Re: Bridgeport retrofit servo questions

YOUR setup very well may be 2:1...mine is 1:1. The reason that they
didn't go direct drive is because you can't do a direct drive on the
Y axis ~ it will hit the knee (no way to do this except in the
front...which is just plain unsafe and ugly)...Also couldn't do it on
the Z unless they had a ballscrew direct drive on the Z.

Plus, belts absorb shock and vibration and add a margin of safety to
the setup.

-Brady

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "cnc_4_me" <cnc4me@g...>
wrote:

>
> Well, now i am confused...I thought bridgeport went to 2-1 pulleys
> with steppers...if they are 1-1 why didn't they just mount motor on
> the end of the screw, with a flex coupling...
>
>
> Wally
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "braidmeister"
> <braidmeister@y...> wrote:
> >
> > The X and Y are running 1:1 right now for sure. The Z I cannot

tell

> > at the moment because the pulley is buried in the head. Most

likely

> > it is 1:1 as well. All of the axes move with authority with the
> stock
> > steppers...this is of course after replacing a bad power

transistor

> > to get the Y working again. Just jogging the axes around doesn't
> > really thrill me...I already have 2 CNCs that actually cut...I

have

> a
> > bad ERS board, so remote data is not happening at the moment.
> >
> > -Brady
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "cnc_4_me" <cnc4me@g...>
> > wrote:
> > >
> > > Brady, can you tell me what the pulley ratio's are for your x,y
> and
> > > especially Z axis is...
> > >
> > > Wally
> > >
> > >
> > >
> > > --- In CAD_CAM_EDM_DRO@yahoogroups.com, Luke1027

<luke1027@p...>

> > > wrote:
> > > > Hello Brady,
> > > >
> > > > I am in the EXACT same Boat with my Boss5.
> > > > I have the EXACT Same Questions.
> > > > I am looking for the EXACT same solution.
> > > > This however is not my "Bread & Butter", just trying to get it
> > > > working without losing steps and add much more memory for

long

> run
> > > > NC CAM programs (3D-Surfaces).
> > > > Can I ask what motors you decided on and where you are

getting

> > them?
> > > > I too am trying to do this without spending too much $$$.
> > > > I can tell by your questions and answers you are FAR more
> > > > knowledgable in doing this retrofit then I have.
> > > > I will be tracking this thread VERY closly ... Please share
> what
> > you
> > > > end up with -- Pros & Cons you may run across on the way.
> > > >
> > > > Luke
> > > >
> > > > "I have no idea how much weight I will be pushing around with
> the
> > > BP.
> > > > I have picked out motors that are economical, similar in

power

> > and
> > > > performance of 'real' servo motors that the expensive
> > > upgrade 'kits'
> > > > use, and generally what I 'think' will get the job done. For
> the
> > > time
> > > > being, I am just looking for a decent combination that will

get

> > me
> > > > 120 IPM rapids and excellent repeatability.
> > > >
> > > > -Brady"
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Luke,
> > > > luke1027@p...
> > > >
> > > > braidmeister wrote:
> > > >
> > > > >OK guys...I've been reading posts on here for the past few
> days
> > > > >regarding servo motors. After replacing a dead power
> transistor
> > in
> > > my
> > > > >BOSS 5 Bridgeport (just got it....Y axis DOA)...and spending
> way
> > > too
> > > > >much time trying to interface to what appears to be a bad

ERS

> > > board
> > > > >(via serial)...I am now heading towards doing a complete
> > retrofit
> > > of
> > > > >the controls using Mach2.
> > > > >
> > > > >I'm on the fence about whether to retain the working

steppers

> > and
> > > use
> > > > >Larken stepper drives ($200 ea....up to 16A/ph) plus some

type

> > of
> > > > >appropriate power supply, Campbells breakout and Mach2. The
> down
> > > side
> > > > >of this may be that the machine doesn't move as fast as the
> BOSS
> > > > >control can move it...but this is based on feedback from
> several
> > > > >Gecko users on a BP. I am not looking to break any speed
> > > > >barriers...but 50 IPM rapids aren't going to cut it. I need
> > > something
> > > > >that can handle running several hours at a time. I saved for

a

> > > while
> > > > >to get the BOSS...now I have to scrape some $ together to do

a

> > > > >conversion...just so I can run the thing. I really don't

want

> to
> > > do a
> > > > >conversion twice (always time for that, right guys??!!)
> > > > >
> > > > >The other choice that I have is to go with servos. The BP is
> > > > >definately well into the servo side of the servo/stepper
> choice
> > > > >threshold. Not partial to Gecko or Rutex as either will do
> > > (actually
> > > > >I am because the Geckos are cheaper). I have read that

several

> > of
> > > you
> > > > >suggest using some of the treadmill-type motors available

from

> > > > >surplus center. There are several DC dual shaft motors there
> > with
> > > > >pros and cons to each. I am curious as to what models would

be

> > > best
> > > > >for a BOSS machine. Here are a few that were mentioned...and

a

> > few
> > > > >more that I picked out: (All listed can be found on this

page:

> > > > >http://www.surpluscenter.com/sort.asp?
> > > > >UID=2005012813411678&catname=electric&keyword=MBDD )
> > > > >
> > > > >1. $30. 10-1573 ~ 5100RPM rear shaft long enough for encoder
> off
> > > of
> > > > >10-1834. Rated at 1.5 HP & 110v. Does this have enough juice
> for
> > > the
> > > > >BP @ 75v? Current not advertised other than 1.4A no load.
> > > > >
> > > > >2. $22. 10-1783/10-1783-A 2.5 HP rating 6750 RPM 18.5A 130v
> int
> > > duty,
> > > > >95v continuous. Back shaft only .25" long. Will have to

extend

> > to
> > > use
> > > > >any type of encoder. I am guessing that this would be a good
> > motor
> > > if
> > > > >run @ 75v/18.5A (within Gecko specs)...only thing I question
> is
> > > the
> > > > >RPM/belt reduction. What ratio do you think is best on the

BP

> > with
> > > > >this motor?
> > > > >
> > > > >3. $80. 10-1906 2.0HP 130v/15A 3210RPM Continuous duty. Has
> good
> > > > >shafts for driving and encoding. Shipping wt 24#s...starting
> to
> > > get
> > > > >heavier. This seems like a good motor...the current rating
> tells
> > > me
> > > > >that it has some cookies and the RPM is half of the previous
> > > > >one...helping to curb insane reduction ratios.
> > > > >
> > > > >4. $90. 10-1723 1.5HP 111v/7.6A 3100RPM 2-4hr rated

continuous

> > > duty.
> > > > >Looks like a good motor as well...but it is a pig. Ship wt @
> 30#
> > > and
> > > > >13" long...not liking that, but rotor inertia makes up for

the

> > > length.
> > > > >
> > > > >What do you think??? I think #3 so far might be a

winner...yes

> > it
> > > is
> > > > >more $ than 1 & 2, but it has a beefy shaft on it, long

enough

> > in
> > > the
> > > > >back for an encoder and the RPM isn't outlandish. I'd like

120

> > IPM
> > > > >rapids and enough torque to mill at conservative speeds.
> > > > >
> > > > >Sorry post is so long...I like to be as detailed as I can.
> > > > >
> > > > >Thanks!!!
> > > > >-Brady
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >
> > > > >Addresses:
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