BuildsByGideon

Posts for Tag: Shapeoko

Oneshop Redding Cutting Aluminum (part two)

Over the past few days, since I did the first aluminum cut, I've been researching the most efficient ways to cut aluminum with a clean finish.

I found that the vertical cutting height should be much higher than my previous 0.2mm. This time I set it at 6mm cut depth and place it at 0.1mm optimal load; the sound wasn't quite like I would have liked, so I tweaked it a bit and got to sound a bit better.

I also found that using compressed air helps with chip removal; I already knew this, but I found with a combo of compressed air, and the silicone gets a clean-cut, and you can see what's going on.

I was able to cut down the stock to about 5mm and then start cutting out the logo design that I modeled a few weeks back. It all went very smoothly without any hitch, though I did have to be there as I didn't trust it on its own.

I started with a 1/4" 4 flute carbide bit to mill out the smaller stock, then switched over to a 1/8" 4 flute carbide bit to clear out the shallower areas and to do the final touches.

The significant difference between this cut and the previous cut operations I did the other day of the same model as I didn't understand how to set the Rest Machining option; this means the rest of the stock to cut from the previous operations.

I tried something new here as well, which was taping the underside of the stock and the board and glued the two sides together for a more secure fit. I did this primarily because I knew I wanted to cut the part out of stock, and I didn't want it loose.
I noticed that toward the end, one side of the stock was higher than the other and so I started cutting into the tape before its final pass, which was not ideal.

Since I had to be there watching and blasting it with air, it was not ideal. I've got an idea to add a few nozzles which I can attach to the air compressor so I can let it run on its own.

So the bits I got from my brother (see earlier post) were for cutting steel and titanium, which, as it happens, is not ideal for cutting aluminum. I thought it would be just using a harder bit than necessary but would work just as well, but not.


Oneshop Redding Cutting Aluminum

After acquiring the aluminum stock and endmills to cut it, I need to figure out what feeds and speeds to start cutting the material to achieve a decent outcome.

I started with a flat plain cut to remove some of the access material and give it a smooth surface to begin my next operation. I didn't realize till I started cutting that the aluminum stock is not perfect perfectly flat on top, I added an extra 0.5mm to the top of the stock to clear it off in case it was imperfect, which worked out well.

I set it at 203mm/min (8in) and 0.5mm stepdown with a 1/4" 4 flute endmill. I can probably have more of a stepdown and even increase the speed, but I'm playing it safe for now. These bits are seriously expensive, and I don't want to ruin anything in my first go.

The outcome was not a huge success; the tool edges were a bit worn just slightly enough that it left some stock when it should have cut. The chip evacuation wasn't the greatest either, so I'm going to try using compressed air and silicone wd-40 lube to give it more of a chance. Overall though the places it did cut have a very nice finish to it, something about CNC cut aluminum feels so good, such a perfectly smooth top.

The sound of the machine didn't sound like I was hoping. So for the next cut, I'm going to lower the optimal load on the bit, which should decrease the size of the chips and have a smoother finish. While cutting the aluminum heated up quite a bit and got to the point where it was too hot to touch, I think the reason why it was heating up so much is because of chip evacuation; the chips couldn't get out fast enough and so were recut and started welding with the tool. The outcome was a very rough finish and a definite color change along with it being much sharper of a surface finish.


Attempt number two, it was more successful than yesterday, I bought a can of wd-40 silicone lubricant and sprayed it periodically while it was cutting, and that did the trick, I sped it up quite a bit faster than before, and it kept up. This time the aluminum only got a little warm and all the chips consistent and small. It sounded much much better than before and had a cleaner finish. 
I tried running a few cleanup passes but didn't quite get them down right, so I ended up cutting places where I shouldn't. Very pleased with the outcome, even though it didn't look as clean as I would have liked. One thing I keep forgetting to try is compressed air that would remove the chips from getting recut, and I feel it would keep the material from overheating.

Oneshop Redding CNC Aluminum & Bits

I finally got down to it and ordered a couple of aluminum cutting bits for the Shapeoko CNC router. I bought them off of the site Bits and Bits which has a wide selection of them to choose from. I ordered a 1/8" 3 flute end mill bullnose and the same of 1/16" for smaller details. They were both about $22 each and adding shipping that bumped it up to $54.00 which is quite a lot for just two bits.

Shortly after they came in my brother gave me 14 used endmills from his shop down in Nevado CA as a late birthday gift. This was great as they were easily $20-35 a piece which I could never afford on my own. They were a bit worn from cutting titanium but a few of them where in decent shape. They ranged from a 1/2" thick to 1/16" which is going to really give me a wide range to practice with. Unfortunately, the Shapekoko can only hold up to 1/4" bits so I won't be able to use the 1/2" unless I get a new holder for it.

As for cutting material I looked a bit around online for different grades what's recommended for first cuts and found some inexpensive 6061 aluminum for $17.00 for a block 11.5"x 2.5"x 1/2".


CNC Machining Oneshop Redding error33

Alright, back at it again. So after running through a simple path to see if it would stop before completion I found that it still does, what would happen is it would go through about 40% of its path, then give the carbide an error code (error33) and stop the toolpath, I've gone through a bunch of different cuts, sometimes trying them several times and nothing worked. I've tried different outlets, different power banks entirely for the router but always had the same result. I asked my brother as he mentioned having some similar issues and tried his solutions but didn't work. What he had done was to lower the fine tolerance of the passes to have a rougher cut out, then come by later with another tool to clean it up.

After looking a bit online forums I found a few possible solutions. 

Carbide 3D's Shapeoko cnc machine was originally designed in metric VS imperial. It supports imperial, however it wasn't designed specifically for this and so has to do calculations to convert it to that and so has a lot more of a load than if you where working with metric. If this is the issue then simply designing everything in imperial then just switch the units it measures to metric when setting the tool paths.

This would also explain why not so many people are having this issue as most people use metric for designing and creating toolpath's. Which I primarily use as well but didn't have any metric measuring tapes when setting the stock and so set the unit of measurement to imperial.
Another possible reason for the issue is the sheer amount of digits it has to calculate and one guy said he solved the issue by rounding everything to only have at most 3 decimal spots. For instance, if the side load cutting rate is at 0.04195 you would simply round that to 0.042 and etc with all the settings. Apparently this reduces the overall load the machine has to take.

Here is a link to the forum that I got this information on: https://forum.shapeoko.com/viewtopic.php?t=8237

So after making a few modifications to the tool path settings, I set it running again and await the results.


CNC Machining Oneshop Redding (router problems)

Today, when I got to Oneshop the router for the CNC machine, wouldn't turn on, the light would come on indicating that it has power, just the tool wouldn't spin. Was looking around thinking maybe a cord came loose or something of the sort, but nothing was loose. I asked Tyler (oneshop owner) about it and he said the brushes on the motor top may have worn down sufficiently to need to be replaced. Thankfully he had a couple of extra which I installed and that got it working again without a hitch.

After starting up another cut of Kevin (small circular paperweight) it started without issue and ran through about 80% of its path before it suddenly stopped moving. This was a bit annoying and I had noticed it doing the same with another cut. After posting this on Instagram, my brother mentioned having the same issue and that the solution was to lower the tolerance from its default 0.004in to something rougher and just create a new toolpath to clean it up afterward to get a cleaner finish. The reason it does that is the computer has to calculate each layer and multiplies over and over to the point where it overloads and crashes. I believe this is just an issue with this specific machine though I haven't tried it on the larger one they have.

CNC Machining Oneshop Redding

Unfortunately, today didn't start off on a very good foot. Number one, I forgot to save my files from what I did before so I had to start from scratch, which I didn't think would be an issue. Second, I forgot a few of the steps to getting started. My first problem arose when I tried setting the tool for the router and it wouldn't accept a 1/8" drill bit when I put in all the info. I tried other bits and those worked without issue. I called my brother up @jehtradedollar and asked him why this would be. I feel pretty dumb because this was specifically mentioned in the tutorial I watched nearly a dozen times, and that is, drill bits can't be used to mill out a stock, they can only be used for up and down, so drilling a hole straight down would be an example. He said that if its some cheap bit that doesn't have specifications on the packaging then just to set it as either a flat tip or ball. In this case, I chose a ball head tip even though the actual bit is something different. One of the other issues I kept running into was the router would dive into the wood. How it should work is a slow spiral down descending at about .5mm per layer until it touched the wood at which point it would slow down even more and continue on its toolpath. This would prevent it from starting too early if you were to set the y-axis too high, or measured something wrong in the program. The issue I was having is where the machine would stall as its rising then crash down skipping a gear and the machine would think it's still high above the wood and would cut more than it could eat. The problem, like the other one, was pretty obvious, the wood I was using was 1 5/16" and the router was set too low so when it was raised it would get raised to the maximum height at which point it would stall, then plummet. The solution for this was simple and had a couple of different options. The one I went with was to swap the wood out with something shorter. This was a simple fix which may not be a solution for larger parts. Another fix would be to set the router higher, this would allow the maximum height to be set higher and so wouldn't stall going over 1.5". Another solution would be to set the raised height at which the router descends from to start its spiral to be lower over the wood. For this I set it to be about 1/2" above the wood at which point it would start its descent.