Ungluing accident.

 

See my coolant delivery system in action in the video.

I had a problem with this part. The sawn piece was a tight fit in the pocket in the wood sub-table, so it didn't glue well, so it came unstuck soon after the start of machining. You can see the bent path left in the metal, in the video. I remachined the wood and chiselled the side of the pocket bigger and everything else went well, but there is a bit of a gouge out of the top of the circular post feature. Maybe it won't matter too much? The surface finish doesn't seem any different ( the one on the left of the picture is the most recent part ), despite lowering the feedrate to 50 mm/min instead of 100 mm/min. The tool looked slightly worn after the ungluing accident. It doesn't look much more worn after all the machining, so I think that 200 mm/min is better than 300 mm/min. Hopefully the next one I make won't have any mistakes in it.

Part 0012, number 2

I have made another of these parts. This time I tried 3mm depth of cut. It was OK. Also I tried using climb milling for the finishing pass, instead of conventional milling. It isn't much different. Also I put the coolant guard back on, so I could pour the coolant on quicker. I made a mistake with the program for this one and there is a gouge, see the second picture. The tool is very battered. It has only made 2 parts. I noticed it was a bit damaged after the first part, but it is a lot more damaged now. I will try reducing the feedrate from 300 to 200. I will use a new cutter now. Also, the later roughing cuts are leaving the material up to 0.1 too thick. I can't explain this yet, so I will try it again to see if it happens again.

Part 0012 without holes

 

 

  

I made this part. No holes in the ends yet, though. The surface finish could be better. I am doing the finishing pass at a feedrate of 100. Maybe I should try 50?

Most of the time was spent doing the roughing, because I was only happy descending 1mm at a time with the 6mm tool. It took about 2 hours machining.

Part 0012, Roughing

The next thing is to calculate roughing toolpath. Here I have made the flat faces into sketches. I have had to draw some extra sketches. If the sketches touch each other, HeeksCNC joins them together nicely. I had to enter the z values correctly. Maybe one day I will automate all of this. There are 6 separate pocket operations.

Part 0012

I am going to make this part out of aluminium alloy.

The first thing is to saw out a piece of Delrin as the sub table and pocket a shape oversize, for the aluminium rectangle to fit in. I can specify to cut a sketch oversize by putting a negative value in the "material allowance" box. I am using a development version of HeeksCNC, which includes a commercial pocketing library written by Lou Lavery, that I am planning on reselling as an option for HeeksCNC when it is ready. I am trying to write a free version of pocketing, but it's not easy.

Pocketing Reorder

Now, in HeeksCNC, you don't have to worry about which direction ( clockwise or anti-clockwise ) your sketches are drawn. Simply select them all, do "Combine Sketches", then select that resultant sketch before making a pocket operation. The python script now uses the new function area.Reorder(), which checks which curves are inside which and reorders their direction ready for offsetting.

Commercial Pocketing Software

I have been asked to help someone make a commercial Windows dll to do pocketing like in HeeksCNC. Unfortunately the polygon offsetting used in HeeksCNC is derived from the "kbool" software, with its' GPL license, so it has to stay free. I have done quite a lot of work recently to adapt the "Clipper" polygon clipping library to do offsetting too.

Here are my results.
The first picture was made using kbool.

The second picture was made using my modified version of clipper.