Category: CAMing

AHhh, Tapping! That activity invented by the human race which is destined to provide countless hours of hair pulling, carpal tunnel, broken taps and all sorts of vocal maladies launched into mid air while fueled by disproportionate demons.

Unless you do it right…

Except it is not that easy to make it right!

One of the beauties about using CNC machines is that it removes the burden of tapping from your shoulders. Is the tap at 90 degrees with respect to every possible axis on all parallel universes? CHECK! Is the right force being applied? CHECK! Will I break a tap? Well, it won’t be you, but the machine. CHECK!

The only problem with using a CNC machine to do your taps is if you, like me, do tapping every three months. Although most of the time I do it I get it right, the truth is next time I need to do it I have COMPLETELY forgotten how on Earth I did it. When that happens, I find myself looking through all of my reference material and wasting about two hours of time before I can let Sprutcam compile the G Code.

And that is where I am today as I write this post. I have completely forgotten how to do this, so I have decided it won’t happen again. Next time I have forgotten (which will be in a couple of days…) I will simply tune to this blog and WHAMMO! Problem solved!

First place I go to check how to tap the crap out of my material is Tormach’s Blog. Although this posting is practically ancient (more than 4 years old), it has some of the nuggets which get my memory cells jump started:

http://www.tormach.com/blog/tensioncompression-tapping-and-sprutcam/

Unfortunately, there are still a few questions I can’t answer by looking at the 4 pictures they have provided. For example:

1. How do I choose the RPM?

2. Are Aliens visiting us?

And so I then tune to John’s (from NYCCNC) Youtube channel and watch the next video where I still don’t get much of an answer on how to select the 300 RPM but I kind of answer question #2. Just kidding man! This video has a bunch of very useful information!

NOTE: I didn’t ask John for his permission to link to this video, so I truly hope he doesn’t send a horde of lawyers to pursue my sorry butt. John, if you want the link removed feel free to let me know!

I did a quick search and found this table which gives a bunch of RPM rates for different materials and depending on the screw. It gives us the same equation we have seen over and over (Feed = RPM / Thread Pitch). The RPM values, however, is what blew me away! If I have been using 300 RPM for aluminum, I have been doing this wrong!

http://balax.com/sites/default/files/Suggested-Tapping%20Speeds.pdf

Another option is to use GWizard. I thought of giving this a try and found that 300 RPM is also a big mistake! Intriguingly, the GWizard output is not identical to the table I linked above. Then again, this table may be meant only for those taps. Right? How would I know? What I found interesting is that according to GWizard, the same RPM applies for both aluminum and plastic. At first I thought the program was not updating the selection, but choosing Stainless steel quickly modified the values to smaller numbers, which makes sense. Why is GWizard different to the table?

And why on Earth is everybody assuming 300-500 RPM for aluminum!!!!

Well, no fret. It is time for me to give this a try and hopefully I don’t send my scarce number of taps into hades. At least now I know that a few weeks from now, when I need to tap again, a guide on how not to soil my underwear will be available!

I do not recall how much I paid for my Sprutcam license, although I imagine it must have been somewhere in the vicinity of $1500.00. There are many CAM software suites out there, and although Sprutcam has managed to piss me off countless times, I am still confident it is one of the best deals out there.

What truly pisses me about Sprutcam, as well as any other software based on the ultimate form of mistrust, is the darned dongle crap. It truly bugs me for two reasons:

1. Dongles imply that you can only use the SW on one computer (which is of course the main reason why there is a dongle in the first place) and

2. I still wake up at 3:00 AM in the morning fearing my dongle has been lost in which case I have miserably wasted whatever amount of money I paid for in the first place.

Item #2 will plague me forever as there is no legal way of copying this dongle in case something heinous happens. Item #1, however, I set myself to solve.

But why?

Well, as it turns out, Murphy’s law makes it imminent that the most that you need a software to run in only one computer, the more that you will need to use it in two.

My main computer is inside the house, on the second floor, might I add. This is where I work my designs and do the CAMing. As I specified, it is in the second floor which brings us to the Murphy’s law stating it is 100% certain the better you have done a CAM in the second floor of your house, the more probable it becomes you will find bugs while you are in the first floor.

Of course I can’t have my PCNC1100 milling machine in my second floor, but I can’t have the main computer on the first floor either, so what to do?

Well, I decided to install a second computer to do quick fixes whenever I am running a job in the garage, where the CNC machine is located. Unfortunately, for this to work, I would need to be moving the dongle up and down on a continuous basis. This is a clear violation to the Murphy’s law which states that as soon as you start moving up and down that ridiculously expensive item you dread to lose, you will either loose it or misplace it whenever you need it the most!

Once again, what to do?

I thought of installing an USB switch so that I could remotely specify which computer is entitled to use the USB dongle. It doesn’t work 100% perfect because every now and then the USB switch develops a temper, but for the most part it has become the solution.

This is the USB Switch I am using, and you can find it here: http://www.amazon.com/Cables-Unlimted-USB-Automatic-Switchbox/dp/B0006N213K/ref=sr_1_10?ie=UTF8&qid=1393466095&sr=8-10&keywords=cables+unlimited+usb+switch

This solution still poses a problem. Sure, you can now have two computers to claim the dongle, but how on Earth are you going to hook two computers into this thing when one of them is on the second floor and the second one is on the garage? USB standards forbids such a long cable!

No worries! The solution comes in the form of an USB cord expander which utilizes a CAT5 cable connection, or this: http://www.amazon.com/SANOXY%C2%AE-over-Extension-Cable-Adapter/dp/B003BDMK3S/ref=sr_1_1?ie=UTF8&qid=1393466340&sr=8-1&keywords=USb+RJ45

I have been using this solution for three years. In that time, one of the USB extenders died so I had to replace it. But man, at less than $10, who is counting?

So here you go! An entire solution for less than $30 which beats buying two licenses of Sprutcam. Now, if I were a Rockefellarian, then I could buy 2 licenses. Although the truth is if I was a Rockefellarian, I would have a shop so awesomely big, my main computer would be besides the milling machine.