My new build in Oregon

Mostly Printed CNC - MPCNC Your Builds
#1

I didn’t take any pictures, but I did record some video. https://www.youtube.com/watch?v=zWrBgTnJXZ0 She’s a 4’ x 4’ x 6" beast, but from the start I was having problems with the top corner parts from the kit breaking as I was trying to tighten them. I have a very cheap and crappy 3d printer (Tronxy xy-100) that I tried to make the parts on (before I bought the kit) that I was able to make replacement parts that mostly work.

Later I noticed one of the bearings on the x-axis was spinning freely. When I looked closer, I seen there was a crack on part. I glued it with abs and acetone to close the gap.

I got her running and I was screwing up the feed rates, depth per cut, you name it, I did it wrong. When I thought I was comfortable trying to make cuts in pieces of furniture I had spent a lot of time on making, I’m seeing the bearings are chewing up the conduit. You can see a little of this in the video around the 30 second mark.

I sanded the flat spots a little, rotated the conduit, and replaced some bearings I couldn’t easily clean the metal off of. Does anyone have a clue how to fix this? Should I have bought smoother conduit, sanded it before I started building, or is this just normal? I only ask because all of this started when I noticed my x-axis seems to dragging. Hence rabbit hole of finding the loose bearing, then the crack, then the gouging of the conduit.

Conduit is cheap enough, if I have to source more. I just don’t like messing around too much with the plastic parts, since I keep breaking them.

 

Maybe I can steal the hotend and extruder off my crappy printer and add them to the mpcnc to make a set of replacement parts.

#2

It’s not usually a problem. You can do what you did and rotate them to get a fresh surface. Mine was actually a lot smoother once the galvanized stuff came off.

#3

The galvanizing usually comes off but it should take a little while. I am thinking that combined with all the broken pieces and bearings not touching you might be over tightening things. With no tension on any of the tension bolts all bearings should touch, kind of tight actually. The only time they tend to come off is when to many things get over tightened. Most of the plastic parts as well do very little work. The corners are just spacers and don’t need to really clamp much at all, just enough to counter act the belt tension.

#4

I am known for breaking bolts when I work on cars, so over tightening might be the case. I did assemble the carriages with two combination wrenches to make sure I wasn’t torqueing them down too tight, but I wasn’t paying attention to how much force I used. I think I just kept going until they bottomed out.

 

As a size note, I’m having one hell of a time getting back to 0,0,0 after a tool change from rough cut to finish cut. Is there a trick to that? I included a picture this time of the finish pass being what looks like a millimeter off in the x and/or maybe the z axis.

I started a new test with the same 3mm ball mill for both the rough and the finish passes to see if I can finish at least one piece. The machine says it will take a little more than 22 hours, which is painfully slow for a test. :slight_smile:

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#5

Where in Oregon are you? I’m in Salem.

#6

Yeah, salem, but I have it setup at a buddies house in keizer.

#7

That cut looks crazy what was your recipe for that, feedrate, depth of cut, step over? I am guessing you went to shallow with too high of a step over.

#8

You guys are too far west. I’m in The Dalles. :wink:

#9

On that one in the picture? I deleted the file so I have to go on memory, 6mm flat mill with 1mm step down, 2.4mm step over, 50mm/s for both feed and plunge rate. I thinking it’s hairy because the end mill is getting dull from hitting a hold down screw. The 1/8 ball mill was being run with, 1mm step down, 0.3175mm step over, 70mm feed rate, 30 plunge rate.

I just figured out how to cut just the part I want and not the whole board. I still have to write a program to cut down the base material enough so there is room for the 1/8in ball mill to reach the bottom without the collet hitting.

#10

Hey Bill, has the smoke cleared up any? I have to make a trip to Pendleton tomorrow and my girlfriend is so mad at that kid for that fire. I think her family grew up in the dalles so the fire was an attack on her childhood.

#11

Those numbers are pretty much all bad.

On your next cut take a screen shot or something, but you are pretty lucky that cut at all.

50mm/s plunge should have reset the board, max for a T8 is 30mm/s, most people cut at 12mm/s or under, you did 50?

https://www.v1engineering.com/milling-basics/

#12

I’m getting ready to head over there now and I’ll lower the plunge to less than 30mm. I’ll try to take a few pictures.

#13

So, my phone wasn’t liking this site and my pictures are to big to send, but:

rough out:

6mm end mill

Stepover: 0.09449 inches

Stepdown: 0.0393701 inches

Feed Rate: 65 (I assume in mm)

Plunge Rate: 30 (I assume in mm)

 

1/8 inch ball mill

Stepover: 0.0125 inches

Stepdown: 0.0393701 inches

Feed Rate: 90 (I assume in mm)

Plunge Rate: 30 (I assume in mm)

 

#14

What program are you using to get those numbers?

You can not assume mm, and you are missing the speed, normally mm/s, or mm/min.

But estlcam doesn’t use number like that so you need to give a lot more information now or switch to estlcam to get you set right.

#15

I’m using Artcam and when I hover over it once, it said mm/sec. But, your are right, the 1/8in ball mill is in inch/min.

1/8in ball:

feed: 38.1mm/sec

plunge: 12.7mm

#16

from looking at Estlcam 8 The tool list on youtube, it would be (if I’m reading this right):

1/8in ball mill

Z+: 1mm

F(xy): 2286.0mm/min

F(z): 762.0mm/min

 

6mm end mill

Z+: 1mm

F(xy): 3900.0mm/min

F(z):1800mm/min

 

#17

I don’t know where you are getting those numbers. I gave you some numbers above in the link.

I think you should really use Estlcam until you learn all the ins and outs. Using another CAM program as a beginner is tough, and your numbers are all over the place. Stick to my walk though’s for a bit.

Estlcam does carving very well and it is extremely easy to use. Just open an stl and a whole new program pops up.

https://www.v1engineering.com/estlcam-basics/

 

#18

I was able to get it to finish with only one lost a step in the x axis because I didn’t line up the 0,0,0 right after a tool change. I let it finish to see if it was going to happen again. I lowered the x and y speed and raised the z speed match what I seen in estlcam to see if that makes a nicer finish.

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#19

So, I added a NodeMCU to serial 2 (mini-rambo 1.3) for a wifi connection. The connection a little flakey, but when it work, it works well.

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#20

How does that work? How do you actually connect, what program?