Ed
Good info,well researched.
Would you not be ahead buying a new CNC mill ?Cost and time wise.
Also you still have the perennial problems inherent with the NON solid column type mills
if considering mill CNC conversions.
How people accurately control these machines (head drop) (flexing) no quill feed with a DRO is remarkable.
John
Spain
John
Spain
On Saturday, December 5, 2015 9:04 AM, "Hannu Venermo gcode.fi@gmail.com [GrizHFMinimill]" <GrizHFMinimill@yahoogroups.com> wrote:
The range is vast .. depending mostly on how well you do it.
There is no real correlation with usfulness/cost/quality yet, ime.
Some really good stuff is cheap (some ballscrews, PokeysCNC, 2M542
drivers, small AC servos)
Some pretty expensive stuff is not too good.
Most motion controllers are weak for conversions, in many ways.
A basic industrial VMC, can be done for;
Small ac brushless servos, 290€/axis.
Belt drives, 30-50€ /axis.
Ballscrews, 32 mm D, 1200 mm long, mounts, 300 €/axis.
Sundries, 90€/axis
== 750 € x 3 = 2250€.
Lower cost good motion controller, 125 kHZ, 4 axis, 150 € or so (Pokeys
CNC).
Wire for 50-80 points, sundries, 200-300€.
+450 €
== 2700 € in kit, 200-300 hours work.
A top end industrial lathe, 4 axis with 6 axis controller;
Top end motion controller - CSMIO-IP-S, 900 €
(200 io lines, 150 IO in controller, DIN rails, 100 contacts,
400+ferrules, wires, tools, 2xDC PSU 24V, MPG,ENCoder threading, boxes,
cables (5), industrial MPG)
All in sundries == 1600 €
== 2500 €
750 W AC brushless servos 220V, x, z, 690 €/axis x 2 = 1400 €
400 W AC brushless servo, tailstock b, 290 €
32/25/25 mm ballscrews with mounts, 300€/200€/200€ for z,x,b (tailstock)
== 4900 €
AC brushless servo drive, C axis, 2.5 kW, 1200€ + 300 € for belt drive, 5 kW
+ 1500 €
Mounts, 120 kg steel, need about 30 pieces to fab to size, 20-50 mm
thick tool steel, == 240 €.
+ 240 €
== 9200 € in kit, 300-400 hours work..
Cheapest, best, really good results.
2M542 series stepper drivers, 40 €
about 2.5 Nm stepper, 40 €
HTD5/15 drives, 20€
= 100 € axis.
So, the best low cost bang/buck is == 100€/axis for steppers,
290 € for small brushless servos, 400W
690 € medium 750 W servos
A big stepper setup costs == same as servos, that are much faster (4x),
accelerate faster (4x) are more accurate (3-5x).
Stepper drives (80V, 8 amp and up) == 100-150, motors == 150€, cables
etc == 20 €, 300€axis, give or take.
At 80V, nema 34 steppers might run at 600-700 rpm, with == 0.5-0.8 Nm
torque at 6-700 rpm.
All sample costs are general ballpark numbers, see your favourite supplier.
All costs include VAT taxes at 22% here in EU land, and shipping in EU.
Not recommending one path or another - just putting sample costs, for
best-in-class bang/buck options.
Pick what you feel is the best from those above.
Key findings:
The sundries cost more than the main components.
The work costs a lot in hours.
The best option in hw costs almost the same, overall, as the
too-small-poor option.
Example:
Ie a tiny screw, low stiffness, low rigidity, mount too small and not
enough rigidity, costs about 130.
(16x5 screw)
A full axis, all-in might cost 250 € low end.
At 350 €, it will be over 5x more accurate, and rigid.
(25x5 screw)
Work hours are still == 40-60 hours/axis.
Most work hours (60-70%) are wiring, electronics, cables, runs,
painting, conduits, finishing, sheetmetal, chip covers, etc.
Especially once You go past the very low end, using small
screws/mounts/steppers starts to make increasingly less sense, vs. the
work invested in the whole thing.
The problem with that, is that each step up makes even more sense in
bang/buck, until you get to fairly high costs per axis, 700-2000€ per,
depending.
My experience, for what its worth, is that small servos and 25 mm screws
are the sweet spot for hobby use at around 700 per axis.
This would be somewhat better than a tormach, a pretty good commercial
solution, off the shelf at 10k or so for full machine.
My top end lathe example is for a single-micron resolution lathe, to
make instrument screws, optronics stuff.
Similar-capability commercial stuff == 60k€ and up.
Another example:
1400€, MT2 spindle (like LMS minimills, MT2 in general).
My first spindle is a Bridgeport M head, circa 1950. Runs fine.
400€ ebay usa, 400€ transport to spain (air), 400 for VFD, 200 sundries,
1400€ running.
0.01 mm TIR, 4000 rpm, manual drawbar, 1 Hp (MT2 limited).
Spindle, now:
Spindle 1200€, ISO-BT30, auto drawbar for toolchanger
0.002 mm TIR, 6000 rpm, 8 kW
Add motor of choice (1200 € for 2.5 kW servo, rigid tapping, 2 speeds
for high-torque and high 8000 rpm speeds)
(or 300 € for 3-phase and VFD)
So, for low of 1500 €, 10x better spindle of industrial quality.
Add 300 € for 5000 € value in rigid tapping, high speeds, triple the
torque (servo peak torque), triple the accceleration.
Add 500 for auto toolchanger, 5000 € value.
Add 500 in sundries to make mounts, brackets, bolts, paints etc.
== 3700 € with ATC, and industrial VMC mount (100 kg in steel).
Range for spindle:
LMS minimill head, 240€ or so (? was),
BP M head 1200€,
ISO30 1500 € manual,
ISO30 VMC 3700 €.
Range is about 20:1 with increasing levels of capacity, usefulness, and
bang for buck.
Could go for 8kW on spindle, with about 800€ more, but does not make
sense, for me for example.
If I needed to do larger amount of material removal, it would make a lot
of sense.
Gotta go, need to go get some support arm bits, for chip shield on lathe.
On 04/12/2015 17:52, j1g2004@yahoo.com [GrizHFMinimill] wrote:
> I have been going back and forth trying to decide to upgrade to a
> bigger mill, or just convert my G8689 to CNC. I was wondering if
> anyone has done a recent conversion and the cost associated with it.
>
> Thanks
> Ed
--
-hanermo (cnc designs)
__._,_.___
Posted by: John Lindo <bechetboat@yahoo.com>
