Re: [CAD_CAM_EDM_DRO] Re: Need help to decide what rack and pinion to use in a 6'x10' table

Hector, at this point I actually don't, I'm still building but when I'm done I'll send some pic's for sure. I'll be posting a brag page too :-)

Jarrett

----- Original Message -----
From: Hector <hector_a_quintanilla@...>
Date: Wednesday, April 26, 2006 3:10 pm
Subject: [CAD_CAM_EDM_DRO] Re: Need help to decide what rack and pinion to use in a 6'x10' table

> Jarrett,
> Do you have photos of your setup, i quite interested in taking a
> look at it.
> Regards
> Hector,
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Jarrett & Heidi Johnson
> <hjjohnson@...> wrote:
> >
> > Hector, Make sure you use a strong spring. There
> > is more force there than you'd think. For my
> > system. I'm using a 640 oz-in stepper, it goes
> > through a 10:1 gearhead and the out through a 2"
> > pinion gear to my rack. This gear will put about
> > 400 lb's of force to move my gantry. It will also
> > put about 146lb's force, trying to push the gear
> > out of the rack, so that's enough to need a fairly
> > strong spring.. or a pretty long arm on your
> > spring.. or both.
> >
> > Can I ask you where your located [city/state/town]
> > I'll find you a couple suppliers for rack/pinion
> > stuff nearby. [feel free to send it to me directly
> > instead of on here if you wish.]
> >
> > Jarrett
> >
> >
> > ----- Original Message -----
> > From: "Hector" <hector_a_quintanilla@...>
> > To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> > Sent: Tuesday, April 25, 2006 5:12 PM
> > Subject: [CAD_CAM_EDM_DRO] Re: Need help to decide
> > what rack and pinion to use in a 6'x10' table
> >
> >
> > > Hi Jarrett,
> > > In some posts from cnczone ive seen some mods of
> > > pre-laods, I think
> > > a plain good selected spring will do the trick,
> > > I seem different
> > > ways of acomplishing this, some also recomended
> > > by 'Al the Man' I
> > > tend to go for the 20 PA but it seems I can get
> > > it anywhere online.
> > > 14.5PA is available from lots of source, ex.
> > > mcmaster but 20PA not,
> > > if you know where i can get it from, please send
> > > the link...
> > > Regards,
> > > Hector
> > > --- In CAD_CAM_EDM_DRO@yahoogroups.com, Jarrett
> > > & Heidi Johnson
> > > <hjjohnson@> wrote:
> > >>
> > >> Hector, just a side note. If your running rack
> > >> and
> > >> pinion. I'd recommend using some type of
> > >> pre-load,
> > >> to push the pinion into positive contact w/ the
> > >> gear. I'm using rack and pinion [ well not
> > >> using
> > >> yet as its still getting built] but I'm going
> > >> to
> > >> use two gas shock's per each pinion/drive
> > >> assembly. This will cover for any variation on
> > >> the
> > >> rack mounting, by allowing the pinon to 'float'
> > >> in
> > >> contact w/ the rack. There are forces that are
> > >> trying to push the gear back out of the rack
> > >> when
> > >> its being used and they can be calculated and
> > >> then
> > >> you base your pre-load force on this number.
> > >> I
> > >> still think you should go w/ 20PA. It's been
> > >> recommended to my by others who have 'been
> > >> there
> > >> done that'. Do some Rack/pinion searching on
> > >> cnczone.com and watch for 'Al the Man' as he's
> > >> one
> > >> of those guy's who know's what he's talking
> > >> about
> > >> .. [and no.. thats not me :-). Mind you.. I
> > >> did
> > >> reply to your post on there..]
> > >>
> > >> Jarrett Johnson
> > >>
> > >> ----- Original Message -----
> > >> From: "Hector" <hector_a_quintanilla@>
> > >> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> > >> Sent: Sunday, April 23, 2006 5:34 PM
> > >> Subject: [CAD_CAM_EDM_DRO] Re: Need help to
> > >> decide
> > >> what rack and pinion to use in a 6'x10' table
> > >>
> > >>
> > >> > Hi, folks, thanks for the replyes,
> > >> > Ballendo,
> > >> > I see you mention you are using steppers, in
> > >> > my
> > >> > case i want to use
> > >> > servos.I dont realize if you have to take
> > >> > different aspects into
> > >> > account in the decision of what rack and
> > >> > pinion
> > >> > if your are using
> > >> > seros or steppers. To make it clear does it
> > >> > matter what kind of
> > >> > motors are you using in the rack & pinion
> > >> > decision?
> > >> >
> > >> > --- In CAD_CAM_EDM_DRO@yahoogroups.com,
> > >> > "ballendo" <ballendo@>
> > >> > wrote:
> > >> >>
> > >> >> Hello,
> > >> >>
> > >> >> Snips, inserts below...
> > >> >>
> > >> >> >In CCED, "Hector" <hector_a_quintanilla@>
> > >> >> >wrote:
> > >> >> >Hello,
> > >> >> >Im confused on which combination of rack
> > >> >> >and
> > >> >> >pinion to use for a
> > >> >> >6'x10' table.
> > >> >> >1.- which presure angle (PA) to choose,
> > >> >> >14.5
> > >> >> >PA or 20 PA?
> > >> >>
> > >> >> I have long used and suggested--look in this
> > >> >> group archive for my
> > >> >> many previous posts-- 14.5 Pressure angle,
> > >> >> as
> > >> >> it will minimise
> > >> >> backlash caused by changes in pinion to rack
> > >> >> distance.
> > >> >>
> > >> >> Others have replied that the undercutting of
> > >> >> teeth on small
> > >> > pinions
> > >> >> using this PA is not a good thing, and
> > >> >> mention
> > >> >> that certain
> > >> > machines-
> > >> >> -including Bystronic CNC laser cutters--use
> > >> >> 20PA.
> > >> >>
> > >> >> I still prefer and suggest 14.5 PA. (But
> > >> >> would
> > >> >> use 20PA for
> > >> >> a "lightly loaded" machine, where I might
> > >> >> want
> > >> >> to economise by
> > >> > going
> > >> >> with a smaller rack and DP.)
> > >> >>
> > >> >> >2.- after knowing what pressure angle will
> > >> >> >be
> > >> >> >used, the next step
> > >> >> >is to decide the diametral pitch to use.
> > >> >>
> > >> >> The DP (Diametral Pitch, which is the number
> > >> >> of
> > >> >> teeth in a one
> > >> > inch
> > >> >> gear) affects cogging, strength, and cost. I
> > >> >> use 16DP. Coarser
> > >> > gears
> > >> >> can carry more load, but also are more
> > >> >> susceptible to backlash
> > >> >> (especially is 20PA is used.) Smaller
> > >> >> teeth--larger DP--will have
> > >> >> less ability to endure shop swarf and dust,
> > >> >> and
> > >> >> a lower strength.
> > >> >> They may even cost more. 16DP seems to be a
> > >> >> good compromise for a
> > >> >> 4'x8' or thereabouts size machine...
> > >> >>
> > >> >> >3.- In this step we already know the PA and
> > >> >> >DP
> > >> >> >we are going to
> > >> > use,
> > >> >> >now comes to decide how many teeth on the
> > >> >> >pinion, so what governs
> > >> >> >this decision?
> > >> >>
> > >> >> I nearly always use a 1" pinion. This gives
> > >> >> about 3" of travel per
> > >> >> rev, and is large enough to have reasonable
> > >> >> undercutting of the
> > >> >> teeth in my preferred 16DP.
> > >> >>
> > >> >> What governs this decision is your speed and
> > >> >> resolution
> > >> >> requirements. Larger pinion equals faster
> > >> >> speed, but a lower
> > >> >> resolution, all else being equal.
> > >> >>
> > >> >> I use a 4:1 reduction from motor to pinion,
> > >> >> so
> > >> >> in the old days<G>
> > >> > of
> > >> >> halfstepping, I would get 240IPM at only 300
> > >> >> RPM at the stepper.
> > >> >> This kept the drive cheap, and was plenty
> > >> >> fast.
> > >> >> The resolution was
> > >> >> traded to get speed, as it was only about
> > >> >> .002". (500SPI)
> > >> >>
> > >> >> Using modern drives and motors, you can
> > >> >> easily
> > >> >> exceed these
> > >> > results.
> > >> >>
> > >> >> >I think is better if someone could really
> > >> >> >make
> > >> >> >clear this for me
> > >> >> >and others, i guess other have the same
> > >> >> >doubts.
> > >> >>
> > >> >> Hope I've donethat!<G>
> > >> >>
> > >> >> Ballendo
> > >> >>
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
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> http://groups.yahoo.com/group/jobshophomeshop I consider this to
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> are there, for OT subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING
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