Modding an off road vehicle drive train part

KeithB

Resident Half Fast Machinist
Have a friend who is helping his son build an off road vehicle. They are modifying the drive train and wanted to replace the brown "spider" with the red ones shown in photo #1. The old spider had the OD turned for a grease cup and they wanted to put grease cups on the new spiders. A relatively simple machining job except ... how to line it up accurately and hold it securely.

1. Old spider (top) and new spiders (bottom)
wheelspider1.jpg
I thought about pressing out the studs so I could grab it in a four jaw chuck. That seemed like a lot of trouble with a good chance of screwing something up. OK, rotate the part in the four jaw so the studs were off the jaws - but it didn't look like an adequate grip and I was afraid that I would spring the legs while dialing it in.

My solution was to take a scrap aluminum disk, face it parallel, drill four holes in the right places for the studs, and bolt the spider to the disk. With the disk in the four jaw I simply dialed in the part and turned the OD to match the old spider's dimensions.

One of those jobs that took several hours prepping for about 10 minutes machining. Would have been done quicker but the d**n thing had M10 x 1.25 threads and I didn't have any nuts on hand so a trip across town to our fastener supplier was required.

2. Spider mounted to disk being indicated in using a four jaw chuck.
wheelspider2.jpg

3. Once aligned the OD is turned to size.
wheelspider3.jpg
 
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Ian

Notorious member
High-angle agricultural driveline joint? Almost looks like a giant rag joint.
 

KeithB

Resident Half Fast Machinist
I have no knowledge of what this thing fits to or is officially called. Not an unusual occurrence in my line of work…
 

Paul Gauthier

Active Member
"One of those jobs that took several hours prepping for about 10 minutes machining."

Use to do jobs like that only the pieces I worked on weighed in the area of 10's of tons, we would spend two or three days setting up and a few hours of machining then tear it all down again.
I don't miss those jobs since I retired.
 

Jeff H

NW Ohio
"One of those jobs that took several hours prepping for about 10 minutes machining."

Use to do jobs like that only the pieces I worked on weighed in the area of 10's of tons, we would spend two or three days setting up and a few hours of machining then tear it all down again.
I don't miss those jobs since I retired.

I was thinking it before I read it.

My dad was a tool & die maker and he always said "it's all in the setup." I can't count the times he explained what he had to go through to actually run a machine for five or ten minutes.

Being the ornery cuss that he is, if someone irked him enough in the process of engaging his services, he'd give them the honest answer to "how long do you think it will take to cut this groove, make this hole, etc." of "five minutes." Such an answer was reserved for those who knew how to cut through the fluff and pin a slippery tradesman down - someone who might've been educated in such endeavors and is, therefore, so much smarter than simple tradesmen.

Two hours later they start complaining and he'd remind them that they didn't ASK how long the setup would take, they asked specifically how long ____________ would take.

I'm always amazed when I get to see the resourcefulness of people solving machining problems.
 

Ian

Notorious member
Two days to think about it, two hours to set it up, maybe five minutes machining time to make two, fuve-inch passes just to clean up two, parallel surfaces. It's ALL in the setup. Ever wonder why machinists have at least as many measuring instruments as they do machining instruments (aside from drills, of course)? I don't. Found out right quick you can't do squat without outside mics, hole gauges, bore gauge, depth mic, parallel blocks, height gauge, surface plate, sliding block, thread wires, pin gauge set, two Nogas, mighty mag, test indicator, multiple dial indicators, precision level, and so on. Still need a gauge block set and angle block set, a rotary table, collet block hex and square holder with full set of 5C collets, and a super spacer, and all that just to walk in the shop and blow my nose.

20210613_200011.jpg
 

Bret4207

At the casting bench in the sky. RIP Bret.
Think back to a time when you couldn't buy any of that stuff, and you probably couldn't really make it because it hadn't been thought of yet. Still, amazingly precise machines of all sorts came out of various shops around the world. Of course the set up might have take 10x as long or mare than today, but they got it done. Guys like Pope did things with shims of paper and a wood framed drill!
 

CZ93X62

Official forum enigma
At a very young age, I developed a keen appreciation for machinists and millwrights. I remain in awe of their skill sets as I advance steadily toward decrepitude.
 

Bret4207

At the casting bench in the sky. RIP Bret.
A word on set up time. After my father died and I got out of the Corps, I ran the gunshop. We had a Forster sight jig for drilling and tapping actions for scope mounts. I'd used it 50 times at least without a problem. Guy comes in with a Savage 99 300 and wants it drilled and tapped. I set it up and away I went. Everything was rock solid and I gave him the rifle with all the confidence I'd always had. The next day his father calls me and proceeds into a swearing rant of epic proportion. Long story/short, a small metal chip got lodged between 2 pieces of the jig and threw the whole thing out of line to the point that there wasn't enough adjustment in the scope to compensate. Didn't matter that I found the problem to the guy whose rifle I'd messed up. I fixed it, but anyone taking the mount off would see it was buggered. I still think about that and it's lead me to not have a lot of trust in things mechanical. Check, check, check, re-check a dozen times before you drill/cut/weld/etc.
 
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