Messages

91

General Mach Discussion / Re: Need help: Z origin reference changes one code starts ????

« on: January 22, 2018, 06:30:46 PM »

There are two sets of coordinates, machine home, and work origin.  Which are you resetting?  When I pick up the top of a part using a 3/8" pin under the tool I just click on the value in the Z DRO and enter .375 and hit enter.  The machine says the tool is 3/8" above the part and we are good to go.

92

General Mach Discussion / Re: How to resume after G code is stopped safely - problem

« on: January 21, 2018, 06:10:21 PM »

zmajmr,
When you pressed feed hold it was already too late!  The speed change was already in the buffer. Seriously, thousands of machines operate this way without problem and you want to argue that it is wrong because you lack the necessary programming skills to do it correctly.  Work on that, you'll get there faster.

93

General Mach Discussion / Re: How to resume after G code is stopped safely - problem

« on: January 21, 2018, 11:23:56 AM »

Mach 3 can’t rewind the buffer. So it starts up again at the next line after the buffer. Mach 3 can be restarted anywhere in the program. However you really need to think about this because if the 300mm feed rate got applied in the buffer then you need to start at a point before the 40mm feed was called and you should make sure the first move after that is a safe one. Preferrably it is a move to the clearance plane.

94

General Mach Discussion / Re: How to resume after G code is stopped safely - problem

« on: January 20, 2018, 07:42:38 PM »

The why is very simple. All CNCs apply look ahead. They don’t process one command at a time. A G1 is a cutting move and what follows is important too. If it is the last cut the tool must come to a complete stop. If it is an arc and you have continuous motion enabled it needs to consider the radius to decide how to slow down but not stop. It also must calculate the deceleration moves involved. These calcs get done as quickly as possible and stuffed into a buffer that is feeding the commands to the motor. so to actually maintain position you need to empty the buffer in a feedhold. Hitting Stop basicly says forget about where the tool is and stop as fast as possible.  See your 300mm rapid? On my machine the rapid move is 7600mm/min!

95

General Mach Discussion / Re: How to resume after G code is stopped safely - problem

« on: January 19, 2018, 07:36:16 PM »

Zmajmr,
What you want is to do something wrong and the machine will gracefully stop and let you try again?  Hitting the Stop button, not E-stop while any axis is moving looses position. It may be a small amount if your machine is slow and you don’t notice it. My machine travels quite fast and no way I can recover from a Stop push, but no problem with feed hold. So lets work on your skills.

When drilling a hole almost any depth always use a peck until you know how the material reacts. The CNC can’t that you can drill 3 holes and will suddenly wrap the chip. A peck is a chip breaking technique that is why it is there.  

When opening up a hole you drilled using a boring bar try pecking that too. Going from a 1/2” drilled hole to a 1” hole x 2” deep, do it in 1/4” pecks leaving a little for a full depth finish pass.  This will keep the chips from packing.  The part will be stiffer for each cut and may reduce chatter.

When you program a part set your feeds higher than you think you need. Mach 3 feed overide goes up only 250% but it can go down 20 to 1 to 5% with no problem. Then always start with the overide way down and increase it until it is cutting properly.

The faster you can feed the better. Not only do you get done faster but tool life goes up to. That happens because the cutting edges pass through the material less time. A heavier cut also helps to break the chip. If you haven’t broken any cutters by feeding too fast you should. You will likely be shocked how far from too fast you really are. I had a slotting job in steel that was 1/3 done and had worn out 3 end mills. Pushing the feed way up finished the job in half the time using one endmill.

96

General Mach Discussion / Re: 3d scanning with mach3

« on: January 19, 2018, 10:59:02 AM »

Tony,
Can’t help you with the probing, I am just familiar with Keyance having used their stuff in the past.
Their laser displacment sensors are so fast they can measure a tuning fork position while vibrating at 20 Khz! So if you get this to work scanning should be really quick compared to moving the Z up and down constantly.

97

Mach4 General Discussion / Re: Is Mach4 really Hobby Material?

« on: January 18, 2018, 08:53:11 PM »

This discussion reminds me of a conversation I had with a customer who bought one of the robotic greenhouse watering/spraying machines that I used to build.  He calls up all pissed off because the machine crashed into the end wall, got the boom all twisted up in the motorized vent louvers, and continued spraying water damaging a lot of plants.  I asked him what the machine said, because our machines had voice synthesizers and would tell you exactly what the problem was.  I asked did it say "Collision, Boom twisted' or anything like that?  He said no and I thought about it for a moment.  Then I said "YOU were driving, you had it in manual and weren't watching it. Why didn't you run it in auto?"  He "Oh I haven't had time to learn how to do that!"  I hung up on him.

Two months later he comes into my booth at a trade show and says "Well, that was embarassing!"  I said "You mean the part where all you had to do was flip the switch to auto and press start and the machine tells you how to enter a speed so it knows how much water to apply then does what you ask with no crashes?"  He says "Yeah that part too."  So this machine was capable of doing useful work right out of the box despite the fact it was extremely programmable for those who were interested.

98

General Mach Discussion / Re: 3d scanning with mach3

« on: January 18, 2018, 06:03:42 PM »

Tony,
Good stuff, probably cost more than your machine if purchased new!

99

General Mach Discussion / Re: DIY plasma no movement after first arc

« on: January 17, 2018, 06:16:15 PM »

Since it is serial not a parallel port and you send and recieve signals the com and the Bob must both be working. So it sounds like you have not enabled something in Mach or on the Bob. Since you changed the grounding my suspicion is you were using the ground as the DC common and have lost that.

Plasma is extremely noisy and difficult to shield. So you may need to more than just redo the grounds. I have seen so many grounding issues in my career it would be interesting to see a picture of your grounding system.

100

General Mach Discussion / Re: 3d scanning with mach3

« on: January 17, 2018, 05:59:45 PM »

Tony,
Take a look at the lasers offered by Automation Direct now. I think they have one that would meet your accuracy requirements, at a price that is worth the effort you won’t need to make. Reflection is not a real problem, pro photograhers have tons of tricks to deal with that which would work here.