Losing Tram on an EZTrak DXII

[jmorris@mailmds]

We have a 3-Axis DX2 that appears to be in really great shape. The ways show little sign of wear and ball screws are tight. One of the main problems with this machine is that it falls out of Tram very easily. We can get it dialed in to better than .001 on 12" circle but must constantly check and adjust tram. A seasoned maintenance mechanic that I know inspected the machine and confirmed it's excellant condition. He also said that the Bridgeport machines with Z Axis control tend to fall out of tram easily. He says that it is just something that you have to live with. As a self proclamed perfectionist, I find that hard to accept. I am looking for second opinions.

THanks for the help!

[gus]

bridgeports are pretty bad anyway, compared to later heavier machines[My Lagun was last trammed 3 years ago, and is perfect]

If you are taking heavy cuts then maybe you must live with it. If you are just doing regular drilling, 1/2 EM type of work then something is wrong.

Which is going out? You may want to take it apart and check if the surfaces are flat. Someone may have messed with it.

[machintek]

Which way? Left and right, or forward or backwards?

I have noticed on the S2 TRAK machines that even the new ones (back then) that as the vise moved from one side of the knee to the other that the knee would rock. I tightened the gibs and asked the operator to use the knee locks. What I am trying to say is make sure it is the head and not anything below it.

George

[jmorris@mailmds]

Gus,
Thanks for the feedback. We do work the machine pretty hard sometimes. Our largest cutter is a 2.5" shell mill. We try to optimize speed & feed for maximum through put that give a decent finish. It is typically the X-Axis tram that gets knocked out. My maintenance buddy thinks that the extra weight of the Z screw and motor cause the head to be unbalanced and prone to losing tram. Does anyone have suggestions about how to best maintain tram on the X?

[jmorris@mailmds]

Machinetek,
The problem with Tram is always left-right. We rarely need to adjust front-back.
We do routinely lock the knee but rarely the X-Y. Recently we indicated the bed at better than .001 over 30".
Has it also been your experience that BP's have issues with left right tram? Do you have a silver-bullet solution?

Thanks,
Jon

[NC Cams]

If you center the X, tram it and then move the table left or right, you can expet tram to go out. WHyJ?

two things. Clearance int he gibbs and table rock/bow/droop. As you move the talbe left to rright or vice versa, gravity will pull down on the table and take up any gib clearaince. YOUcan MINIMIZE this via carful and dutiful adjustment of the gibbs - we spent nearly 1.5 days messing with ours. Even so, when you move offf center, ANY clearance you have so as to be able to move the thing, gravity droops it and you have loass of tram. The more you move off center, the worse it will get.

Frankly, .001 (total or per side) isn't all that bad if you measure it over 30 inches of table travel.

Take to torquing the head when you tram it. Simply reefing on the nuts/bolts can provide unequal clamping which can warp the machine and lead to wierd tram issues in itself.

In spite of all this, you have to accept the fact taht the machine is a glorified drill press to some extent. It simply isn't rigid enough to do some heavy cutting. A clamped joint is NEVER as tight as a rigid joint. WHen we want to mill a master which needs to be dead nuts on, we first move the table where we want it (centered), lock it in place and then retram.

No matter how well or tight you fixed it from the last tram, it doesn't stay once yo move the table up or down or from side to side - we're talking about trams to withing 0.0005 TOTAL or nearly zero differential from side to side.