On Thursday 04 August 2016 11:27:23 Leonardo Marsaglia wrote:

> 2016-08-04 10:38 GMT-03:00 Gene Heskett <[email protected]>:
> > Pretty short movie, doesn't stay on the screw long enough. I've no
> > experience with delrin nuts but have read good things about them. I
> > would expect clean but lubricated with the right stuff is the key to
> > long life.
>
> I just took a pic of it, so the dimensions can be seen a little bit
> better.
>
> https://s32.postimg.org/jjb069dj9/IMG_20160804_121717069.jpg

I see it better now. It looks like you are heat treating a camshaft with 
that induction coil at the bottom of the pix, and that the big screw is 
between the two guide rails at the top of the pix. Unless the cam is 
being rotated as its being heated, that is the first one axis machine I 
have seen linuxcnc run.

> I can't do a lot now because it's working. The lenght of the screw is
> about 2 meters and the diameter 60 mm. The nut is a square block of
> delrin of about 130 mm long. I can't take pictures of that now, but
> originally it had a brass nut that was destroyed when we acquired the
> machine. The motor handles it very well considering is standard  four
> poles AC. It has problems when I'm moving it below 6 hz.

With the inverter controlling the current if properly programmed, a std 
AC 4 pole motor is not going to have a lot of torque at 6hz.  You may be 
able to increase the low speed current boost, but it will be a limited 
time as it accelerates before either iron saturation, or coil heating 
becomes excessive. Iron saturation may destroy the inverter rather 
instantly, and of coarse coil heating beyond its rating will cook them 
eventually.  This looks to be mostly short run times except when raising 
to exchange to the next camshaft. That appears be 100% manual.  What I 
am getting at is the duty cycle is low when doing its normal job.

I presently have a 1hp on the table I'm playing with, to be used on the 
11x36 Sheldon I just bought. With amprobe's on two phases, it is up to 
its FLA current rating at 20 hz, no load.  Long time at that speed heats 
it some, but not excessively even though the fan isn't all that 
effective at 550 revs. But it will spin up to 120hz and probaby more 
quite happily.  I just put fresh bearings in it so thats not a worry on 
whats left of my watch. :)  Once I get this inverter figured out, I'll 
be able to reverse it a lot faster, something I'll need for rigid 
tapping.

> There's also this video with crappy quality but you can see better how
> it moves:
>
> https://www.youtube.com/watch?v=Rv2Y9xEkwpI

Not really. :)

Cheers Leonardo, 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)
Genes Web page <http://geneslinuxbox.net:6309/gene>

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