Very late, but...

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AlBorland
Posts: 75
Joined: Mon Jun 23, 2014 5:26 pm
Location: Austria

Very late, but...

Post by AlBorland » Tue Dec 23, 2014 2:41 pm

I built my machine (from myhobby-cnc.de) long ago, so it really is very late to start a build log. However, I figured I better start one thread to post my upgrade projects. So many ideas, so little time...


Aluminum 7075-T6 spindle mount
The first post is about a new spindle mount. I had the design and the materials for a few months already, but never got around to finish it. Partly due to time constraints, partly because I was thinking about a different way to mount the spindle between two makerslides. Finally gave up on that idea because I could not get it more rigid and still affordable without sacrificing work area. So now I had the chance to finish the mount.

CAD/CAM: The design is very similar to my old Delrin mount, except that I made the holder for camera/microscope/endoscope an optional screw-on part. I drew it in Fusion 360 to try the integrated CAM functionality.

Image

The dimensions are 75mm x 65mm x 20mm, the center hole is 43mm which fits all electric drills and most router motors in Europe.

CAM for the inside and outside profile was straightforward, but although the CAM module is very capable, I just could not get correct CAM operations for the two pockets for the mounting screws. Either it tried to mill around it outside of the pocket, generated gcode in the positive z direction, or crashed completely. I ended up writing that part of the gcode by hand.

I did not want to mill 20mm deep slots with a 1/8" bit because of bit deflection, so I used a 6mm bit for the profiles. The pockets for the mounting screws required a smaller radius, so I did a roughing pass with the 6mm bit and a finishing pass with a 1/8" bit.

Material and Milling: I used Aluminum 7075-T6 for this. Before starting, I wanted to do some experiments to find good parameters. Started out with the 1/8" bit, FSwizard: told me feedrate 350mm/min @ 10000 rpm, 0.2mm stepdown. Tried that on a scrap piece and got a very clean cut on the first try. Similarly for the 6mm bit, with nice chips. Used these parameters (could definitely go faster/deeper but speed was not my goal here):

Bit: 2 flute 1/8" carbide
Feed: 350mm/min
Speed: 10000 rpm
Cut depth: 0.2mm for slots with 100% bit engagement, 0.4mm for finish pass
Plunge: Not used, always used ramp-in

Bit: 2 flute 6mm carbide endmill
Feed: 400mm/min
Speed: 6730 rpm
Cut depth: 0.2mm for slots

Lubrication: I normally use come cutting oil when milling aluminum. But here I found that I could not get the swarf out of the slot when reaching >10mm depth. So I used the oil only on the pockets, but did not use any lubrication on the profile slots. The dry chips came out of the slot much easier.

All in all, I found 7075-T6 to be a very simple material to use. Much simpler than the softer alloys I used.

Image

Post-processing: The horizontal holes have 55mm length, I could not do this with the normal endmills, so I opted to finish the holes on the drill press, but use the Shapeoko to make some 10mm deep pilot holes. Also did the 20 mm deep slotted hole for the clamping screw with it. Had to use some creative workholding for it...

Image

Shattered an extra-long 5mm drill in the drill press (this material is hard!), but luckily could get out all pieces from the hole and finish it with a shorter drill from the other side. Finally cut one side open with a hacksaw. If I did it again, I would probably make it two separate pieces, would be much easier to handle.

I think the finished mount looks even nicer than the Cad rendering:

Image
Shapeoko2, 4xNEMA23, tinyg, Kress 1050, various Z axis modifications

chomdh
Posts: 179
Joined: Sun Jan 19, 2014 3:43 pm
Location: Bettendorf, IA

Re: Very late, but...

Post by chomdh » Mon Dec 29, 2014 6:45 pm

Al,

Really miss seeing you on tool time. (Love the user name assuming it's based on the home improvement character)

But honestly, those mounts turned out great. I want to mill some aluminum mounts in the near future and will probably have some questions as I get closer. Trying to find tune the design with wood first.

I wouldn't have known the topic of this post from the subject line. I found it thru a link on the wiki materials page under aluminum 7075. Glad I came across it.
Shapeoko2 #3702:
DW611, arduino uno, gshield v5, NEMA23's on X & dual Y, NEMA17 on Z with ACME rod, 9mm belts, Mean Well NES-350-24V power supply, re-inforced gantry rails.
Soon to have inventables spindle mount and 1M X axis.

AlBorland
Posts: 75
Joined: Mon Jun 23, 2014 5:26 pm
Location: Austria

Re: Very late, but...

Post by AlBorland » Sat Jan 03, 2015 2:36 pm

I think so Tim. ;)

My old Delrin mount was basically the same design, so I knew how it would work. But if I were to do the mount again, I would do it as two pieces. The one-piece unit was easy to handle in Delrin, but 7075 is so strong that I have to hammer a chock into the slit whenever I want to remove the spindle from the mount.

As for the title, I did not want to make a separate thread for each upgrade project, so yeah it is not very expressive. There's more to come.
Shapeoko2, 4xNEMA23, tinyg, Kress 1050, various Z axis modifications

AlBorland
Posts: 75
Joined: Mon Jun 23, 2014 5:26 pm
Location: Austria

Re: Very late, but...

Post by AlBorland » Sun Feb 01, 2015 10:52 am

Here are some cutouts from milling round holes in 6mm Aluminum 7075:
Image
The rightmost one is 0.8mm in diameter, and I'm very surprised that it survived the attacks of the milling bit when it pushed through the material.
Shapeoko2, 4xNEMA23, tinyg, Kress 1050, various Z axis modifications

AlBorland
Posts: 75
Joined: Mon Jun 23, 2014 5:26 pm
Location: Austria

DrillOko

Post by AlBorland » Sun Feb 01, 2015 11:46 am

I had around 30 holes to drill in a 6060 Aluminum plate and was too lazy to do the measuring and drilling by hand on a drill press. On the other hand, I could not mill the holes with a spiral toolpath because the holes have the same diameter as my smallest endmill with 15mm flute length. And I hate plunging into Aluminum with an endmill.
So I have temporarily converted my ShapeOko to a DrillOko:
Image
I was a bit disappointed with the accuracy, because when the drill touched the material surface, I could see it was diverted to the front (Y- direction). The vertical cutting force on a slow-spinning drill is much higher than on a fast-moving mill. I blame the delrin wheels and bearings on the Z axis for the deflection, thankfully those are to be replaced very soon.
Shapeoko2, 4xNEMA23, tinyg, Kress 1050, various Z axis modifications

twforeman
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Re: Very late, but...

Post by twforeman » Mon Feb 02, 2015 8:24 pm

Love the DrillOko... :)

I've been thinking about mounting a Sherline headstock to my ShapeOko 3 (after I play with it for a while.) That would support drilling, as it will run at low speeds with higher torque. But it's pretty heavy.
Ender 3 3D Printer
ShapeOko v3 serial #0004 - upgrade thread
All of my ShapeOko related blog posts

AnonymousPerson
Posts: 758
Joined: Sun Apr 26, 2015 1:16 pm
Location: 3753 Cruithne

Re: DrillOko

Post by AnonymousPerson » Sun Jan 17, 2016 5:18 pm

AlBorland wrote:I was a bit disappointed with the accuracy, because when the drill touched the material surface, I could see it was diverted to the front (Y- direction).
Resurrecting this old thread... but it's still of interest to some. :)

With the inaccuracy, do you reckon doing a pilot drill hole first (say 1/8" or 3mm) with the DrillOko might fix it?

So, running the gcode first with a 1/8" - which would hopefully not deflect - then following up using the bigger size drill bit into the same holes?
Shapeoko 3 #516

Jimf
Posts: 233
Joined: Wed Feb 11, 2015 8:58 pm

Very late, but...

Post by Jimf » Sun Jan 17, 2016 5:33 pm

I always use a center drill, on the drill press and CNC. Short stubby, doesn't deflect to accurately position the hole. I have them in several different diameters. It takes longer but it's better than having to redo the part if the drill bit walks on the last hole. Done that before.
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