2736Re: Tramming Spec?
- Jun 6, 2002Hello,
Stan mentioned something a bit earlier in this thread that I'd like
to endorse. That is, checking the table for flatness before trying to
When I check a new mill/drill, first thing after cleaning and
deburring is to adjust the gibs. Then check the table for flatness
by "traveling" the surface with a DTI in a fixed position in/on the
spindle ("reading" the table). I take readings every 1/2 inch or so
and use graph paper to "map" the table (putting a +1 or -3, or
whatever in each square; using as many squares as necessary to
represent the whole table. Then this topographical representation can
have "contour lines" drawn (by looking for patterns of similar +1,-3,
etc., and connecting the "dots") which can tell you a lot about your
Now as Stan says, when you go to tram the table, you won't be chasing
the depressions inherent in your table.
After tramming, I repeat the process of "mapping" the table, and
store it(the graph paper) in a binder along with other "pertinent"
details about that particular tool, such as the readings gotten when
checking the leadscrews for errors, and the REAL downfeed travel.
This info can be VERY useful when you are trying to make something a
bit more precise than usual. Worth the time spent, IMO.
Hope this helps,
P.S. I also endorse Stans mention of finding ways to do things
without purchasing new tools. Mills can be (and have been) accurately
trammed with a "Z" shaped rod of wire held in the spindle and feeler
--- In mill_drill@y..., Stan Stocker <skstocker@a...> wrote:
> Hi Duncan;
> Glad to be of some help.
> A DTI is fine, in fact, as you can drag the indicator and it's
> point behind the swinging arm and avoid the whole T slot grabbing
> indicator rod hassle, while avoiding a lot of neck twisting to read
> dial. The fact that a DTI doesn't indicate true when the arm
> is changed doesn't matter in this case, you're just characterizing
> range of difference rather than an absolute from a reference point.
> You've noticed by now that the shim thickness doesn't seem to map
> cleanly as some percentage of the indicated reading, so it all comes
> down to a seat of the pants creep up on the target sort of affair
> Most folks who are just tramming a mill the first time haven't got a
> DTI, I usually try not to imply the need for yet another tool when I
> post, it seems everytime you turn around someone is telling you to
> buy another tool when you are getting started with a new machine.
> can start thinking that boats or private aircraft might have been a
> better choice, at least you know your wallet will get emptied by
> Duncan wrote (in HTML - you bad, bad boy! This keeps your messages
> being quotable :-( )
> Thanks for all the info Stan. I used a lever type DTI that will read
> down to 0.0005" but not that great an overall
> distance (0.030"?). Should I use my 1" travel 0.001" reading DI
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