Re: [CAD_CAM_EDM_DRO] Re: not stiff enough!

A 1/16" router bit generates negligible side load. This is about the size that people are using with much less rigid setups than
yours.
It sounds like you have either slop in your bearings or backlash. A 1/16" cutter isn't causing a 1-1/4" Bar to flex here.
Also, if flexing is your problem then you should be able to cut in any of the 4 corners of your setup and get good results. In
other words your machine will be much stiffer if you operate the router near the supports. If this doesn't fix your problem look
for the other stuff I mentioned. Backlash can come from either clearance between the screw and the nut or the screw itself having
lash in the axial thrust direction. If you are using linear bearings then you should have some provision to tighen those up too.
From the picture of your machine you should not have the trouble you described with a 1/16" cutter.


richard@... wrote:

> I'm machining wood.
>
> For instance, put a 1/16" bit on the trim router I'm using, and
> program it to make a 3/16" round hole. The hole isn't much bigger
> than the bit. This is in 1/4" hardboard.
>
> Or, cut small squares with the same bit, the sides will be odd shapes
> because of side loading from the bit.
>
> Used a 3/4" bit in an attempt to find what the machine thinks is the
> zero plane. Was getting up to 1/8" movement in the bit do to side
> loading. Went to a 1/4" bit, worked much better, but still noticable
> ridges in a nice spiral patern, again caused by side loading on the
> bit.
>
> I did notice that a low value for acceleration helps let the
> bit "settle" when making cuts...
>
> Maybe I'll try real light cuts, say 1/16", and see how it responds..
> Certainly have more time than money.
>
> Thanks.
> --- In CAD_CAM_EDM_DRO@egroups.com, Joe Vicars <jvicars@c...> wrote:
> > Rich,
> > Take lighter cuts. Your machine looks much better than alot of
> the "kits" available right now. I think you're just taking too
> > heavy of a cut. You can also experiment with cutters. Different
> cutters will produce significantly greater side loading than
> > others.
> > I guess you should be specific about how much flex is too
> much. You are machining wood right?
> >
> > Richard Spelling wrote:
> >
> > > I built this cncrouter:
> > > http://www.spellingbusiness.com/robot.jpg
> > >
> > > X is 1 1/4" shafts, 60".
> > > Y is 1" shafts, ~40"
> > > Z is 1/2" shafts, 18"
> > >
> > > The problem I'm having is that it's not very stiff. I realized
> there would
> > > be some flex in the unsupported shafting when I built it, but I
> didn't
> > > realize it would be as bad as it is.
> > >
> > > I have 3/4" for Z, which would take care of some of the stiffness
> problem,
> > > but I can grab the top of the top of Z and move it by hand and
> the 1" shafts
> > > will flex visibly.
> > >
> > > My current back to the drawing board effort focuses around theses
> items:
> > >
> > > 1) use the 3/4" shafting for Z
> > > 2) move the Y shafts further appart to reduce leverage
> > > 3) possibly rotate Y shafts 90 degress to bring the "top" one to
> the same
> > > level as the bottom one
> > > 4) use the 1 1/4" shafting for Y
> > > 5) use the 1" shafting for X, drill and tap holes for support
> posts
> > >
> > > and maybe
> > > 6) use open bearings an ALL shafts, attach "angle iron" steel
> supports and
> > > cross bracing.
> > >
> > > comments and suggestions requested!
> > >
> > > Richard Spelling, http://www.spellingbusiness.com/boats
> > > >From the muddy waters of Oklahoma
> > >
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