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

No 25 lbs. was as high as my spring scale would go. Like I said 25 LBS force
on the mill head is about all the force that a Sherline would take
without deflection if that amount. I sure that it has significantly higher
axial thrust because pushing with all my might I could not stop the x axis
at full speed.. Again all I said was that I measured the force at 25 Lbs.
then I quit.
Dan
-----Original Message-----
From: Jon Elson <jmelson@...>
To: CAD_CAM_EDM_DRO@yahoogroups.com <CAD_CAM_EDM_DRO@yahoogroups.com>
Date: Monday, March 26, 2001 1:21 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Gecko + Servos + Taig Mill

>
>
>Dan Mauch wrote:
>
>> 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.
>
>You are saying the stall torque is 25 Lbs. force? Hmm, that seems pretty
>light. I designed my servo system on my Bridgeport conversion for 1000

Lbs.

>force. I probably do not get quite that, due to an accumulation of losses

in

>the chain of components, but I'm sure it gets close. I have broken off a

3/8"

>endmill in the collet without even causing a fault. It DID knock the head

out

>of tram, though.
>
>> 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.
>
>Well, I'm sure I suffer many deflections in my machine before I get

anywhere

>near the full stall limit, but it will continue cutting under the heavy

load.

>I think 25 Lbs. Force is just awfully weak, and that you could easily
>bog down on fairly normal cutting jobs. I know from my manual machining
>days that I would often feel those levels of force when doing moderate
>milling cuts.
>
>Jon
>
>
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