 |
|
|
|
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On Sat, 07 Mar 2009 14:26:10 -0400, Jim Henderson <nos### [at] nospam com>
wrote:
> On Sat, 07 Mar 2009 10:45:14 +0000, Rarius wrote:
>
>> It came through OK for me.
>
> It did here as well, but your post was a mix of plain text and HTML,
> that's probably why clipka had problems with it.
It doesn't come through on the Web interface, though it works fine on my
Web browser's integrated news reader.
I noticed that your news poster, "MSHTML" (I wonder who that is?), makes
copious use of the <font> element. <font> was officially declared
unseemly at least 10 years ago, and no less that Micro$oft explained part
of the problem in a brilliant article:
http://www.microsoft.com/typography/web/designer/face7.htm
I love large corporations that practice what they preach. Good thing that
Web browsers are maintaining, uh... (subtracts in head), 19 years of
backwards compatibility, and keep tabs on each other so that, say, Opera
knows how MSHTML formats its attachments. Alas, povray.org's software
doesn't. (Just continue using plain text and avoid the whole mess.)
--
<Insert witty .sig here>
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
On Sun, 08 Mar 2009 01:24:44 -0400, Cousin Ricky wrote:
> On Sat, 07 Mar 2009 14:26:10 -0400, Jim Henderson <nos### [at] nospamcom>
> wrote:
>
>> On Sat, 07 Mar 2009 10:45:14 +0000, Rarius wrote:
>>
>>> It came through OK for me.
>>
>> It did here as well, but your post was a mix of plain text and HTML,
>> that's probably why clipka had problems with it.
>
> It doesn't come through on the Web interface, though it works fine on my
> Web browser's integrated news reader.
>
> I noticed that your news poster, "MSHTML" (I wonder who that is?), makes
X-Newsreader: Microsoft Outlook Express 6.00.2900.5512
:-)
Jim
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
> X-Newsreader: Microsoft Outlook Express 6.00.2900.5512
Yes I do use Outlook Express for accessing Usenet newsgroups.
I apologise to everyone who had difficulty reading my original post. I
accidentaly had HTML turned on for news posting. I have rectified this and
should now be posting in plain text.
Rarius
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Here is a plain text post with a updated image of my CNC design.
Rarius
Post a reply to this message
Attachments:
Download '3AxisRouter3.png' (196 KB)
Preview of image '3AxisRouter3.png'
|
|
| |
| |
|
|
|
|
| |
| |
|
|
> As always when designing such machinery, 'success lies in the
> details'--the
> proper bearings, the elimination of mechanical backlash, etc. I'm curious
> as
> to what type of threaded drive shafts you plan on using?
The drive spindles are 12mm trapezoidal with a 3mm pitch
(http://www.worldofcnc.com/products.asp?recnumber=61) running in bronze nuts
(http://www.worldofcnc.com/products.asp?recnumber=47). The rails are 12mm,
16mm and 20mm ground shafts
(http://www.worldofcnc.com/products.asp?recnumber=14) running through linear
bearings (http://www.worldofcnc.com/products.asp?recnumber=16).
I bought a job lot from eBay. It included four spindles, three pairs of
> Something to be aware of (and this is from my own personal experience) is
> that
> using *multiple* threaded shafts to drive a single axis can create
> problems and
> headaches in trying to get things to work reliably (not insurmountable
> ones, of
> course)-- the shafts need to be as parallel as is humanly possible--in two
> axes--so the moving platform doesn't 'lock up' at some point. Perhaps
> you've
> taken that into account already.
You make a good point. Originally I was going to drive the two Z axis
spindles with two stepper motors. By tying the two Z axis drives together
with the toothed drive belt I don't beleive that I should have any problems
such as you describe.
I have changed the system from driving the spindles so that the spindles are
now locked in position and the nuts are rotated around them, thus pulling
themselves along the spindle. This should remove any problems from the
spindles wobbling as they turn and also removes the need for bearings at
both ends!
I think the problem of "racking" on the X axis is more of a worry. Although
not shown on the image I have decided to add a cable system like that used
on large draftsmans drawing boards to stop any rotational movement as the
carriage moves backwards and forwards along the X axis.
Rarius
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"Rarius" <rar### [at] rariuscouk> wrote:
> Here is a plain text post with a updated image of my CNC design.
>
> Rarius
Hey, someone stole the drilling tool!
Attachment worked fine this time, thanks.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"Rarius" <rar### [at] rariuscouk> wrote:
>
> The drive spindles are 12mm trapezoidal with a 3mm pitch
> running in bronze nuts. The rails are 12mm, 16mm and 20mm ground shafts
> running through linear bearings.
Some nice components! Especially the linear bearings with the recirculating
balls. I'm not familiar with 'trapezoidal' threads; from the photo at the
website, they look kind of like 'Acme' threads here in the 'States.
>
> I bought a job lot from eBay. It included four spindles, three pairs of
You lucky guy!! I'm jealous.
Ken W.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Rarius wrote:
> I think the problem of "racking" on the X axis is more of a worry. Although
> not shown on the image I have decided to add a cable system like that used
> on large draftsmans drawing boards to stop any rotational movement as the
> carriage moves backwards and forwards along the X axis.
>
> Rarius
Yeah, that could be an issue. Since you've got two sliding rails and a
third driving rail, your system is kinematically over constrained, so
any racking between the two sides would put a lot more frictional load
on the drive motor, possibly causing harm. This can be helped by doing
what you said with extra cables, or another workaround is using thinner
bearings spaced farther apart, instead of a single long sleeve bearing.
That way any rotation can move the individual bearing races a little bit
out of alignment, instead of putting a huge torque side load on each end
of a long bearing.
How are you keeping z vertical? If x is the first motor, I'm slightly
worried about it bending around y, especially if you have a large load
on the cutter - it could bend against the long thin rails.
Another thing - the timing belt pulleys on the z axis aren't centered on
the threaded rods?
-cshake
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
"CShake" <cshake+pov### [at] gmailcom> wrote in message
news:49b3f716$1@news.povray.org...
> Rarius wrote:
>> I think the problem of "racking" on the X axis is more of a worry.
>> Although not shown on the image I have decided to add a cable system like
>> that used on large draftsmans drawing boards to stop any rotational
>> movement as the carriage moves backwards and forwards along the X axis.
>>
>> Rarius
>
> Yeah, that could be an issue. Since you've got two sliding rails and a
> third driving rail, your system is kinematically over constrained, so any
> racking between the two sides would put a lot more frictional load on the
> drive motor, possibly causing harm. This can be helped by doing what you
> said with extra cables, or another workaround is using thinner bearings
> spaced farther apart, instead of a single long sleeve bearing. That way
> any rotation can move the individual bearing races a little bit out of
> alignment, instead of putting a huge torque side load on each end of a
> long bearing.
I would have liked to move the X bearings further apart, but that quickly
starts to eat into the available work area. If I had been buying the rails
new I would have bought much longer ones, but as I bought them second hand I
am stuck with what I have.
> How are you keeping z vertical? If x is the first motor, I'm slightly
> worried about it bending around y, especially if you have a large load on
> the cutter - it could bend against the long thin rails.
Just to clarify: In my design, the X and Y lie in the horizontal plane. X
is the front/back axis, with the motor on the far right. Y is the side to
side axis and Z is the up/down axis.
The Z axis is held vertical by the two vertical rods that drop through two
pairs of linear bearings. I agree that three would be better but I'll see if
the two can cope. I can always rebuild later. It is lifted by the two
vertical spindles that are both driven by the stepper motor.
The sideways force on the router bit should be reasonably small as I will be
using small bits and low feedrates.
> Another thing - the timing belt pulleys on the z axis aren't centered on
> the threaded rods?
Thanks for pointing that out. A typo crept into the script during an edit
lat last night! Fixed now.
Rarius
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
| |
|
|
Cousin Ricky nous illumina en ce 2009-03-08 00:24 -->
> I love large corporations that practice what they preach. Good thing
> that Web browsers are maintaining, uh... (subtracts in head), 19 years
> of backwards compatibility, and keep tabs on each other so that, say,
> Opera knows how MSHTML formats its attachments. Alas, povray.org's
> software doesn't. (Just continue using plain text and avoid the whole
> mess.)
>
>
MSHTML makes me think of MicroSoftHTML, or a microsoft propriatary extention
over the HTML specification.
Well, not even compatible with IE7 here...
--
Alain
-------------------------------------------------
If you're ever about to be mugged by a couple of clowns, don't hesitate - go for
the juggler.
Post a reply to this message
|
|
| |
| |
|
|
|
|
| |
