Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
Posted by
R Rogers
on 2004-09-15 18:42:28 UTC
Eric,
Watch for them on Ebay. Baldor, Allen bradley and Gould all make a Nema42 servo around 40lb/in and 100 volts. they are usually rated like 40v/k rpm so if the RPM is 2500 they are 100 volt. If you do a search for just DC motors there are alot of them in that range. I heard you can use them for a servo by simply adding an encoder. I'd like to see some of the others on here weigh in on this assessing the practicality of it. 10lb/in = approximately 1 Newtonmeter, some servos have torque ratings in Newtonmeters or N/m. The Fanuc's are rated that way. They must be DC brush type. You dont need an internal brake.
Ron
pondindustrial <pondindustrial@...> wrote:
Ron,
Thanks for the help, considering the retro with no ball-screw
(w/brake) or counterweights, I figured it would take a considerable
amount of servo/stepper power to raise the knee at an acceptable rate.
Do you have a good `economical' source for the 40in/lb servos? As I'm
sure you know, these larger servos can run a small fortune when
buying new!
Thanks, Eric
--- In CAD_CAM_EDM_DRO@yahoogroups.com, R Rogers
wrote:
the weight of the knee there is zero backlash. It would be dangerous
to use a ballscrew because if you ever broke a belt the table would
fall. Ballscrews when pushed against will "feed" themselves unlike an
acme thread which has an inherent binding effect. I'm using a
40lb/in servo @ 100 volts driven by a gecko 320 @ 72 volts with a
2.5:1 belt reduction. As has been stated before you can run large
servos at less voltage sacrificing speed but not torque providing you
are supplying the necessary amps. I dont have any counterweights or
gas springs for assist. That motor and Gecko whips the knee up and
down like it was a feather. I've ran like profile programs that are
approximately 2 hours long and the knee was whipping up and down all
the while. I did that just to test the motor and drive. They stayed
right with it and got slightly warm but were not
difference. And you need a larger motor for Z than X and Y.
machine has a 4" riser). That comes in really handy when doing deep
bores or tall weldments. The quill is limited to 5". I dont know if
you've ran a Bridgeport much but it doesnt take long to get tired of
cranking the knee up and down. Invariably, I'd be working on
something .25 thick and the next job was 12.0" tall. I remarked
after my retrofit was complete and I was jogging the knee up and down
with the keyboard "If it didnt do any more than that I'd be
satisfied" What a relief to not have to crank that chunk of iron up
and down anymore.
it if you have trouble.
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Watch for them on Ebay. Baldor, Allen bradley and Gould all make a Nema42 servo around 40lb/in and 100 volts. they are usually rated like 40v/k rpm so if the RPM is 2500 they are 100 volt. If you do a search for just DC motors there are alot of them in that range. I heard you can use them for a servo by simply adding an encoder. I'd like to see some of the others on here weigh in on this assessing the practicality of it. 10lb/in = approximately 1 Newtonmeter, some servos have torque ratings in Newtonmeters or N/m. The Fanuc's are rated that way. They must be DC brush type. You dont need an internal brake.
Ron
pondindustrial <pondindustrial@...> wrote:
Ron,
Thanks for the help, considering the retro with no ball-screw
(w/brake) or counterweights, I figured it would take a considerable
amount of servo/stepper power to raise the knee at an acceptable rate.
Do you have a good `economical' source for the 40in/lb servos? As I'm
sure you know, these larger servos can run a small fortune when
buying new!
Thanks, Eric
--- In CAD_CAM_EDM_DRO@yahoogroups.com, R Rogers
wrote:
> Hi Eric,ballscrew for the knee. The acme screw is 10:1 reduction and due to
>
> I'm using the knee for Z on my Bridgeport retrofit. You dont need a
the weight of the knee there is zero backlash. It would be dangerous
to use a ballscrew because if you ever broke a belt the table would
fall. Ballscrews when pushed against will "feed" themselves unlike an
acme thread which has an inherent binding effect. I'm using a
40lb/in servo @ 100 volts driven by a gecko 320 @ 72 volts with a
2.5:1 belt reduction. As has been stated before you can run large
servos at less voltage sacrificing speed but not torque providing you
are supplying the necessary amps. I dont have any counterweights or
gas springs for assist. That motor and Gecko whips the knee up and
down like it was a feather. I've ran like profile programs that are
approximately 2 hours long and the knee was whipping up and down all
the while. I did that just to test the motor and drive. They stayed
right with it and got slightly warm but were not
> overheating. Originally the machine had an 1100 oz Slo-syn stepperand it would move it but very slowly.
>do with a quill. So it is a bit slower however, not a huge
> The cons to using the knee? you cannot accelerate as quickly as you
difference. And you need a larger motor for Z than X and Y.
>linear programmable Z travel coupled with the quill its about 19" (my
> Now for the pros: Driving the knee gives you approximately 14" of
machine has a 4" riser). That comes in really handy when doing deep
bores or tall weldments. The quill is limited to 5". I dont know if
you've ran a Bridgeport much but it doesnt take long to get tired of
cranking the knee up and down. Invariably, I'd be working on
something .25 thick and the next job was 12.0" tall. I remarked
after my retrofit was complete and I was jogging the knee up and down
with the keyboard "If it didnt do any more than that I'd be
satisfied" What a relief to not have to crank that chunk of iron up
and down anymore.
>wrote:
> Ron
>
> pondindustrial
> Hi all,torque
>
> I will be retrofitting my Bridgeport mill soon and know that some
> have used the knee for z-axis control. Does anyone here have any
> experience with this method? If so, what should I take into
> consideration if I decide to go this route? The mill has a 9" X 48"
> bed.
>
> Is a counterweight to offset some of the lifting load preferable?
> Did you use the original acme screw/nut, or retro with a ballscrew?
> What would be a reasonably sufficient drive in terms of motor
> and gear reduction?timg@k...
> What are the pros & cons of using the knee opposed to the quill?
>
>
> Thanks, Eric
>
>
>
>
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URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
OFF Topic POSTS: General Machining
If you wish to post on unlimited OT subjects goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if you have trouble.
http://www.metalworking.com/news_servers.html
http://groups.yahoo.com/group/jobshophomeshop I consider this to be a sister site to the CCED group, as many of the same members are there, for OT subjects, that are not allowed on the CCED list.
NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
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---------------------------------
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Discussion Thread
pondindustrial
2004-09-15 13:23:00 UTC
Knee for z-axis control?
Stephen Wille Padnos
2004-09-15 14:30:51 UTC
Re: [CAD_CAM_EDM_DRO] Knee for z-axis control?
R Rogers
2004-09-15 16:12:20 UTC
Re: [CAD_CAM_EDM_DRO] Knee for z-axis control?
Fred Smith
2004-09-15 17:04:51 UTC
Re: Knee for z-axis control?
pondindustrial
2004-09-15 17:39:16 UTC
Re: Knee for z-axis control?
R Rogers
2004-09-15 18:26:44 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
R Rogers
2004-09-15 18:42:28 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
Jon Elson
2004-09-15 19:30:43 UTC
Re: [CAD_CAM_EDM_DRO] Knee for z-axis control?
Jon Elson
2004-09-15 19:36:59 UTC
Re: [CAD_CAM_EDM_DRO] Knee for z-axis control?
Stephen Wille Padnos
2004-09-15 19:58:29 UTC
Re: [CAD_CAM_EDM_DRO] Knee for z-axis control?
Peter Renolds
2004-09-15 20:15:24 UTC
Re: [CAD_CAM_EDM_DRO] Knee for z-axis control?
Peter Renolds
2004-09-15 20:47:19 UTC
Re: [CAD_CAM_EDM_DRO] Knee for z-axis control?
Jon Elson
2004-09-15 22:13:50 UTC
Re: [CAD_CAM_EDM_DRO] Knee for z-axis control?
R Rogers
2004-09-16 07:48:14 UTC
Re: [CAD_CAM_EDM_DRO] Knee for z-axis control?
doug98105
2004-09-16 13:28:03 UTC
Re: Knee for z-axis control?
jlsmith269
2004-09-16 14:28:38 UTC
Re: Knee for z-axis control?
Bob Muse
2004-09-16 14:29:13 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
R Rogers
2004-09-16 15:00:14 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
doug98105
2004-09-16 16:12:39 UTC
Re: Knee for z-axis control?
metlmunchr
2004-09-16 16:33:14 UTC
Re: Knee for z-axis control?
Peter Renolds
2004-09-16 16:35:58 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
Larry Wright
2004-09-16 16:59:50 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
Sven-Åke Larsson
2004-09-17 00:38:57 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
pondindustrial
2004-09-17 09:29:02 UTC
Re: Knee for z-axis control?
Fred Smith
2004-09-17 09:44:33 UTC
Re: Knee for z-axis control?
R Rogers
2004-09-17 11:42:04 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
Fred Smith
2004-09-17 12:43:35 UTC
Re: Knee for z-axis control?
R Rogers
2004-09-17 13:11:29 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
Fred Smith
2004-09-17 14:24:48 UTC
Re: Knee for z-axis control?
R Rogers
2004-09-17 15:03:05 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
Paul
2004-09-17 16:45:37 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
pondindustrial
2004-09-17 17:19:03 UTC
Re: Knee for z-axis control?
Brian
2004-09-17 18:04:00 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
R Rogers
2004-09-17 19:43:11 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
wanliker@a...
2004-09-17 23:29:44 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
pondindustrial
2004-09-17 23:49:49 UTC
Re: Knee for z-axis control?
alenou arakar
2004-09-18 06:43:29 UTC
Re: Re: Knee for z-axis control? 4 holes ? and EDM
jlsmith269
2004-09-19 09:43:39 UTC
Re: Knee for z-axis control?
Fred Smith
2004-09-19 10:36:31 UTC
Re: Knee for z-axis control?
Jon Elson
2004-09-19 13:00:20 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
industrialhobbies
2004-09-21 00:48:03 UTC
Re: Knee for z-axis control?
volitan712003
2004-09-22 17:29:18 UTC
Re: Knee for z-axis control?
turbulatordude
2004-09-22 18:26:12 UTC
Re: Knee for z-axis control? pnuematic actuator
Stephen Wille Padnos
2004-09-22 18:38:07 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control? pnuematic actuator
Jon Elson
2004-09-22 21:34:09 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control? pnuematic actuator
R Rogers
2004-09-23 09:25:11 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
Peter Renolds
2004-09-23 17:43:48 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
R Rogers
2004-09-23 19:25:59 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?
volitan712003
2004-09-23 19:27:38 UTC
Re: Knee for z-axis control?
Peter Renolds
2004-09-24 05:24:01 UTC
Re: [CAD_CAM_EDM_DRO] Re: Knee for z-axis control?