12 replies to this topic
Posted 07 June 2007 - 08:55 PM
I searched in the tutorials for the answer to this but came up with nil. I want to copy a crank using foam. My question is, do you mold it with the lip still attached to the original or do you remove or sand the lip off and just cut a slot in the copied bait and glue a lip in later.
Posted 08 June 2007 - 12:49 AM
These are just my thoughts on the subject, as I have not successfully molded foam as yet, but still working on it.
If you leave the lip on, the resulting foam lip will not be strong enough to take the battering of a rocky retrieve.
If you mold the slot, my humble opinion is that you will have problems retrieving the cast without destroying the mold (my big problem).
The best solution is to cut the slot after casting.
My plan is to shape or flare the body out to the lip and mold it all in one piece. Whether the result will be strong enough to take the rocks remains to be seen. Has anyone tried this method?
Posted 08 June 2007 - 06:12 AM
Never thought of making the lip out of foam but that's an interesting idea. I was thinking about inserting a pre-cut lip ( lexan) into the mold and then pour the foam. Since I never tried foam before I don't know if the foam will stick to the lexan or if I need to epoxy it in later.
Posted 08 June 2007 - 06:23 AM
I generally make the mold with the lip slot. If the lip slot is cut correct in the master this makes it about the best. Only trick is that the foam iif removed at the wrong time may continue to expand and result in a lip slot that isn't exactly strait anymore (not a big deal to correct and easier than cutting each one). I haven't had any lips fall out yet with just slapping them in with devcon. I have some molds that I didn't put the lip slots in because I can cut the slots easily at slightly different angles and use different lips.
Posted 08 June 2007 - 07:55 AM
Bassn1, Welcome to Hard Baits.
Copy? What type of bait do you want to copy?
Posted 08 June 2007 - 12:17 PM
How much further expansion have you noticed? How long are you keeping the castings in the mold? I thought I was losing it when some of my castings were 3/16 wider than my model and that was being cast into Rigid Bondo molds.
Posted 08 June 2007 - 12:50 PM
I like your baits alot.....good work on the lips and paint!
Posted 08 June 2007 - 04:00 PM
Thanks for the compliments guys. I think I have observed about the same amount of expansion at times. It is dependent upon temperature and mix ratios however. Exapansion and cure time I find dependent upon how accurate I am with my scientific method of using a couple of spoons. With RTV molds I don't worry about set time as much they demold so easily. With the bondo I pull them early becasue I have a tendency for baits to get locked in if I don't. I usually just go by how the "mushroom head" has set. I like a little flex in the shaft connecting the mushroom head and body of the bait typically. Typically I mix in a paper cup and fill three to four molds and clamp together. I then get a new paper cup mix some more foam and do three to four others and usually the first set is ready to demold at this point. I will pay more attention to actual time next time.
Posted 08 June 2007 - 10:05 PM
I'm trying a Bagley B2 with a foil finish. It has a paint scheme that's no longer in production. A friend of mine wanted me to try to foil and repaint some other cranks with the same paint style but I thought I'd go for it and just try and replicate the whole thing.
Posted 11 June 2007 - 08:59 PM
I think my problem is that I was using casting plaster as I already had a 10Kg bag in the workshop. I tried all kinds of release agents, the result was always the same, I needed a hammer to get the foam body out. This is soul destroying.
I think I'll try the rtv next, when I get organised.
I find that the expansion is considerably more than the double quoted on the bottle and seems to be related to how thoroughly I mix it. What diameter do you make your vent hole? Mine blocked and I ended up with an inch of flash all round.
When I finally lick this foam s$%t, I'll have to post an article on how not to do it, should give everyone a laugh.
Posted 11 June 2007 - 09:17 PM
I used vasoline for a release agent when using rigid mold materials. I also demold these as soon as possible. I forgot a few times and left several in for around 20 minutes and destroyed the molds to remove them. I have saved a few by using a butter knife and depressing into the thickest portion of the crank along the mold seam line and Plaster of Paris it out. Then I fill the dent with wood puddy, bondo, or excess devcon from gluing in lips. As long as undercuts are minimized the lure doesn't get locked into place as bad. For vents I usually just use a piece of cut drinking straw to mold for the main vent and then just cut shallow grooves in problematic portions. As far as expansion I find temperature and proper measurement to be the two main variables.