

Share this post


Link to post
Share on other sites

This is just my opinion on this so take it for what it is worth. If you make the resin float just like wood or pvc then the quality of the resin is so broken down that it compromises the bait unless it is wire through. Even then it will be so cut down that it will be brittle. Try the 10% mb and see what you think. I think you will be pretty happy with the results.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0