I’ll start off by saying, I’m new the the CNC world.
I had a brand new Millright MegaV (the larger, 35x35) fall into my hands - I just had to assemble it.
I got it all put together and signs up for Easel Pro. Got my machine connected and ready to go.
I’ve tried doing some projects and have run into all sorts of issues that I can seem to figure out.
Spindle lift - when setting up for a carve and positioning the spindle for the starting location, when I hit the button the raise the spindle sometimes it will raise a few MM other times it will raise and inch or 2. This inconsistency is causing issues with the cut depth. Sometimes it doesn’t lower far enough when it starts cutting. Other times, it Lowe’s too much and as it moves to the starting carve, I get a drag mark across the material and it cuts too deep.
Carving off material - when I do a carve, 90% of them the spindle ends up trying to carve in an area off of the material. It’s as if the machine doesnt know its position and is carving where the material doesn’t sit.
breaking bits - I have been trying to carve a large piece of acrylic. Before doing that I am testing with some smaller 12x12 cast acrylic material. I’ve now broken 3 bits, each time the bit snaps almost as soon as it starts to carve. Here are the details of the config I have for this particular project
I am using a 1/16” O flute carving a logo onto a 1/2” piece of cast acrylic. Doing about 1/8” tot depth for the carve.
Feed rate: 180 in/min
Plunge rate: 25 in/min
Depth per pass .05”
DeWalt set on speed 1
I’ve also tried a feed rate of 60 with the same results.
I really want to get into this a hobby, but this is becoming quite frustrating. Hoping someone might be able to help.
First, I would practice on something easier to cut, like wood. I’d try a V bit instead of a 1/16” bit. If you haven’t done the set up and set the size of your work area through computer set up, I’d do that. You can change the GRBL settings for your particular situation. For now I’d back off the plunge rate to about 10 or 12 inch/min. Once you get the hang of it, then you can play with other materials and it won’t be so frustrating. There is a learning curve and I think you’ll be more successful with easier resources at the beginning. If you have home switches I’d use them. Make sure that you zero out the bit. The piece of paper adjustment works pretty well if you don’t have a Z probe. I’d make sure the material size is the correct size for your project too, but keep the first projects within the cutting area of your particular machine before you try to venture into more complicated setups with tiling.
Hey Martin
Thank you for the reply!
The reason I was using 1/16 is because there is some fine detail in the logo that requires a bit smaller of a bit. Would a V bit all for that?
I have done some other carves on wood and still experience the same inconsistency with the machine.
You mention zeroing out the bit. Do you have any more information on how to go about doing that?
Lastly - the acrylic I’m cutting isn’t a tiling project. I have been practicing on smaller pieces like 12”x12” and 1/2” thick. The machine is just doing “phantom” cuts, where it starts to carve in areas where the material doesn’t exist (like 2-3” offset from the material)
Normally I set my Z plunge rate at about 10 or 12 and I’m using more stout bits. That right there may help the cause with 1/16” bits which are rather fragile. Depending on how deep you are going to go, the V bit for engraving might provide the same effect.
A z probe helps set your Z0 to the top or bottom of the material. You can set it on the spoilboard for zero, or at the top of the material for zero. People without a z probe take a thin piece of paper and jog down until the paper just kind of drags under the bit. You do this with the router or spindle off. At this point you reset your work Z zero. If you have home switches, you should home the machine. That will give you the machine Zero point. Work Zero can be anywhere you want it to be, but home zero is where the machine puts it after it hits all the switches.
Check to make sure all pulleys and couplers are tight, as well as all the fasteners.
Something like this probably would help.
DashHound Woodworking Carving Bit Solid Carbide CNC Spiral Router Bit Engraving 20 Deg with 1/4 Shank - Amazon.com
I typically zero it in the Lowe left corner of the material.
Should I be lowering to the material or to the spoil board? I’ve found that when zeroing, when I click the raise bit button to start the carve, it’s inconsistent on how much it raises. Sometimes just a few mm other times it’ll go all the way to the top, almost touching the z limit switch.
I don’t control my cnc with Easel, I use the Universal Gcode Sender so I can’t really comment on that one. I’ll generate the gcode in Easel and then open that in UGS.
All the settings are adjustable I bet within Easel. Work Zero from the top of the material is fine as long as you have the room above the material before the Z hits the end of travel.
Check your “ general settings” to see if they are OK for your machine.
I’ve checked those and they appear to be correct based on what I’ve found online.
any idea on why sometimes the spindle will raise a few mm and other times a couple of inches? This has given me scenarios where it begins cutting and it’s just spinning in the air above the material or it plunges way to deep (deeper than what I set the job to)
If a coupler is loose, you maybe losing steps, and that is a common issue. If you can read your gcode, you could see if it is telling the machine to do that. It could be a faulty part in your controller. Just for the heck of it, I’d download the current working version of UGS and try that.
When you are just jogging around does it appear to work OK? I’d try a simple shape in Easel and see if it makes that without problems.
Have you actually measured the spindle movement? Suggest you try drawing lines or circles in various sizes in Easel then carve them, and then measure them. Set the depth of cut to .001 or some other number to be barely visible. Use the paper method to set the Z position. Hope this helps.
Just following up on this. I adjusted some settings and was able to make a successful carve from the perspective that I didn’t break any bits - so that you for that!
I also set it up to do a rough cut with a 1/8 and a finish with 1/16 bit
That said - something is still going on. The carve path is WAY off from what I’ve sent to the machine. Attached are images of a carve I did along with an image of what I was carving (ignore the red, it’s blocked out for privacy reasons).
The second image shows how the R and Q are very close to each other and the C is partially cut off of the material
The last images shows where the spindle “homed” to when I ended the carve the green dot indicates where I set the home to when starting the job.
Something is still off and I’m not sure what
Try it in wood. I’m just guessing here, but I think you are losing steps. Perhaps slow your feed down. What size motors are you using?
Was this drawing made in Easel as I have found that you can not trust that the borders of the characters all seem to have different boundaries so you can not trust that the letters or drawings will always be in the correct position. There was a chat about how to make a smaller bounding box attached to a letter a short time ago. I almost always use the centered node number and adjust the position manually using the Easel DRO. I won’t say that I trust the digital more than my eyes but numbers don’t usually confuse the issue for me. It’s clear if you look at the “6” bounding box size. I would not trust my eyes for some of my works. I trust in the drawing readouts more. For quickee project I rely on the “graph paper” type backgrounds.
readings 100%
I’m not sure on the motor sizes - they are the motors that came with the MegaV.
My feed rate for the roughing is set to 100in/min with 25in/min plunge rate and .03in per pass. What would you recommend it be set to?
Im not sure that I follow what you’re saying.
I converted an image into a vector, so they arent individual letters that I am working with. If you look at my drawing in Easel, it is pretty clear that the “R” and “Q” are pretty far apart, yet if you look at how it carved, the R is overlapping the Q.
I don’t think I go more than 80 ipm in wood and 12 ipm in the Z on wood. Those speeds could be some of your problem. I’d back them down to half and try it on wood just to see if it comes out. Bit type, feed rate, depth of cut, and material are all variables that you need to play with.
I would suggest that you make a bunch of concentric circles on easel and centered on your work piece. Cut the program directly from easel. (don’t use another program to run g code) How do the circles look? It would be best if your work space is on cut it full size work table. After checking the easel cut circles, run the g code and compare.
