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D44 Flat Top Knuckle Machining - what's the consensus on the angle

bgaidan

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I have a couple friends that need some knuckles milled. I have everything to do it, but reading up on it it seems like there's a bit of debate on whether to mill the tops flat (90*) and use angled arms or mill them at 80* and use flat arms.

Bolting it straight to the table on the lower ball joint hole makes the top almost perfectly flat. I could just as easily make a jig out of a piece of 6" angle and bolt it to that with the spindle studs and it would be right at a 10* tilt.


Is there a benefit to going one way over the other or is it just a matter of what arms you're going to buy?


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90 degrees. Machining them at an angle cuts too much metal, weakening them (or so I'm told). Whether or not its significant, I can't say for sure. But I know milling the arm at 10 degrees doesn't change the strength of the arm or knuckle.
 
It’s been a long time since I machined some but iirc I compared the drivers side arm bolted completely flat to the table and machined the passenger arm at the same angle.
 
Alright. Sounds like the consensus is "flat", which makes sense to me. In my searches I found a few references to 80 degrees and it made me nervous to mess up someone else's knuckles. They're getting hard enough to find that I don't want to fuck them up and have to source another set. I just need to whip up a quick jig to make them perpendicular to the Y axis and go to town. Already got the holes laid out and programmed.
 
Alright. Sounds like the consensus is "flat", which makes sense to me. In my searches I found a few references to 80 degrees and it made me nervous to mess up someone else's knuckles. They're getting hard enough to find that I don't want to fuck them up and have to source another set. I just need to whip up a quick jig to make them perpendicular to the Y axis and go to town. Already got the holes laid out and programmed.

Just bolt the spindle bore face flat to the table, tilt the head to your preferred angle and face them. Way easier to re-align a head than to do a custom jig.
 
Just bolt the spindle bore face flat to the table, tilt the head to your preferred angle and face them. Way easier to re-align a head than to do a custom jig.

That's incredibly hard to do with a rigid ram machine. :flipoff2:
 
Then use a sine plate. It only needs a couple of degrees.

I was asking what the angle needed to be, not how to set it up! :laughing::flipoff2:

There are a bunch of threads on other sites debating if you should tilt them to 10 degrees (along the axis of the arm) or just use an arm that has a 10 degree taper already in it.

It seemed split 50/50, but I tend to agree that flat is the way to go to get the most meat around the threads and keep it simple.


I decked one off the other night. Spotted the holes and then realized I didn't have the 9/16 UNF taps I need. Ordered a set and I'll finish it when they get here. I was half tempted to thread mill it, but it's been a while since I've programmed a TM and I don't want to fuck up someone else's arms dicking around.






I just welded a spindle to a peice of 4" tubing.

:ogre:

If I were tilting them, this is a great idea. If I do more, I still may make a jig to make setup time a little quicker. Manual probing a hole is a bitch, even with the Haimer.
 
I forgot I had a factory GM flat top sitting on my shelf. Threw that on the table and it was pretty much flat relative to the bottom so good enough for me.

Bonus safety points for not putting the cover back on the breaker panel before I started flinging chips. :laughing:


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They turned out great. Metal chips in the electrical panel, seems legit
 
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