Cnc race!

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Ladies and Gentleman, get ready to break stuff!!

Let’s see who can make a decent* cut the fastest.

Rules:
1 - Use this DXF, import in millimeters.100mm_drag_racer.zip (8.3 KB)
2 - 12mm Depth of cut.
3 - Only in MDF (MDF should be fairly universal, making the test as even as possible).
4 - Take a video (we might need proof, you don’t have to post it unless it is really fast or something breaks!)
5 - As many attempts as you need, post them all, lets see how you improve!

Any tool, spindle, endmill, MPCNC or LowRider, any CAM. No bending the rules, or getting creative with them (unless it makes a good video). This is for fun, but if I can’t win my feelings** will get hurt!

How to check your work.
You can use the video to check the time. Time start when the plunge starts, and ends when your bit clears the surface on the final retraction (not when it gets back home).
XY dims are across the diagonals.

PXL_20210422_234809289
PXL_20210422_2348092894032×3024 2.53 MB

Z is where the calipers can hit both sides.

PXL_20210422_234957686
PXL_20210422_2349576864032×3024 3.28 MB

*decent cut = absolutely under 1mm deviation, shooting for much better.

**Joking, I know most of you are much better at actual cutting than I am.

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I did a baseline cut. 15:33 to completion. Safe as recommended cutting strategies. You should be able to easily match that.

My dimensions are
XY: 100.32, 100.45, 100.69
Z: 11.91, 11.66, 11.9

I am not super happy with those, you can see my spindle is tilted, and I must not have got the board all the way down with the clamps. This does serve as a great starting point though.

drag race base line
drag race base line1808×1256 343 KB

I am predicting I can get it to half the time!

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Did you mean to post the gcode file or a dxf?

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Whoops, I will fix that in 2minutes.

New run #2. 9:57 Same endmill no frame or tram tweaking, different numbers from linear cam pathing instead of inside out. Faster feedrate 4mmDOC

XY: 99.58, 99.71, 99.52
Z:12.09, 11.97, 12.06

Run 3 getting harder to shave off time. 8:56, 12mm/s 6mm DOC
XY 99.42, 99.57, 99.61
Z 11.91, 12.05, 12.05

#3dragrace
#3dragrace1904×1252 243 KB

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Have you tried cutting at the full 12mm? I want to try this soon

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Not yet. I Added some notes.The 3rd run was 6mm depth of cut. I am going to try 12mm next, but I am thinking 6mm will allow for a faster over all cut…we’ll see. Lots of learning.

Typically, I make a test cut or two and go. This is super interesting to cut just to cut and learn.

I have some 1/4" bits as well. Really interested to see how that goes!

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I bet you can crank that up to about 20mm/s easy with the 1/8 and 1/4 bits. That’s typically what I run for my standard cuts. Nice to see you sneaking up on it though instead of doing the hail Mary approach

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This is also with a bit that has cut a bunch of aluminum. When I start seeing some tolerances slipping and odd noises I will put on a freshie.

There are a ton of variables, I think you have to sneak up on it. And I am trying not to change too much at once.

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What is the smallest radius in that drawing?

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I’m surprised you aren’t going the other way. Just go deeper and speed it up. Give yourself an upper limit.

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Heads up, I’m still not seeing the dxf. Maybe because I’m on mobile?

Given that those corners are radiused are you able to get totally repeatable measurements with your calipers?

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Fixed, again.

I think so. I slap them on a couple of times and use the number that comes up the most. It is actually pretty solid.

A fail is heartbreaking, I need a few wins before I just go for it.

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Ohhhh good question. I meant to check that but getting it to 100mm took longer than expected.

3.642mm…nice!

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Woohoo - racing time! But SHOOT. I was going to do a quick run, since I already have som MDF mounted. BUT - it’s only 11mm. If I cut all the way, I would need holding tabs, and the spoil board would also suffer a bit. We’re heading to the cabin in the weekend, so I don’t have time to mount some new material.

That being said - I really can’t stand MDF. It burns so easily and the dust is really awful. I’m not sure if all MDF is similar. The type I’m using now seems more “glue-y”, it frays a lot and sticks to the endmill. It might be that the endmill is bad, I got in from aliexpress, I don’t have any know-how to determine if so: https://www.aliexpress.com/item/33018778488.html?spm=a2g0s.9042311.0.0.27424c4dOVKwgs

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The MDF that Lowe’s sells is different than the MDF that home depot sells. The Lowe’s MDF has larger grains of wood and cuts different than Home Depot MDF. It seems to chip a lot easier.

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Interesting to know, thanks! The MDF I’ve been working on recently is from packaging sheets, that I get for free at the hardware stores. Perhaps it’s quality is worse than regular MDF used in construction. Probably!!

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The MDF from home depot looks like Ryan’s. A really small grain to the point you can’t really see it almost. Like compressed saw dust. The stuff from lowe’s is larger and almost looks like grains of sand.

It’s crazy how much difference there is in just those two sizes.

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Well shoot. I will check both spots again, around here I am pretty sure I got this chunk from Lowe’s.

Any ideas for something that should be more consistent? Should we move to particle board? I would hate to waste Baltic Birch Ply on this.

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What about plain and simple pine?

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Consistency is tough in natural, and it really is just too easy to cut.

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