Re: [CAD_CAM_EDM_DRO] Re: Gecko + Servos + Taig Mill

One of the big reasons that makes a sherline/taig nice is the .050 pitch
leadscrew. You get enormous mechanical advantage with the stock leadscrews.
On the sherline mill I added a servo motor with 200 CPR encoder and
directly coupled the motor shaft to the leadscrew. I measured the speed of
the table at 72 IPM which is really to fast for a sherline. The reason I say
that is because at 72 IPM the motor was running at 1440 RPM. The Sherline
doesn't use radial bearing in their end plates however the motor that I plan
to add to my products list will have ballbearings on the driven end. With
direct drive I measured the axial force at over 25lbs.
At this force you would have deflection of the Z axis so cutting speeds
would have to obviously be less unless cutting a very soft material.
If there is interest I can take a picture of the sheline with the servo
motor mount setup and email it off line to those interested.
Dan
-----Original Message-----
From: lasernerd@... <lasernerd@...>
To: CAD_CAM_EDM_DRO@yahoogroups.com <CAD_CAM_EDM_DRO@yahoogroups.com>
Date: Sunday, March 25, 2001 7:36 PM
Subject: [CAD_CAM_EDM_DRO] Re: Gecko + Servos + Taig Mill

>Ok. So I need a servo that's rated for about 5-15W (although higher
>couldn't hurt). With a 5000RPM servo I'd need an ~8:1 gear ratio.
>
>Where can I find such a motor on the surplus market? And where would
>I find the gearing? Should I make it myself, or buy one? (I have
>access to a HAAS VF-2 along with a number of lathes including a
>Hardinge HVL, Colchester Master 2500 and Harrison M250.)
>
>I've seen that some servos have brakes on them. Is the necessary?
>Does the Gecko support a brake? I think I'd be using The G320.
>
>Thanks again,
>
>Robin
>
>
>--- In CAD_CAM_EDM_DRO@y..., mariss92705@y... wrote:
>> Hi,
>>
>> Here's how to start, be it steppers or servos:
>>
>> (1) How fast do you want to go (IPM) and how much push (Lbs) do you
>> want at that speed?
>>
>> (2) Calculate the power needed: Watts = ( Lbs X IPM ) / 531
>>
>> Ex: 400 Lbs at 250 IPM = 188 Watts
>>
>> (3) If Watts are:
>>
>> 0 to 200, use a size 23 servomotor
>> 200 to 500, use a size 34 servomotor
>> 500 to 1000, use a size 42 servomotor
>>
>> In the above example, a size 23 motor will do
>>
>> (4) Servomotors usually have to be geared down because they develop
>> power at speeds higher than can be used for direct drive.
>>
>> (5) Calculate the reduction ratio:
>>
>> Motor no-load RPM / ( 1.25 X IPM x TPI ) : 1
>>
>> Ex: 6000 RPM / ( 1.25 x 250 X 5 ) = 3.84 to 1 reduction
>>
>> That should get you started.
>>
>> Mariss
>>
>> --- In CAD_CAM_EDM_DRO@y..., lasernerd@h... wrote:
>> > Hello all,
>> > snip <
>> > So, without further ado, here's my question: How much power
>should
>> I
>> > be looking for in the servos, and where should I be looking? I
>have
>> > some Vexta 125 oz steppers and they seem pretty powerful, but
>I've
>> > heard the Taig likes 200+ oz. How does this transfer to servos?
>> >
>> > I'd like to change the Taig over to ballscrews, so I suppose this
>> > should be included to get a good answer.
>> >
>> > I'll be cutting everything from plastic to stainless steel on the
>> > mill. I'd like decent rapid feed rates (is 100ipm too much to ask
>> > for?).
>> >
>> > Sorry about the simple question. I'm a newbie to all this super-
>> sexy
>> > CNC stuff :)
>> >
>> > Regards,
>> >
>> > Robin
>
>
>Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the

discussion of shop built systems, for CAD, CAM, EDM, and DRO.

>
>Addresses:
>Post message: CAD_CAM_EDM_DRO@yahoogroups.com
>Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
>Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
>List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...
>Moderator: jmelson@... timg@... [Moderator]
>URL to this page: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>bill,
>List Manager
>
>FAQ: http://www.ktmarketing.com/faq.html
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>
>