[noobCNC]

I know its customary to tram the mill before milling. But with high cutting forces in all axis directions, and some loose parts of the machine, wouldnt you lose tram after a while, even during a run? So isnt tramming a little bit futile?

I havent done any 'precision' machining yet, so I just make sure my mill is relatively well trammed. But I've seen people tramming their mill by say tapping on the spindle or hammering some parts and then look back at their indicator to ensure 'perfect tram' to within the resolution of the indicator and go "wah la... perfecto!", is it a bit futile? I guess as long as the maching turns out to be within acceptable tolerances its the best you can do?

[fizzissist]

Wow. If you lose tram while milling, you didn't tighten things down properly, or you need to lose that mill.

Like da man says... "set it and forget it"

[LUCKY13]

As long as you dont crash, or try using the machine over its ability you should be good. Of course some of these machines are a bit weak and cutting with high forces could cause some need to retram. But normally they will hold.


Jess

[691175002]

As has been said, you shouldn't need to tram before milling. It is not customary to tram before machining. Its a one-time setup operation.

If you are losing tram due to normal machining something is seriously, seriously wrong.

[DMF_TomB]

losing tram is not normal with normal milling operations
.
but at
50 sfpm
1" diameter, 2" sticking out, 1" shank, 2 flute end mill
milling 304 SS
193 rpm
max Depth of cut 0.409"
max Feed 1.9 ipm
estimated hp = 1.94
end force at mill tip 855 lbs
torque 428 in lbs
.
so basically end mill is hammering at 386 beats per min at 855 lbs
......... slow speeds can produce enormous forces. but if you run at higher rpm's with small diameter end mills you will not normally see high forces

[DareBee]

losing tram is not normal with normal milling operations
.
but at
50 sfpm
1" diameter, 2" sticking out, 1" shank, 2 flute end mill
milling 304 SS
193 rpm
max Depth of cut 0.409"
max Feed 1.9 ipm
estimated hp = 1.94
end force at mill tip 855 lbs
torque 428 in lbs
.
so basically end mill is hammering at 386 beats per min at 855 lbs
......... slow speeds can produce enormous forces. but if you run at higher rpm's with small diameter end mills you will not normally see high forces

As was already mentioned above ^ This type of machining would only be done in a large heavy machine. Tram is not an issue.

Anybody running a tool room mill or less is gambling heavily on serious machine breakage and is going to lose in short order.

That scenario is like pulling your yacht through the Adirondacks with a Chevette.

[DMF_TomB]

how tram can be lost

1) mill heavy enough that part moves in the vise and as it moves a higher and higher depth of cut happens

2) 1/2" or bigger end mill snaps / breaks

i'll admit it has happened to me. i even had a foreman tell me he could see the mill was out of tram from 10 feet away and it was well over 2 degrees. so now i check tram immediately if i break an end mill. i also check tram before any critical job.

why?? because of course as you extend a quill that is out of tram you are drifting in a x and or y direction at the same time. higher tolerances recommend raising or lowering the knee rather than extending the drill quill.

[noobCNC]

Not that I was speaking from experience or anyting. I never usually tram my mill before every job because I havent done any 'precision machining'. I mean it seems possible for some machine to lose tram over time. Then again I agree, perhaps if tram is lost after milling when everything was setup properly then the job was a little too aggressive for the machine.

But even tramming a machine doesnt create perfection either, since there is equal and opposite reaction forces, so any sort of cutting will cause deflection of the mill/cutters and material stock to some degree so its never perfect anyway.