[LouF]

Looks good your moving right along what software are you going to use?



Lou

[alan_3301]

Since the last update, I have integrated the computer stand into the machine.
It was hard to keep it level every time I moved it, and the stand would rock back and forth, and I could hear the hard drive banging around inside every time.. Not good..
The control box has been relocated inside of the frame instead of hanging off of the front. Now the computer sits on top of the control box.
The keyboard/monitor are hung from a interesting looking arrangement of extrusions. It does have some flex to it, and it does move around a little when machining, but not too much.
Now the front of the machine is cleared up, easier for loading material.

Sorry for the crappy phone pics, I need to remember to bring my camera

[alan_3301]

I got a chance to make one of the aztec calenders. Can't remember exactly where the gcode came from...
It came with 8inch,16inch,24inch with 60 and 90 degree vbit toolpaths made with vectric. It only used a 0.25 or so stepdown, so it took a lot longer than I thought it would.
74 minutes estimated in linuxcnc, actually took 2 hrs 45 minutes. I wonder how long it'd take with only 1 pass.
It was cut with what I *thought* was an onsrud 37-82 60 degree 2 flute v-bit. However when I look it up, that bit has straight flutes, but the one I have has a slight curve on the V.
Not sure how it changes the look, but it worked good.

I touched off Z in the middle of the piece, but I guess I had it clamped to tight on the lower edge, or my spoilboard needs to be resurfaced, OR something on my machine isn't right.
Anyways it wasn't cutting as deep as it should on the lower middle, so it lost some detail.. Oh well it still looks good.

[alan_3301]

I have an aluminum table top 40x55" 30mm thick. I want to make a vacuum holddown table. The table had some big and little holes scattered around on it, so I marked off the largest (almost) hole-free area to cut out. I thought about sending to machine shop because of thickness and weight of slab. However I decided to give it a shot and see what happens.

Bit used was onsrud 65-025 carbide super-o 0.25" single flute. The cutting length of this bit was 0.8", so i had to let the shank rub for the remaining 0.38" of the cut, because I didnt have any longer cutter and didnt want to wait.

It worked good! I set it up for 0.075" Depth of cut, full width slot @ 23ipm.
It took ~2.5 hours to do the 16 passes. the first couple passes had large chips and good evacuation, but started clogging later on, and I used wd-40 to help, It did help alot with the chips, and only took a few squirts for the whole job.

The table top slab weighed over 200 pounds I'm guessing and the finished part weighs around 80 lbs.

Now I need to figure out grid spacing and depth for the seal cord, which i haven't chosen yet. Also need to figure out how to work around the remaining few holes in the part.

and a few pics.

[alan_3301]

I got some more work done on my vacuum table. I was able to cut out the grid for the sealing gasket.
I went a little more aggresive this time around 0.083" DOC.
g-wizard recommended 0.002 inch per tooth last time, I looked in the chipload chart from onsrud this time, they recommend 0.003 - 0.006" per tooth.
I went with .003 which came out to 34ipm @ 11400rpm. It shaved a good amount of time off, and still had good finish. next time maybe Ill try 45ipm (.004 IPT)
I ran out of wd40 about 1/4 way into the job, and let it run dry for about 30 minutes, with no problems seen.
With lube it will sing when cutting, when it dries out it makes a rattle sound, The chips getting re-cut a little I think. I ended up putting ATF in a spray bottle and soaking the surface of what was left to cut, and let it go on its own the rest of the job.

I am really happy with how well this machine cuts through aluminum.
and a couple pics and a video.

<iframe width="560" height="315" src="http://www.youtube.com/embed/UhwZqgQjlak" frameborder="0" allowfullscreen></iframe>

[cambosoup99]

lookin good..shoot can't wait till mine is ready to make flakes and dust..

[alan_3301]

I was doing a little checking/maintenance yesterday and realized I forgot 2 important steps when I put everything together.
I never greased the Z axis thrust bearings. Oops! They were sounding nasty. Luckily with grease they are nice and quiet like they should be.
Also I had never checked spindle runout before, and wow It was bad.
I found my 0.125" calibration pin that came with some precise bits collets from an old router. 0.006" runout. And the pin only stuck out of the spindle half an inch.
I never would have guessed. I still had my collet-care and found some cu-tips I was able to clean a bunch of gunk out of the taper.
Now I'm getting between 0.0003 and 0.0025 (best I can tell with a 0.001 dial indicator).
Im not sure if the remaining runout if from the spindle taper or from my collets. I got er20 collets from ebay seller halmia.
They were $8 a piece and supposedly comforms to DIN 6499 standard. Not sure if there are any runout specs on that standard or if that just means its er20.
I'd like to buy a couple collets with specified runout to check against. Also would like to get a longer gauge pin to know what the runout is an inch lower than I'm checking now.

[alan_3301]

Today I was trying to check how square the x and y axes are.
What I ended up with was a 12x24 carpenters square clamped to the table, and probing the sides to see how far out it was.
With clamps and stuff in the way, i probed 10 inches apart on the 2 sides of the square. I came up with a 90.008469 degree angle.
If my machine travel is a parallelogram of 50 inches, then it will be off by 0.00147" at the limits of travel. Sounds right?

(20in diameter * pi) / 360 = 0.1745 inches per degree
0.1745" * 0.008469 degreees = 0.00147"

Now this is assuming the cheapo square I am using is exactly 90 degrees, and my probe runout is exactly 0.
Maybe I will get a quality one and check again some day.

If thats right, then I wont bother with another Y home switch to square the gantry.
Right now I am pulling it against the endstops, then turning on stepper power.
Now if only I could get my bits to spin with less than 0.001 runout, I'll be happy.

[LouF]

Alan,Why don't you cut some squares a couple different sizes and then take your measurements from the squares I would think you could tell if your off and which axis.


Lou

[alan_3301]

Alan,Why don't you cut some squares a couple different sizes and then take your measurements from the squares I would think you could tell if your off and which axis.


Lou

I think that will work if I use an external measuring device. A tape measure and 6" calipers is all I have.
I don't trust my tape measurements for being very accurate. I did measure a 4" wood square I cut out. 4.004" x 3.997"
with corner to corner measuring 5.644" x 5.641". This gives me a 90.0305 degree angle.


Now that I look back at my math, I think i forgot something. The machine will be off by 0.00147"X per 10"Y so at 50" my X will be off by 0.0147".
That sounds more reasonable.

[alan_3301]

I am working on a cnc lathe that I am cutting out with my crp4848, and wanted to share some aluminum cutting success.
I am cutting out 30mm aluminum plate. In the past I had been using onsrud 65-025 single flute bit, but was having problems with the tip chipping and at $45 a pop, I was looking for cheaper options.

I ended up using this ebay bit, 1/4 diameter 1 1/4 flute length 2 flutes. 1 4" Carbide Router Bit 2 Flute Spiral Upcut | eBay

My magic settings were 15000rpm 30ipm @ 0.070 DOC. comes out to exactly 0.001 IPT.

It cut beautifully, though I did have to air blast the chips out after every pass. It took 17 passes. A little slow, but I will not be cutting metal that thick very often.

One thing that was suprising, and I'm sure it was a fluke, all the dimensions of my parts the I can measure with a 4" micrometer came out to within 0.0001
I'm not sure about the larger parts, but with a 12" digital caliper they are all within 0.001"
I'm pretty impressed.

Here is a link to the lathe build.
http://www.cnczone.com/forums/vertic...cnc-lathe.html

[alan_3301]

it helps to know how to read a micrometer correctly.
all parts that were programmed to be 1.5" measure between 1.4982 to 1.5013 so more realistic, but not too bad.

[alan_3301]

I finally remembered to take a picture of something I made, I haven't made much in the past year, hopefully one day I will be unemployed, and that will change!
It is a standing desk converter, just an extension to make it comfortable when standing at a desk.
Now I just need to remember to use a better camera when taking pics.
Attachment 250476

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[LouF]

Alan, nice job I like it what kind of lumber did you use?

[alan_3301]

Thanks, It is MDF.
I had planned on plywood, but didnt have any and didn't feel like going to the store.
I was a little concerned because MDF usually has a poor looking edge after cutting out, it looked ok though.
I wanted it to leak really nice, so I used a roundover bit with the bearing on it, lowered the router to the correct depth, and finished all the edges by hand, with the router stationary.
I worked out really well, and I will do this in the future.
I don't know why I hadn't tried this before, for some reason I though i needed a manual router table, but this works great.

[LouF]

The MDF looks good.

[alan_3301]

Finally got around to cutting some steel on this thing. This is a 12-1 tooth trigger wheel for a motorcycle fuel injection system.

Material is 1/8" A36 Hot rolled steel sheet.
Cutting bit is a 1/8" 2 flute TiAlN coated carbide
Cut settings for a very conservative 0.0003" per tooth chipload, but the end mill didn't seem to mind, and the part had a good finish.
12000 rpms
0.008" Depth of cut
8 ipm

Probably lots of room for optimization, but I don't think I will be cutting steel very often.

[dgage]

Nice! Steel? What machine(machine,spindle,base) do you have?

[alan_3301]

Thanks, It's the machine in this build thread. An original version of the cncrouterparts 4848 machine, with a chinese 2.2kw spindle

[dgage]

Wow. Nice. Thanks for sharing. Was that a dry cut or did you spray any lubricant?