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Need Help Blueprinting A Part

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Izzy

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#1
Hey guys, I have a few parts from a car project I'm working on and I'd like to recreate old cast iron parts from aluminum to reduce weight, one of the most difficult parts (or atleast most difficult in my eyes) is the steering knuckle and I'm having trouble figuring out how I shoukd go abouts measuring and blueprinting it? Only thing I can think of or see to use as a nice flat refference surface is the front face of the bearing bore.
Any ideas on how I can accurately measure all the different angles, hole placement, and tapper is another thing I'm having troubles measuring any adivce is appreciated! There's a couple pics of the part, I can get more if need be. IMG_20161028_144853.jpg IMG_20161028_144904.jpg
 

rgray

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#2
That will take one large block of aluminum to make. I'm thinking everything should be measured to the bore of the bearing. That might require an insert to put in place of the bearing. Could be built with a shaft attached to it to measure from or have a hole like the bearing and then build a close fitting dummy shaft to insert to measure from.
A lot of the Gm's have aluminum knuckles. Have to wonder if one of those could be fitted.
 

Izzy

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#3
@rgray this is for an older heavily modified Japanese car there are no American cars that will have anything that works for this without me extensively changing the rest of my pre-existing set-up. I didn't even consider how difficult it would be to track down a 1foot cube of aluminum I think I may have to cast my own cube unless someone knows where to get something that size?
I never considered Using the bearing bore to measure from but this deffinetly might solve my problems I'll have to explore this option a little deeper!
 

Izzy

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#4
As far as reference surfaces and blueprinting goes, would it be in my best interest to have a reference surfaces for each axis? Sorry for the noobie question but I'm not overly experienced in this sort of thing
 

4gsr

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#5
You need a minimum of a surface plate, height gage, a precision protractor like a Starrett 356, and maybe a machinist square. In your first picture posted, use the back side as your datum for plane "A". This surface would be against the surface plate. Now the rest of it would be by taking precised measurements, every thing referenced from the surface plate. May require making locating pins to put in the different holes as shown. This is not an easy task to perform for someone that doesn't have good equipment to work with. Ideal would be to find some one with a CMM that could record coordinates for all of the points/planes on the part. There are companies out there that do this kind of stuff every day, even for automotive parts. Ken
 

RJSakowski

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#6
@rgray I didn't even consider how difficult it would be to track down a 1foot cube of aluminum I think I may have to cast my own cube unless someone knows where to get something that size?
I wouldn't try to cast my own block of aluminum for a part that's critical to personal safety. A home foundry does not lend itself to proper control of all the parameters required for good metallurgy. You're looking at casting a 170 lb. block in a single continuous pour.
 

4gsr

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#7
With what RJ said, I strongly do not believe that is a cast iron part. More than likely, it is cast steel and is heat treated to a degree of hardness. I don't believe 7075 would give you the strength needed for that part, even if it was forged to that shape. There's a reason it's made from steel.
 

John Hasler

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#9
How about a functionally equivalent weldment? Also, you might want to make your replacement much beefier anywhere that there's room for more material: it doesn't have to look exactly like the part it's replacing.
 

Izzy

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#10
@4gsr ive got those tools I've just never done anything this complex I've done alot more blueprint reading than I have making my own but I'd much rather do it myself and learn something in the process and maybe even expand my tooling that part itself is cast iron same stuff they would use for the block. What it's made out of doesn't really matter tho I would just like to remake it in aluminum there are aluminum automotive knuckles so I know it can be done I was planning on having a steel sleeve splined and pressed into the aluminum knuckle for the bearing.
I deffinetly plan on making it beefier but still have to keep the holes in the same place and on the same angle
I wouldn't have thought 12" cube of aluminum would be that heavy! What are my opyions with that if any?
 

Izzy

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#11
I should add my crucible is big enough to melt down an entire 4cylinder head, I could do some calculations to see if my crucible would hold that amount if you guys think it might be worth a shot?
Some of the aluminum knuckles I've seen are one hell of alot thinner than this part and hold up just fine but I'm open to ideas!
 

John Hasler

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#12
@4gsr ive got those tools I've just never done anything this complex I've done alot more blueprint reading than I have making my own but I'd much rather do it myself and learn something in the process and maybe even expand my tooling that part itself is cast iron same stuff they would use for the block. What it's made out of doesn't really matter tho I would just like to remake it in aluminum there are aluminum automotive knuckles so I know it can be done I was planning on having a steel sleeve splined and pressed into the aluminum knuckle for the bearing.
I deffinetly plan on making it beefier but still have to keep the holes in the same place and on the same angle
I wouldn't have thought 12" cube of aluminum would be that heavy! What are my opyions with that if any?
Don't cast a cube. Cast a rough shape (but plan on machining away all the as-cast surfaces). You don't have to attempt a thinwall casting to cut down a lot on volume.
 

Izzy

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#13
I was only saying a cube cuz each part is roughly 12x12x6 but I've never casted parts only melted metal for scrapping purposes lol I do know the basics of green sand casting tho and a simple cube would be easy was my thinking...
 

Billh50

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#14
I would use the bearing bore for center and the longer lug for for alignment in one axis. Then take all the dimension I could. It would be nice and easy to turn in different direction as needed if you made a fixture to hold the part. The fixture could be made of wood if it was easier. The fixture can be laid flat or clamped to an angle iron to get dimensions.
As far as casting a block, I would consider lost foam casting to make a part just slightly oversize of the part itself.
 

Izzy

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#15
I completely forgot about foam casting! That's not a bad idea at all. I still think it would be cool to machine this from a solid block of aluminum just to be able to say this part used to be a solid block of aluminum :p
 

rgray

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#16
I don't think a cast aluminum part is going to be strong enough.
I attempted to look up the GM aluminum steering knuckle and was surprised to find dorman replacements in cast iron with this advertising: Dorman-improved to address weakness in the original aluminum construction.
I've bought a few Pontiacs and impalas that were totaled out from a hit that broke the aluminum steering knuckle.
The effort required to do this may not be worth the reward.
 

Izzy

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#17
For sure the aluminum knuckles will break if you crash them but then again that's only an issue if you get into an accident. the knuckle breaking in that situation might not even be bad thing though as forces from the crash will be taken up by the broken part rather than transmitting that force to the driver. this is a dedicated track car so I just want to get my unsprung weight down and there are plenty of cast aluminum knuckled vehicles that hold up just fine, I'd rather a solid block over cast but I'm willing to explore my options. Please don't take this the wrong way I'm not trying to be rude in anyway but I'm not asking if its safe to do or not I'm just asking how to go abouts making the part...
 

rgray

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#18
I recently bought a wreaked 2012 impala. Wheel torn loose on passengers side. at first glance I thought "another broke aluminum knuckle" .. Was surprised to see the aluminum knuckle and caliper all fine. Steel lower control arm broken in half. Direction of impact has a lot to do with it. Most of the broken knuckles were side impacts.

One of the biggest challenges to make that out of a block of aluminum would be to really think through the steps. There may be machining that could be done in one setup that shouldn't be done because it will be a clamping or reference surface for a later operation.
Bore of the bearing being 90 degrees to the caliper mount is probably your most critical set up. Most other surfaces can be adjusted for on the car. You may even want to change the angle of the lower ball joint attachment hole depending on the ride height of the car. I've seen plenty of cam style strut bolts to make adjustment possible, or just having the hole elongated so camber can be set (usually elongated the hole in the strut). I don't think it will be as difficult as it first appears.
 

Izzy

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#19
@rgray that was my thinking and why I decided to farm out the question, process of operation here is going to be critical!
I have camber adjustment through my coilovers, my lower strut mount and my control arms. ride height is different from stock but angle of arms are pretty close to the same as my coilovers allow completely independent adjustment of ride height, spring load, camber, caster, compression and rebound also I've got extended monoball pins instead of ball joints so that's not really an issue. What I did want to do is move the little arm for the tierod attachment down and flip the taper upsidedown this is another thing that's going to be critical as the angle that arm is on is crucial to the vehicles cornering ability due to Ackerman's principal.
My first hurdle however is where do I get something 12x12x6 is that even available?
 

JimDawson

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#20
Neglecting any safety issues since this is only going to be used on the race track, I might try a bit different approach.

First weigh the part, then calculate the volume by putting it in a bucket of water. Mark the high water mark and, remove the part and add water to the high water mark using a graduated measuring device (measuring cup). Now you have the weight and volume. Then figure out how much material you would have to remove to get the weight down to the same equivalent volume in aluminum.

In many parts you can remove a lot of material that is not needed in the un-stressed areas by drilling holes and making pockets to form I-beam sections in the stressed areas.

To make this part from scratch from a solid block is not something I would want to do without a CNC, even then it would require a few setups and fixtures. A 4 axis machine would be best.

If you had a 3-axis DRO on your mill, you could use a touch probe to generate a point cloud and plug that into a 3-D cad program to generate the part. Other than that, I'm going the have to agree with @4gsr that you will need some precision measuring tools.

Unless you are equipped to do high pressure aluminum casting, I would not even attempt to make that part that way. Sand cast aluminum is too porous to make a part with the strength needed. Carving it out of a block of 7075 would be a long process, but possible, even on a manual machine.
 

JimDawson

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#21
My first hurdle however is where do I get something 12x12x6 is that even available?
It's available somewhere, I would start with the local metal vendors. Local to me, Coast Aluminum shows 6 inch thick plate listed in 6061-T6. But again, I would want 7075 for that application.
 

Izzy

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#22
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?
Essentially that's what I wanted to do is just get all the coordinates, plan the process of operation and make chips! I have all the tools I need to measure this I just wasnt sure how to go about measuring it all.
As far as safety goes I honestly don't think I'll have an issue like I said before there are plenty of cast aluminum knuckled vehicles that hold up just fine and the fact that they could break in an crash could be somewhat advantageous in the sense less force is transmitted to the driver in the event of an accident, they wont fall apart on their own and in the event of an accident something has to break doesn't it?
I deffinetly leaning more towards the solid block route I don't really want to cast this part but I'm willing to try if that's my only option but I know it's not :p I don't have a DRO but I could just 0 my hand wheels and mark the table and it should all work out the same right? I know this is a big project but time isn't a factor and I honestly just like challenging myself and keeping myself busy I like to learn in anyway I can! :D
 
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JimDawson

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#23
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?
What I am suggesting is to remove enough material from the steel one to bring it down to the weight of the aluminum one. You need the volume to be able to calculate the weight in aluminum. I guess you could just do it mathematically also.

I don't have a DRO but I could just 0 my hand wheels and mark the table and it should all work out the same right?
Probably close enough.

For the feature and hole location, pick a point and measure from there. I would probably start with the bearing hole and the mill table as my 0,0,0 point and plot the X, Y, Z coordinates from there.

For the tapers, use the mating part to measure the rise over the run, a little trig will give you the angle. You can use the same technique to measure the angles on the part.

A cheap touch probe would be a real help here.
 

Izzy

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#24
Aahhh ok I understand what you where saying now, that's a good option too I'll have to see how much I can take off.
measuring the male part didn't even cross my mind but that's a simple solution thank you! maybe I'm just over thinking this I feel blonde right now XD
 

Izzy

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#25
Welp time to scrap this idea unless anyone knows where to get cheaper material got quoted 600 for a 6x12x12 block of 7075...
 

John Hasler

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#26
Welp time to scrap this idea unless anyone knows where to get cheaper material got quoted 600 for a 6x12x12 block of 7075...
I still think you should consider a weldment. You'd machine the parts, send them out to be welded, and then machine the weldment to final dimensions. Would require a lot more design work, of course.
 

John Hasler

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#28
@John hasler how does a weldment work? I've never really heard of those...
A weldment is just a thing made by a welder. The idea is to design and make a set of parts out of plate, bar, tubing, etc that can be welded up into something that you can then machine to exact dimensions. This would get you away from the need for a humongous block of metal.
 

davidh

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#30
as you said you have the capacity, to melt aluminum, i would do a lost foam casting. careful thinking could give you a great part to start with. . . . . . . do your research on lost foam. it may surprise you.
 
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