Hi I am part of the Dallas Formula Racing Team at the University of Texas at Dallas,
I am part of the composites team and was tasked to do a one piece Front wing element. the mold required to make that part is 60 x 30 x 4 inches is there a machine big enough to make such a part at the Dallas Maker Space if I wanted to manufacture the mold from high density foam? and would I need training to use that machine?
I donât think weâve got anything to do high density foam molding, per se. We might be able to carve it out of a bigger block, but we couldnât mold it.
The MultiCam can definitely handle the X and Y, not sure about the Z. As far as getting qualified, timeframe involved, and allowing the high density foam you would have to ask the MultiCam SIG guys.
Molds do not always have to be made in a single piece, either. This channel has some interesting stuff on mold making, composite forming, and using CNC in several ways to meet the objective, often blending with more old-school âcut-n-sandâ to achieve the necessary shapes, like in this series
Love to see the results, and love even more to hear about how theyâre achieved (failures included!). Good luck!
It was wooden, but another member has made large molds for composite airfoils with the multicam. I wasnât involved but from what I saw they sliced the mold into thinner pieces that the multicam could handle and put dowel pins on the outside to help with alignment.
Yeah I tried that last semester it didnât work really well from an accuracy/ mounting/ bonding perspective due to a small budget so I figured one continuous mold would solve all those problems
You could make your mold in sections, and then fix it together to make one big mold.
At the design envelope youâre requiring, multicam is the only machine that can possibly meet your spec, and even then itâs going to be a trick of developing clever machining strategies to work with the machine. You would need a medium to high level understanding of cnc to develop these strategies and protect the machine from crashing.
Simply put, thereâs not enough space between the head and bed to fit your mold material and a singular bit large enough to cut the entire profile you want.
I know for a fact that several of the top FSAE and FSAE Electric teams develop molds by âslicingâ the file apart for machining and then reassembling it as mentioned above. It takes practice to get this right, alignment and post processing of the mold pieces is delicate but doable.
I also know of a few teams that do one shot molds like what youâre suggesting but they have partnerships with entities like GM or Boeing who give them building size CNCs to cut on.
Happy to chat more if youâd like some suggestions. I donât personally have the time to guide you through developing strategies like I mentioned above. Others might, but I donât know.
The one thing I will say with composites, is to practice it a lot. Youâre going to burn a lot of parts to get it right. Make lots of small things to learn how to do it. Particularly if youâre doing infused and not pre-preg. All of that goes hand in hand with learning how to make the molds the best way possible so that you get the part you ultimately want. Make mistakes and fail fast. Good luck in Michigan (or which ever race you go to.)
Oh and yes you can cut HDF on the multicam. To a limit. But most molds for the size youâre suggesting use 15-20lb foam which will cut fine on the multicam.
See this article from Kitplanes magazine:
The MultiCam SIG is basically a group of dudes who make hardwood furniture for their friends. Youâre asking them to be responsible for you and to understand your goals and to help you achieve them, which very few people are qualified to do. If you mess up badly enough somebody will get hurt, and itâs not like yâall will be attending the same indie furniture trade shows.
The good news is, thereâs a class and a formal checkout, which should be ready soon. In the meantime, you should just stick around here and answer all my annoying questions. Like, what does the mold look like, are any of the elements movable, whatâs your layup schedule, what are the goals for the wing, and how do you plan to test the wing?
Yeah I tried that last semester it didnât work really well from an accuracy/ mounting/ bonding perspective
Do you have any pictures of it?
If the wing profiles are simple 2D curves (not compound curves) you might look into building a CNC hot wire foam cutter. They are popular with R/C aircraft builders.
