Hi
I would do it about the same way you did it first, with a few changes.
First, clamp it as high as possible on the vertical part. Get rid of the
cylinder, or if the vise is not clamping properly without, use a thinner
one (say 6-8 mm diameter) placed as close to the upper lip as possible.
Support the horizontal part. Assuming the top of the vise below the
overhanging part is flat and horizontal, make a small block to support
it. Clamping the part would start with pressing it on this block, then
tightening the vise. Make a long clamp to press down on the part over
the block - might need to use two screws on either side of the vise.
Place a bit of Al or Cu wire between the part and the clamp, as at this
length it will bend. Machine the part in several cuts, so that you can
move the clamp and support block so that they don't interfere with the
cutter and its holder.
On 8/4/2021 00:27, John Dammeyer wrote:
That's a good suggestion John F. Thanks. I did do some more playing around
and it's clear the part flexing and the backlash both were at fault especially
with the plunge to the next depth.
And that brings up another issue. One of my pet peeves with electronics
project magazines is they are great at a schematic and either point to point
wired or PC board but very little energy is spent on describing various ways of
mounting or installing in a cabinet. Especially with the concept of Human
Factor Engineering which is the practice of making something easy to use or
even intuitive. Like an ESTOP button is always a red mushroom Not a toggle
switch.
Same goes with work holding. Youtube has tons of videos that show a tiring
sequence of a milling cutter sprayed with coolant making chips for 3 minutes
with 3 commercials interjected, one every minute. But very little on work
holding.
The next part I am making is shown in the attached screen shot rendering. My
raw material is in the second photo. So the question is about work holding and
how or what features of LinuxCNC can be used to make this easier.
I can use my band saw to create the initial width and split it into two L shapes.
But after that I start to have problems, due to lack of experience I think, on how
to firmly hold it and mill the stuff with a 5mm and 6.35mm (1/4") cutter.
Suggestions?
Thanks
John
-----Original Message-----
From: John Figie [mailto:zephyr9...@gmail.com]
Sent: August-03-21 11:59 AM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] Something went wrong.
Speaking of backlash. My tiered old Bridgeport has about 0.002" of backlash
in the ballscrews. So if circular interpolation is used there is a small
bump at each 90 degrees of the circle. But if I make the finish pass first
clockwise and then repeat counter clockwise the imperfections are much
smaller. I know from experience with my first CNC machine that's built that
actually used leadscrews with lots of backlash the clockwise followed by
counter clockwise method was remarkable compared to a single direction
final pass.
John
On Tue, Aug 3, 2021, 10:10 AM jrmitchellj <jrmitche...@gmail.com> wrote:
You might try the run again without the backlash compensation in LCNC to
get a feel of what it is actually doing.
--J. Ray Mitchell Jr.
�I predict future happiness for Americans, if they can prevent the
government from wasting the labors of the people under the pretense of
taking care of them.�
THOMAS JEFFERSON
On Tue, Aug 3, 2021 at 6:24 AM Gene Heskett <ghesk...@shentel.net> wrote:
On Tuesday 03 August 2021 05:31:56 andy pugh wrote:
On Tue, 3 Aug 2021 at 07:58, <marcus.bow...@visible.eclipse.co.uk>
wrote:
I draw all this from my own ballscrew conversion of my own mill,
some 20 years ago. If I was doing it again, I would use two nuts,
with spring tension between the pair
Springs might not be the best way. The common way to tension double
nuts is to (basically) screw them into each other and lock the angular
relationship.
You _can_ get preloaded single nuts, using oversized balls. That only
works if the ball track is the right shape, though, it needs to be a
4-point contact shape.
Which I'd suspect as being subject to rapid initial wear until it was
just a normal screw with about a thou of backlash.
For me, I bought C7 grade which may have 2 thou but in several years has
not gotten significantly worse. Protecting the screw from contaminants
is the most important thing for long life. On my Sheldon, the Z screw, a
1450mm long 25mm C7, got sealed bearings on both ends, a collar to clamp
a bellows to on both ends of both sections, and 2 of the 6 mounting
holes in the nut were drilled all the way thru so air could get from one
side of the nut to the other as the nut moved. The nut gets one pump of
grease a year. Backlash, some of which is in the end bearing, was about
1.9 thou 5 years ago and still is. It has not been uncovered in that
time. I don't have a bellows on the x screw but its channel in the
carriage is sealed top and bottom unless the carriage is clear in.
exposing the screw behind the QCTP boss. No compound since LCNC is
better than mechanical you set by eyeball. Plus it was busted from a
fallover when I bought it. I keep a rag over the slot in that event.
That faint thumping? Me, knocking on wood, no swarf has gotting into it
yet...
Cheers, Gene Heskett
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/gene>
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
