[Shalecnc]

I'm very new to machining, just got a Grizzly G0704, and am trying build a 36" x 48" CNC router, using 80/20 extrusions.

What I'd like to do, is use the G0704 to facemill the surfaces of the X-axis extrusions, so that I can more accurately mount the linear rails without any binding. (The X-axis extrusions will be 1545, about 48" long)

The problem is, how should I go about setting up this milling job? The Grizzly has a max travel of about 18", so I can only facemill a bit before having to reposition it.

I've tried different clamping setups, using the spindle DRO, the vice etc..., but I can't get a consistent surface once I reposition the extrusion. Any pointers for milling very long items that extend beyond the bed?

[Shalecnc]

Sorry this is such a basic question -- i've searched the web and found lots of details on how to clamp things to your bed, but nothing on how to ensure that the piece is accurately positioned when you slide it forward another x inches.

- also, I'm using a 2" diameter facemill for this operation. Is that the right tool for this?

[warrenb]

Sorry this is such a basic question -- i've searched the web and found lots of details on how to clamp things to your bed, but nothing on how to ensure that the piece is accurately positioned when you slide it forward another x inches.

- also, I'm using a 2" diameter facemill for this operation. Is that the right tool for this?

My home built CNC router is with unmachined 8020 and it doesn't bind. 8020 comes out of the extruders very straight.

But since you asked. If you are only face milling the top and not trying to square all 4 sides you don't have to worry too much about having it perfectly aligned to the table's x axis. But what I have done is... Clamp some consumable aluminum or even wood and then cut a square edge with a flat endmill (leave a chamfered edge so you don't have to cut all the way to the table). Now you have a x axis fence guide to align your 8020

Toe clamp about 4 inches inside one end and somewhere else down the 8020. Face the outer 4 inches. Place a toe clamp with some padding on the freshly faced section. Remove the 4" toe clamp then face the rest of the way. Once you're at the end of your table travel leave the z axis in the same spot and move your y axis off your part. Then simply relase your clamps and slide the extrusion further down the table against the guide you cut first, reclamp, and reface. Rinse and repeat.

Pretty simple for a single face. But do a favor to yourself and check the straightness with a dial indicator to see if it's necassary.

If you are referencing to other holes or features that will end up outside of your travel then you can cut reference features or drill some dowel holes you can use for indicating. Dowel pins are your friends.

Hope this helps.

[louieatienza]

Misumi sells extrusions that are already face-milled on two sides; I'd check that out first and save yourself the work!

As for DIYing it, I'd make sure that you have bellows covers or such on your bed ways, as that anodized dust os probably no good for them.

[warrenb]

I think off the shelf 8020 is just fine.

Misumi sells extrusions that are already face-milled on two sides; I'd check that out first and save yourself the work!

As for DIYing it, I'd make sure that you have bellows covers or such on your bed ways, as that anodized dust os probably no good for them.

[Johnny@MISUMI]

I actually work for Misumi but I am not biased when I say that Misumi also has not cutting fees as well as different color extrusions for much less than 80/20.