buggy
Hi Gene,
I tend to approach this in the same order, more or less as if I was
machining metal on a 3 axis mill - write out the dimensions, get the
block, and hack it about. If your background is more along the lines of
3d printing, I guess it would be more from the point of view of
extruding shapes.
Anyway, I've stuck some code below, and drilled a couple of bolt holes
for you. Unfortunately openscad does not exactly follow the machining
sequence, unless you put every operation in a module, but you will get
the hang of it. You should be able to change the values, and it will
work OK, but if you want bigger(or smaller) fixing bolts, you may want
to position them differently. (combined fixing and clamping bolts).
bd=20; // od of ball bearing race
pt = 14; //thickness of plummer block
ph =45; // pb height
pw = 30; // plummer block width
cg = 0.5; // compression gap
$fn=100;
module bearingblock(){
difference(){
// make block - laid flat
cube([pw,ph,pt],true);
// make bore and slot longer where possible (multiply by 2 will do)
// you would do that if machining it, too - gives a cleaner edge
// bore for bearing
translate([0,0,-pt]) cylinder(pt2,d1=bd,d2=bd);
// slot it
cube ([cg,ph2,pt*2],true);
}
}
// put it wherever you want.
translate([50,50,40])rotate([90,0,0])bearingblock();
// thought I'd add the holes for clamping bolts
bolt = 6; // clamp bolt diameter
module drilledblock(){
rotate([0,-90,0]){ // turn it flat again having put it on the
edge - below...
difference(){
//turn on edge, to make easy to drill the holes
rotate([0,90,0])bearingblock();
// # to help in seeing where to position holes
# translate([0, bd/2+bolt,-pw]) cylinder(h=pw2,d=bolt);
# translate([0, -bd/2-bolt,-pw]) cylinder(h=pw2,d=bolt);
}
}
}
translate([100,50,40])rotate([90,0,90])drilledblock();
On 01/04/2021 07:30, Gene Heskett wrote:
On Thursday 01 April 2021 02:27:00 Gene Heskett wrote:
I am DITW, and its 2:30 AM my time, bedtime I believe.
Thanks all.
Cheers, Gene Heskett
On Thursday 01 April 2021 02:45:44 Michael Marx wrote:
BTW, if you have trouble with a difference()'d item use #
e.g. your cylinder() without the rotate()
#cylinder(h=2.1,d=bb,center=true, $fn=60);
Never saw that in the tuts.
Anyway, that has been fixed. Now if the printer would Just Work. I just
sent dremel a fix it or refund my $1800 msg.
Thanks Michael.
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
On Thursday 01 April 2021 02:46:22 Bob Carter wrote:
Add a rotate to the cylinder kit to get it facing the right way
rotate([90,0,0]) cylinder(h=2,d=bb,center=true, $fn=60);
A better way would be to generate the same object as a 2D flat cross
section (use square and circle then use rotate_extrude to generate the
bearing holder
I wondered about that, plus the lack of a buffer to store the difference
output so it didn't have to be recalculated for every degree around a
circle. Or is there such and I didn't read the tuts well enough?
The tuts don't encourage mixing 2d and 3d, so since I'm brite green at
OpenSCAD I didn't. :)
But next I need to find a printer that works, I have wasted a month,
$2000, and two rolls of plastic trying to make the best dremel 3d45
work. I'm done. No support other than worthless boilerplate from them.
Cheers Bob
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
On Thursday 01 April 2021 08:16:26 Ray West wrote:
Hi Gene,
I tend to approach this in the same order, more or less as if I was
machining metal on a 3 axis mill - write out the dimensions, get the
block, and hack it about. If your background is more along the lines
of 3d printing, I guess it would be more from the point of view of
extruding shapes.
Anyway, I've stuck some code below, and drilled a couple of bolt holes
for you. Unfortunately openscad does not exactly follow the machining
sequence, unless you put every operation in a module, but you will get
the hang of it. You should be able to change the values, and it will
work OK, but if you want bigger(or smaller) fixing bolts, you may want
to position them differently. (combined fixing and clamping bolts).
I'll look at it, but I've got the final assembly pretty much in mind
already. And I changed the printer in the middle of the night, can't
get usable stuff out of a dremel 3d45 for my $1900, it goes nicely
laying the brim, but turns the next layer into very bulky snow that the
catches on the nozzle and gets ripped off the glass and welded to the
nozzle the next time it comes by. No support from dremel.
So I swapped a modified Ender 3 onto the work table, and resliced the
code for it, and its doing a perfect render at about 82% done right now.
Just one problem, I have played with the steps/mm settings as it did not
come calibrated OOTB. Unpacked and built, the flow setting was so light
you could read the paper thru the sample waving cat, so that had to be
upped from about 80/mm to about 350 before I started getting solid
prints. xy was preset to 80/mm but that gave slightly smaller parts, so
I'll have to measure this and figure out what it will take to get an ID
of 119.5 on the next print. Then the balls groove might need adjusted
once I stuff it full to see how it fits.
Thats all done now, and the next print s/b usable.
This all goes on the outside of the moving spline gear of a 30/1 harmonic
drive to be used as a 4th axis on one of my milling machines. But the
flexure of the cup in a harmonic drive has limited its life time as the
plastic breaks at the base of the cup in less than 24 hours run time.
I can attach pix of what I'm doing if the list allows it, sometimes its
true about a pix is better than 1000+ words.
Some backstory here if interested.
So just for S&G, we changed the drive design to use a prebroken cup in
the form of a plastic belt, teeth on the outside running inside a
matching tooth count spline with internal teeth, so the flex of the belt
to make it eliptical is in only one direction, something a PETG belt can
do for a long time as that flexure is well under 5% out of round. The
belt is running inside to two rings, one anchored stationary, the other
becomes the output shaft and has 2 more teeth. so a 60 tooth belt,
nominally 19mm wide, running inside two 9.5mm thick splines, turns one
relative to the other, 2 teeth per revolution of the input shaft which
drives an arm with twin ball bearings on the end of its 2 arms as it
rotates inside the belt pushing it out of round just enough to fully
engage the splines. With the sizes right, the pullin of the sides of the
elipse is just enough the spline tips clear each of enough to hop over
the splines and gives the drives gear reduction. There's some youtube
videos from a "samco" if you want to see his 100/1 version.
With suitable grease, crisco comes to mind, it should make an excellent
rotary drive for a poor mans hobby machine shops use (thats me), and if
the belt does break just print a new one for 2 bucks. Beats hell out of
$2k to $10k for a new one carved out of steel, and which has the same
failure mode given long useage.
Not to mention that a cylinder($fn=3) generates the ideal tooth shape for
a very linear response and at zero backlash if made precisely enough, as
a normal involute tooth shape is all wrong for such a eccentric motion.
Thats whats in some of the leg joints of the boston dynamics Big Dog you
can see videos of on u-tube.
For those of you interested inconverting old human driven lathes and
milling machines to cnc, there is a new motor driver tech just now
coming to market that makes a stepper motor into a servo by putting an
encoder on the back of the motor, and the motor is a 3 phase driven new
design that turns 1.2 degrees for a full step, and uses the error
between where its supposed to be, compared to where it is, to modulate
the motor currents applied. So the motors are much more efficient in
terms of the power use. I put 2 of them and my 11x54 Sheldon Lathe thats
close to my age and wear, replacing normal steppers that ran burn your
hand hot, with smaller motors that run 5 degrees above ambient. Now
instead of vibrating tools off the machine onto the floor and making
music with the whine of the steppers, it now moves like Casper the
Ghost.
And draws power with teeny sips. And I'm doing it with a Raspberry pi 4b
for a computer.
Why a pi? Just to see if I could. And I've succeeded well beyond my
dreams.
This lathe is now able to do many things it could not do when new, many
times faster than a human operator could turning the cranks that have
been replaced by jog dials at .0001" graduations, or gcode files I have
written.
I'll finish, for this post, by thanking those that have made me feel
welcome, and have also donated openscad code for my project, teaching me
more in 30 minutes than I've learned in 2 months looking at the manual.
And if I get long winded, I'm now alone as my wife of 31 years passed
from COPD early last December, so I've no one to "talk" to. I may only
have a GED, but I am also a C.E.T., and a retired tv Chief Engineer that
has a looong histoy of BTDT's in case I can be helpfull by contributing
some of that back to what is obviously a thriving community of OpenSCAD
users.
Thank you all.
Take care, and stay well everyone.
bd=20; // od of ball bearing race
pt = 14; //thickness of plummer block
ph =45; // pb height
pw = 30; // plummer block width
cg = 0.5; // compression gap
$fn=100;
module bearingblock(){
difference(){
// make block - laid flat
cube([pw,ph,pt],true);
// make bore and slot longer where possible (multiply by 2
will do) // you would do that if machining it, too - gives a cleaner
edge // bore for bearing
translate([0,0,-pt]) cylinder(pt2,d1=bd,d2=bd);
// slot it
cube ([cg,ph2,pt*2],true);
}
}
// put it wherever you want.
translate([50,50,40])rotate([90,0,0])bearingblock();
// thought I'd add the holes for clamping bolts
bolt = 6; // clamp bolt diameter
module drilledblock(){
rotate([0,-90,0]){ // turn it flat again having put it on the
edge - below...
difference(){
//turn on edge, to make easy to drill the holes
rotate([0,90,0])bearingblock();
// # to help in seeing where to position holes
# translate([0, bd/2+bolt,-pw]) cylinder(h=pw2,d=bolt);
# translate([0, -bd/2-bolt,-pw]) cylinder(h=pw2,d=bolt);
}
}
}
translate([100,50,40])rotate([90,0,90])drilledblock();
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
On Friday 02 April 2021 12:07:51 Gene Heskett wrote:
On Thursday 01 April 2021 08:16:26 Ray West wrote:
Hi Gene,
I tend to approach this in the same order, more or less as if I was
machining metal on a 3 axis mill - write out the dimensions, get the
block, and hack it about. If your background is more along the lines
of 3d printing, I guess it would be more from the point of view of
extruding shapes.
Anyway, I've stuck some code below, and drilled a couple of bolt
holes for you. Unfortunately openscad does not exactly follow the
machining sequence, unless you put every operation in a module, but
you will get the hang of it. You should be able to change the
values, and it will work OK, but if you want bigger(or smaller)
fixing bolts, you may want to position them differently. (combined
fixing and clamping bolts).
I'll look at it, but I've got the final assembly pretty much in mind
already. And I changed the printer in the middle of the night, can't
get usable stuff out of a dremel 3d45 for my $1900, it goes nicely
laying the brim, but turns the next layer into very bulky snow that
the catches on the nozzle and gets ripped off the glass and welded to
the nozzle the next time it comes by. No support from dremel.
So I swapped a modified Ender 3 onto the work table, and resliced the
code for it, and its doing a perfect render at about 82% done right
now. Just one problem, I have played with the steps/mm settings as it
did not come calibrated OOTB. Unpacked and built, the flow setting was
so light you could read the paper thru the sample waving cat, so that
had to be upped from about 80/mm to about 350 before I started getting
solid prints. xy was preset to 80/mm but that gave slightly smaller
parts, so I'll have to measure this and figure out what it will take
to get an ID of 119.5 on the next print. Then the balls groove might
need adjusted once I stuff it full to see how it fits.
Thats all done now, and the next print s/b usable.
Except I see I've made a mistake already. I intend to put this bearings
ID over the outside of the shallow cup of the output shaft, but I
haven't allowed for the thickness of the wall of the shallow cup that
will be interposed to couple the output spline to the output shaft. This
bearing is intended to go on the outside of that shallow cup. Probably
needs to grow by 7.2mm in diameter. So maybe I should grab a piece of
1/2 alu and make that "cup" next. After I check and make sure I haven't
run out of width on the 2" piece I bought for the other half of the
housing for it. Just barely.
Now you know why I do this stuff one step/piece at a time.
But first, my kitchen is closed cuz I'm sick of my cooking so I think
I'll find a shirt and go see if L.J.Silver's has any cod left. Its
friday and I've probably had too much sugar already, and fish is sugar
free. Later folks.
This all goes on the outside of the moving spline gear of a 30/1
harmonic drive to be used as a 4th axis on one of my milling machines.
But the flexure of the cup in a harmonic drive has limited its life
time as the plastic breaks at the base of the cup in less than 24
hours run time.
I can attach pix of what I'm doing if the list allows it, sometimes
its true about a pix is better than 1000+ words.
Take care everybody.
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