Looking to have a car part cast.

Discussion in 'Request casting service' started by steveu812, Jun 6, 2019.

  1. steveu812

    steveu812 Lead

    I'm looking at making or having someone make - 4 aluminum pieces for a car project I'm working on.
    I have the ability to 3D print the pattern and while building a home furnace is an option for me, I thought if there were someone near me who already has the equipment, that might be a better option.

    I'm located in Warrenton, VA - about 45 miles west of the Wash. DC area. Also close by are Front Royal and Winchester, VA.
    Each piece will fit over a wheel adapter and have straight radial fins.
    The fins will extend out from the center - beyond the brake drum diameter 1/2-3/4" and extend over the drum.

    Thanks!

    Something like this:
    The left picture is to show the profile of the fin only. It doesn't show the band that will fit over the adapter. DrumFan.png
     
  2. oldironfarmer

    oldironfarmer Silver Banner Member

    Those fins look thin. How thick?

    My take is that this would be better fabricated from plate than cast.
     
  3. DavidF

    DavidF Administrator Staff Member Banner Member

    Roadster project going on??
     
  4. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Questions:

    1. What's its function? Supposed to cool the drum?
    2. Is it ornamental and non load bearing?
    3. Can you put some dimensions on your sketch?
    4. Are you willing to do finish machining of close tolerance features?
    5. What are you looking to spend and what is time frame of need?

    Best,
    Kelly
     
  5. Melterskelter

    Melterskelter Silver Banner Member

    Besides thin they look unsupported. If you think about impellers for high volume blowers, they have thin fins, generously filleted with a disc-like base base as well as a hub.

    http://centrifugalfanengineering.blogspot.com/2013/01/basic-design-of-centrifugal-fan.html

    upload_2019-6-6_22-15-54.jpeg

    It could be there is good reason to deviate from proven design. Just sayin...

    Denis
     
  6. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I was thinking the same thing. Load bearing or not, at 100mph it's still 1500+rpm so it will need some structural integrity just to stay together, and it's what...probably 10-12" in diameter. Don't know why I'm asking anyway. I need another project like another hole in my head.....but just thought that's what any interested party would want to know.

    Best,
    Kelly
     
  7. oldironfarmer

    oldironfarmer Silver Banner Member

    In addition, at lowers speeds you can get a lot of vertical vibration you don't get with a balanced fan. Going over a pothole at 35 mph will put a significant downward load on the fins traveling upward at the point the tire hits the far edge of the pothole.
     
  8. steveu812

    steveu812 Lead

    The vehicle is a replica of/tribute to - a non-specific pre-war race car.
    Think something like this: https://retrolegends.nl/stock/alvis-1695-special-speed-20-3l-rhd/
    They are ornamental. The car will mostly be driven below 60mph, maybe up to 75 at a burst. Never raced.
    The more I dig into the era, the more interesting it gets, so the "look" of these pieces is not a major concern - i.e. rough cast fins etc. are fine.
    I have a good wheel balancer and was planning on balancing the fan first, and then the drum/adapter/fan/wheel & tire as an assembly.
    Not knowing the 'limitations' of casting, affixing them to the adapter remains a question I have.
    My drawing is representative of the idea only - so thickness of all surfaces is yet to be determined.
    I suspect there will no doubt be some dressing of the surface at the top of the pour - to the fins and hub area.
    My son has a higher end 3D printer and CAD experience. Plan was to perfect the design of a printed fan, then use that as the mold pattern.
    Again, I'm going for casting tech pre-1940, so looking rough is fine.
    Adapter diameter is approx. 7", thickness 1.5" The drum o.d. 10.75" width 2.25"
    As for budget? I have no clue so by all means please be frank as to what the going rate would be for these.
    Please bear in mind that I have no foundry experience. I
    If it's an option - I have access to scads of soda cans and a set of aluminum wheels for the material.
    I've fabricated many things for this project already. Welding, grinding, cutting shaping etc. are part of that.
    Learning foundry skills interests me so I may delve into it, but weighing the startup costs against the chance or doing stuff beyond this...just thought I'd reach out to this forum.

    Hope that answers some questions, but by all means any feedback is appreciated!

    Thanks.
     
  9. oldironfarmer

    oldironfarmer Silver Banner Member

    How does the band attach to the adapter?
     
  10. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    ...and is it really an adapter or just a spacer? Adapter being a load bearing member that is bolted to the hub with separate studs change bolt center of mounting pattern. If it was just a spacer it could be potentially integral with the fan but wouldn't recommend it if its a load bearing adapter.

    Can you print the with draft and shrink allowance? It won't be useful to sand casters unless you can. I'd say you should figure 1/4" minimum wall and more where machining is needed.

    IMO, it would be more castable and higher integrity part if it the fins attached to a hat like shown by the blue lines below. You would need some generous tolerences for the fins to use as cast. Trying to machine them to closely fit the drum with that interrupted cut would be unrewarding. You could add another surface with the bolt center machined for the studs, like a disc brake rotor hat, so it could just be captured between the wheel and adapter for mounting.

    DrumFan.jpg

    Best,
    Kelly
     
  11. steveu812

    steveu812 Lead

    A lot depends on how tight it would fit.
    In reality, once the wheel is bolted on, the fan is not coming off in one piece.
    May add some set screws spaced at 90 deg.
    Maybe a large o-ring slipped over the adapter between the fan and the wheel. https://www.mcmaster.com/4061t339
    Maybe some RTV or Shoe-Goo* (between the fan and adapter). Balance the assembly before it sets up.

    Just a few ideas - again, a lot depends on how tight it would fit.

    *OK, laugh - but if you've never used it... It's like silicone when applied, significantly harder when dried - but still somewhat flexible - and incredibly durable. Wouldn't use it for a gasket or in an oily application, but stuff is amazing for many things. And you can get it in black.
     
  12. steveu812

    steveu812 Lead

    The machined part is an adapter - it bolts up where the wheel would and then provides a smaller bolt circle for the wheel.

    A thickness of 1/4" would be fine.

    My intent was that the fan blades would attach to the central part here (yellow). The gap between the fin and the drum (remaining blue) is not critical in this application.

    Fins2.png
     
  13. Rocketman

    Rocketman Silver

    I think the best way to mount the piece to the hub is to use the wheel to mount it. Sandwich it between the wheel and the hub.

    You'll end up with a closed cylinder with fins attached. Secure design, mounted solidly. I would not trust setscrews. Compression fit with the rotor/drum might work but with heat cycles & harsh environment it's getting tricky.
    Can you afford an extra 3/16" or ~4mm spacer between your adapter and wheel?
     
  14. Rocketman

    Rocketman Silver

    Something like this. The fins would contour to the drum.
    forumguy hub thing v1.png
     
  15. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    That's what I was describing being captured between the wheel and hub like a brake rotor hat, but as drawn, I think he has another step in there for the fins on the OD of the drum (is that what you meant by contour to the drum?). Does that rendering just mount over the adapter or the adapter and the drum as shown in his post?

    Best,
    Kelly
     
    Last edited: Jun 7, 2019
  16. Rocketman

    Rocketman Silver

    Just a quick model I threw together in Fusion. I intended it to go over his adapter as pictured, It looks like I missed the bit where the fins wrap over the drum.
     
  17. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Well done on the fly. Heck Rocketman, you almost have it whipped. Now you just have to apply actual dimensions to the features, apply draft, fillet, shrink, add some machine stock, make a follower, print it, ram it, pour it….machine it, done! :D

    Steve, you're in luck!

    Best,
    Kelly
     
  18. There's something very similar available for UK made cars like the Mini, "Alloy super fin brake drums":

    MINIFIN.jpg
     
  19. steveu812

    steveu812 Lead

    Wow! This is above and beyond.
    We don't have acceptable internet at home so I've been "disconnected" all weekend until just now.
    I took a couple more picture of the drum and adapter.

    As for the "full hat" with holes for the lugs, I was thinking it would be an easier cast if that were open. Again, I don't really have any idea. I suspect it would certainly be stronger though. And even an extra 3/16 between the adapter and the wheel is fine - or I suppose even between the drum and the adapter maybe? That way the fins could be supported for a longer (and vertical) span between the adapter and the drum...hmmm.

    But yes, the fins extend outward (like sun rays) from the billet adapter, then "spill" over the 2" outer area of the drum - the surface the shoes are contactting - thinking 1/2-3/4".

    20190608_074530 (Small).jpg 20190608_074619 (Small).jpg
     
  20. Rocketman

    Rocketman Silver

    It would probably be easier to cast a full hat, it is going to need machining regardless & that part of it would not be a big deal. Between the drum & adapter would probably be most ideal. That would solve the mounting issue easily
    I'm about 4 hours from Winchester VA. This is a project I could take on, but time is a bit scarce this summer, and I don't think this would be a cheap project between the tooling, casting & machining. It would likely need to be balanced as well to keep things proper. Feel free to PM me if you would like to discuss further.

    -Rocketman
     

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