Good idea about the core prints Trevor, that would never have occurred to me, but since I've already done it I'll stick with what I've got. Not that it would have been that hard to enlarge them, I suppose.
Been making slow progress over the last couple of months. I have decided to stick broadly with my original plan for doing this, and to that end have taken a fibreglass mold off the upright pattern. That's all stuff I'm used to doing and they have come up well.
I had planned to use modelling clay inside the mold to replicate the wall thickness of the upright but because of the quantities involved in the end decided to make up some "play dough" to use instead. I also thought it may be easier to work with and possibly it was.
The central core shape was done in custom wood as it was easier. This was placed in the mold and the play dough was rolled out to 10mm thickness and placed in the mold in sections and smoothed out with a wet finger. 12mm has also been used in places, mainly around the bearing housings to allow for machining. All fairly easy but, as always, took a bit more than the hour or so that I had thought. What's new about that! LOL.
I was going to pour some resin into the resulting core cavity, but went along with Trevors suggestion of casting plaster (plaster of paris) mainly because of the heat buildup which may have been a problem with that quantity of resin. Also the casting plaster will be easier to work.
I wasn't sure how strong the casting plaster would be, so decided to quickly and roughly reinforce it with some wire, just in case.....Then it was just a matter of mixing up the plaster and pouring it in. So far so good, tidy the resulting plaster castings up a bit and they are the patterns to make the core boxes from.
Before that, a quick trip to the foundry with the cores etc before I make the core boxes, just to make sure I am on the right track. I will also check with them to see if they really want a split pattern as that would save a little bit of work being able to use the existing wooden pattern as suggested by Trevor.
I must say that the amount of work involved in making hollow uprights is quite considerable, and bearing in mind the amount of weight one is saving, like minimal, I can see why Leonmac went with solid uprights. However it is all unsprung weight and it is a race car so we do these stupid things.
It's also aesthetically more pleasing, as well as a bit of a challenge and a learning process. When I've done the core box I'll calculate the weight saving of doing the hollow upright, just out of interest.....Then I'll work out hours per gram saved. Then again, maybe I wont do that last calculation!
Photos are pretty much self explanatory.
Been making slow progress over the last couple of months. I have decided to stick broadly with my original plan for doing this, and to that end have taken a fibreglass mold off the upright pattern. That's all stuff I'm used to doing and they have come up well.
I had planned to use modelling clay inside the mold to replicate the wall thickness of the upright but because of the quantities involved in the end decided to make up some "play dough" to use instead. I also thought it may be easier to work with and possibly it was.
The central core shape was done in custom wood as it was easier. This was placed in the mold and the play dough was rolled out to 10mm thickness and placed in the mold in sections and smoothed out with a wet finger. 12mm has also been used in places, mainly around the bearing housings to allow for machining. All fairly easy but, as always, took a bit more than the hour or so that I had thought. What's new about that! LOL.
I was going to pour some resin into the resulting core cavity, but went along with Trevors suggestion of casting plaster (plaster of paris) mainly because of the heat buildup which may have been a problem with that quantity of resin. Also the casting plaster will be easier to work.
I wasn't sure how strong the casting plaster would be, so decided to quickly and roughly reinforce it with some wire, just in case.....Then it was just a matter of mixing up the plaster and pouring it in. So far so good, tidy the resulting plaster castings up a bit and they are the patterns to make the core boxes from.
Before that, a quick trip to the foundry with the cores etc before I make the core boxes, just to make sure I am on the right track. I will also check with them to see if they really want a split pattern as that would save a little bit of work being able to use the existing wooden pattern as suggested by Trevor.
I must say that the amount of work involved in making hollow uprights is quite considerable, and bearing in mind the amount of weight one is saving, like minimal, I can see why Leonmac went with solid uprights. However it is all unsprung weight and it is a race car so we do these stupid things.
It's also aesthetically more pleasing, as well as a bit of a challenge and a learning process. When I've done the core box I'll calculate the weight saving of doing the hollow upright, just out of interest.....Then I'll work out hours per gram saved. Then again, maybe I wont do that last calculation!
Photos are pretty much self explanatory.
