My first CNC Build - MPCNC

Thanks for the explanation - I will order a rigid coupling.

I agree with all that. Those a basically springs. If I could find a cheap source for the right sized couplers I would include them in a heart beat, but at about $8 in bulk I’ll stick with a printed one.

Rigid is better, spider couplers would be best. The one you listed is not good, it is an 8mm, we use a 5/16" I know they are close but they are not close enough in my opinion. You will need to shim it with something like a soda can piece of metal. I have wrapped literally hundreds of these for a previous company I worked for to get rid of the wobbles that the off center clamp creates.

“the uglies” your wife sounds awesome! Next time I break something I am sure that will pop in my head. hahaha

Does anyone have a link for 5mm to 5/16 inch rigid couplers? I already ordered the one Dave C. linked to, so I guess I can shim it like Ryan says, but I’m curious, because I haven’t been able to find the exact size.

I order this one from china, is an 5mm to 8mm coupler
http://www.ebay.com/itm/171785430603

5/16 inch = 7.9375mm, the coupler use 2 screw for each shaft, it will work for the 5/16 inch rod.

price 2.7euro = 3 dollars…

LOL!! It’s quite catchy, isn’t it??

Was able to get all 3 axis running via computer control. Sorry, no video just yet.

One question though…on the Z axis should down be a negative value and up positive? I know on my delta printer up is positive. Just not sure if this is the same way.

I will take a video tomorrow and post of it in operation.

Yup towards your waste board is negative.

Finally got to the fun part of this build and got my MPCNC to actually move. Had a few mis-steps at first, but after some tinkering it worked out in the end.

My first hiccup was that the upper connector for the Dewalt does not seem to want to close completely. So, in an effort to prevent it from breaking I have one of the bolts just holding in there by itself w/ no nut on the end.

Next, I could not seem to get the correct GCode generated in EstlCam. I followed the walkthrough and still got nothing. The time in Repetier said 45 seconds to complete. I downloaded a Celtic knot to carve. All that I would get is the bit drilled a hole down in the same spot and that is it.

Finally, after downloading GCode from the walktrough, I was able to get the MPCNC to do its thing. When I did so, the carving was a mirror image of what it was supposed to be. In addition to that, there was a part of the carving missing. It was as if that section of the wood was lower than the other.

Turns out, I had the X-axis reversed. Once I switched it all around the carving came out perfect.

Here is a link to the video of the third and final “first cut”.

The cut looks great! Good Job.

As for the mount I couldn’t see the top mount but try turning it over. I don’t have mine on right now but I think the top one gets put on flipped over. It effects the angle as well.

I actually have the 3rd prototype printed of the new mount, but I haven’t had free time to measure the angle or test it yet (taxes, boring). The 2nd proto had a 0.45 degree angle on it not much but I really want to get it perfect now that I found and easy way to measure the tool angle.

I might have missed it, but what bit/endmill did you use in your test cut?

I will try that. I will also take a picture tomorrow of the tool holder in its current position.

Here is the endmill I am using. I purchased it as a result of a recommendation on another post.

    http://www.ebay.com/itm/5-1-8-1250-CARBIDE-2-FLUTE-ENDMILLS-WOOD-OR-PLASTIC-/151932437845?

Thanks for the link!

I am trying to build up a collection of basic endmills. I think the 1/8th will be good for cutting an object out of something or doing small pockets, but I think I need to find a 1/4 for doing larger pockets too.

Great looking machine by the way!

As promised, here are some pictures of the Dewalt mounted to my MPCNC.

Bottom:

“Top”:

Flip the bottom mount, take a look at the pics. Although it is wider there it must just be out of alignment or something. Make sure you don’t have any extra material on the part. If I print the first layer to low there is some extra material that I usually file off.

Will do!! Thanks for the picture examples. It actually helps.

Ryan’s mount is the one I incorporated into HicWic’s universal mount: http://www.thingiverse.com/thing:1245848. With either of those, you can use this part: http://www.thingiverse.com/thing:1091450 that let’s you mount PCFlyer’s dust shoe: http://www.thingiverse.com/thing:927909.

Okay, I tried the suggestion of flipping the bottom mount for the Dewalt over and I still cannot get both bolts on the upper mount secured. I made sure both halves of each were flipped in the same direction, and still nothing. Best I managed to do is twist the Dewalt a little but it still isn’t 100% secure. For now, it will have to do. From what I can tell it seems to be secure so as long as there are no issues with it as I start cutting more and more I should be fine. I do plan on upgrading the spindle at some point anyways.

I also swapped out the top Z motor mount for one with a Vac holder attachment. I plan on adding a Vac plate to the bottom so as to help keep the dust to a minimum.

And lastly, I managed to figure out what I was doing wrong in EstlCam and why the cuts I programmed in didn’t come out. The DWG file I downloaded was WAY too small, so the tool was performing the cuts, just on a microscopic level. I had to scale the image up 200%.

Ahhh. I think it is because of the twist of the dewalt. Does the bottom mount clear the little tabs? It has a notch that should line up on the lower mount. And the body isn’t round so with the little half twist you have it at is making the “corners” of the round dewalt body stick out.

Yes, I noticed the notches in the lower mount and made sure they clear the tabs on the dewalt.