Re: Taig CNC Mill vs.Homebuilt Machine

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "onealcustom
<onealcustom@a...>" <onealcustom@a...> wrote:

> I have read with great interest many archived and all current
> postings since joining this Group. I am encouraged enough to move
> from the periphery and into the fray and would like to know whether
> there is a compelling reason to buy a mill and modify it for

CAD/CAM

> use rather than assemble one from discrete components attached to a
> welded frame, whether in traditional mill form or gantry.
> I have been leaning towards building as it seems to promise larger
> than "benchtop mill" size and I have several ball screws, linear
> bearings, motors and drivers. I have believed that the use of these
> components is inherently better than leadscrew and dovetail ways in
> obtaining a tighter tolerance and longer life. My specific concern,
> however, is the linear bearing's ability to withstand repeated

stress

> and my ability to construct a frame to proper tolerance.
> On the other hand, the temptation to purchase a CNC ready Taig is
> justified in my research having yet to read a single complaint or
> regret. I could even us it to build a gantry mill as my second
> machine.
> I appreciate this group and have been impressed by its contributors
> namely Les, Tim, Wes and Jan to name a few.
> Sorry Bill, is that flaming?
>
> Thanks for the consideration,
> Bob O'Neal

One thing for sure is that building a machine becomes a lot easier
when you have another machine to make the parts on.

As far as Building verses buying goes I think money wise is may be
a wash, however if you are a good designer and craftsman you are
likely to end up with a better machine more specificly suited for
your purpose.

Linerar bearings have very low resistence to movement but a
low load bearing, best suited where lighter forces are in effect.
Dovetails have a huge varietion of resistance to movement depending
on if they are well ajusted and lubed, cold or warm.
Due to the large contact surface they are well suited for heavy duty
cutting forces.
So which one is better will depend on what you want to build there
is also a gray area where both would be suitable, the question then
is do you want to spend more on linear bearings and get possibly
higher speeds or use bigger motors and go with dovetails.
The best compromise for your design will come down to your skill as
a designer.

If you are comfortable with your abilities and this is going to be
a labor of love then go ahead and build the thing.
On the other hand if you need to know exactly what the machine
is capable off up front and also count the time building it with
your regular hourly wage, Buying it would be the better option.
Good Luck