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Offline Katoh

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Re: 1/2 speed spindle
« Reply #10 on: May 26, 2017, 08:32:39 PM »
Hi Craig
Once Again many thanks for your assistance, your help is so much appreciated and you don’t realise how much you have helped me out.

To be honest if your machine is accurate and rigid enuf to require C axis resolution of 2.6 arc min then you
obviously have LOTs of bucks, why piss about with Mach4? Time to get real about what you want vs what
you can achieve within your budget/expertise.
I will be total honest and yes I agree with what you said. Firstly to start with I don’t have the BUCKS :-X wish I did then I could get things done, I’m purely a bargain hunter, but do spend on what I need too.  I actually started this lathe build 6 years ago and have slowly bean updating as I go.I built my Router 4 axis back in 06, now back then it was cutting edge, but I built it from the ground up with what I could find at the time. Back then manufactured machines where in the 100's of thousands of dollars to buy it was a good build and has paid itself off many times over, actually I still use it to mill parts for my other projects now. I started a mill conversion 5 years ago funny thing is its 90% done with everything here ready to go to complete, Ill talk about that one soon.
My issue and I really hate to admit this possibly I could be a little "OCD", I have trouble with knowing that if something can achieve say good precision when I know it can achieve great precision even though none of the other components are that capable of that precision. This irritates me, it gets under my skin and I’m simply not happy till it does what I want! Funny thing is I know its totally impracticable and not needed but for some reason if it can do it I want it to do it, or its simply not doing its job.

Quote
I have recently made a mill spindle with a 1.8kW servo. I will at some stage require an indexing spindle for
rigid tapping, but not 2.6 arc min!!!  15-20 arc min will be plenty good enuf for me. In the mean time
all I require is speed control, and not much of that...max spindle speed is 3500 rpm. Unless I use a large diameter
facing tool I set it to 3500 rpm and leave it there. Saves a lot of messing around to achieve little except bragging
rights. Man does this spindle make chips...glorious chips!

Sounds like a nice mill. I am re-ferbing a Bridgeport, when I bought it for near nothing it was was somebody else's project from a local uni, the mill hardy has done any work but the nice thing was they already went to the trouble of fitting ball-screws that really was my big bonus. I have X and Y setup ready to go, I am just rebuilding the spindle (bearings ect) bringing it all back to new. What I am using for the spindle drive is an after market 2.2kw induction motor VFD controlled 1:1 timing belted to the spindle. Here is the crunch I have made up a independent slide unit that turns a 2000line encoder directly from the drawbar, tools are changed with a QC so no need to access the drawbar at all. This again gives me 2.7min/step and feedback even if using the backgearing. The other thing I have chosen to use Vitalsysetems interface as the controller, this has bean my largest expense to date just the controller, everything else was bargain basement.
Cheers
Katoh
Re: 1/2 speed spindle
« Reply #11 on: May 26, 2017, 09:41:08 PM »
Hi,
from one OCD to another....yeah I got you!

My mill is homebuilt. I used cast iron elevator weights to mill the axis beds. 15mm linear rails and cars, C5 20mm ground ballscrews,
5 phase steppers with low backlash planetaries and German made 1hp 24000 rpm spindle all bargain hunted off Ebay.
Machining volume is very small, 190x190x190mm. Amongst the things that I wanted this machine to do is make circuit boards and
it does so really well. In addition I wanted to be able to mill steels and other tuff stuff. The high speed spindle is hopeless at that.
The problem with milling steel or stainless is that you need relatively low surface speed but plenty of torque. I hadn't appreciated how
whimpy the torque is from high speed spindles is.

That's what lead me to making a slow speed spindle necessary to spin 1/2-5/8 inch endmills in steel. Budget precluded me from
buying outright or even having a precision engineering company make it for me.

I've had to learn that despite my wanting a certain thing or level of precision I can't achieve it, be it budget, skill, machining capability
and the list goes on. I've come to realise also that if I insist on a certain standard say then I may in fact prevent myself from doing anything!
This spindle is a case in point. I did buy a genuine RegoFix ER25 cylindrical tool holder and matched NSK angular contact bearings. The
problem was that I wanted it to be perfect, or as near to it as I could get, and yet couldn't afford to have someone else make it and with
the lathe I have access to and my skills suggested that if I did it myself it was going to be less than perfect. I had talked myself to a standstill.

I eventually did break thru that nonsense and did make it myself. Surprise, surprise, its not perfect! On the other hand its not to bad either,
in fact its better than not too bad, I'm rather proud of it! It works a treat, enuf torque to drive just about any tool I can fit in it and certainly
more than my machine is rigid enuf to contain the cutting forces. TIR=0.01mm, not as good as I hoped but not too bad and it certainly works.
All up including the Allen Bradley servo, servo drive, toolholder, bearings and seals plus some extra tooling for the lathe $2000 NZD.

Sometimes you've just got to overcome that OCD thing and get on with it, this example is a good one for me.

Craig
My wife left with my best friend...
     and I miss him!

Offline Katoh

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Re: 1/2 speed spindle
« Reply #12 on: May 26, 2017, 10:35:02 PM »
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from one OCD to another....yeah I got you!

HaHa! Yeah I sometimes think it is prerequisite that you must have some sort of mental condition to play with stuff in the first place!

Wow built your Mill, and Lathe, Hats off to you Sir!
I thought I was good with the router, but mind you its a bit of a beast, 3m long 1.8m wide 350mm in Z and has 1200mm "B"axis down the bottom for turning work. Gantry is all Aluminium plate on a prime mover bull section the rest of it is mild steel, It runs twin 900 steppers on each axis, not quick but quick enough for me.

The lathe  again I was really lucky with, Hare and Forbes (machinaryhouse) in Sydney  had these lathes that where fitted up with wrong motors, and sold them non motor, I bought one at a generously discounted prise, $800Au new lathe 280x750mm when it arrived I simply stripped it and only used its base and head and tail units altered the cross slide to fit a 12mm X ballscrew and a 20mm Z ballscrew driven by 500oz steppers. Was induction motor and vfd driven till 4 weeks ago now servo spindle with ESS. Don't get me wrong it was fantastic before but now I think better.

Cheers
Theo
Cheers
Katoh