Re: re: Turbocharging a bigger MaxNC

Message: 24
Date: Thu, 10 May 2001 21:39:28 +0800
From: John <machatak@...>
Subject: Re: re: Turbocharging a bigger MaxNC

Andrew , my comments <<< >>>>

Message: 15
Date: Tue, 8 May 2001 10:08:44 +0100
From: Andrew Werby <drewid@...>
Subject: Turbocharging a bigger MaxNC

Message: 12
Date: Tue, 08 May 2001 19:33:19 +0800
From: John <machatak@...>
Subject: Turbocharging a bigger MaxNC

Folks, need advice!
Have a MaxNC that has extended x axis table (600mm or 24"), still using
1/4-20 rod.

[Did you build that yourself?]

<<< yes in a local machine shop, with preground steel inserts on the
angled section of the dovetail >>>

[That sounds like an interesting mod. Did you also put steel inserts on the
corresponding surface of the x-block? Otherwise, I'd worry about wear,
running steel against aluminum.]

Now feel the need for speed, and the routes i see are:
a) software stay with MaxNC, get a phase to step and direction adapter,
and fit step and direction drivers e.g. Gecko
b) software (still in DOS and freebie if possible), s+d drivers as above
c) Master 5 from Art, (windoze), s+d drivers
d) make the jump to EMC, and s+d drivers (open loop initially, then go
for closed loop steppers)

[Why not use MaxNC's closed loop system? I've been pretty happy with it
for
contouring, and it sure goes a lot faster than their open-loop drivers.
I
was never able to go faster than 12 ipm with the latter (using their 145
oz/in motion control kit) but I can go 90 ipm reliably with the
closed-loop
stepper system.]

<<< Andrew, cannot see pricing for a retrofit system, maybe as u are
dealer for MaxNC u can inform us of the cost? My is/was a MaxNC 10
with the low powered motors, around 65 oz/in i think >>>

[Sure, I sell the 3-motor retrofit kits for $1140, the 4-motor kits (in
case you have a 4th axis) for $1306.]

Without starting a flame, it it possible to get some advice on which way
to go.

[Just keep it clean- we've got some unmarried people on this list
now...]

<<< Lucky i did not mention that we also machine prototype formers for
the latex condoms.....oops! >>>>

[Uh-oh. Hereafter, please refer only to "wide-mouth balloons"...]

Mechanical bits will be a scaled up version of a MaxNC, using an angle
grinder motor (200 to 11000 RPM) for Spindle. Have done over 1000 hours
on one already, with no problems, will admit the carbon brushes do spark
a bit.

[Are you fitting this with a collet chuck, or using it to drive the
existing spindle?]

<< use the standard spindle, but the RPM is kept low, even so the
spindle tends to heat up. have replaced the spindle bearings 3 or 4
times, when they are rough >>>>>

[The new spindles (made by Taig, actually) are supposed to be better. They
found a source of bearings in Turkey which allow them to spin faster- I
imagine they would also last longer if they went slower. Of course, if you
go faster, your patterns won't take as long, so the spindle can get some
rest. Changing the motor mount to something more rigid than the MaxNC "2
stilt" system might also help. ]

What i use it for is organic shapes, most of my work is surface
modelling, i do mainly formers for dipping latex balloons, using HDPE,
no metal work, but would like to go for 7075 T6 for motorsport
components if possible.

[Aluminum shouldn't be a problem as long as the spindle can keep up with
the feedrate. This can be a problem with the standard 1/5 hp motor, but
maybe the grinder motor will perform better.]

To give some better ideas of the way i abuse the current
machine, some
programs are over 4 MB without line numbers and longest duration was
over 52 hours continuous machining, just tidied up with a industrial vac
cleaner every few hours. Main reason it is soo long is that i use same
tool for roughing and finishing pass, a bit of a compromise, but beggars
cannot be choosers! Anybody got a solution for economy ATC????

[The duration would go down if you got the feedrates up. Why do you use
the
same tool for roughing and finishing- can't afford two? For what I've
been
doing, I find that roughing with a 1/4" tool and finishing with a 1/8"
is
more efficient than trying to do it all with the 1/8". But if there
weren't
any places that the 1/4" couldn't reach, I suppose it could all be done
with the one tool, perhaps finishing crosswise from the roughing path.]


<<< honestly it is not the cost of tools, but commonly just set up and
go off to work, and my wife just looks in and vacs away the plastic
swarf, when it looks "untidy" and if it has finished she just shuts it
down. Frequently i am away overnight, so i have gone this one tool
route.

[Changing tools isn't too hard. One trick I use is to put the new tool in
just tight enough so it doesn't slip out, then jog it down onto the top
plane of the workpiece a little (not spinning). This will slide the tool a
bit further into the collet, but ensures an accurate z- zero. While it's
still there, zero the axis (6) and then tighten with wrenches. I think that
with patience (and bribes) you could get your wife to do this. ]

Of course i cut with very sharp tools, and the tool paths are
usually of very high quality using Visi and or hyperMill. Have recently
started playing HSM machining techniques for both roughing and
finishing, actually they are quite effective even on a machine with a
rapid of 150mm (6") per min. Notice only a very minor change in tone of
spindle motor! >>>>

John

[What techniques are those, Z-level roughing? I don't think you quite
qualify for High Speed Machining yet...]

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Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff
http://unitedartworks.com