Re: [CAD_CAM_EDM_DRO] Termites, tree, box ways

Hi John H:
Your guess is right on. Box ways are easy to make and easy to measure.
They also have more metal to resist upward forces, so they're a bit stronger
too, but that's not really a practical concern.
They require three gibs instead of one; one side gib and two bottom gibs, so
the machine maker gains some in the machining of the ways but loses it again
in having to make all the other bits.
The only Tree mill I ever worked on was a late 70's kneemill with 2 axis
CNC.
The body of the machine was massive compared to a Bridgeport, but it had a
puny little head on it with a ridiculous Erickson quick change collet setup
that put the tip of the cutter so far out from the spindle bearings that you
couldn't take a reasonable cut without the cutter screaming like a cat in
heat.
Not only that, it had such a small bolt circle to hold the head in
alignment, that you couldn't keep the head square, and if you reefed too
hard on the bolts, they all popped their heads like popcorn.
Needless to say, I was quite underwhelmed by the design.
Later Trees may have been better, But whenever I hear the name mentioned, I
will always remember the poor sod who tried roughing a cavity with it and
didn't realize the head was progressively tipping as he cut.
He was shaking in his boots when he found out and had to tell the boss that
he had just scrapped out a $5,000.00 steel block. (This was a particularly
unforgiving boss)
Cheers

Marcus
-----Original Message-----
From: johnhe <johnhe@...>
To: CAD_CAM_EDM_DRO@yahoogroups.com <CAD_CAM_EDM_DRO@yahoogroups.com>
Date: Wednesday, October 24, 2001 5:04 AM
Subject: [CAD_CAM_EDM_DRO] Termites, tree, box ways

>I took a look at the pictures of the Tree mill, that is one mongo piece of
>iron, any clues as to the weight? Is there any major advantage of box ways
>over dovetails? I saw on the Beaver mill I am looking at they use one
>slightly raised ridge as one the ways on the x axis and then the other is
>much higher. Is this idea to limit the amount of delicate cutting needed
>with dovetail mills? I was thinking perhaps the more substantial raised way
>is used to carry the load and the other is just a guide. Are the designs
>actually based on any physical properties of how they'll behave or is it
>more just how they can be bothered making them?
>
>John H.
>
>> Tree made a few milling machines, somwhat similar to the Bridgeport
>> design. Apparently, from the above info, they also made one a bit bigger
>> than a Bridgeport Series II. Some people feel that a Tree is far

superior

>> to a Bridgeport. I think they may have box ways, not dovetail. I have
>> only seen one or two, and not the bigger ones.
>> Jon