Messages

311

Mach4 General Discussion / Re: Just starting out

« on: January 29, 2023, 10:56:46 PM »

Hi,
my fourth axis is pictured above as is the new worm drive that will become the fifth axis. The chuck will be removed from the fourth axis and a trunnion
table will be fitted in its place. I will probably use a stepper for the fifth axis to start with until I can get another servo. They cost $1000NZD by the time
they get here, so I usually have to save a bit!

The mechanical and electrical fitting are no trouble.

The real challenge will be to get the post processor to produce good code. I've had pretty good results with the rotary fourth but a fifth is going to be a step up.

Craig

312

General Mach Discussion / Re: tips for getting started with 2 axis plasma cutter

« on: January 29, 2023, 09:14:38 PM »

Hi,
that breakout board you pictured is a parallel port breakout board. Are you intending on running Mach3's parallel port?
If so you'll need a 32 bit PC Windows 7 or XP. Are you really sure you want to start with such an antiquated solution?
I haven't used a parallel port in ten or eleven years.....and I certainly don't want to go back there.

Craig

313

General Mach Discussion / Re: tips for getting started with 2 axis plasma cutter

« on: January 29, 2023, 09:05:02 PM »

Hi,
firstly, flat material does not stay flat when plasma cutting, thinner materials are notorious for buckling and you'll need THC to keep up with the height variation.

But I saw a video somewhere where he did it by measuring voltage with arduino and sending a signal to this board, but it was not clear how.

That is basically DIY THC, perhaps you should ask him how he did it. Many people have tried and some have even succeeded. Good luck.

Craig

314

Mach4 General Discussion / Re: Just starting out

« on: January 29, 2023, 08:00:07 PM »

Hi,
it's taken me nine years to get around to fitting a fourth axis, and I've made a start on a fifth axis. I will need to complete it fairly soon because
I have paid $2000NZD for a 12 month subscription to Fusion Machining Extensions for four and five axis and I need to use it before it expires. It's by no means certain
that I can afford to renew the subscription especially as it will be full price this time, $2700NZD! Katz is right, four and five axis is ambitious, even five axis
CAM is going to set you back on your heels without counting the hardware.

Craig

315

General Mach Discussion / Re: just bought a little baby cnc 280mm square davinci style thing

« on: January 29, 2023, 07:20:45 PM »

Hi,
my first mini-mill which I used for eight years had five phase Vexta steppers and they are superb. Admittedly my steppers only had five wires and the
drivers (direct off-line) had the colors marked, so it was easy. I tuned them to do 2400 rpm through an integrated 10:1 low lash (<2 arc min) planetary
gearbox direct coupled to the ballscrews. Once I got them dialed in they were perfect, never missed a step unless I did something stupid.

The natural resolution of a five phase stepper is 500 pulse/rev, compare that to a two phase stepper of 200 pulse/rev, so the 5 phase wins hands down there.
You try and get ANY two phase stepper to do 2400rpm. I did use 3000 rpm at one stage, but they got just too hot so I dialed them back a bit. The drivers
are direct connected to incoming 230VAC supply. The drivers themselves put out about 150VDC so that's why they can go so fast.

I paid big dollars for them second hand nearly ten years ago now, and they lasted all the eight years on my mini-mill. I managed to blow one up when
I put it on my new fourth axis on my new mill a while back.. I have no regrets, those little motor did thousands of hours for me, and they were old when I got them!

The bottom line is that five phase steppers are all high quality premium steppers, reuse them if you can. There were only a few manufacturers of them, Vexta (Oriental Motor),
Largher and Pacific Science are the ones I remember, but I seem to recall Sanyo-Denki made them as well. All top tier companies.

I have four Vexta RKD514L-C drivers if you need them. 230VAC input, 5phase full step and half step output, up to 1.4A/phase. They are old now but still Japanese quality.

Craig

316

Mach4 General Discussion / Re: Just starting out

« on: January 29, 2023, 03:31:39 PM »

Hi,
if you are considering high torque 34 size steppers, be careful. While they have great low speed torque they often hqave high inductance which means the torque falls
to near zero at as low as 500rpm. They are also subject to mid-band resonance. You need a machine that exhibits an inertia ratio of 2:1 or 3:1 or better otherwise
mid-band resonance will screw you.

The important spec that you need to consider when buying stepper is inductance, the lower the better.

23/24 size steppers, 1mH-2mH, 1mH preferred and reject anything over 2mH
34 size steppers, 2mH -4mH, 2mH preferred and reject anything over 4mH

Often a modest 23/24 size stepper say 400oz.in but with low inductance and therefore retain useful torque at 1000rpm, say 35% of its initial 400oz.in or 140oz.in
whereas a 34 size stepper having much higher inductance will have only 5% of its torque at 1000 rpm. So even if it had 1600oz.in initially it would have only 80oz.in
at 1000rpm, if it did not stall already! The 24 size stepper is better overall.

This runs contrary to the popular belief among new buyers, I mean high torque has got to be better than low torque right?....but sometimes no. Its all about how much
torque a stepper retains at speed, and there often a 23/24 size stepper will beat a 34 size stepper.

Craig

317

General Mach Discussion / Re: Spindle stops and then immediately starts up again (Mach3)

« on: January 29, 2023, 03:04:12 PM »

Hi,
you need to use a multimeter to measure the PWM 0-10V that controls the spindle. If it fluctuating then Mach/UC100 is at fault, if its steady
then the spindle or VFD is at fault. May also need to look at the On/Off relay.

Craig

318

Mach4 General Discussion / Re: Reading spindle true RPM

« on: January 29, 2023, 01:25:39 PM »

Hi,
no that is not what I remeber but there is a some good stuff in that thread.

I was of the opinion that Mach4 did the spindle speed calculation and averaging but am now beginning to wonder if
I'm not mistaken, maybe this occurs in the motion controller.

Craig

319

Mach4 General Discussion / Re: Just starting out

« on: January 28, 2023, 06:42:45 PM »

Hi,
just as a case in point I earlier posted a pic of a new servo reducer I bought off Ebay. The reducer cost $180USD and the shipping within the US was $36USD.
It is being shipped to my NZPost address in Portland Oregon and the reducer, about 10kg, is coming from North Salt Lake Utah. I paid Ebay at 10:00 am Friday
morning (NZ time) and its already in Portland at 1:00pm Saturday (NZ time). It hasn't hit the NZPost depot yet, and probably won't until Monday (US time),
but still pretty damn good.

Craig

320

Mach4 General Discussion / Re: Just starting out

« on: January 28, 2023, 06:24:57 PM »

Hi,
I had determined that I wanted C5 ballscrews or better when I designed and built my mill, but there is no way I can afford genuine
ground C5's....so I bought second hand. The problem with second hand is that you can't always get exactly what you want, so you have to make
your machine fit to what you can get.

I'd have to recommend getting the ballscrews and linear rails BEFORE designing and building the frame, otherwise you'll find that you have to pay
a big premium to get parts to fit your machine, when if you'd made your machine 50mm smaller (or bigger) you could have gotten such and such ballscrews for
1/4 the price.

I have made many purchases from this company:

https://www.ebay.com/str/industrialpartsshop?_trkparms=folent%3Aindustrialpartsshop%7Cfolenttp%3A1&_trksid=p3542580.m47492.l74602

For the same money you would pay for new C7's you might find second hand or new old stock C5's or C3's.

I have three THK 32mm diameter, 5mm pitch, 650mm long, double nut (BNFN) C5's that I got from this company, and cost $1000USD including shipping to New Zealand.
They look like new old stock to me. I don't think they'd ever been used. I could be mistaken about that, but whatever they are in perfect condition for my machine.
I would expect to pay $2000 each new, and that's just the ballscrew, and does not count the BK25 support bearings which would easily be another $500 a pair.
I would say I got $7500USD worth of products for $1000USD, and that is quite a saving and allowed me to build a much better machine than I could otherwise
have afforded. Funnily enough I didn't have to pay GST on those either!

I got new old stock 20mm THK linear rails (648mm) and HSR cars from the same company for $700USD including shipping, and that's for three sets, ie six rails
and 12 cars. A big saving on new, not quite as dramatic as the ballscrews, but certainly made it possible to build a nice machine for the money I had. I didn't pay
GST on those either!

You may detect that I take some delight in avoiding the 15% GST that is occasioned on all products entering New Zealand, and shame to say it, it's true.
Mostly however I do pay. For instance, now if you buy off Ebay the 15% GST is automatically collected and forwarded to the NZ government by Ebay.
Most other products where the supplier does not lie about the true value of the products then customs comes after me for the GST. My favored means of getting
stuff from the US is to use a freight service offered by NZPost. I effectively have an address in Portland Oregon, and have a US supplier send it there, no trouble.
US post is good within the US just crap outside the US. Then NZPost handle the international shipping which includes me paying the required GST. So its not so much
that I don't pay GST but I look for a discount where I can get it

To reiterate I would get the ballscrews and linear rails BEFORE building the machine. If you are patient and troll through EBay you'll pick up some bargains that will
mean a much better machine than the cost would suggest.

Craig