Messages

6831

General Mach Discussion / Re: Mill Spindle Speed Control - DC Motor

« on: August 19, 2017, 03:01:33 AM »

Hi,
years ago I was working in a workshop and we had an old lathe, big sucker but pretty worn. I had no problems turning bushes and things like that
provided I didn't need to get closer than a couple of thou.

When a boat propshaft came in the boss would call Bob, a local guy, retired fitter and turner trained in the UK old school. He had a little notebook that
he had made for this lathe and he would get it out and turn tapers to PERFECTION! It was my job to blue and lap the prop onto the shaft and I never
had to work hard for it... I asked Bob any number of times how he did it but the old bastard would just smile and tap his head with his finger.

I've tried for years ever since trying to improve on the basic accuracy of the machine tool I'm using at the moment. The real trick is not just the quality
of the tool but the smarts that you need to add to get really good results like old Bob did.

Craig

6832

Mach4 General Discussion / Re: mc code to read and wirte to chance motor steps.

« on: August 19, 2017, 02:45:09 AM »

Hi Gary,
it might be nice to be able to use the InfoStruct in a script but how realistic is that?

If I understand correctly the only data structure that LUA has is  a table. While a table can and is used in some ingenious ways its not
like the MotorInfoStruct with Booleans, integers, longs and doubles all thru it.

There are a few data structures in Mach, AxisInfoStruct for instance. For the same reason you can't access that structure complete with LUA API
but quite a few of the individual variables in the structure can be accessed with the LUA API.

I'm wondering if you might be able to achieve what you want by having two motors assigned to the same axis but only one enabled at a time
each with different 'step per' values?

Craig

6833

General Mach Discussion / Re: Mill Spindle Speed Control - DC Motor

« on: August 18, 2017, 11:09:24 PM »

Hi Keith,
pics often need to be compressed somewhat before they can be attached or alternately linked to a suitable site like photobucket.

I used a RegoFix ER25 cylindrical tool holder and turned up my own housing to accommodate matched ABEC7 angular contact bearings at the nose.
I used plain deep groove bearings at the tail, mainly due to budget....ABEC7 bearings are bloody expensive! It worked out pretty well.

I am quite obsessive and want much better than I can afford or have the skill/machinery to make. In this case I just had to buckle to the fact I couldn't
afford what I really wanted and so made the best I could from what I could afford. I'm glad I did, its by no means perfect but its certainly good enuf to
use and I take satisfaction from its making. That is after all what the hobby is about.

Craig

6834

General Mach Discussion / Re: Mill Spindle Speed Control - DC Motor

« on: August 18, 2017, 04:15:28 PM »

Hi,
I think the frame is a 'standard' size, just what standard...its the great thing about standards is that there is so many to choose from!

You are right, 3000 rpm is a common rated speed for servos in this power output. There are a number of manufacturers who regularly produce
fast servos, Baldor comes to mind. They tend to be expensive tho. While Baldor servos can be had on Ebay pretty cheap the drives are
eye-wateringly expensive, Baldor is owned by ABB and they traditionally are really expensive, I avoid ABB on principle!

The Allen Bradley servo I bought is rated to 3500 rpm. Its listed max is 5000 rpm but  without trying to hoodwink the servodrive software I cant
get it to go beyond 3500 rpm. The extra speed would be nice for 1/4 inch tools but I'm not stressing, this is a hobby machine, if a job takes an extra
5 min then so be it.

I would suggest that you consider the price of a replacement spindle motor be the cost of the combined motor and drive. Depending on the
sophistication of a DC drive it may tip the total cost to be more than an AC servo and drive. An asynchronous AC motor (ie induction motor) and
matching VFD will be cheaper than any servo but probably 50% bigger for the same power.

As far as servos go... there are servos and servos! Some brands like Fanuc and Seimens are just over the top price wise and then there are brands like
Baldor and Allen Bradley and many other US or European brands which  are just expensive. Delta servos from Taiwan have a good reputation and are
well priced, not bargain basement but not bad. There are cheaper Chinese brands and a lot of those have been rebranded to sound US/European and
for hobbyists probably good enough.

The further you get from known brands the more online research you should do BEFORE you stump up your cash, once they've got your money
its too late for you to decide that the unit is not good enuf!

The range of control strategies is so broad that its hard to specify beforehand. I personally have found that very simple speed control is adequate.
I will at some stage use position control for indexable operations like rigid tapping, that capability is built in and just waiting to be used.

I note that in your original post that you have a USS. At the current time the ESS has a Mach4 plugin but the USS does not. Warp9 are working on
producing a Mach4 plugin for the USS but you may be frustrated waiting. I use an ESS/Mach4 and VERY happy with it.

Craig

6835

General Mach Discussion / Re: Mill Spindle Speed Control - DC Motor

« on: August 18, 2017, 05:27:32 AM »

Hi,
if you require speed control only then all you require is a variable DC voltage. If you wish to have an indexable spindle for rigid tapping say
then you will require a DC servodrive that can accommodate the encoder fitted to the servo. The latter option while desirable for future operations
or bragging rights does severely limit your choices and possibly makes such a drive expensive by virtue of rarity.

Is there a reason you've chosen this particular servo for a spindle? The over whelming majority of servos these days are AC servos, no pesky brushes
to wear out. I suspect that due to the abundance of choices they would be cheaper too....I would recommend a matched servo and drive.

I adopted this strategy when I bought a servo for a spindle, I bought secondhand a 1.8kW Allen Bradley servo and matched it to an Ebay Allen Bradley
drive. I did have to buy the servo setup software from Rockwell Automation (current owners of Allen Bradley) but it made combining the two was easy.

I now have (at least) three choices for driving the spindle:
1) Set up 8 distinct speeds in a table and select a speed entry by asserting three servodrive input pins in binary fashion
2) Have the servo follow an analogue voltage applied to one input pin, the gain and slope are programmable
3) Use position control, with or without electronic gearing which allows superb resolution and accuracy for rigid tapping

Despite having such a variety of control modes I find that in practice most milling jobs require the spindle speed set once at then left alone for the
rest of the job. Unless you use a wide range of tool diameters like fly cutters and facing tools don't get to hung up on speed control, you may find you've
invested a lot of time, effort and money which in practice don't get used much.

Craig

6836

Mach4 General Discussion / Re: Script not updating. Please help.

« on: August 17, 2017, 11:25:27 PM »

Hi,
where are you saving the m6 script? Sounds to me like you're saving it in a different profile.

Craig

6837

General Mach Discussion / Re: Question about Mach3 and inductive proximity switches

« on: August 16, 2017, 04:27:31 AM »

Hi,
without a reliable diagram of the input pin circuit you have to guess and experiment. The probability of blowing it up while trying to work out
how its supposed to work is quite high. If it were mine I would probably try anyway, if I can't work out how to use it then its no bloody use
to me, and if I wreck it while trying well that's just bad luck.

I damn well know that the next BoB I buy will be US/European/Austrailian or anywhere really but a company that publishes the REQUIRED
circuit diagrams....and answer their email!

Craig

6838

General Mach Discussion / Re: Question about Mach3 and inductive proximity switches

« on: August 16, 2017, 01:02:11 AM »

Hi,
I guess that the BoB of KL1212 would signal the UC400 back and forth at TTL levels as described above.

The required levels at the input pins of the KL1212 are a matter for the manufacturer of the KL1212.
I have not seen a manual for it but would be looking for the circuit diagram for the input opto-isolators.
Do you have a manual?  If this is Chinese made they may not have included such a diagram, a real PITA.
US/European breakout board documentation is often better in this regard.

Having said all that it is highly probable that the voltage levels required at the KL1212 inputs are not really critical.
In fact if they are opto-isolators you're more interested in current, decrease your series dropper resistance until you see
about 10mA with the input active. Don't go too much over  10mA, it doesn't increase signalling reliablity much but
increases heat inside the optos.

Craig

6839

General Mach Discussion / Re: Running Mach 3 as Administrator on Installation: Windows 7 PRO

« on: August 15, 2017, 07:00:54 AM »

Hi,
I'm dubious that its anything to do with the OS. Clearly in order to use Win10 you have to be using an external motion controller. The PC
provides PVT (position velocity over time) data to the controller and the controller handles it from there.

To my knowledge Mach runs on Win7 or Win10 without problems. User Account Control as applied in Win7 requires that Mach be run as Administrator
it doesn't change how it runs or the PVT data it produces.

I have two licenced copies of Mach4, one on my machine PC, a dual core Atom with onchip graphics, a real gutless wonder, and my i7 16Gig laptop.
The Atom runs 32 bit Win7 and the laptop 64 bit Win8. Aside from the Win8 machine loading big files faster and regenerating graphics way faster
both run my machine just fine. No difference in speed, accuracy or anything else. I suspect if I monitored the PVT buffer I might see the laptop being
able to keep it full but having said that the little Atom doesn't run out of data anyway.

Once you get away from the parallel port and the restrictions/requirements that it brings then Mach3 or Mach4 will run fine on just about any PC from
about Win2000 onwards. Just pick an OS that you like, work out the details necessary to get that OS to run Mach and cut chips!

Craig

6840

General Mach Discussion / Re: Question about Mach3 and inductive proximity switches

« on: August 15, 2017, 03:39:33 AM »

Hi,
if using a parallel port Mach is reading TTL levels. If your PC is 5V then logic high is about 3.5V and higher and logic low about 1V and lower.
If your PC is 3.3V logic high is about 2.5V and higher and logic low about .8V and lower.

It is not necessary to get 'up to the max' nor 'down to the min', within a volt or so is good enuf. Its a good idea to think about the current
to be sourced or sunk at the PP. Most TTL will source 20mA or so but I prefer to keep it under 5mA however I like to make sure that it has
to source 1mA or so. I find noise immunity is best within these max-mins.

Craig