Re: Re: Engraving and engine turning

-----Original Message-----
From: Bertho Boman <boman@...>
To: CAD_CAM_EDM_DRO@onelist.com <CAD_CAM_EDM_DRO@onelist.com>
Date: Saturday, July 31, 1999 7:25 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Engraving and engine turning

>From: Bertho Boman <boman@...>

Bertho
If you have backlash on the quill, and it is not preloaded, when taking a
deep or heavy cut, the action of the cutter will take over and pull the
cutter into the job by the amount of backlash that you have, not very good
if you want a nice flat surface, hence the preload to keep the cutter up,
and the quill pulled against the pinion and worm drive.

Peter Smith

>
>There are fancy "constant force" springs available but the simple/ crude

solution is to use rather long springs. That way the

>percent elongation is not large and the force is rather constant. With the

spring system there will not be any significant mass

>added to accelerate and deaccelerate. I realize that this might not be

important in some systems but it is always interesting

>to compare options.
>
>It also surprised me a little that you are using it as a method of

pre-load. I thought the idea of weights and pulleys or

>springs is to reduce the load on the motor and make the load similar in

both directions. Thereafter the system's PID constants

>can be optimized and will be optimum moving both up and down.
>
>Bertho Boman
>========================================
>
>Peter Smith wrote: <peter@...>
>
>> Ian/Peter
>> I have been using the wire rope, pulleys, and weights ploy, for a couple

of

>> years on my mill, it started as a quick fix to the backlash problem, but

I

>> must admit it works very well, maintaining a constant load on the quill,
>> instead of as with a spring the further the quill goes down the tighter

the

>> spring gets the greater the load on the motor, but my god it does look

ugly.

>> The countrbalance is about 3lbs heavier than the quill, but as the Z

stepper

>> is at a ratio of 20 / 1 it does'nt seem to mind the preload.
>> I might get around to doing one of Dans permanent fixes, but I

suspect

>> that the quality of the rack and pinion on my far eastern mill might not
>> allow such a proper cure. ( why upset something thats working ok)
>
>
>--------------------------- ONElist Sponsor ----------------------------
>
>Having difficulty getting "in synch" with list members?
>http://www.onelist.com
>Try ONElist's Shared Calendar to organize events, meetings and more!
>
>------------------------------------------------------------------------
>Welcome to CAD_CAM_EDM_DRO@...,an unmodulated list for the

discussion of shop built systems in the above catagories.

>To Unsubscribe, read archives, change to or from digest.
>Go to: http://www.onelist.com/isregistered.cgi
>Log on, and you will go to Member Center, and you can make changes there.
>bill,
>List Manager
>