Tramming With Kurt Swivel Base

J

john_c_kennedy

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I need to tram my Bridgeport but to get the Kurt vise off I have to separate the vise from the swivel base 'cause I can't lift them together. I got the vise off ok but then saw that nice circular ring on the swivel base and thought Humm can I tram using that as a reference? So I tried it and it seemed to work OK. Anyone else have any thoughts or criticisms about this method?
John
 
Welcome to hobby-machinist!

You can tram the vise or tram the table, or both. It sounds like you were taking the vise off to tram the head to the table. You can use the ring on the vise, but now you are tramming the vise base, and not the table or the vise jaws. It depends on what you are trying to accomplish. There are possible addtitional errors whenever you use something on one part as a surrogate to measure something else. Whether that is enough to matter is up to you, but be aware of it. For a first time check I would tram the table side to side, and front to back, then tram the vise ring, and then tram the vise jaws and bed, looking for inconsistencies. Anything you find that is odd or off should require further investigation. A milling machine is a whole lot of parts all working together to produce results. They all need to be correct for the machine to be correct. Ideally...

Make sure all the axes of the machine are locked down when you tram it!
 
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Thanks for your reply. I trammed the table about a week ago but when making a part yesterday I noticed it was out of tram, don't know what happened. So I took the vise off the swivel base and checked the tram using the ring on the swivel base it was dead nuts on in X but out in Y. So I guess I didn't tighten the ram adapter bolts enough? I trammed it in Y again and torqued the ram adapter to spec. I replaced the vise and recut the part and all was well. I just thought tramming with the swivel base was a lot easier than moving my dial indicator around the table T slots.
 
If you set your dial indicator up so it is barely engaged with the table, by only a few thousandths, no more, and have a rounded nose tip on it, you can run it right over the table slots with no worries. Gently, of course...

Edit: You can also gently lift a dial indicator rod with thumb and forefinger as you swing it across the slots.
 
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I say as long as all of your work is in the vise you are fine. When the time comes to work off the table I would recheck the tram from the table first. The swivel base might be why you appeared to be out of tram.
 
We picked up some large machined rings of good steel that may be a true of bearing race or spacer.

Verified parallel edges and they work well for tramming.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk
 
When tramming my mill, I Put a 6 or 8" 3/8 rod in the collet and snug it down, clamp a 8" 1/4 in rod on the 3/8 rod and put my indicator on the end of the 1/4" rod. I put one of a pair of Jo blocks, maybe .050, under the indicator tip and swing it to the other side. No bumping on the T slots, just hitting on the Jo blocks. That way I get at least 16 inches of swing, 2 1/2 times the span of a 6 inch circle.
 
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