Jump to content
UKandy

Urgent casting resin advice needed!

Recommended Posts

Hello everyone, I'm new here & to lure making, so I hope I don't make too much of a fool of myself!

I would like to ask for some guidance regarding some 7" resin lures that I cast yesterday, these particular ones where going to be a slow sink jerk bait. After speaking with the supplier of the products I needed, he suggested what casting epoxy resin I should be using & told me he already supplys this resin to other lure makers.

I have watched numerous YouTube videos of how to cast resin lures & pretty much followed them to a tee. I calculated the resin needed to create my lure which was 120ml/g total & added 10% 12g fillite (company's branded glass spheres), which by my understanding of the YouTube videos should give me a good buoyant lure.

After the resin lure had cured, I weighed it and it was 106g, I next tested it's buoyancy and it sank like a brick ha ha. I was quite confused by this, so I made another lure but added a 50% 60g fillite mix to the 120ml/g resin mix.

The result seemed good, it floated, however if I added 5g lead it sank slowly, bearing in mind I need to add 2 hooks, split rings and a through wire still, I would already be over, or near too the 5g with the hardware & if I was to make a topwater glide bait for instance it would already be sinking.

I would have thought, with a 50% mix of fillite glass spheres I should be able to add more lead than 5g to get my desired sink rate & swim action?

So can you help me please?

Are different brands of casting resins more or less buoyant than each other? I see on YouTube that a few lure makers use alumilite resin & I'm wondering if there are specific brands I should be using to aid buoyancy.

Does the 5g lead added that sinks the lure sound correct? They are my first so I'm unsure!

And could the fillite glass spheres that I'm adding somehow be different to the microbubbles that I've seen in videos, as in creating better buoyancy?

I really appreciate you guys who read and help me with this.

Thank you, Andy.

 

Link to comment
Share on other sites

You certainly are not making a fool of yourself. Always remember, there are no dumb questions.

You may feel like you have failed with this project so far, but what you don’t realize is that you have amassed a lot of experience AND an enormous amount of physical data that can be put to good use. As long as you haven’t thrown away the castings that you have made so far, together we can calculate what is required regarding the glass beads, to make your lure work for the next attempt.

The only tool that you require to fix all your problems is a gram scale. If you have a gram scale, then we can either do this by PM or do it here on this thread, it is up to you.

It may well be that you need to go for a lighter resin, but regardless, the engineering techniques that I can talk you through are the same. I promise nothing more difficult than add, subtract, multiply and divide, and writing information down for future use.

Dave

Edited by Vodkaman
  • Like 3
Link to comment
Share on other sites

46 minutes ago, Vodkaman said:

You certainly are not making a fool of yourself. Always remember, there are no dumb questions.

You may feel like you have failed with this project so far, but what you don’t realize is that you have amassed a lot of experience AND an enormous amount of physical data that can be put to good use. As long as you haven’t thrown away the castings that you have made so far, together we can calculate what is required regarding the glass beads, to make your lure work for the next attempt.

The only tool that you require to fix all your problems is a gram scale. If you have a gram scale, then we can either do this by PM or do it here on this thread, it is up to you.

It may well be that you need to go for a lighter resin, but regardless, the engineering techniques that I can talk you through are the same. I promise nothing more difficult than add, subtract, multiply and divide, and writing information down for future use.

Dave

Hi Dave,

Firstly thank you for your kind reply, I really appreciate your help & advice.

You are right I do feel like I've slightly failed at this stage, I put so much effort into getting the mould & casting looking correct & thought the next stages would be straight forward after following the guidance from YouTube!

I have kept the 2 lure casts that I made & have further made 4 little resin test casts from some silicone bun cups, I used a 20g resin mix for each test but with differing amounts of fillite, been a 20% mix, 30% mix, 40% mix & 50% mix, the 20% & 30% mixes sank! The 40% & 50% floated & you could easily see the difference in buoyancy between each cast when in the water.

The 40% mix slowly sank after adding 0.62g of lead.

The 50% mix slowly sank after adding 1.5g of lead.

I have a gram scale & I'm looking forward to learning from your advice.

I'm happy for you to help me over PM or on this thread Dave, I'm just happy your here to help out.

Thanks again, massively

Andy.

 

  • Like 1
Link to comment
Share on other sites

Excellent. It seems that you have the right type of mind that can deal with my engineering approach.

Great work with the test pieces, we may be able to use them. BUT it would be much better if you weighed the Fillite rather than measuring volume. But we can deal with both methods.

There is a lot of measuring and recording, so to make things a lot easier, and to possibly help members with similar problems in the future, I am building a spreadsheet which will totally remove all the thinking, but I will back this up with explanations of what is going on.

Like with other 'stuff' that I have done, this will be available to everyone.

I have spent an hour or so on the project, but the vodka is kicking in, so I will need another day or two to complete the exercise.

The reason why weighing the Fillite is better; is for accuracy. Volume includes a lot of air space which corrupts the results.

This is my kind of project, for me this is fun :)

Dave

  • Like 2
Link to comment
Share on other sites

30 minutes ago, Vodkaman said:

Excellent. It seems that you have the right type of mind that can deal with my engineering approach.

Great work with the test pieces, we may be able to use them. BUT it would be much better if you weighed the Fillite rather than measuring volume. But we can deal with both methods.

There is a lot of measuring and recording, so to make things a lot easier, and to possibly help members with similar problems in the future, I am building a spreadsheet which will totally remove all the thinking, but I will back this up with explanations of what is going on.

Like with other 'stuff' that I have done, this will be available to everyone.

I have spent an hour or so on the project, but the vodka is kicking in, so I will need another day or two to complete the exercise.

The reason why weighing the Fillite is better; is for accuracy. Volume includes a lot of air space which corrupts the results.

This is my kind of project, for me this is fun :)

Dave

Brilliant Dave thank you, I will eagerly await the information & spreadsheet, I'm sure it will help others in the future also, so a big thumbs up too you!

Hope you enjoy the rest of your vodka

Andy.

 

  • Haha 1
Link to comment
Share on other sites

Mass gives greater control, but percentage plays a key because you don't pour all the resin mix into the mold. But, I would sooner the spreadsheet determine the percentages.

I have just finished the first draft of the spreadsheet. I am sending it to UKandy to test it out. If it works, I will make it available to all members. I will post here when the testing is complete.

Dave

  • Like 2
Link to comment
Share on other sites

3 hours ago, Anglinarcher said:

Great plan Dave.  I did a graph for Alumilite using Microballons several years ago and I totally agree that mass, not volume is the key.

Hi Anglinarcher,

Can I ask how you've found Alumilite for casting your lures, do you rate it highly?

I would be interested to see your information also.

Also what kind of microballoons & amounts do you add to your casts to get good buoyancy?

Many thanks

Andy.

  • Like 1
Link to comment
Share on other sites

I rate Alumilite very highly for casting lures, I use it exclusively, but the more microballons you add the less "pourable" it becomes.  

I chose to use volume as a quantity because microballons are so light that a small error in mass/weight will make a huge change, while a small error in volume will not.

If I did the graph differently again, I would label the axis differently, but 10cc of microballons and 10cc alumilite is a 100% mix on my graph.  As you can see on the graph, 9.2 cc of microballons and 10 cc Alumilite white give a density of .69,  Water has a density of 1.00.

This should at least get you started.

Revised density graph.JPG

  • Like 2
Link to comment
Share on other sites

Anglinarcher – I agree with a lot of what you have written. A volume measurement in the right measurement vessel (long, narrow and graduated) would give accurate control.

Personally, I think that a gram scale with 1DP (decimal place) is simply not accurate enough. I use a 2DP gram scale capable of measuring up to 500g. This is obviously 10X more accurate than a 1DP scale, and within the realms of accurate measurement of MB fillers.

From a calculation perspective, weight of filler is necessary to calculate the density of the filler content. The volume of dry filler in a measuring vessel is large, but once mixed into the resin, the volume decreases dramatically, this is because the dry volume contains a lot of air between the grains. This air is eliminated during the mix.

It is possible to determine the mix density of the filler and therefore make accurate predictions of a lure’s final outcome.

Two test pieces need to be made; to determine the true density of the pure resin and the true density of the filler. These tests need only be performed once as long as the same materials are always used. A new brand or type of material would require a new test piece.

A third test piece, a pure resin pour of the lure body is required, to enable calculation of the body’s volume. Again, only one test is required for a particular mold. The reason for this is that for larger bodies, the ‘Archimedes Dunk Test’ is not possible due to the capacity of the gram scale, even a 500g scale could not cope with the weight of water required to submerge a large body. But, knowing the weight and the density of a resin body, the volume can be calculated accurately (g/cm³).

Volume of filler is fine for a trial and error build of a resin/filler lure. But, as in this case, you will likely be disappointed with the sink rate of the lure, and it is going to take many pours until you find something remotely acceptable.

The aim of my spreadsheet is to get you to exactly where you want to be regarding sink rate without the need for half a dozen or more prototypes, simply by adjusting numbers on a spreadsheet, simply by adjusting filler weight and ballast weight until the required buoyancy number is what you desire.

This is what the spreadsheet currently looks like. It looks complex, but the user only uses the yellow boxes, the rest is automatic.

Dave

743460671_turesinspreadsheet.thumb.JPG.3a1f085a9dce4201ba163e675ec49cf9.JPG

Edited by Vodkaman
  • Like 1
Link to comment
Share on other sites

13 hours ago, Anglinarcher said:

I rate Alumilite very highly for casting lures, I use it exclusively, but the more microballons you add the less "pourable" it becomes.  

I chose to use volume as a quantity because microballons are so light that a small error in mass/weight will make a huge change, while a small error in volume will not.

If I did the graph differently again, I would label the axis differently, but 10cc of microballons and 10cc alumilite is a 100% mix on my graph.  As you can see on the graph, 9.2 cc of microballons and 10 cc Alumilite white give a density of .69,  Water has a density of 1.00.

This should at least get you started.

Revised density graph.JPG

Thanks for the information it's really helpful, the graph is very interesting, I'm going to do some testing over the weekend using Dave's spreadsheet to work out what's going on with the products I am curently using.

I think the way forward is Alumilite & proper glass bubbles though, the supplier of my products has told me their resin & fillite product ate more dense than Alumilite & glass bubbles.

I think by what Dave has suggested this can make a huge difference from the start!

Andy.

  • Like 1
Link to comment
Share on other sites

Dave, could you measure the weight per volume of the filler material by adding it to a more viscous liquid in a graduated beaker.  A before and after weight should tell you the weight of the filler added, and the change in the level of the test liquid should tell you the volume of the filler after the air around it is removed.  I think you could do it with a small amount of one of the resin's components.  But, then again, what do I know.  Hahaha

  • Like 2
Link to comment
Share on other sites

Mark - Yes that would work. BUT, the problem is in the inaccuracy of reading off a volume. You would be lucky to get within 1cc of the correct volume.

By my method, I can calculate the filler volume to 0.01cc, 100x more accurate.

Good thought, but it is a question of accuracy.

Dave

  • Like 2
Link to comment
Share on other sites

Dave, I still think you are overthinking this for a beginners level.  Most 2DP scales need to be calibrated for each use as well so make sure you have a certified mass.

I do use a graduated tube for volume that I obtained from a Laboratory supply house.  The good ones will measure well below 1/10 cc and now that the can of worms has been opened, the larger the samples you use the smaller the errors.

Large volumes, or large masses make small errors less meaningful.  In other words, when testing, make sure you are using larger amounts.  How large you ask?  Well I was once told to test 5 structural bolts to confirm the lot was sufficiently strong, but the bolts were custom made and only two bolts were made for that application.  Obviously I could not test 5 bolts because I only had 2, and testing 2 left nothing for the application.  In short, use your best common sense.

Now, for my level of experience, and with my equipment, I would actually like your spread sheet for my own use.

  • Like 2
Link to comment
Share on other sites

Anglinarcher - AndyUK may well be a beginner when it comes to lure building, but he is certainly not new to engineering, and fully understands what I am talking about, otherwise I would not have embarked on this tedious and time consuming project. The idea is that I take care of the complexities of the many calculations, leaving the builder with a few measurements to make and a couple of numbers to play with.

My 2DP scale is repeatable, and that is the most important factor, and yes, I have a certified 500g mass. I also have a250ml class-A HERMA graduated measuring cylinder, and with 1cc being less than 1mm I will be calling BS on your claim of 1/10cc. I stick by my claim that the best you can hope for is an accuracy of 1cc and add to that a tolerance of =/+ 0.5cc.

Yes, the larger the sample the better the accuracy, we should always use the largest sample possible.

The reason I went down to 2DP for my gram scale was that when I was experimenting with neutral buoyancy several years ago, I found that 1DP was right on the edge for a 1DP scale. We are looking for an accuracy of 1/200th of the volume of the lure to even getting close to the accuracy required, and as you know, there are tolerances with each measurement made; resin, filler, internal hardware, external hardware, ballast. If you are lucky then the tolerances will balance each other out, but that does not always happen. And then, you have top coats to deal with. For larger lures, even a 500g scale is useless for doing water displacement measurements.

I am sure you will enjoy playing with the spreadsheet, and I will send you a copy once the beta testing is done.

Dave

  • Like 2
Link to comment
Share on other sites

7 hours ago, Vodkaman said:

The testing of the ‘Lure Resin and Filler Calculator’ is completed. I am VERY grateful for the time, materials and effort that member ‘AndyUK’ put in on this project.

 

Anyone who would like to test out the spreadsheet tool, simply PM me with your email address.

 

Dave

1855529264_TUresincalc.thumb.JPG.fd192ed7d6168e2589bf307ac413f3a0.JPG

It's been a pleasure working on this project with you Dave, can't thank you enough for your time, knowledge & hard work.

I hope many others benefit from your spreadsheet.

Cheers buddy, Andy.

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...


×
×
  • Create New...
Top