Messages

111

G-Code, CAD, and CAM discussions / Re: How to change the speed of spindle on the same line without stops.

« on: January 08, 2018, 09:48:32 AM »

Dan,
Lots of people try to use Mach for a custom machine because the thinking is that if it can control a CNC machine then it should be easy and cheap to use it here.  Nearly everyone winds up where you are, some little tweak you need but can't do. Figure in the cost of the PC and keeping it running and the cost is way higher than you realize. 

However there is a really good answer now for what you are trying to do.  You need to use an Automation Direct DoMore BRX plc.  You can get them with up to 8 high speed outputs to control stepper or servo at up to 250Kz step rate.  Lots of digital IO. Up to 4 channels analog inputs and 2 channels of analog output on the base module.  Expansion modules available of all kinds.  The BRX has a ton of motion commands and can do what you need easily.  Programming is via DoMore Designer ladder logic software which is FREE. Phone tech support is excellent and FREE. Has ethernet, serial, modbus communications and can do email and talk to anything.

I use them at work, and just installed one in my homebuilt CNC so that I can get control of my lathe spindle running on a large stepper motor, which Mach can't do, plus controlling the heat for the 3D printer extruder, and the heated build plate, and analog output to my DC mill spindle controller.

112

G-Code, CAD, and CAM discussions / Re: Need help with this drawing for G Code

« on: January 07, 2018, 05:36:36 PM »

EDIT: Just so you know, six weeks ago I did not know how to spell G Code...LOL I am into a serious learning curve. I am retired and have no need to work and all this is just something that interest me. The machine shop I work at is just a fun place for me to pass time at. Yes, I actually do things there that are useful to the owners, but it is not a real job for me. All the code they run is manually programmed...kinda crazy but it is what it is. I understand trig and geometry well enough to muddle through it so that helps.

A larger issue I am having is the use of I and J. I can make it work some times and at others I get totally lost!!...LOL It is a critical part of learning G Code, especially if one need to do much mirroring. The quadrant issues are required understanding to make all this work. Well...poco a poco as we say here in Miami. 

Any shop doing all manual programming in this day is just plain stupid. I've done lots of manual programming and the operators thought I was really good it at.  However you can't make money programming for hours when even a HOBBY Cam program can blow your doors off.  We do really simple parts for our own products.  We use a hobby grade program called CamBam.  40 Sessions for free, $150 to buy perpetual license with upgrades.  We use it do internal and external tapered pipe threads, 3D machined nozzles for our plastic welding guns, 3D machined housings for the bottom of a strainer, used the mill as a lathe to cut a large diameter gasket mold and ground the tools for that task, modified a stainless pump housing, engrave nameplates with text and our logo, circular mill tapered flanges for valves.

There really is NO excuse to waste money manual programming everything.

113

G-Code, CAD, and CAM discussions / Re: How to change the speed of spindle on the same line without stops.

« on: January 07, 2018, 10:54:55 AM »

Dan,
Is this a mill, router or custom machine you a controlling with Mach?

114

Tangent Corner / Re: Looking for ideas / advice, i think :)

« on: January 05, 2018, 08:16:01 PM »

Dave,
This is a really tough one. There is a really huge problem that no one thinks about but actually happened to me.  I built a machine that kinda sorta worked and then sold it to a company.  It was too slow to get all the work done so they built a mirror image copy on the same frame.  When an employee got hurt because they cut a few corners, like guards, they said he got hurt on the machine I built.  $15,000 later I was able to prove I didn't build the machine and the judge let me out of the suite before going to trial. It would have cost $100,000 to go to trial, even if I won!

You can be sued 30 years later, so insurance doesn't help unless you pay until you die.

Since then I have designed and built lots of machines. Some were one offs. They all had one thing in common.  For every one I got a regular hourly pay check and W2.  If a customer employee got hurt he couldn't sue me or the company, only workman's compensation.  If I got hurt I could sue workman's comp.  Without that paycheck I could sue the customer for all he is worth.  So both of us were protected.  One year I got 4 W2s and not because I changed jobs!

A product you make and sell is the holy grail of nearly every small manufacturing company doing job shop work.  I even have my own product.  A special paint scraper for removing bottom paint from a boat.  I got it patented, then lost my job at a company that closed and didn't have access to the equipment to make it.  A few years later I was out of a job again and the patent came up for maintenance fees of $500.  Eat or keep the patent?  Recently I made ten of them on my CNC but my wife threatens to divorce me if I try to sell them!

So I highly advise you spend lots of time honing all your skills.  I am 64 and the director of engineering, not cheif engineer because I don't have a degree.  I do have 4 patents.  But I do electrical design and wiring, PLC programming, CNC programming, machining, welding of all kinds, and use Rhino, AutoCad and SolidWorks every day.  So at an age when lots of guys are no longer relevant I hold my own with the young guys surrounding me.

115

General Mach Discussion / Switches for Home position

« on: January 04, 2018, 12:29:48 PM »

For those of you that want to home your machine very accurately so that you can resume a job after a shutdown for any reason I see that Automation Direct is now offering precision limit switches down to as low as 3 microns repeatability.  That should do it for most of us!  I have sloppy limit switches to prevent crashing into the ends of axis travels and can home to them but the repeatability is very poor. I might add a couple of these so I can home it for position.  These switches might be good for building an accurate tool touch off plate to.

116

General Mach Discussion / Re: M6 Macro tweaking

« on: January 01, 2018, 06:54:38 PM »

Yes, the issue I thought was that you couldn't make a motion move while the M6 macro was active.

117

General Mach Discussion / Re: First Run on CNC machine

« on: January 01, 2018, 06:53:25 PM »

Craig,
For DC motors speed is proportional to voltage and torque is proportional to motor current.  So for a common DC controller with I^2R compensation the torque and therefore the current will remain constant. So power=current x voltage will be 1/4 at 1/4 voltage.

118

General Mach Discussion / Re: M6 Macro tweaking

« on: January 01, 2018, 02:23:50 PM »

Dave,
My thinking was actually driving the table vertical axis entirely separate from Mach 3 and only passing the actual tool length to the PLC in the M6 macro.

119

General Mach Discussion / Re: M6 Macro tweaking

« on: December 31, 2017, 10:18:19 PM »

Dave,
My multi-purpose machine has a PLC in it because it allows me to do things not easily done by Mach 3. I recently replaced the surplus DL06 I was using with a DoMore BRX because of all the stuff it brings to the table. It has high speed inputs and outputs with motion commands so it could control the motion of your knee lift. It talks ethernet, serial, and modbus so you can send the tool length to the BRX and let it position the table and tell mach 3 the position move is done. Mine runs everything including air blowoff, misting, flood, vacuum cleaner, lights, safety circuit, heaters for the 3d extruder, 3d bed heater, lathe spindle and index pulse for threading etc.

120

General Mach Discussion / Re: First Run on CNC machine

« on: December 31, 2017, 10:07:46 PM »

John,
You don’t say anything about your machine other than spindle power and if it came with a 400w high speed spindle it is very likely it is no where stiff enough for a larger spindle motor or larger diameter cutters.  You need to match cutter diameter, engagement, rpms, and power for the best performance. A software tool like FSWizard is really valuable in doing this. You should try for a tool that will run at full motor rpms. Cutting the speed in half means you only have 200 watts to the cutter. There will be an optimum tool diameter for each material and for some materials at the maximum speed there will be no good choice.

I wrote in another thread about machine stiffness and how to measure it. You should give that a try before buying a bigger spindle.