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tramming mill with brake rotor (practical machinist advertising)

I don't understand the Bookface interface and I'm annoyed by public facing entities that choose to exclusively push content there, Instagram or Twitter. I refuse to participate on any of them. Maybe that kind of content appeals to the audience drawn to it? We're just too old to understand?
 
Was he actually using the rotor to tram the Bridgeport (i.e., is the video description correct)? Seems more like the guy in the video would have been leveling the rotor to machine it (possibly drill some stylish spiral pattern holes of dubious utility).

Note: If this was supposed to be a joke video, I don't get it lol. Looking at the comments, seems there are many others who also don't get it
 
You guys don't think that a factory-new brake rotor is straight enough for tramming a Bridgeport head? It's fresh out of grinding. I'd be disappointed if that wasn't flat and parallel within a half or better.

If I wanted to absolutely tram out any error in the vise, I'd probably do similar: stack up a few parallels, brake rotor on top. What's the alternative?
 
I have seen more than a few use brake rotors to tram a Bridgeport. New rotors for some import cars are not expensive. And both sides are turned and ground at the same time so they are flat and parallel to each other.
 
To tram the head, I put a precision granite square on the table, a dial test indicator in the quill, and run the quill up and down. I do not rotate the spindle and test against a "flat" surface.
First I've heard of this method and I'm going to begin using it. Thank you for sharing.
 
If I wanted to absolutely tram out any error in the vise, I'd probably do similar: stack up a few parallels, brake rotor on top. What's the alternative?
I do not tram to a table top, vise or ring. Always thought this silly.
I tram to the X&Y way motions. The actual moving axis that do the work.
Yes this means a lot of handle cranking but now you are true to the actual cuts being made.
No way I am trusting a table top. Lessons learned here over the years and many B-ports.
Then of course is still the knee which never runs square to the above X/Y.
Bob
 
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I appreciate what you guys are saying but, perhaps you missed what I posted: I want the parallels to be trammed to the spindle. We've got stack-up of whatever machine geometry there is, plus a vise, possibly a swivel base under it (we're talking knee mills here). At the end, I'm worried about doing something dead square to a bottom datum.

Since a number of us were over in the motorcycle thread, I had engine cases that needed Time Serts at the cylinder bases. Picture here:


The engine cases were attached to pieces of bandsawn 2x12 lumber that was clamped in a Kurt. Nothing else in the universe mattered except the spindle being dead square to the gasket surface. Even after all the effort, the 10" tall cylinder studs were not perfect when the barrels and heads went on.

I could see many setups where you have interrupted surfaces and need to pick up 3-4 contact points and would like something that could allow you to sweep at the quadrants and align it. With what I have right now, the best I'd have on hand would be 1/4" thick ground parallels (and trusting they're flat). That setup was a PITA. I kept running out of travels in one direction or another and had to start over, rechecking each step.
 
I appreciate what you guys are saying but, perhaps you missed what I posted: I want the parallels to be trammed to the spindle.
No. just no. Or maybe not.
Given enough oh-shits you will wonder the whys.
I do surely understand where you are standing and the logic. Most of the time this works.
In the end what ever works for your part runs is great.
 
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I have had good results using a large 8" diameter outer race from a discarded bearing. The faces are accurately ground. An Indicol with a DTI and the job is quite quick and as accurate as the machine itself is. Once the left and right X are the same the two Y readings should then equal the X. Knowing that helps get it so that the needle is quiet on the full 360.

Denis
 
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I do not tram to a table top, vise or ring. Always thought this silly.
I tram to the X&Y way motions. The actual moving axis that do the work.
Yes this means a lot of handle cranking but now you are true to the actual cuts being made.
No way I am trusting a table top. Lessons learned here over the years and many B-ports.
Then of course is still the knee which never runs square to the above X/Y.
Bob
i'm with Bob here, if i saw anyone doing this kinda shit in my shop, they'd be lucky not have anything flying at them on their way out the door.
but my topic was also just about the awful quality of practical machinist posts on social media, this being one of the examples.
 
Large pins are good enough to be used as squares on a surface plate ........I have a big collection from various motors ..........they are useful as spacers on milling arbors too.
 
where do you guys get large wrist pins (one or two, new)? i tried for quite a while and gave up.
 








 
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