I just got finished with my Z axis. I made dovetails out of home recycled HDPE jug plastic. I don’t think it gets much more DIY than that.
That recycled hdpe looks much better than any other I’ve seen online. Can you talk about your process for that?
+Peter van der Walt
One drawback I can tell you already is the practical length that can be made. I can’t make plastic any bigger than this. I can’t machine it a lot bigger than this either, even if I had longer plastic. Maybe a bit more than twice as long? I don’t know. As I’ve never tried. I know my mill travel is not endless though. Far from it. Interrupting the internal female cut to re-position the work is beyond my skill level to accomplish. I ain’t saying it is impossible, just that I couldn’t do it.
Even with all of that it still is OK for the Z axis I figure though.
@Rich_Sobocinski
There is a lot of info online about recycling HDPE at home. I will just say what I did for this. This is pure blow molded (milk and water) jug plastic. No bucket, or bottle injection molded stuff. Blow molded plastic is harder and slicker than injection molded. I guess they have different additives in them? Beats me. All I know is they’re different.
Injected would have worked too, but for this I wanted the hard slick stuff. Now blown plastic does not flow molten nearly as good as the injected plastic does. I just run my oven hotter to make it cook better. I run at 380F. 350F should do it. But blown plastic flows bad. So I bump up the temp a bit to help it along.
The other challenge is actually producing a square block of material. To that end I made a square box to melt my plastic in. Brilliant, I know! Loaf pans have draft to them, and round corners, etc.
But the box I made is somewhat unique, so I’ll take a picture of it. It screws apart for easier de-molding. The diamond plate is a top I put on to press the block with clamps as it cools. http://i.imgur.com/RpqLjJq.jpg
The white paper in the top left is some non-stick parchment paper. I line the box with that for a melt.
The holy grail is a convection toaster oven. I just have a plain one now. I have my eye out for a convection model though.
+Peter van der Walt
So far I have only been able to give it the wiggle test. It seems pretty stiff to me. Running on a machine will be the true proof though. So far I’m hopefully optimistic. Then again I was with my last design too, and that did not all pan out as well as I’d expected. This appears far more practical to me though.
@Paul_Frederick I’m in the mix of something similar for the OpenCNC. About have all the tooling together finally. Love the ways, do let us know how things turn out.
That’s pretty nifty Paul. Looking forward to hearing how it goes.
@marmil
Thanks. When I have it running I will post again. I am working out aligning the drive components of the X, and Y axis now. I am recycling parts off my last build, But everything is going to be configured differently. I am mounting the motors on brackets now, instead of on the outside of a machine. So I have to work out the difference in height between the brackets.
I can’t get the motor center line quite as low as the bearings are now. So I am going to have to put the bearing brackets up on a spacer block. I just have to figure out how tall that needs to be.
Right now it looks like I can round it out to a half of an inch. I just have to put the motors up a little on the bracket to hit that. At least that’s the theory.
@Paul_Frederick thanks for the details and the photo. That’s something I’d like to try.
Pretty sweet. How many jugs to fill the box? And what are the measurements of it (the metal box pictured)?
Re: longer female dovetails.
What specifically prevents you from moving the length and milling farther down the length? You shouldn’t(?) even have to remove the bit from the groove. Position it farther down the channel that has already been cut, slide the work piece down to nearly touching the bit, lock it back in to place and mill farther.
Mind you this is all just in my head and I am sure practical application can/will throw a monkey wrench in things. So, I am just asking.
@Kyle_Kerr
in simplest terms a steady even feed directly translates into a nice surface finish. Stopping, reversing, and starting again is not being very steady at all. You’ll go through the work. But it’ll look like you hacked your way through with a dull butter knife. Well, maybe I exaggerate, but it is still not going to look like a top 40 hit.
Consistency is the key to doing quality work. That demands things are done right from start, to end. With no mucking about in the middle. You do that cut, do it! Don’t stop for nothing. Or you’ll be cutting it again.
Here’s a man that appreciates a good milled finish https://youtu.be/Gg2o9mQJHD8?t=543
@Paul_Frederick Thanks for the response. It even makes sense after reading what you wrote. Backlash, along with other things, would find its way in to the mix and cause issues. Or, that is what I am gathering from your comment.
@Kyle_Kerr
As the tool moves along it cuts a record of what is happening, much like an old vinyl record machine used to. Everything that occurred during the cut is laid down for posterity in the finish. I had to change the V belts on my machine because they were making vibrations. I got a huge finish improvement when I did that too. Much bigger than I expected.
Ideally for a fine finish we want to record the sound of silence as steadily as we possibly can.