re:defiance vmc wasRe: Re: wrong conversion factor ...

Marcus,

Yep, once you taste the "good stuff", the "regular stuff" just isn't
the same... I'm using a 56k dial-up connection to "read" and to type
this, and I REALLY miss my DSL!

The Defiance is a great little machine! One of their main selling
points is their "high-speed" contouring algorithms and capability. I
would guess this accounts in large part for the price tag. And it's
software based! Which means we can "figure out how..." Hmmm...

Re: the "synthetic" granite: Isn't this a polymer? Light machines
corp makes a similar size machine (as the defiance) and uses
ANOCAST "filled" polymer castings for the machine structure. When I
first heard of this several years back, I investigated... GREAT
STUFF, unfortunately it has a price to match! Since then, I,ve been
lookin' for the hobbiest version (A metal? filled composite), and
have seen some interesting developments, but nothing that
really "fits the bill". Dennis Bohlke and Greg Pettengill at super-
tech have used some aluminum filled urethane in their "kit" routers.

One of the great things about this sort of approach is that you "hold
the bearings/ways in position" and cast the support around them.
Making repeated (after the setup jigs are made) precision machining
unnecessary. And the damping and structural qualities are inherant in
the material!

You are right about how simple the basic structure of a VMC (or CNC
lathe) is compared to a traditional manual machine. But...

There is a romance to the old machines... And "updating" them (giving
them new life) just feels good. And IF you can get a good 'un at a
fair price, seems a nice way to go. But...

It would be nice to see someone (or a group of someones :-)) approach
this CNC thing from a "defiance" sort of direction. Maybe that's what
Gordon AKA smoke has in mind? I've been thinking a lot lately about
using some cheap "import" grade B granite surface plates "bolted"
together as a machine structure. In an L shape, with some linear
bearings also bolted on. 4x24x36 plates are only 130 bucks! Should be
able to get 12x20 XY travels. Of course the plates are FLAT, but not
necessarily parallel or with perpendicular edges... Maybe...

Thanks for your reply.

Ballendo

<snip>Then I got a chance to drive a high end Okuma for a couple of

>months.Boy did I ever get spoiled!
>I now own a cute little Defiance VMC that I picked up from a company
>that went "buns up" a month after they bought it.
>I look at the construction of that little mill, and I think to
>myself: This would be really easy to build!
>It is basically an "L" shaped synthetic granite block with a couple
>of sets of linear guideways bolted on, a simple head that rides up
>and down, and a couple of surface ground hot rolled mild steel
>plates for the saddle and table. It is driven by servomotors and
>ballscrews. It is a HELLUVA little machine!!
>It is rigid, it is dead nuts accurate, and it runs like a bunny all
>day, every day,for me. (I do a lot of prototyping in plastics)
>It weighs only 500 lb and it plugs into the 110 wall socket.
>Travels are 12" in "X", 8" in "Y" , and 9" in "Z". The table is 21"
>x 7"
>Seems to me that this would make a marvellous machine for a hobbyist.
>Problem is, the all dressed version is about sixty grand

<snip>But to make one... probably not all that hard!

>Marcus