Main > Project Announcements
CNC-2116 - Up and running, sort of (2015-03-21)
Yvan256:
There's a tiny backlash problem with regular threaded rods and my friend and I are afraid the nylon nuts will wear out too fast. The machines would also be way too slow for relief carving, which is something my friend will probably be interesting in.
I'm now cutting new parts for both CNC64 machines so that they will be belt-driven. I solved the problem of the low-profile base by mounting the Y-axis motor upside-down. Simple enough but I didn't think about that solution the first time around. I lose the ability of letting the panels to cut go beyond the back of the unit, but it's a small trade-off so that I can keep using the currently cut, painted and assembled bases.
edit: the MDX-3 keeps failing, I'm now cutting trying to cut parts to replace both the Z-axis assembly and the spindle. I'm making the mounting holes compatible with the Black & Decker RTX mount, so I'm only three parts away from an upgrade (the parts in blue in the image below), I already received the 6mm bushings from China. About half of them were bad, so the seller is sending me another full lot of bushings as a replacement.
edit 2: I've attached the Black & Decker RTX mount to the MDX-3 Z-axis with a single screw. There is a small plastic nub on the Z-axis that sort-of prevents the mount from rotating, and so far all cuts seem to be clean. It's making a lot less noise than the old MDX-3 spindle used to. I'll take a photo of this Frankenstein of a contraption once it's done cutting the current part.
edit3: Photo of what I call the "Roland RTX-3". ;)
Yvan256:
The new Z-axis assembly is in place and working, the MDX-3 now uses my Black & Decker RTX rotary tool instead of the original, badly-designed spindle! ;D
The part being cut is a plate for a NEMA23 stepper motor mount. In all the NEMA 17 stepper motors I currently have, none has a 5mm shaft and can be wired as bipolar, so my only option is to use my NEMA 23 steppers. I wanted to keep them for CNC86 or even my bigger machine that's going to use my Hitachi M12VC, but that can be changed later.
I already received my GT2 belts and 6.35mm ID pulleys, which were needed because those NEMA 23 steppers were made in the USA and the shafts are 0.25 inch.
The other good news is that the NEMA 23 steppers have almost exactly the same height as my NEMA 17 steppers with the S2M metal pulley, so I'll be able to use them on CNC86 if I ever decide to buy NEMA 17 steppers for CNC64.
Driver board: check
Stepper motors: check
Belt and pulleys: check
Progress! :)
Yvan256:
I made a serious mistake with the new Z-axis assembly. I guess I was tired when I did the mistake, because it's really dumb.
Here's how I designed the assembly in Sketchup:
But since I wanted to have flush bolt heads:
I had to countersink the bolt holes:
However, since the design required a slot for a part on the back:
I had to do the countersink on the other side:
But I had to do that countersink, manually, with a drill bit on the other side:
And what had to happen, happened. The thin wall of expanded PVC broke, the bolt could no longer hold the part on the other side, the RTX mount wasn't tied to the Z-axis assembly anymore, the RTX became randomly offset with the programmed pattern and the end mill bit just continued cutting anyway:
Ouch.
I learned two things from this mistake:
* the RTX is powerful enough to cut at least 1/4 of the thickness of the MDF at a time, so I'll program deeper cuts next time, maybe 1/16" just to be on the safe side. With 3/8" thick MDF, this means only 6 passes to cut through, compared to my usual... 70 or so.
* The RTX is powerful enough to actually burn the end mill bit, that means I don't have to worry about the power of my spindle anymore, which is a good thing for future cuts with my modified "Roland RTX-3", for CNC64 and for CNC86.
I'll patch the broken part with a big washer, offset the bolt head thickness with washers, cut new Z-axis assembly parts again (maybe in double, to have a backup), order more Dremel #650 end mill bits (with a few spares as backup this time) and continue forward. :laugh:
Yvan256:
I had problems with the new Z-axis assembly, I think there was too much friction on the Z-axis rods because the cutting depth wasn't as constant as it should have been from hole to hole. So, I had install the original spindle back on. Again. :-[
I've made the motor pivot stronger, so it should last for quite a while now.
In the meantime, my friend ordered two more Dremel #650 end mills this week and received them two days later. Considering how remote our small town is, it's amazingly fast. Kudos to Amazon.ca for the delivery speed.
The MDX-3 is cutting a NEMA23 mounting plate for CNC64/CNC86.
Edit: plate is cut, perfect fit with the motor. I have two GT2 pulleys for the NEMA23 motors of the X and Y axis.
Typefighter01:
Looks like you won the race Yvan :dunno .
1st-I have a crush on amazon.ca.
2nd-Mounting plate looks perfect.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version