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I have so many questions I don't know where to start! But, as Mary Poppins would say "start at the very beginning, that's a very good place to start". Feeds and speeds. Following a couple of you tubers and one of them was kind enough to give away a chart of his feeds and speeds for subscribing to his channel. We both had the same CNC and router, Bob's cnc with Makita router. His chart was designed for hardwoods. As a newbie to this craft, I am using softwoods, pine and birch plywood. He has lead me to believe that I will be able to increase the feed because of the material I am using. Is there a rule of thumb or is it trial and error on just how much I can increase the feed. And also, if I increase the feed, how does that affect my router speed? Will that need to be adjusted as well. Right now with the tables that I have I am getting mostly powder when I carve, when I believe I should be getting chips (no coke) Please excuse my dry attempt at humor , and any help would be greatly appreciated.
 

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David - Machinist in wood
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Right now with the tables that I have I am getting mostly powder when I carve
Welcome to the forum, Jack! Your feed rate is too slow or your router is running too fast. What bit(s) are you using? I run most jobs at 175ipm, 18k rpm, about 0.300" depth of cut and using a 1/4" compression bit. I get chips, lots of chips. But I also cut hardwoods 99% of the time - Walnut, Cherry, Maple, Purpleheart, etc.
 

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I have so many questions I don't know where to start! But, as Mary Poppins would say "start at the very beginning, that's a very good place to start". Feeds and speeds. Following a couple of you tubers and one of them was kind enough to give away a chart of his feeds and speeds for subscribing to his channel. We both had the same CNC and router, Bob's cnc with Makita router. His chart was designed for hardwoods. As a newbie to this craft, I am using softwoods, pine and birch plywood. He has lead me to believe that I will be able to increase the feed because of the material I am using. Is there a rule of thumb or is it trial and error on just how much I can increase the feed. And also, if I increase the feed, how does that affect my router speed? Will that need to be adjusted as well. Right now with the tables that I have I am getting mostly powder when I carve, when I believe I should be getting chips (no coke) Please excuse my dry attempt at humor , and any help would be greatly appreciated.
I am by no means an "expert" in using a router, but I will say that I listen to the router as it cuts. It will have a certain sound for cutting too slow, and cutting too fast. And then there is the sweet spot, where you can HEAR the sharp blade gliding through the material like a water skier on a calm lake! You can also listen to a table saw, a sander, a planer, and other tools. THEY TALK TO YOU! o_O

Joe
 

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Welcome to the forum, Jack! Your feed rate is too slow or your router is running too fast. What bit(s) are you using? I run most jobs at 175ipm, 18k rpm, about 0.300" depth of cut and using a 1/4" compression bit. I get chips, lots of chips. But I also cut hardwoods 99% of the time - Walnut, Cherry, Maple, Purpleheart, etc.
Thanks for the welcome. I'm really anxious to learn how to properly carve because this is a lot of fun. (Except when........)
This is a list of the endmills in tool database, they are all downcuts with .250 shanks: (.031) 10 ipm @ 2700 (.0625) 20 ipm @ 2700 (.125) 35 ipm @ 2200 (.250) 80 ipm @ 1900
I have a .250 compression bit that is set as the same as the .250 downcut.
My V bits are .250 shank; (90) 50 ipm @ 1700 (60) 40 ipm @ 2200 (30) 35 ipm @ 2700.
We haven't done any hardwood yet as we are still tryin to get the machine set up properly. I had a bunch of pine boards and some birch plywood laying around that we are practicing on.
I've attached a few pics of some experiments we worked on
 

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Discussion Starter · #5 ·
I am by no means an "expert" in using a router, but I will say that I listen to the router as it cuts. It will have a certain sound for cutting too slow, and cutting too fast. And then there is the sweet spot, where you can HEAR the sharp blade gliding through the material like a water skier on a calm lake! You can also listen to a table saw, a sander, a planer, and other tools. THEY TALK TO YOU! o_O

Joe
Hey Guy in Town. I read your post on LA Hobby forum. That Vardo trailer you talked about is sweet.
 

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David - Machinist in wood
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You're doing nice work, keep it up. Who set those feed rates? How about a photo of the CNC - can you post one? Unless it's a small, flexible (not very rigid) machine then I'd say you can go much faster than those rates, especially if you're getting powder instead of chips (except for the 1/32" bit, still go slow with that one).

I cut 75ipm to 125ipm with a 1/8" downcut bit and 175ipm to 250ipm with 1/4" bits, rarely much different from those settings.
 

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You're doing nice work, keep it up. Who set those feed rates? How about a photo of the CNC - can you post one? Unless it's a small, flexible (not very rigid) machine then I'd say you can go much faster than those rates, especially if you're getting powder instead of chips (except for the 1/32" bit, still go slow with that one).

I cut 75ipm to 125ipm with a 1/8" downcut bit and 175ipm to 250ipm with 1/4" bits, rarely much different from those settings.
The first pic is the dust we are creating when we are carving. Not sure if it matters but we are using some very old pine boards that have almost no moisture or resin in them at all.
The other pic is our machine. Its a bobs cnc evo 5. We are using v carve desktop software.
The other pics I sent were done on birch plywood. The raised letter took over 3 hrs, and the others a little over 2 hrs.
 

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You're doing nice work, keep it up. Who set those feed rates? How about a photo of the CNC - can you post one? Unless it's a small, flexible (not very rigid) machine then I'd say you can go much faster than those rates, especially if you're getting powder instead of chips (except for the 1/32" bit, still go slow with that one).

I cut 75ipm to 125ipm with a 1/8" downcut bit and 175ipm to 250ipm with 1/4" bits, rarely much different from those settings.
Bob's CNC is mainly a laser cut 1/4" plywood machine that would flex way to mush if he tried to run at the higher speeds you're running. All of the machine is put together using 1/4" rods for reinforcement.
 

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Late to the party as usual but...

I would suggest you learn about chip load. This is what drives feeds and speeds. Chip load is basically the thickness of a chip that your bit slices off with each pass of the cutting edge. Too small a chip (ie dust) and you get rubbing and heat. Too big a chip load and you get tearing and sometimes broken bits. Most bit manufacturers (at least good manufacturers) provide a recommended chip load for each bit and the materials that it is intended for. Most good CAD/CAM software will calculate chip load for a given bit based on your feed rate and spindle speed. See the example Speed and Feed chart from Amana for a 1/8" spiral. Then look at the VCarve Pro Tool data for a 1/8" spiral end below that. You will see that I need to increase my spindle speed or decrease the feed rate to get my chip load correct.

If your machine is flexy, decrease your depth of cut to reduce the resistance force as you push the bit through the material.

Font Rectangle Parallel Screenshot Number



Rectangle Slope Font Parallel Screenshot
 

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Discussion Starter · #14 ·
Late to the party as usual but...

I would suggest you learn about chip load. This is what drives feeds and speeds. Chip load is basically the thickness of a chip that your bit slices off with each pass of the cutting edge. Too small a chip (ie dust) and you get rubbing and heat. Too big a chip load and you get tearing and sometimes broken bits. Most bit manufacturers (at least good manufacturers) provide a recommended chip load for each bit and the materials that it is intended for. Most good CAD/CAM software will calculate chip load for a given bit based on your feed rate and spindle speed. See the example Speed and Feed chart from Amana for a 1/8" spiral. Then look at the VCarve Pro Tool data for a 1/8" spiral end below that. You will see that I need to increase my spindle speed or decrease the feed rate to get my chip load correct.

If your machine is flexy, decrease your depth of cut to reduce the resistance force as you push the bit through the material.

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Thank you for your input. We have vcarve desktop, and from what I understand it automatically calculates the chip load. Is this correct, or should I study up on chip loads or...both? I understand maddogs reply. I can't go 100mph on a machine that can only go 60.
 
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