On Sat, 6 Oct 2018 at 15:02, Leonardo Marsaglia wrote:
> As you pointed out Les, an hydraulic rod is what I'm planning to use. Hard
> chromed and also lubed to avoid premature wear.
Maybe motorcycle fork bushes (PTFE typically, on a metal backing)
would make good bearings.
--
atp
"A
On 10/05/2018 11:17 PM, Roland Jollivet wrote:
Of course you can remove the nut. You just roll it onto a correctly sized
former.
In fact it's a good idea to do this with the linear slides and ballscrews
from china, to give them a wash. While they are greased up and wrapped in
plastic, they are
On Saturday 06 October 2018 08:46:35 Les Newell wrote:
> > No, I plan to support 50 mm bars every 600 mm more or less. I'm
> > attaching some pictures of the design I'm working on
>
> If you really want to go with this I would second Chris' suggestion of
> using HDPE or UHMW. You are still gonna
A lot of discussion! I love this list haha.
Well, I will try to answer this and focus on the main subjects we've been
covering.
As you pointed out Les, an hydraulic rod is what I'm planning to use. Hard
chromed and also lubed to avoid premature wear. I plan to add some sort of
plate to collect
No, I plan to support 50 mm bars every 600 mm more or less. I'm attaching
some pictures of the design I'm working on
If you really want to go with this I would second Chris' suggestion of
using HDPE or UHMW. You are still gonna wear those shafts out pretty
quick unless you use chromed shafts.
On Saturday 06 October 2018 00:56:58 Gene Heskett wrote:
> On Friday 05 October 2018 23:24:38 Chris Albertson wrote:
> > A third option is a REALLY long belt. It is long enough to make a
> > double pass on each side and needs about 8 pulleys but you only need
> > one motor. I saw one of these
On Friday 05 October 2018 23:24:38 Chris Albertson wrote:
> A third option is a REALLY long belt. It is long enough to make a
> double pass on each side and needs about 8 pulleys but you only need
> one motor. I saw one of these once but it used a kevlar cable, not a
> belt
>
> I think the
A third option is a REALLY long belt. It is long enough to make a double
pass on each side and needs about 8 pulleys but you only need one motor. I
saw one of these once but it used a kevlar cable, not a belt
I think the shaft is move simple but but you need precision mechanics to
adjust it.
They are on ebay. Yousearch for "ball screw" and they come up.
Here is an example: https://www.ebay.com/itm/SFU1204-RM-Rolled-Ball-Screw
On Friday 05 October 2018 11:12:01 Dave Cole wrote:
> Chris,
>
> Do you have a link for these "new style ball screws" ??
Just do a google search. The prices seem to be in freefall. The 1 start,
25x5x1450mm screw and nut, with bearings I paid right close to $180 usd
+ ship, about $200, for the
By the time you buy the timing belts, pulleys, shafts, machine the
brackets, to do a double belt reduction to get to 10:1, you are money
ahead to just buy a servo grade 10:1 gearbox. If you mount a pinion
directly to the gearbox shaft and drive the rack with this pinion, you
will have a
Chris,
Do you have a link for these "new style ball screws" ??
Thanks, Dave
On 10/4/2018 3:33 PM, Chris Albertson wrote:
Have you seen the new style ball screws? They are now cheaper then belts
and have pretty "over kill" specs.
The problem with a 30mm wide belt drive is the need to
On Thu, 4 Oct 2018 at 19:45, Leonardo Marsaglia wrote:
> I would love to have ballscrews but I thought I would need to large of a
> diameter to avoid them to whip. Remember that I have a 3.8 meters in lenght
Have a look at the Bell Everman "Servobelt" concept.
I believe it uses standard metric
e xy axis uses to drive those
ball screws directly, Z is still about 3x faster than xy.
> > -Original Message-
> > From: Leonardo Marsaglia [mailto:ldmarsag...@gmail.com]
> > Sent: Thursday, October 04, 2018 2:42 PM
> > To: Enhanced Machine Controller (EMC)
> &
https://www.youtube.com/watch?v=vETkf1sqo3M=220s
On Thursday, October 4, 2018, 3:41:58 PM MDT, Gregg Eshelman via Emc-users
wrote:
Here's a way to drive the gantry with roller chains. Using fewer changes of
drive is always better since going from a shaft, to worm gear, to rack and
Here's a way to drive the gantry with roller chains. Using fewer changes of
drive is always better since going from a shaft, to worm gear, to rack and
pinion has more places for backlash. The same mechanism as in this video can be
used with lengths of toothed belt.
Roller chain drive Plasma
)
Subject: Re: [Emc-users] Yet another topic about gantry homing
First of all, thank you guys for your advices as always!
I'm gonna try an asnwer this on one message because sadly gmail doesn't have
the quote selected text feature anymore.
About the oversized motors. Yes, I also think
Ball screws can be had that long, but they aren't cheap and you're in rotating
nut only territory.
I've bought custom length screws directly from Hiwin for reasonable amounts of
money (a C7 rolled screw and nut cost about half what the machine's OE charges
for a replacement lead screw and so
On Thu, Oct 4, 2018 at 12:48 PM Roland Jollivet
wrote:
> The OP said the table is 3.8m long
>
Yes, a screw is better suited to something about 1.5 meters of under.
Likely best to use a pair of belts, one each side.
How much does a belt tension change with temperature? Normally it is a
On Thu, Oct 4, 2018 at 12:29 PM Ken Strauss wrote:
>
> One possible solution to the ball screw whip issue is to spin the ballnut
> rather than the ballscrew. In this scheme the ballscrew does not rotate
> and if
> you tension the screw you should be able to use a much smaller diameter
> screw.
>
Have you seen the new style ball screws? They are now cheaper then belts
and have pretty "over kill" specs.
The problem with a 30mm wide belt drive is the need to resist the belt
tension and a way to adjust it. Not only the tension between the two
pulleys but there is side load on the motor
smaller diameter screw.
> -Original Message-
> From: Leonardo Marsaglia [mailto:ldmarsag...@gmail.com]
> Sent: Thursday, October 04, 2018 2:42 PM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] Yet another topic about gantry homing
>
> Hello Chris,
>
Hello Chris,
I would love to have ballscrews but I thought I would need to large of a
diameter to avoid them to whip. Remember that I have a 3.8 meters in lenght
for the longest joint. I've reading about using anti whip guides that move
with the gantry and also aply tension in the screw with a
On Thu, Oct 4, 2018 at 5:49 AM Leonardo Marsaglia
wrote:
>
>
> About the last question. Is there any disadvantage other than may be a
> little more mechanical complexity with the one motor and shaft approach?
> Because I've seen lots of routers driven with two motors that I almost
> think it's
Well I've been reading the 2.8 Master branch manual about homing and how to
configure two joints for one axis and I think I understand but since I
don't have a Linux PC here to try it out I would like to clarify something.
In the two motors for one axis gantry configuration, does LinuxCNC export
Hello Les,
No, I plan to support 50 mm bars every 600 mm more or less. I'm attaching
some pictures of the design I'm working on. (The adjustable stands for
levelling are not in the assembly because I'm saving resources on this
laptop)
I like the idea of using the rectangular ways but
Hello Dave,
Well, to avoid the backlash is that or may be using timing belts and
pulleys to drive the shaft too. The gearbox is a good idea but I think that
can raise the cost too much. Anyway I'll give it a look because I don't
want to discard any option.
In any case I'm still not sure about
I'd avoid a worm gear drive. They are prone to wear and backlash.
I'd look for a good deal on a servo grade planetary 10:1 gearbox that
fits your Chinese motor.
Probably the easiest and most rigid drive solution is to use two motors
each with a planetary gear box and direct drive a pinion on
By the way, on the pictures there are missing details I didn't draw yet,
like setscrews for parallel regulation and things like that. Also, I have
yet to modify the design for the one motor and shaft approach and see wich
is better.
El jue., 4 oct. 2018 a las 11:37, Leonardo Marsaglia ()
You need to keep the drive system as simple as possible and keep
backlash in mind.
Also, don't forget about the spring constant of any shaft you run across
the gantry. If you do that, you might want to
run a tube drive shaft rather than a solid shaft for more torsional
rigidity.
There is
Using two motors is mechanically simpler and has lower rotational
inertia but I am not a fan of this setup. If you use a tube rather than
a solid shaft, you won't add a lot of inertia. I'm thinking of building
another plasma cutter and it will probably use a shaft rather than 2 motors.
But
The easiest method is mechanically connect the two sides with a shaft along
the gantry and use one motor. Then it *cannot rack* or have any of the other
issues that can happen with driving both sides of a constrained axis with two
motors.
If you need more Z height, you can elevate the racks on
On Wed, Oct 3, 2018 at 6:45 AM Leonardo Marsaglia
wrote:
>
> I was thinking about making a custom component for offsetting the index
> pulse on the encoders but I don't know if this approach will be reliable
> enough.
>
No. DOn't do that. It is far more accurate mohave the software
I think using the index pulse will not detect "out of square". The reason
is that you get out of square because of a "skipped step" on only one of
the motors.So your idea (I hate to say) works great only in cases where
it is not needed. If the router never skips a step only one switch is
You will probably need two reduction stages to get a 10:1 belt drive
reduction.
There are some fairly cheap servo motor gear boxes out there now being
made in China.
That may be the cheaper/easier way to go.
FWIW, 1 KW servo motors x 2 is probably an overkill unless you want to
go really fast
On Wed, 3 Oct 2018 at 14:45, Leonardo Marsaglia wrote:
> I was thinking about making a custom component for offsetting the index
> pulse on the encoders but I don't know if this approach will be reliable
> enough.
If some racking during homing is acceptable then you can adjust the
alignment of
Sorry for the lack of detail, I wrote the message too fast this morning
when I just got up.
I'm planning to use 1 kw servos on each side with a max RPM of 3000. The
idea is to gear down from the motor to the pinion 10 to 1 using the timing
belts. The pinion I'm planning to use is a MOD 2 with 20
I haven't really looked at the documentation for Master lately, but the means
for setting up a multiple joint axis (like a gantry) was documented reasonably
well last time I checked.
My personal experience with rack and pinion driven wood routers is that for
stepper-motor drive you are going
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