Re: Spindle motor drive belts MAXNC 10 UPDATED UPDATE

Jon,
Update on the motor mount....

My new motor mount solves the belt problem... This mount was made
without a mill ( I had no choice )

http://home.swbell.net/hans_w/cnc.htm It runs smooth, even with a
belt that has been twisted and abused...

Yep ! I also noticed the wimpy motors... The new Compumotor 80 ozin
are fine for what I and I got them cheap...

I've seen Dan's circuit boards, and read his article in Nuts and Volts,
it got me started .. I did my own version of the L297/298circuit, as
electronics is my line...

The Compumotor motors I have are 8.4V motors and I modified a computer
PSU it now delivers 18V at 10A and it make these 80 ozin motor run
smooth... At 18V the L297/298 circuit is in current limit. I added my
"Smart Current Monitor" so the motors can't overheat if I forget to turn
off....

All circuit and layouts are published at my web site...

Thanks again for your help...

Hans Wedemeyer



Jon Anderson wrote:

> Hans,
>
> I moved from the wimpy stock steppers to some approx 120 oz/in motors
> and CyberPak drivers. I've only seen one or two ads for Cyberpak. They
> make a nice little driver that retails for about $110, a bit less in
> quantity. They much prefer the OEM market however. These will half
> step,
> and I was happy with the performance, but ran into a lost step
> problem.
> Went to 198 oz/in PacSci motors which ran quieter and cooler, but
> still
> lost steps.
> Then went with Compumotor OEM 650 drivers I got on a close out deal.
> Much much better setup. At 1000 step resolution the motors are very
> quiet and smooth. Power supply is 40 volts at about 8 amps. I have a
> PS
> out of some medical device that I can pull at least 50 volts/10 amps
> out
> of, trying to get that set up now.
> Even getting drivers and motors surplus and cheap, that all cost me
> almost $500. Not to mention the cost of the Sherline spindle and
> motor.
> Good thing my dad's a dealer...<G>
> I think it's a good frame to start with, but I just saw the latest HSM
> and Sherline now sells a CNC ready mill and lathe. Their brackets with
> thrust bearings are exactly what I've done for mine, they just have
> the
> bucks to make a real slick looking casting instead of fabbing from
> plate.
> I was about to go for Dan's drivers when I ran across the Compumotor
> drivers. That's not to knock Dan's stuff in any way whatever, and I'd
> recommend if you are going to really step up that you take a good look
> at what he's got. Hunt around for at least 140 oz/in motors, build a
> PS.
> Ebay the MAX and get a Sherline...
>
> Jon
>
> hansw wrote:
> >
> > 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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> Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the
> discussion of shop built systems in the above catagories.
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