Hola,

I have access to 2 CNC routers at my local makerspace, a Shopbot Desktop 24x18 and a Shopbot PRSalpha 48x96. I have SpeTools O flute endmills in 1/4 and 1/8 and their (speeds and feeds can be found here) [https://spetools.com/pages/spetool-router-bits-speed-and-feeds]. For 1/4, 18k rpm, 72 IPM, 0.004 chipload. For 1/8 18k rpm, 36 IPM, 0.002 chipload.

I was initially going to make some 1/4in thick parts out of an aluminum sheet the last time I was there, but the makerspace employees said my RPMs are way too high for aluminum and that I should practice on wood first. I understand that they probably don't want noobies breaking their machines.

To appease them, I did just that and had no issues running the macbine. I'm also going to cut my sheet of aluminum close to the size of the parts, that way the end mill is attacking the piece on the side rather than slotting through it. I'm going to try the first run half the recommend feeds and speeds, then 75%, then at the recommend feeds and speeds. For width of cut, I have it at 30% of the end mill diameter, and depth of cut at half of the end mill diameter.

For workholding, I want to use the super glue and blue tape on a clean sheet of MDF, but I was told that lateral forces on the end mill might cause the part to shift.

So my workflow looks like this: 1. Cut sheet down to size. 2. Use tape and super glue to mount the aluminum sheet onto MDF and mount that down to the spoilboard. 3. Use a drill bit and drill where needed. 4. Use endmills and finish those holes. 5. Screw down into those holes to hold them in place. 6. Finish cutting.

Personally, I'd much rather not cut these pieces down to size if the CNC and my end mills can handle it. It'll also make the super glue technique weaker since there's less surface area. And I'd much rather not have to spend time screwing the part down part way through the cut.

I was just wondering what's the best way to optimize this workflow and if anyone has used the same or similar machines as the Shopbot.