Pulled the Trigger on a PM 45 CNC...

[Ray C]

So...Hangin' on a yak is work? I delivered them for quite a few years and considered it a PAID VACATION! Bahamas, Florida, New Jersey? Not a problem. Fill up the fridge and the expense account and we're outta there!

Not having fun here... That's an older CAT with a weird PTO and a slip-shod mounting. I'm in and out of the engine hold disassembling it and figuring-out how to design a new assembly. It takes 5 minutes to wiggle/struggle into position. Also doing some sheave work on the alternators and main generator. Next one I'm working on is much bigger and among other heavy mechanical things, will be making custom dial face borders and trim for the instrument panel.

Ray

 

[turner505]

Hey Ray,
That DRO we spoke about. Will that pretty much eliminate any error from backlash? Guess what I'm asking is will it help you get really good tolerances? Much better than without and probably much easier?
Thanks,
Houston

 

[Ray C]

Hey Ray,
That DRO we spoke about. Will that pretty much eliminate any error from backlash? Guess what I'm asking is will it help you get really good tolerances? Much better than without and probably much easier?
Thanks,
Houston

Well, yes... Kinda. The backlash is physically still present but, it is completely, 100% accounted for in the scale readings and thus, whatever number is showing on the screen is the position of the table.


Ray

 

[Ray C]

Finally found some time to actually fiddle with the CNC machine today. Most of the time, I dream-up parts, draw them in CAD then, setup toolpaths in CAM and just run the simulation. The simulation is very good and all it needs are some sound effects and maybe throw some chips around and there'd be no need to actually mill anything -just make virtual parts all day long . On a more serious note, the value of simulation is to analyze the tool path and tweak it to go easy on the tooling and also produce the best possible finish. The simulation won't show the finish but, by watching how the bit engages the material -and from prior experience of using manual mills, I can predict fairly well how the finish will look.

Anyhow, here's a non-virtual part that the machine took about 35 minutes to make. I'm pretty impressed with the quality of the part and accuracy of dimensions. The semi-circle is supposed to be 0.25 (radius) and best I can measure, it came out to 0.2497.

I've also been practicing a part that's coming-up for a job and this piece shows one of the shapes involved.

As shown, the piece is totally fresh out of the mill. Just wiped with a rag. No deburring, polishing etc...



Ray

 

[dave2176]

I like it! Is that surface one setup with 2 tools?

As far as the sound effects and simulated chips, Mach is very plug-in capable. I see an opportunity for you. :lmao:

Dave

 

[Ray C]

I like it! Is that surface one setup with 2 tools?

As far as the sound effects and simulated chips, Mach is very plug-in capable. I see an opportunity for you. :lmao:

Dave

One setup, one tool. It was a planar move. Image the bump being lined-up in the Y axis (front to back as you're standing in front looking at it). The bit started at one corner moved in the X direction and went gradually up in Z to make the bump, gradually went down in Z to make the other half of the bump and the flat on the other side; followed by a 10 thou increment in Y -and the process repeated.

The bit was a 1" carbide. 1" was chosen to give a large circumference so horizon of each 10 thou move would only be roughly a ten-thou. It's amazingly smooth.

Ray

 

[dave2176]

I can't see any stepping on the bump so I thought it was maybe a round over. Now I'm really impressed.
Dave

 

[Ray C]

I can't see any stepping on the bump so I thought it was maybe a round over. Now I'm really impressed.
Dave

I was really testing a few things with this part. A) Make sure I knew how to set it up in CAM. B) Set course-level tool paths for optimum finish. C) Verify that my backlash adjustments were OK. D) I'm trying to design a simple part so I can test calibration and performance of the machine in the future. E) See what happens when I set the CAM software to a machine precision level of 0.0002" -besides making the tool path calculations very time consuming.


Ray

 

[Ray C]

To heck with CNC and CAM... To make this part, I put it in the vise, laid a piece of really hard 1/2" dia metal on the top and whacked it really hard with a hammer. I had to use some Kung-Fu on that hammer! It dented in the back real good and pushed the circle out the front side :whistle:...






Ray

PS: [3/8" carbide ball mill @ 2000 RPM @ 11.5 ipm. Took about 11.5 minutes].

 

[waddell]

Howdy Gang,

I've been looking at this machine for a while now and still vascillating on whether to pull the trigger on one or go the more arduous conversion route on a machine with the larger 9x39 table? Something along the line of an IH model 12Z or a ZX45L. Price of an IH turnkey CNC is not in the cards

I like the idea of just bucking up and having an operational machine dropped at my doorstep, but I do have a few parts in mind that could take advantage of the longer table and X travel of a conversion.

What kind of backlash are some of you seeing on the PM machines?

waddell