Messages

61

General Mach Discussion / Re: General Tapping questions (which way makes more sense)?

« on: March 05, 2009, 10:19:06 AM »

Radio, regarding the underfeed, yes it allows the floating holder to slighty extend as the hole is tapped. Most floating holders are meant to work that way, with more extension than compression. You want to tweak the factor so that on your machine you see slight extension as the hole is tapped. When the spindle is stopped it will extend again as the spindle comes to a stop, on my machine that's about one additional revolution, so on critical depth holes you have to factor that in to your depth setting, but its very repeatable.

Even on full size VMC's with accurate rigid tapping some machinists use floating holders on smaller taps to minimize breakage issues.

Paul T.

62

General Mach Discussion / Re: General Tapping questions (which way makes more sense)?

« on: March 04, 2009, 11:31:16 AM »

Radio, even without spindle feedback you can tap on mills with Mach very effectively without even having to purchase a tapping head. I use a floating tap holder (www.maritool.com has them) to make up for the inaccuracy of the spindle control, which in my case is just my breakout board sending an analog signal to the VFD to control the RPM of the spindle, along with stop, start and reverse commands.

Below is the tapping macro I wrote to use on the machine. I use spiral point taps and it works great, threads from 4-40 up to 3/8"-24 on both 6061 Al and mild steel. Don't sweat the reversals on the spindles, VFD's are designed to do that and smoothly ramp the motor speed up and down, you can set how fast you want this to happen.
The underfeed parameter should be tweaked for your machine, 9% is what works good for mine.

Would a tapping head be better? Someways yes, someways no, probably faster but keep in mind you lose a fair amount of Z travel with the long tapping head.

Paul T.

(Filename: TapHole.tap)
(Taps the hole at the current X, Y location to the specified depth)
(Thread Pitch in Turns per Inch must be set)
(Z must be set at zero on top of workpiece)

G20 (Units: Inches)
G40 G90

(Set Editable Parameters)
#1=0.36      (Set Depth)
#2=32.0      (Set Thread Pitch in Turns per Inch)
#3=140      (Set RPM)
#4=0.1   (Set Rapid Height)

(Internal Parameters)
#103=0.91      (Underfeed, 0.91 -> 9 %)
#104=[#103 * 1.0/#2]   (feed rate adjusted for under feed)

G0 Z#4        (Move down to rapid height)

M98 P1025 L1 (Call Tap subroutine)

M30

O1025 (Subroutine to Tap)
G95 F#104   (Set to ipr mode and set feed rate)
M3 S#3 M8   (Start Spindle and coolant)
G1 Z[#103 * #1/-1]   (Tap down to compensated depth)
M5         (Stop Spindle)
M4         (Start Spindle in Reverse)
G1 Z#4      (Raise spindle at feed rate to rapid height)
M5 M9      (Turn off spindle and coolant)
G94      (Go back to ipm mode)
M99       (Subroutine Return)

63

General Mach Discussion / Re: Opinions on use of ancient computers to run Mach3

« on: December 19, 2008, 01:02:16 PM »

I'm running well  on a 667Mhz machine, but I'm on an early 3.0 release, not the latest. I run the 25khz kernal. Its been a very reliable machine, and I'm hesitant to move to the latest release because I don't want to rock the boat, but apparently the lastest release is less CPU intensive than the early 3.0 versions, so I'm probably being over cautious.

Paul T.

64

General Mach Discussion / Re: Is my 'underspec' pc causing my problems

« on: December 03, 2008, 02:31:28 PM »

Roy, I doubt the problems you are having are related to an underspec PC, it sounds like a cutter comp problem that some Mach releases are known to have, perhaps some one else can speak on whether they have been fully eliminated from the current lockdown version.

Regarding switching to the new version of Mach3 with your underspec PC, I'm in the same boat, I'm using a 667Mhz system to run an early 3.0 version of Mach and I'm concerned about whether it will have enough beans to run the lastest lockdown version. I asked Brian about this and he claimed that the newest version uses less CPU than at least the version I'm running, which was a release that came shortly after the 2.63 lockdown version you are are running.

I'd like to hang on to my current PC if possible, its been very reliable running Mach. If the current "new" lockdown continues to look good (as it does now, the bug reports in the forum seem pretty low) I'm going to be swapping to it to see what happens. I'm going to keep a backup copy of my current Mach folder in case I need to go back to the earlier version.

I'm probably going to make the swap in a week or 2, I'm waiting for a replacement lube hose to come in for my machine, after I make the swap I'll post the results back here. Please post back how it goes for you if you make the swap in the short time.

Paul T.

65

General Mach Discussion / Re: Z AXIS KNEE

« on: November 11, 2008, 07:45:14 PM »

I just finished powering my knee (Birmingham BP clone) with an 1840 oz-in stepper motor using the stock acme screw. Its working pretty well, 15 ipm even though I'm underpowering the stepper with only 48 volts, it barely gets warm. I suspect by adding gas springs and bumping my power supply up to 72 volts it would probably make 25ipm. The stepper motor has 2:1 reduction pulleys on it.

One thing I"m pleasantly surprised about is less backlash than I thought I would have, only 0.0035" total, although I'm expecting this to increase as the bevel gears wear in some, but that's way less than I expected.

I already have a powered Z quill on this machine, but I got real tired of cranking the knee up and down manually so I added the powered knee as a 4th axis, it works real well with Mach so far.

If I was doing it over I'd likely use one of the servo motors Ray L. used, but that aside I'm pretty happy with how the knee is working so far, its a real step forward from hand cranking, and although most of the time I've been able to live with 5" of quill travel this will give me more Z clearance under program control when needed.

I don't know if I could live with a knee powered Z only, I do a lot of spotting/drilling/tapping and the limited speed and acceleration with the knee would slow that down,  but so far even with the stock acme screw it looks like it would work pretty well.

Paul T.

66

General Mach Discussion / Re: Z AXIS KNEE

« on: November 09, 2008, 02:44:21 PM »

My size 42 stepper drive BP sized CNC mill has Z on the quill, but my 55 year old back is tired of cranking the knee up and down so I'm adding an 1800 in-oz stepper motor to the knee also. I'll configure two start up files so I can use the knee for Z for heaving milling (quill locked) and the quill for Z for drilling, tapping, light milling.
So I'm going to have my cake and eat it too.

Ray L., I'd like to put some gas springs on my knee like you did, to you have any model numbers and the supplier info for the ones you bought?

Thanks,

Paul T.

67

Newfangled Solutions Mach3 Wizards / Re: Not so sweet Cut Circle in Suite of HW

« on: August 21, 2008, 12:27:15 PM »

Did this problem ever get resolved? I'm still getting the problem after downloading the 3.041 version today.

I'm trying to do a cut circle with center at x1.25, y1.25, diam 1.784, cutter diam 0.5, inside specified, climb cut specified, pitch angle 5 (although still have problem if this is set to zero).

I get a lead-in arc on the inside but then it keeps going and cuts another one on the outside.

Not so good, I ruined a nice piece of aluminum.

I've stated this before and I still strongly feel this way, you need to create a thorough test suite for these wizards and test them carefully before bundling them with Mach. Wizards are something you you need to be able to count on as being bulllet proof, but for me they've been my biggest source of crashes and ruined workpieces.

Paul T.

68

General Mach Discussion / Re: printer port vs controller card ?

« on: July 11, 2008, 01:55:38 PM »

I picked Campbells SoundLogic combo board because on one board it had support for everything I needed, DC out to control VFD speed, MPG inputs and relays for my spindle and coolant.

The only rub was the documentation at the time was a little spotty and the speed control voltage isn't quite as solid as I would like it to be, but it works. I beileve they have reworked the speed control voltage and hopefully the documentation has improved.

My motor performance is very smooth and the only time I've lost steps is in a crash, but that's when you want to lose steps. I have a BP sized mill with big honkin' 42 size steppers. I use 60 ipm max on X,Y, 90 ipm on Z. I could probably bump my speed up with a higher supply voltage, I'm running about 2/3'rds of what the motors will take, but for what we use the machine for (prototypes, small production runs) we can live with the current speed.

Paul T.

69

General Mach Discussion / Re: printer port vs controller card ?

« on: July 10, 2008, 05:23:02 PM »

I would say the SS is a bit more than Alpha but thats just my opinion.

Hood, I agree with that (and was attempting to say the same thing in my post), the SS guys have clearly done a lot of hard work and are making good progress and it appears shortly they will be at Beta, ie all PP equivalent functions implemented but further testing needed.

I poked at the SS design a little bit a while ago regarding both 3D performance and absolute real time response (both important to good performance with Mach) and I liked the answers that came back, so it appears that a lot of thought went into the SS design. I'm hoping it both meets the design goals and gets heavily adopted by Mach users, if both those things happen it should have good long term success and I'll be popping for one also.

Paul T.

70

General Mach Discussion / Re: printer port vs controller card ?

« on: July 10, 2008, 05:16:02 PM »

Joe-

I run Mach with a PP on a stripped down XP machine dedicated to Mach only. Its worked well for several years now on my BP sized mill. Its a little under the recommended min now at 667Mhz (it wasn't when I first set it up) but so far that hasn't been an issue, but I'm not running the latest release which apparently is a little more CPU hungry than earlier versions, I'm running a 3.02 version and also I run at the default 25khz kernal rate.

I would stay away from the G100, it looked promising when first introduced but it has a fundamental design bottleneck that limits performance for 3D machining and anything else that requires fast G code execution. I also don't think it acheived a large enough critical mass of users that the support for it will continue much longer, at least not at the priority level given to the PP Mach version.

Paul T.