Re: Spindle motor drive belts MAXNC 10 UPDATE

Jon,
Thanks for the info. As much as I'm waiting for the day I can drop this
mill in the trash, it is just 3-4 months old and reducing the backlash
with ball-screws sound like something I could do.
Do you have a web site link and part number for the items you used to
accomplish this ?

I look forward to seeing the photo's, and I thnk other people will
also....

Hans Wedemeyer



Jon Anderson wrote:

> Hans,
>
> Will have to take some more pics, but I've worked through that one as
> well. First I went to 16 pitch acme screws. Reasoning was that since
> the
> torque curve on a stepper falls off as rpm rises, I could get the same
> traverse rates at a higher developed torque. No, I don't have any
> numbers to back that up, just seat-of-my-pants guessing. It does work
> and I can live with the couple tenths of theoretical resolution I've
> lost.
>
> First try for nuts was to cast nuts into brass sleeves using Moglice,
> a
> castable bearing resin. This worked ok, but over the length I did it
> even the smallest lead variation caused binding.
> Next I bought acme bronze nuts and machined them such that they were
> keyed into a slot machined at either end of the leadscrew holes. One
> nut
> was fixed, the other adjustable. Used Vibratite on the adjusting
> screws
> to hold. Now I could adjust backlash, but lead errors still caused
> problems if I tried to take out all backlash.
>
> Last solution was to pop for self adjusting nuts. I used Ball Screws
> and
> Acutators ActiveCam nuts. These thread into 1/4" thick aluminum plates
> that bolt to the saddle outside where the original nuts were. I can
> keep
> backlash around .0005 or so and this has solved the problem with lead
> error since both halves of the nut are so close together.
>
> If I have time I'll take some pics this weekend and post the links.
> Someday I'll do a proper web page detailing my mods....
>
> Jon
>
> btw, a quickie fix for the nuts is 3/8 brass drilled and tapped 1/4-20
> and long enough to stick out from the saddle. Cross slit, deburr, and
> use a shaft collar clamp to squeeze together.
> You would probably have to machine the collar back some to clear the
> slides. This is crude, but unlike the MAX setup, it won't spring open
> and unlike my opposed bronze nuts, you can get a much finer control on
> the backlash adjustment.
>
>
> hansw wrote:
> >
> > From: hansw <hansw@...>
> >
> > Hi Dan,
> > Lots and lots of backlash, new ot of the box it does OK, but soon
> the
> > nuts start to wear and have to be squeezed back together ! more
> > crap...!.... The figure " .000125 resolution" would I expect be
> defended
> > with the numbers. The lead screw ( looks like threaded stock I'd buy
> at
> > my local hardware store ! ) and the 200 step motors running half
> step
> > mode the figures say the "resolution" can do that... but not the
> > "repeatability" They do have an anti-backlash version, or retro-fit
> for
> > $250.-.... I don't have it... and after this fiasco I will not
> bother...
> >
> > IMHO they have the basis for a good product, but need to take
> lessons in
> > customers relations, hiding behind your 90 day warranty has expired
> is
> > no solution for any customer...
> >
> > However I still like the blue aluminum metal work !!!!!!
> >
> > Hans Wedemeyer
> >
> > Dan Mauch wrote:
> >
> > > BTW Maxnc says their system has .000125 resolution. I know this
> isn't
> > > true
> > > becuase they must have a lot of backlash in the leadscrews. How
> much
> > > backlash does your machine have?
> > > Dan
> > > -----Original Message-----
> > > From: hansw <hansw@...>
> > > To: CAD_CAM_EDM_DRO@onelist.com <CAD_CAM_EDM_DRO@onelist.com>
> > > Date: Thursday, November 04, 1999 6:43 PM
> > > Subject: Re: [CAD_CAM_EDM_DRO] Spindle motor drive belts MAXNC 10
> > > UPDATE
> > >
> > >
> > > >From: hansw <hansw@...>
> > > >
> > > >Jon,
> > > >Thanks for the detailed reply. I looked at your picture, it looks
> a
> > > lot
> > > >sturdier than the crap MAXNC puts out.
> > > >The guy had the nerve to tell me " we designed it to be flexible"
> > > ...I
> > > >also notice the carcass of the MAXNC electronics hanging on the
> back
> > > of
> > > >the mill.... I purchased a complete MAXNC -10 because I needed a
> > > mill, I
> > > >did not want to build one....
> > > >What kind of electronics are you using to drive the motors ?
> > > >
> > > >Well I'm in the middle of making a new motor mount. it will be a
> four
> > > >point mount and will allow full adjustment... I'll post the
> results
> > > at
> > > >my web site when I done...
> > > >
> > > >Sure it's a deal, and now that I've re-built over half of it, I
> > > regret
> > > >not doing it from the beginning, the regrets are about $500.-
> worth
> > > of
> > > >motors and electronics and software.. I ordered 70oz-in motors
> and
> > > >realized after a while that they could not be that powerful. My
> > > tests, (
> > > >see my web site how I do it ) tested the so called 70oz-in motors
> at
> > > >42oz-in..... When I asked to see the manufacturers data sheet on
> the
> > > >motor I was told it was not available and I could get a refund...
> > > I'll
> > > >keep the motors as a reminder that I should not be so dumb fat
> and
> > > happy
> > > >with everything that's fed to me in brochures... I'm not flaming
> > > anyone.
> > > >I'm just stating the plain honest facts...
> > > >
> > > >Would I buy a MAXNC again.... Well no... I do learn from my
> > > mistakes...
> > > >would I recommend it to anyone... Well NO...
> > > >
> > > >Jon, I appreciate the help and all the feed back, hope I can
> repay
> > > some
> > > >day...
> > > >
> > > >regards
> > > >Hans Wedemeyer
> > > >
> > > >
> > > >Jon Anderson wrote:
> > > >
> > > >> Hans,
> > > >>
> > > >> First mod I made to my MAX was to toss the spindle motor into
> the
> > > >> spare
> > > >> parts bin. I fitted a Sherline DC motor and control. It's a
> tight
> > > fit
> > > >> betwen the Z stepper motor and the spindle.
> > > >> Here's a link to a pic of mine
> > > >>
> > > >> http://www.prototype-design.com/images/Shermax1.jpg
> > > >>
> > > >> You can see here the adapter I made to use a Sherline spindle
> as
> > > well.
> > > >> If you (or anyone else) is interested in this adapter, I can
> post
> > > the
> > > >> 3D
> > > >> wireframe in DXF format.
> > > >> You can see that I'm only using one bolt on the end plate on
> each
> > > >> stand
> > > >> off, and have no problems with vibration or flex. I think part
> of
> > > your
> > > >> problem is the standoff isn't seating well against the
> sheetmetal
> > > >> case.
> > > >> MAXNC is getting better at spin control. I seriously doubt that
> > > flex
> > > >> was
> > > >> engineered! The whole thing is cost driven more than anything,
> and
> > > >> it's
> > > >> a decent bargin alright, but some mods will go a long way
> towards
> > > >> making
> > > >> it more useful.
> > > >>
> > > >> BTW, you can see in place of the stock motors, I've made thrust
> > > >> plates.
> > > >> There is a custom stub shaft passing through dual ball
> bearings.
> > > >> With a nylock nut for adjustment, I can dial out backlash and
> > > relieve
> > > >> the motor of thrust loads. Note, this does nothing for backlash
> at
> > > the
> > > >> leadscrew nut... The Sherline spindle adapter has a constant
> force
> > > >> spring inside that is attached to the thrust plate. I forget,
> but
> > > >> think
> > > >> it's rated for 7 lbs, and it releives the Z motor of some of
> it's
> > > >> load.
> > > >> Can also post a DXF file of the thrust plates and the stub
> shaft.
> > > >>
> > > >> As for your setup, I would suspect that either the V groove
> angle
> > > is
> > > >> not
> > > >> right on one or both pulleys, or possibly one of the pulleys
> > > V-grooves
> > > >> isn't concentric to the bore. Does the belt vibrate or flutter
> a
> > > lot?
> > > >>
> > > >> Jon
> > > >>
> > > >>
> > >
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