• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.
  • Guest,  We want to wish You and Your Family a Healthy, Happy Thanksgiving! Click the "X" at the top right corner to remove this notice)
  • PLEASE: Read the FORUM RULES BEFORE registering!

4

Need Help Blueprinting A Part

3
Like what you see?
Click here to donate to this forum and upgrade your account!
10

Izzy

Active Member
Active Member
Joined
Sep 22, 2016
Messages
256
Likes
146
#31
I understand the basics of lost foam casting I was just a little weary of trying it with all the comments against it... if you reckon i did lots research and planning that I could do it right then I might give it a shot! Just got really discouraged from trying is all
 

q20v

H-M Supporter - Premium Member
H-M Supporter-Premium Member
Joined
Dec 12, 2012
Messages
105
Likes
287
#32
Hey izzy,

It isn't my intention to beat a dead horse, so please don't take this that way. I only hope to expand on and hopefully clarify the casting issue.

The reason people are suggesting that DIY casting is a bad idea for this type of part is that without strict control on all manufacturing parameters the likelihood of defects are high (ie porosity, voids, metallurgical, etc). You are correct in that the part may look and function alright, however, if any of these defects are located in areas of high stress (think about the some of the loads subjected to the knuckle) the long term reliability may be compromised. Depending on the location of the defect and stress levels, over time the part may experience a fatigue failure which is very different than failure by a single overload event (like a curb hit or crash). Or, the part may endure light - med duty driving conditions, but a high speed corner with a pothole may fail the part. In industry when there is a demand for a high criticality casting , non-destructive testing (NDT) is employed to detect these defects (surface and sub-surface) to ensure a sound casting has been produced. There are national standards that cover the types and processes of NDT for metal parts based on manufacturing process, material, shape... Yes, auto manufacturers may use aluminum for their knuckles as standard parts, however these may be forgings rather than castings, which will be superior from a metallurgical and mechanical property standpoint to the casting. And if castings are used for these parts, the quality control processes would ensure defective parts are caught before they are installed on the assembly line.

Have you thought about starting with something that from a manufacturing standpoint is a bit easier, but is still performance/automotive related? Adjustable control arms using heim joints and steel tube? Adjustable sway bar links or maybe even a beefier sway bar? Strut mounts w/spherical bearings that allow caster/camber adjustment?

Hope this helps,

Barry
 

Izzy

Active Member
Active Member
Joined
Sep 22, 2016
Messages
256
Likes
146
#33
@q20v I appreciate the response, I deffinetly don't have the sort of equipment for NDT. The auto manufacturers are cheap though they're deffinetly cast parts they don't even so much as clean up the parting line from the 2halves of the mold... I've already done away with all my bushings and my control arms are all chromoly tubing already the point here was to adress the only thing I haven't yet and that's the weight of the oem knuckle. There are options for my car but the parts cars needed to find the parts are hard to come by so I was exploring other options. I think i may be scraping the idea until I come across a parts car with the knuckles I'm looking for.
 

Wreck™Wreck

Active User
H-M Supporter-Premium Member
Joined
Sep 29, 2014
Messages
1,919
Likes
1,463
#34
Do you have a mill that you are planning on making this part in? If so clamp it to the table and put an indicator in the spindle and find the position of every feature in 3 axes from a 0,0,0 reference. this is the poor mans CMM. Having a 3 axis DRO will make this much easier.

As far as removing mold and die marks from components that are not seen when manufacturing consumer products, who would do such a thing? My mother does not care if GM left tool marks on unseen parts of her car if it gets her to the bingo game on time.

I built racecars and components for a long time in the past, weight is important, function is more important, appearance is unimportant unless you are selling them to people that require a shiny part. If on the other hand you are trying to claw your way up in the racing game make the parts so that they are lighter, work and last, most cars have a less then 1 season lifespan in use.
 
Last edited:

Izzy

Active Member
Active Member
Joined
Sep 22, 2016
Messages
256
Likes
146
#35
@Wreckwreck thats some solid info! I deffinetly want to get a 3axis DRO and I do have a mill I'm currently working on getting up and running! And i couldn't agree more with your last statement, I deffinetly over engineered the car to handle alot more than it will ever probably see! Appearance has never been a factor to me just functionality, that being said I would have liked to make this part myself but the time/cost to make this might just be cheaper and take less time to track down a parts car. Maybe someday in the future I'll build this part myself and i appreciate all the help that may one day make it possible but for now I think I'm gonna lay the idea to rest.... Atleast until I'm a little better situated and ready to give it another go!
 

Pappabear

Swarf
Registered Member
Joined
Apr 3, 2016
Messages
3
Likes
1
#36
Assuming 6061, I believe your best option is to use round bar, last time I looked it was available up to 16" diameter. I did not read all replies so apologies if I am repeating what has been said previously.
 

Izzy

Active Member
Active Member
Joined
Sep 22, 2016
Messages
256
Likes
146
#37
No, nobody has recommended round bar, I dunno if it would be any cheaper than the plate stock but I'll give it a try!
 

Desolus

H-M Supporter - Premium Member
H-M Supporter-Premium Member
Joined
Apr 27, 2017
Messages
117
Likes
72
#38
If needed, I don't mind sitting down with you, video chat for instance, and drawing the part in fusion 360. At first glance there's not a terrible ammount of complex geometry here.

I agree that everything should reference the center bore.
 

magu

Active Member
Active Member
Joined
Jun 6, 2014
Messages
75
Likes
37
#39
So I am going to come off as an A$$ here, and I am probably going to get some nasty PMs from the leadership, but oh well.

YOU DON'T KNOW WHAT YOU ARE DOING!

You clearly don't know what goes into the design of these things, you're simply looking to make a part out of a "lighter" material then close your eyes and hope it will be okay. That is stupid and the kind of thing that gets people killed. If you don't care about yourself that's fine, but the part that flies off and hits another driver's car won't stop because he wasn't an idiot, and the rescue workers trying to cut you out won't be magically safe because they didn't redesign their nomex suits with much lighter polyester.

I'm not trying to be a jerk, but I am a mechanical engineer, I have actually designed fabricated knuckles for heavily modified, specialty vehicles before, I know what goes into these things. There is nothing wrong with making new parts (cue the amateurs built the ark, engineers built the titanic thing), but stop and think a bit. There are very knowledgeable people and forums out there who would be glad to help you come up with something, but you have to ask, and more importantly you have to listen.


Correct me if I'm wrong but wouldn't the exact same part in aluminum be lighter simply due to aluminum being lighter than steel? why would I have to measure the volume?
By volume Aluminum is lighter than steel. So is pine, but there is a reason no one makes knuckles out of pine. Strength to weight is a better comparison, and a key difference will include consideration of fatigue.....

@John hasler how does a weldment work? I've never really heard of those...
This statement scares the crap out of me from someone fabricating critical vehicle components.

@q20v I appreciate the response, I deffinetly don't have the sort of equipment for NDT. The auto manufacturers are cheap though they're deffinetly cast parts they don't even so much as clean up the parting line from the 2halves of the mold... I've already done away with all my bushings and my control arms are all chromoly tubing already the point here was to adress the only thing I haven't yet and that's the weight of the oem knuckle. There are options for my car but the parts cars needed to find the parts are hard to come by so I was exploring other options. I think i may be scraping the idea until I come across a parts car with the knuckles I'm looking for.
Casting in large volumes is cheap because over 10 million parts you pay for the cost of the hundred engineers that designed, prototyped, and tested the parts. You also pay for things like x rays and heat treatment. When you say that you are going to cast something and when GM, Toyota, whomever else says it, you are not talking about the same thing!

Also.... "chromoly" steels are great, they are also a PITA to weld, and like to crack when not welded properly. Just something to consider, but control arms becoming control sticks doesn't usually end well.
 

Desolus

H-M Supporter - Premium Member
H-M Supporter-Premium Member
Joined
Apr 27, 2017
Messages
117
Likes
72
#40
So I am going to come off as an A$$ here, and I am probably going to get some nasty PMs from the leadership, but oh well.

YOU DON'T KNOW WHAT YOU ARE DOING!
That was the least assenine comment on this thread by my estimation...
 

4gsr

HM Chief Foreman
Staff member
H-M Supporter-Premium Member
Joined
Aug 8, 2011
Messages
4,414
Likes
2,669
#41
Izzy hasn't responded to this thread since this time last year. I doubt, he tried to do anything on this due to all the response he received earlier.

Thank you for your post on this and let's be a little nicer on what is posted in the future.

Ken
 

EmilioG

Active User
H-M Supporter-Premium Member
Joined
Jul 20, 2014
Messages
970
Likes
342
#42
Maybe get a 3d print of the part that you can then mold for casting? You can have that part scanned and printed. The 3d print can made slightly oversize to account for any grinding and final dimension finishing. All of the knuckles I've seen have been made of cast iron. A steering knuckle needs to last a long time under a lot of stress.
The ears on the knuckle are thin and I would think aluminum would hold up well. Any way you choose to go is going to be rather expensive and labor intensive with very precise machining, like that bearing bore. That's a tight tolerance press fit. Again, not a good choice for aluminum.
Good luck.
 
[6]
5 [7]