Need Help!- Dumpstercnc flange options

[Drools]

I'm about to order a couple of Anti backlash nuts from dumpstercnc but I'm having trouble deciding on the flange option I need.
I would like to see how others have mounted their dumpstercnc parts.
Also I'm going with the Black-Oxide finish on the Mcmaster Acme rods, are these a good fit on dumpstercnc nuts?

Thanks.

[jjacstcy]

From what I have read the black oxide rods may melt plastic nuts. The coating on the rods isn't as smooth as an unfinished rod is. Generates more friction result in heat which will wear the nuts out early.

[microcarve]

It isn't a dumpster nut...it's roton...but they
may be similar enough to get some useful idea of
one way to mount one.

The 3/4" bore I had in the slide block was too big.
The screws holding the nut in place would've been
in the bore about 1/2 way, so I made a 3/8" plate
from a piece of aluminum as an adapter. *Much* better
and more secure...

The thinness of the anti-backlash nuts, where the threads
are, definitely makes me want to avoid black oxide myself.
The friction may be enough to soften the thin delrin. There's
a big enough difference in 40-50 degrees of temp that can
make a difference with plastics.

Maybe being a bit too particular...as there are many-many
people using them with no problems, but I have noticed enough
of a difference in how hot screws get from fast travel and
more friction enough to make a conscious effort to avoid
oxide coatings in the future.

I seriously considered a quick acid dip to remove it from the
ballscrew I've been experimenting with. I'd much prefer the
ballscrew was polished instead...and if it were a teeny bit
less of a hassle, I'd get that oxide off of the screw.

A motor at 150F won't burn as bad as when it's at 190F...and
that's a common temp range they run at. It's also in the range
of the softening point of many types of plastics.

FWIW...


John

[microcarve]

Harbor Freight used to have a thing like this on sale near
constantly for about $12.

Non-Contact Pocket Thermometer - Thermometers - Hand Tools

I use it all the time. Mainly for adjusting my current to my motors
down until they run at about the 160 F temp range. I never liked them
running as hot as they do when full allowable current is applied...which
gets them near 190 F. That's too close to their max temp ratings and
I have had odd behavior from "too hot" motors in the past.

I also used it to measure temperature of some really hot screws that
left a burn pattern on my hand once. It melted the inside right out
of an HDPE nut.

A very useful little thing to have on hand just to check things if nothing
else....

Off topic, but maybe useful to someone...


John

[ger21]

I use dumpster nuts on black oxide screws. The finish on my screws is as smooth as glass. It may have more friction, but I don't have any plain screws to compare it to.
I do use oil on my screws. Pneumatic tool oil, which is very light and thin. I run mine at up to 800 rpm.

As for the flange, I use the 4 hole square flange, mounted to aluminum angle.

[microcarve]

I started out trying the black oxide probably like
most people...I reasoned that if they cost 30% more,
then they must be somehow better. Also, I do plating
and anodizing so I guessed they picked out the "better"
parts to take the extra time and trouble to do the coating.

But, one batch would be matte finished and another would
look like high gloss paint. There's a few different ways
of doing the coating. Which also suggested that maybe McMaster
got them from different suppliers....maybe like Walmart...
whoever is cheaper at the time...

I noticed about a year ago that whenever I was having problems
with nuts fitting perfectly and travel being a little different,
the thing they had in common was the black screws. Then one
day, my big machine gantry just stopped dead in the middle of cutting
out a panel of MDF. The threads in a 1" thick block of HDPE
had just softened and pushed right through. I grabbed the screw
and got a pattern burned into my hand. I hadn't wanted to
spray lubricant that might...(surely)...get all over the MDF
I needed to paint.

Then again, plain screws have come in so badly bowed or with dings
in them that they had to be sent back. But I can't say I've had
any problems with the good clean ones once they get a polishing
on the lathe.

Lots of people have Great luck with black screws. I'm just now
beginning to avoid them myself. IIRC...the one that burned my hand
was near 200F. The nut did last a good long time, but backlash kept
showing up a bit more at a time.


John

[microcarve]

Some screws

Some differences are so subtle that they aren't easily noticed
until the nut is fitted. Sometimes a tap has to be made for
a particular shipment...if the hassle to ship them them back
and risk the same thing happening all over again is to be
avoided.....

Life is like a box of chocolates. Was that what the guy said?....


John