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Gnarly Brown trouble

Hey gang!

So, I made my first cut. I chopped the Charlie Brown from the marketplace. Very cool program by the way. Thanks and good work to the author. Anyway, I ran the straight cut bit for the whole shebang. Unfortunately, I broke the one that I originally had on the router during initial setup and calibration. The sled looked as if it was rocking from time to time, resulting in some gnarly looking cuts. I’ll attach photos for reference.

A couple of questions I have in terms of resolving it:

  1. How do I slow the rate of the X/Y motors? I am assuming the rocking may be coming from the sled movement happening faster than the router can keep up with on this one.

  2. What bits will work with the sled? Of course my router is on a 1/4" collet but I assume it needs the extra length to clear the sled and still penetrate the stock. Since mine broke, I will need to look for replacements. I know that the ones from MakerMade are available but I hate to buy great bits until I work out the kinks unless the bits ARE the problem.

  3. The stock I used was a particle board type junk with a vinyl covering (mostly because it was $8 and I didn’t want to butcher a good sheet of A/C plywood during my learning period :sweat_smile:). How much would that interfere?

As always, I appreciate this community and any advice you can give! Have a great day!

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  1. slowing the X/Y motor movement speed is set with the feed rate in the gcode generation step. If you are in mm, the max is 800-1000 mm/min depending on your system settings. turn it down to 500-700 and try to cut no more than 1/2 your bit width per pass. Are you plunging for the full depth on the first pass or doing multiple passes at successively deeper cuts?
  2. any 1/4" or 1/8" (with adapter) will work, but best results are usually with 1 or 2 flute up-cut bits since rotational speed is typically too fast rather than too slow. I bought a set of 10 1/8" bits off amazon for my first set to burn through for $15. They dull quickly, but will help you get some experience. the do break easily, but were totally worth it to learn on.
  3. the hardness of the material will dictate how fast it will cut. if it is hopping, then slow down.

Practical use:
I run 1/8" 2 flute upcut at 2mm per pass. so it is 10 passes for 3/4" ply at 19 mm thick. or 7 passes for 1/2" ply at 12.5 mm thick at 670 mm/min. I use a 5 mm wide and 3 mm high tab that easily knocks off with a multitool. These settings are not universal and there are others who have success using different settings. I offer them as a point to start from, but they are by no means the best for everyone or for every material.

I think that this is really solid advice. One of the keys to getting clean cuts is to start off with super shallow passes and then gradually try deeper and deeper settings as long as things are looking good.

Great advice. Thank you both so much for your responses! I will give that a shot. Quick related question- where do I set the depth per pass? Should I just set my z-axis 0 point a little above the stock before I run this and gradually lower it each pass, or is there an easier way? Thanks again!

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it is set as part of the CAM step, where you generate the gcode.

David Lang

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