I’ve done a pretty good job of not cutting into my spoil board too badly, but I wanted to get some thoughts on approaches for face milling the top of the boards. The screws holding the board down are countersunk fairly deep, so it would seem that we can safely mill off a couple hundredths to get a fresh surface a few times before the board is spent.
I recently ordered a 1/4" three flute carbide end mill from mcmaster and the appropriate er11 collet to fit it (from amazon). The collet is not up to the standard of the Carbide3d supplied collet, but it will suffice for roughing work.
Any thoughts on how to approach milling this? I’m thinking of generating an stl file in SketchUp which is a flat plate .05" thick and slightly larger than 8" in width and height.
I’ve defined the 1/4" end mill in MeshCam and am eager to cut with it to see what speeds I can get in wood. Perhaps I’ll try a piece of scrap before I attack the spoil board. Can I get by with a roughing pass for face milling the surface, or will I need to do finishing passes? I’m assuming that I should be able to do everything with the 1/4" end mill.
I am going to try a different approach. I have a number of pieces of 1/8" thick hardboard in my shop. I have cut one of these to fit the wasteboard. I will attach it to the wasteboard using lots of double-sided tape. Then I will fasten my material to this sacrificial board. I simply discard the sacrificial board, probably after each use.
Dick- I like your belt-and-suspenders approach. We usually try to stay just barely above the top of the wasteboard. When we do go too deep, we just knock down the burrs with a sanding block and keep using it. For what we do, they can take a lot of mis-cuts before we need to make new ones.
The other option is to tape down an 8x8" piece of MDF to the almost-dead wasteboard and make it the final job of a wasteboard to mill its replacement. If you’re interested I can upload an STL of the part.
I just tried this with good results. I created an 8"x8"x0.05" flat plate in SketchUp and loaded it in MeshCam. I generated the toolpaths for my 1/4" end mill that I purchased from McMaster Carr. I did a parallel surface finish in the X axis with 0.1" step over.
One of the things I ran into was the tight tolerance between the edge of the work surface and the X axis limit switch. I had to test the job several times and play with tool zeroing to get the job to run without hitting the limit switch. Changing the machining margin to 0 in the toolpath window in MeshCam was critical.
I’ve uploaded two youtube videos on the process. One showing the job running, and the other showing the results.
So, I’m calling this a success for probably tripling the life of a spoilboard.
I was planning to upload both my stl file and nc file here, but it looks like we can only upload images. Guys - it would be nice if we could use this forum to share models and toolpaths. Is that doable?
I also try to surface the waste board and doing that I also found the limit switches: There is one switch on X high value and one switch on Y high value and one on Z high value, but no switches on low value for the three axis. I can understand that on the Zaxis the tool will hit the board before reaching the physical limit, but for the other axis. I found during the wast board surfacing and also doing a test with Jog mode, on X axis low value the machine stops moving. On the contrary on the Y axis you can reach the limit but the motor doesn’t stop.
I think (limited experience) if you change the “additional area to machine” to zero it will work.
If it doesn’t, the other change I made was to do the finishing pass on the Y axis instead of the X axis.
Somewhat necro reply, but Carbide 3D now has a 1/4" collet and nut in their store. http://shop.carbide3d.com/collections/tools
Rob said they went through a lot of testing to find collets they were happy with, so I doubt you’d go wrong with this.
I don’t know if I did it the best way, but here was my workflow…
I made an 8" x 8" black square in photoshop. Opened it in meshcam, defined stock as being 8 x 8 x .375 (I think that’s the thickness, can’t recall), set maximum cut depth to .020, machining margin 0, and clicked on parallel pass only, 40ipm feed, 10ipm plunge.
I used the new .250 cutter / collet combo from Carbide3d, and took great care zeroing the board. Loaded the file, and it cut it without issue.
I used Randy’s advice on this - I moved the cutter to the edge of the stock and put a thin piece of paper in between. As soon as it started to rub, I raised the bit, and moved the cutter into the stock 1/2 the diameter of the cutter, for both X and Y.
So basically whatever value the X/Y was when the cutter touched, I would raise the bit above the stock, and add .125 to the value. I believe that would put the centreline of the bit right on the edge of the stock.
This worked out really well. The cutter did exactly what I wanted it to do.
So you lower the bit below the top of the stock when it is outside the stock area then move it until the bit touches the corner then raise the bit and manually add half the diameter to the zero points? Just want to make sure I have this clear…
And I just ordered a feeler gauge so I know exactly the width of the surface between the bit and the stock so I can add that + 1/2 the bit diameter.
And when I can run the spindal while jogging the machine I’m going to try the edge finder out. Thats actually how I learned how to zero the cutter - by listening to the logic people used in edge finder tutorial videos on YouTube.