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Legacy Maverick 4x8 #1: My first effort with rest machining . . .

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Blog entry by copythat posted 07-22-2018 05:10 AM 1888 reads 0 times favorited 6 comments Add to Favorites Watch
no previous part Part 1 of Legacy Maverick 4x8 series Part 2: Having a CNC allows for creativity even with the most basic of projects. »

I have a 3D file of St. Michael that I purchased on Etsy. As a retired cop, it holds special meaning for me and I have been wanting to carve it for a while now.

I spent some time this weekend trying to reduce the file size, both the physical size and carving size, to something a little more reasonable than 3.5 inches thick and over 20 inches tall. I got it down to 10 inches tall but almost fell over when the carve time was estimated at thirteen hours.

I heard about “rest machining” from PreciseBits.com and that it can seriously speed up a carve time. I did some research online and found that Legacy CNC, the makers of the GREATEST CNC ON EARTH, offered a couple classes on the technique. (Sorry, I got carried away there.) ;-)

I spent a couple hours watching videos and manipulating my file until I had it reduced to a seven hour carve time. Yep, from thirteen hours to seven . . . oh happy day!! I’m sure the file could have been made to carve even faster by a pro but I was pretty happy with my newbie effort.

So, here are some pictures of the carve in progress. I was not happy with my choice of bass wood. The bit would barely make contact with an area to be cut and a corner of the carving would just break off. I think cherry or maple would have been better choices.

NICE ADVERTISING RIGHT THERE!!

Like I said, the wood simply broke in certain spots but it wasn’t as bad as I thought it was going to be. There was a small piece of wood missing on Michael’s chest, and one of Satan’s horns was missing the tip and he had a finger missing on his left hand (poor Satan). :-(

Anyhow, here is a picture of a quick glue up fixing Satan’s horn and finger.

The final tool path remedied most all of the issues. I still cannot believe how brittle bass wood is. I also cannot believe how “stringy” it was throughout the carve. I took a small, unused glue brush (somewhat stiff bristle) to the surface of the wood and knocked most of the stringy material away. I spent about ten minutes on it touching up areas with a fine grit sanding sponge. I will work on it tomorrow and hopefully make it worthy of some stain.

-- Rob



6 comments so far

View mikeacg's profile

mikeacg

715 posts in 1257 days


#1 posted 07-22-2018 10:22 AM

Turned out pretty good but I would definitely pop for some hardwood. I’ve found that I spend more time cleaning up fuzzies and chip-outs with softer woods and never get that smoothness we all want. |
I notice a lot of depth in the model and on most machines movements in the Z axis slow the machine incredibly. Try flattening the model out a bit and see if your time doesn’t decrease dramatically. Watch so you don’t lose too much detail in the process but you can sharpen up the detail before you start flattening the model. What program are you using to generate your code?

-- Mike, A Yooper with a drawl, http://www.artcentergraphics.com

View copythat's profile

copythat

161 posts in 805 days


#2 posted 07-22-2018 07:03 PM



Turned out pretty good but I would definitely pop for some hardwood. I ve found that I spend more time cleaning up fuzzies and chip-outs with softer woods and never get that smoothness we all want. |
I notice a lot of depth in the model and on most machines movements in the Z axis slow the machine incredibly. Try flattening the model out a bit and see if your time doesn t decrease dramatically. Watch so you don t lose too much detail in the process but you can sharpen up the detail before you start flattening the model. What program are you using to generate your code?

- mikeacg


I’m going to get some cherry and see how it carves out. I actually liked the depth of the carving but I did reduce it down from over 3” thick to 1.5”. I used Vectric Aspire to dial in the image and run the code. Here are a couple pics with some dark stain applied.

-- Rob

View mikeacg's profile

mikeacg

715 posts in 1257 days


#3 posted 07-22-2018 07:47 PM

The stain really emphases the depth! Nice!
I’ll have to check out Etsy! Would you think badly of me if I put a St. Michael plaque up on my front door? I’m sure most of my friends would get a good laugh, trying to picture me as a saint…

-- Mike, A Yooper with a drawl, http://www.artcentergraphics.com

View Mainiac Matt 's profile (online now)

Mainiac Matt

8552 posts in 2528 days


#4 posted 08-22-2018 03:15 PM

Please fill in the details Rob.

I’m assuming you started with a larger cutter and then did a tool change and picked up where you left off to machine the “rest” of the details with a much smaller cutter.

tools?
feeds?
speeds?

inquiring minds want to know.

-- I yam what I yam and that's all what I yam

View copythat's profile

copythat

161 posts in 805 days


#5 posted 08-23-2018 03:27 AM



Please fill in the details Rob.

I m assuming you started with a larger cutter and then did a tool change and picked up where you left off to machine the “rest” of the details with a much smaller cutter.

tools?
feeds?
speeds?

inquiring minds want to know.

- Mainiac Matt

I have since modified the file and achieved an even better carve time. I no longer have my Aspire summary sheet with the tools, feeds, and speeds. Once I carve the design in cherry, I will post the information.

-- Rob

View TheFridge's profile

TheFridge

10713 posts in 1685 days


#6 posted 08-23-2018 03:38 AM

That is fantastic. That would make me want to gild half the thing and the frame in gold leaf. I bet you could make some awesome baroque stuff with that.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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