Posts for Tag: PocketNC

Home Workspace | First Test Cuts with the New Vice | Pocket NC

Today I started doing some test cuts and dialing in the new clamp I made this week. 

I started by inserting the new clamp on the disk into a few CAM setup files. I then took the bar stock I had for this project and modeled it up and located it in Fusion. I knew I needed some adjustments as if the clamp was even a hair off; it would throw everything else off as well. I did a facing operation on the front face and dived into the material by about ten thou when it should just skim over the surface. I let it cut a small amount before stopping the machine; I then measured how far it cut and divided it by two to see the offset of the hard stop in the design. I then reran it, making small adjustments where necessary; it doesn't need to be perfect but close enough to ensure I wouldn't run my endmill into any significant amount of material. 

After getting it within about five thou on both sides, I noticed there were slight stepover marks that you could feel as if the stock was at an angle. I took another square piece of stock and aligned it vertically with the aluminum in the clamp and found it was at a slight angle that threw the tool off when doing horizontal passes. You can really see how far it's off in the picture where I have one lined up properly with the base of the clamp and the other in it. 

I figured this might be just due to the clamp not being perfectly flush with the base disk; however, after doing a few facing passes on that, I still had the same issue. I'm honestly pretty lost as to why it's doing this, and if anyone has any idea what it could be, advice would be much appreciated. One thought I have on it is tool runout, I don't have a dial indicator, so I don't have any easy way of checking if that's the case.

I'm going to be redoing the main clamp piece again, so that may fix the issue, but I would like to know what caused it for this piece to avoid it in the future. 

Home Workspace | Drilling and Tapping | Pocket NC

The last thing I need to do to get the new clamp in place is to drill and tap the holes on the new bed.

I was planning on using a 1/16" square endmill to boar out the holes in the disk. However, none of my tools were long enough to do the job. So I opted to use an actual drill bit this time; I first spot drilled where the holes would go then pecked my way down with a 1/8" drill bit. I wasn't entirely sure how easy it would be, but I was pleasantly surprised and only took a few seconds to make all three holes.

I then took the 4mm x 0.7mm tap I bought last week and hand tapped the center hole; this is my first time using a threading tool, and it was surprisingly easy and only took a couple of minutes. I then test fitted the main clamp piece, and it fits perfectly! I used the locating pins provided by Pocket NC and dropped those into place as well, a very nice fit for it all!

The reason for tapping the center of the disk as if I ever wanted to make another clamp/vice system it would make my life easier knowing its exact location.

Home Workspace | Finishing the Main Vice Piece | Pocket NC

I had most of the part already machined out the night before, so all I needed to do was poke a few holes for the locating pins and cut it off the stand. For the holes, I used the 1/8" endmill I used to do the rest of the part with and did a pecking drill operation. I really shouldn't have done it with an endmill as it made the hole quite a bit wider than I wanted, and there is a bit too much wiggle room for my liking. If I thought about it, it makes sense, since endmills have side cutting capabilities, any kind of vibration would cut into the walls of the cylinder, whereas a drill bit would only cut down.

After milling out the holes, I then moved over to parting the piece off the base of the stock. This was much easier than I thought it was going to be, I created a sketch on the face of the side I wanted to mill from and made a rectangle in which I could restrict the path of the endmill. I then used an adaptive clearing to remove the material from underneath. Unfortunately, about halfway through the cutting operation, I forgot the stock wasn't perfectly square in the clamp, which caused the endmill to dive into 1/6" of aluminum thinking it was air; this flipped the stock partway out of the clamp. I did get it on camera, and you can almost hear me jump when it happens. 

Thankfully I was able just to loosen the clamp a bit and get it back in place, and after that, it was pretty uneventful. I came in from the four different faces and cut each about 0.8" down then for the last operation left about 0.05," which I would cut off manually. I did this rather than having the endmill cut it all the way off in case the part fell and scraped up the finish on the piece.

I noticed that the holes for the set screw and pins didn't go all the way through the bottom of the part, so I took it over to the drill press and finished the job. I then used the small files I picked up last week to deburr the edges and clean off the bottom, where I parted it off the base.

I then took a piece of bar stock I had that this project was based around and drilled two 0.25" holes on the drill press to match the holes on the new clamp. Since the clamp screws I'd be using are smaller than the 0.25" holes, I had no problem aligning them appropriately to fit. After tightening the clamp screws, it was not going anywhere, super stable!

Since I also now have the new bed/disk that came in today, I removed the old clamp and installed it. It fit perfectly, and I only need to machine a few features on it before its ready for the part I just finished! I just rested the new clamp on the table to see how it would look in its final state.

Home Workspace | New Clamp | Pocket NC

After coming up with the new clamp design last week (see previous posts), I finally got around to machining it. Not going to lie, I was a little bit dreading since my last aluminum project failed. 

I designed the clamp fixture to match some 6061 stock I had already to make it easier on myself. I decided to use the recommended speeds and feeds for cutting aluminum by Pocket NC, and it seemed to work pretty well though a bit slow. I'm using a three flute 1/8" square endmill at approx 20 IPM. The local machinist was giving me some tips on machining it and told me to move the endmill farther into the tool holder; he said you only want it 0.01" more than what your most extended depth is to get the most rigidity out of it. That alone improved the sound of the milling by quite a bit.

I was also looking into coolant systems for the Pocket NC and asked around one of the Facebook groups, where I heard someone using it and ruining one of the belts in the table/bed. The machinist suggested I use coolant, even a light misting every hour would make a world of difference; however, after talking to the people at Pocket NC, they urged me not to. However, midway through the operation, when I was sending a few videos of it running to the machinist, he suggested I try coconut oil on a brush and lightly dab the part about to be milled, just a drop or two. I tried it and holy smokes; it improved the sound tremendously, and I even cracked the feed rate up by 20% without any change in noise.

After doing a 3D adaptive, I did a few pocket clearing and facing operations to cut the holes and clean the sides. I, unfortunately, I wasn't able to finish it due to time restrictions, but I will pick up where I left off tomorrow. Overall very pleased with the outcome thus far.

Home Workspace | New Stock and Milling Advice

While I was out today, I also stopped by a local machine shop to discuss better ways of milling out small parts, primarily the pendant that I worked on a couple of weeks ago. 

He suggested that instead of having the two pegs for the part to stand on, it would have better rigidity to have a thin flap of metal surrounding the piece. It would also help with cutting the pendant loose; for my system, I would simultaneously cut off the part and finish the face, which was quite difficult and left a bunch of imperfections I couldn't remove later. He also suggested using putty to fill in the first side milled out; this would prevent vibrations, which could cause a bad surface finish. You can see in the images of how he milled out similar parts.

In addition to all this, he mentioned that it would be easier to get the side's filleted with a square endmill vs. a ball endmill. The reasoning behind this was you would need the ball endmill to reach farther down past the part and would interrupt the metal flap around the piece. I initially thought he meant to do step-downs with the square endmill, which would leave steps on the finished part, but rather mill it to flow over the sides.

Another great piece of advice he gave me was for the tooling itself. He was saying that you only want as much flute length as you're going to use, and any more than that would be pointless and give you less tool rigidity. I've heard this from Saunders and a few other people as well but forgot it when ordering the new endmills. He also gave me a Harvey tool catalog which he said would explain the purposes behind coating and the best endmills for the material being used.

After giving me this very much needed advice, he gave me a bunch of new stock I could use to mill. Mostly 6061 aluminum but also a bar of 7071, and aluminum & bronze compound, some more acrylic, and black material that I forget the name of but reminds me of micarta.