Hello everyone I am struggling to get a clean cut using a 90 degree vbit on some letters. Some letters, parts of letters are fine, but most are not smooth in the channel , like attached picture, and it is even more noticeable when I paint it. Any idea what I am doing wrong or what may be causing this? Thank you. trying to make a sign for my dad and I have failed 4 times with the same issue. I have changed bits even though both were brand new.
Are you doing an actual V carve tool path? Or pocketing with a V bit? What software are you using? You are clearing material with a pointy end mill with too high of a step over. Do a roughing pass first with a small regular endmill to remove the bulk of the material at the bottom of the carve. Then use the v bit with a carving tool path
I was simply doing a vcarve toolpath and nothing else. Don't think the cut was very deep and I had seen a video that seem to do the same thing but without the horrible result LOL In your suggestion how would I run the pocket toolpath, what parameters would I use? Not familiar, as I am very new to CNC, with this type of process to clear material out before the vbit use I am using Vcarve Pro also, I wonder why half of the letters/numbers turn out fine
What type of wood is it? Some cuts fine, some not could just point at inconsistencies in the material, dial it in slower to deal with the toughest parts of the wood. If its something cheap like pallet wood, its unlikely to cut nicely sometimes. What was your feedrates and spindle RPM? Give the bit a sharpen just before the run (factory edges can be quite dull): https://www.youtube.com/shorts/6hUGTkSS2wU
Is there any possibility that the wood is damp or unseasoned? It looks to me a bit like what happens if you try and machine wet wood. What sort of feedrate / spindle speed are you using?
Seems reasonable to me (but somebody else might know better). Sometimes with pine, especially if the grain is a bit coarse, it doesn't like to cut cleanly. You could try doing a rough cut first, leaving about 1 mm / 0.040" then a second pass to clean it up. (I'm not familiar with V carve, so can't advise you on how to achieve that, sorry).
Pine is very bad in this regard, maple or poplar will be much better, also if just going to paint MDF works great. In the pic it looks like you get a bunch of wondering and chatter, maybe somethings are mechanically not very optimized, loose V-wheels or screw collars for example. Gary
I would paint it with a primer after the first cut, let it dry, then cut it again with a smaller stepover, say 75% of the first cut. DO NOT remove from the machine while painting/drying. If I was in a hurry I would put CA glue in the grooves and wait 30 minutes for it to cure hard then recut. Be sure to wipe the grooves with paper towel before cutting to make sure it has all cured. This will form a hard layer which may affect paint surface 'look', do a test piece to find out what works for you.
MDF is the ultimate test because it's very machinable. I would do a test on a piece of (fresh and dry} MDF and see what you get. The "W" you posted is not only grubby in general but the tips of the character are badly defined. As far as the Pine being in your garage is concerned, the material can still absorb moisture so don't take it for granted it's bone dry. Your observation that some characters are fine, leads me to suspect the material may be causing it. V carve will determine the proper cut depth automatically. Anyway, having said all that, I am still open minded about the cause.
I was also wondering if something may be off mechanically. any thoughts on how to test for such issues?
Do the MFD test - if that comes out fine, the issue was your material. If not, then time for a closer inspection. Hold the endmill and give it a firm wiggle. Humans sense of touch can detect micron movement - far finer than the eye can see - the sense of touch will reveal any unwanted play and allow you to follow where it comes from
Sorry Alex…I am familiar with mdf …my question was referring to what am I actually cutting to test the parameters. my plan will be to simply cut the same sign to get an apples comparison
Thought you had misread it (you said "mad" ) - yes, cut the same toolpath to see if the original problem was caused by the material. Alex.
Well i ran several passes on the mdf and still getting the chatter rough cut. Tightened up some wheels on the z axis but i am still not able to get them all tight. just seems impossible any tips?
You have another small adjustment available on the V-wheels - the play in the screw acting as their axle. Adjust the eccentric to its loosest position, loosen the screw on the top wheel, push the wheel against the V-slot (lifting the gantry plate), tighten the screw, then adjust the eccentric again - you should JUST be able to turn the wheel with your finger. When you have adjusted the eccentrics as best as you can, starting at the bit, wiggle things looking (sense of touch is actually more sensitive than eyesight) for anything moving that shouldn't. Best done with the steppers powered on. Alex.
Sorry for the late reply. In your Vcarve tool path. click on the "use clearance tool" box. Here is a video from Vectric describing the process. It stars around the 20:41 mark.
