Topics

11

General Mach Discussion / power supply tolerance

« on: March 06, 2012, 10:25:00 AM »

just bought a second hand multi output power supply from ebay

but there is quite a bit of difference between req'd output and

actual measured

req'd voltage (dc)   actual measured voltage (dc)

+12v                     +14.06v
+12v                     +13.79v
+24v                     +27.8v
+50v                     +48.5v
-12v                       -13.7v
+5v                       +5.2v

will this level of overvoltage damage breakout boards etc?

what is the normal tolerance on power supplies

cheers George

12

General Mach Discussion / lathe spindle control pwm or step/dir ?

« on: June 09, 2011, 12:17:15 PM »

I am currently in the early planning stages of small lathe conversion

I am looking to use 1.5kw (3ph) motor controlled by VFD

possibly a IMO Jaguar VXR inverter (1ph input)

When using mach is there preference to the type of

motor control ie either pwm or step/dir I should aim for ?

I am pretty green at this so I am trying to get everything

clear in my head first before I part with cash.

Cheers George

 

13

General Mach Discussion / 8 position lathe toolchanger

« on: June 01, 2011, 06:12:48 AM »

Hi all

I am in the early stage of converting  an Emcoturn 120
to Mach control and at the moment I am looking at the toolchanger
it appears to be a really well made bit of kit (see photos)

It is a pawl design with a spring loaded pin used for location
meaning it can only rotate in one direction ( although the manual I
have says it can move either direction but I cant see any method for
retracting pin so I think it may be for a later version unless someone
out there can put me right) The turret position is controlled by 4 sensors
and cutaway vane which produces 4 output signals shown in the table.
Movement is via a small dc motor controlled by an emco board.

It is my intention to change the dc motor with a stepper and have a fast
rotate followed by a slow reversed rotate to lock pin as I have seen a
macro on the forum to tackle this type of setup. I have also seen another
macro setup to handle pin position input. (with if possible including the
option of a manual selector or rotate switch)

I have some user experience of mach3 mill but none of mach3 turn
and this if my first venture into the nuts and bolts of system setup.

I would like to be able to either modify existing programs or write
new to suit but dont have any knowledge of vb script .Can anyone
out there tell where I can find list of commands and construction rules
or recommend a book. As this is a skill I would love to master.

Also I am  a bit lost at the moment on how to convert the sensor
output results (see table) so mach knows that for example
1011 is position 5

any help would be greatly appreciated

cheers George

14

General Mach Discussion / Spindle drive specification

« on: March 16, 2011, 09:56:24 AM »

I have an Emcoturn 120 3 ph cnc lathe am I am looking to convert to 1 ph  Mach3. To make the project more manageable it is my intention to split the overall project into smaller lumps, so for the moment I am concentrating on the Spindle drive.

My electrical knowledge is very limited so any help from the forum would be greatly appreciated particularly at this early stage to stop me going off in the wrong direction.

Existing spindle setup

The current spindle drive is a 2.6kw DC Siemens motor (GL5104-OEZ40-6JU7-Z)
with integrated  3ph cooling fan. Direct belt driven (see photos) output speed 150 -4000 rpm max torque 17.6 NM and belt driven encoder (approx 300 slots)











I have noticed on the forum that a Parker ssd 514c unit would control this motor but I had a look at the manual and it didn’t look particularly straightforward also not sure how I would tackle cooling fan. Also not sure if this motor to powerful and costly to run for hobby needs.

Question 1 Do you think it is worth persevering with this motor ?

I was thinking of saving money by going for a smaller motor say 1.5 kw with ac inverter

Question 2  Is this a false economy ? ( I want to cut threads and not sure about torque level at slower speeds)

2,4,6 pole motors !!! I am not sure what would be better for my application relating to torque, running cost and surface finish

Question 3 For average working speed say 1500 rpm.  Is it better to get a faster motor slowed down by inverter drive or slower motor speeded up by inverter?

I have noticed a massive price difference for ac inverters of the same power rating
as much as 300% the more expensive quoting vector control

Question 4 For my application is this extra cost justified? Does this just give more accurate speed control or are there any torque/ heat implications particularly at lower speed?

I have been looking at various breakout boards on the internet to see how the spindle controls are hooked up and many show inverter connections going straight back to BOB. But I have also seen speed controllers advertised and connected up to similar ac inverter drives.  Eg

http://www.cnc4pc.com/Store/osc/product_info.php?cPath=25&products_id=303

Question 5 What are the benefits of these controllers?

The lathe comes with its (very well made) own spindle encoder (see photo) approx 300 slots

Question 6 Is this too many slots for mach3 to handle and does single slot produce accurate threads?

Not sure what voltage output is for this encoder or of wiring details.

Question 7.  Do you think I should change this for new or can anyone help with info?


Any comments from the forum would be greatly appreciated. Even if you only have answer for one of the questions. It all helps

Cheers George

15

General Mach Discussion / Hot Stepper Motor

« on: June 29, 2008, 12:03:38 PM »

Hi All

I am currently adding a 4th axis to my mill (Wabeco 1210E)

The setup is now rotaing accurately but the motor runs hot

very quickly even with rotary table assembly removed.

Please find attached rough drawing showing

A) The motor details supplied by Arceuro

B) Details of how I have wired to G201 Geckodrive

Any help would be greatly appreciated

Cheers George

16

General Mach Discussion / 4th axis setup

« on: June 19, 2008, 03:11:14 PM »

Hi All

I am running a wabeco 1210 and I am currently trying to add a 4th axis.

I have used an Arceuro 4"" rotary table and stepper and connected up

using an oldham coupling arrangement.

Problems.

1) The stepper is moving very slowly compared to the other axis

2) I have a loss of accuracy. eg when I tell it to rotate 10 deg it will rotate approx 9.5 deg

(measured using the scale on the table)

I have gone through the full coupling and there is no signs of slippage or backlash

(when power is disconnected the movement turns easily)

My motor settings are as follows

                steps per            vel               acc                 g

x axis          1000               1500             192             0.019579

y axis          1000               1500             190.8           0.19464

z axis          1000               888               89.77           0.0091548

a axis          400                3592.8           689.06         0.070267

Kernal speed 25000

I have tried to up the vel/acc with only marginal improvement

My logic for the 400 steps per is as follows

rotary table ratio 1:72
system uses geckodrives G201 with 10 micro steps
motor step angle 1.8 deg =200 steps per rev

mach steps per rev = 200 x 10 microsteps = 2000

steps per = 2000 x 72 / 360 = 400


Can anyone help ?

Cheers George

17

General Mach Discussion / Near crash

« on: July 18, 2007, 02:46:15 PM »

Dear All

I am new to cnc and still on a steep learning curve. Today I produced a pocket with island using Autocad 14, loaded it in to  Lazycam pro 2.08 then ran it with Mach 2.065. All was well until near the end the cutter did a rapid speed through  the workpiece. Thankfully I was using a soft plastic so no harm was done.

N1050   G0
N1055   X225.7769  Y35.6699
N1060   Z10.1
N1065   G1 Z-1.000 F50

It looks to me as though Z10.1 needed to be before the G0 command. The programme did several repositionings prior to this without incident.

 Am I doing (or not doing) something stupid?. Is this a common error I need to be aware of.?

Any help would be greatly appreciated as my underpants can only take so much trauma

Cheers George

18

General Mach Discussion / Abnormality (Exact stop vs constant velocity)

« on: July 16, 2007, 02:44:18 PM »

Dear All

I have just purchased a tapping head which has a geared ratio of 1:1 (ie same feed going in as withdrawing). Tha manual recommends programming using G85. This works to a point except it chatters on the way out. The trouble shooting guide says the problem may be due to the fact process not using constant velocity mode. I have altered the general config file to cv mode but during the process it always reverts back to exact stop.

Does anyone have any ideas on what is controlling it?

19

G-Code, CAD, and CAM discussions / Tapping using G85

« on: July 12, 2007, 04:52:01 AM »

Dear All
I am new to the cnc world and am still finding my feet. I have just puchased a Tapmatic tapping head SPD5 which has a geared ratio of 1:1 . Want to use tapping head rather than rigid tapping as I want to reduce wear and tear on machine
as it is a small benchtop model (wabeco 1210). As the feed for this unit needs to be the same going in as out the instruction manual recommends programming with G85. When using lazycam I have treated the drawing as 2 drilling operations then I manually edited the second drilling operation from G81 to G85. This works to a point. Except there is a small amount of chatter on the way out. The trouble shooting guide says this problem may be due to the fact process not using constant velocity mode. I have altered the general config file to constant velocity mode but during the process it always reverts to exact stop. (the backlash is not enabled and cv less than angle is not enabled) I have tried the program by modifiying the program to use two G01 lines and this works but this method is a pain when there is a few holes . I liked the sound of LAZY cam for a reason. My two questions are A) Is there an easier way of using the tapping head via lazycam that I don't know about?   B) Any ideas on what is controlling the constant velocity mode?
Cheers George