Community challenge #11, 2019-2020 edition

Now that you all had a few days to sit and ponder about the meaning of life, it’s time to kick-off the next challenge!

Challenge #11 is: Two-(or more)sided machining

I thought it would be fun to try that theme to motivate those who never tried two-sided machining to have a go at it, while challenging those who master that technique to raise the bar and do multi-sided machining (dodecahedron anyone ?) or some really tricky two-sided pieces. So basically this is a challenge about dowels, jigs, and head-smacking when not flipping the stock in the right direction between sides.

The rules for this 11th challenge are:

  • submit your entry in this thread:

    • the project must be made on a Shapeoko or Nomad
    • the project must involve machining at least two opposite sides of the stock (i.e. finger joints on the side of the stock do not count), EDIT: and the project must involve alignement of the cuts on the different sides to achieve the final effect.
    • you must include pics of the finished piece.
    • you must include the design file (so watch out for any licensed vectors you might use, that might not be shareable)
    • tell us about your mistakes, tips and tricks, etc…
    • posting your project to CutRocket will get you a +2 bonus on the vote tally.
  • you can post multiple entries if you want.

  • timeline:

    • deadline is set to Aug 2nd, midnight PST
    • there will then be 7 days for voting.
      • voting will be open to legit community members only, and the jury reserves the right to remove votes from “outsiders”, and will also break any tie.

Here are the prizes for this challenge:

  • First place: $200 credit on Carbide3D store
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  • Second place: $100 credit on Carbide3D store
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  • Jury’s prize: $100 credit on Carbide3D store
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And some priceless Carbide3D swag too (+2 Karma)

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Have fun machining

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![20200803_015100|375x500]
(upload://axdUhMiaa6EN9BNOn6W27xN6qTO.jpeg)

Last minute entry! turns out twelve sided parts can take a decent amount of time to machine…who knew.

The want for a 4th axis has been high for years and most recently has been up on the “rabbit hole” list. This challenge was a great opportunity to not only test and practice positional cam, but also to see if actually having a 4th axis would be worth it.

And while I didn’t use a dodecahedron, I designed my A axis fixture to use a dodecagon, this meant 30 dgrees of movement per spot. First was to bandsaw 3" solid round to around 2" and machine a fixture to hold the stock while the 12 sides and middle contour cuts were made. I then machined the 4th out of 0.750 plate and used the dodecagon to locate and do the final profile of the stock. Once three of those were done, the fixture was tapped for the pitbulls (love love love) and it was indicated in.

Luckily I was able to design the part to suit my tooling on hand and that meant all the work to avoid collisions and clearance problems was mostly done.

CAM - The most challenging thing aspect was trying to get Fusion to rest machine right between setups. I would rough halfway down the part to hit as many spots as possible, however on the next rotation I could not figure out how to rest machine off of the previous stock AND the setup stock. I believe this was because it was a manual rotation and I rotated the stock in the design window then created a new setup per side. I did this to use the same sketch driven boundary constraints.

When performing the next roughing cycle I was forced to air cut most of the side again which let to almost 2 hour per side cycle time. I estimated cycle time would have dropped to 40ish minutes if I could have rest machined the stock with the rotation taken into account.

If using a real 4th axis I don’t think this would be a problem because you just use tool orientation in one setup. There are tricks I don’t know but that’s the point of things like this.

Cam was nothing special, 0.001 minimum chiploads but changed to a low doc high stepover to try and minimize the amount of air cutting.

Things and stuff - Fusion 360 rest machining is awesome but I couldn’t get it to work very efficiently with this type of cam, even using specific stock files. A Nomad with a 1.5kw aircooled spindle can be run day/night at 18,000rpm. When using long stickouts try using less axial depth and more radial, also more flutes can mean a more rigid core. This can make a difference in 0.125 tooling if you have good room for chip evacuation.

The part - Interestingly enough this part is only adaptive roughed right now and will definitely be finished soon. It will be fun to play around with some toolpaths to see what happens. Overall I’m beyond satisfied with this Nomad’s performance. This was the most complicated part I could think of and it handled it perfectly!

Currently the machine time is about 20 hours
But man, is it shiny and curvy! :star_struck:

I’ll add more photos and vids in the morning.

https://a360.co/2BRWnZY

16 Likes

Hey judge,

Can I clarify the definition of machine both side, as in creating a spoon / must be 3d or are we saying I could for instance vcarve one face flip and vcarve the other- sorry if I am being dull, lol nothing new there.

Edit - Vince you made me laugh I love it, should have added at the end “to show every awesome car part I have ever made”

Thanks
Jon

4 Likes

Very good point, I meant anything that requires aligning the cuts on the two (or more) sides, so two completely independent surface cuts would not work (that’s not the idea). I’ll edit the rules to make that clear.

2 Likes

Half Hull boats. Created model myself in Fusion 360, Programmed in Fusion 360 Shapeoko3 Standard no modifications, stock machine.
My first 2 sided project, required some deep cuts and longer tool.
2" thick stock


Hunter 39 - 3 v15.stl (750.3 KB)
https://a360.co/3fblt3K

10 Likes

Oh dang do I have a project log of double sided machining. I’ve done these trays that have a curved back and did a sort of how I did it outline post here:


Files are already up on cut rocket.


Cutrocket file here: https://cutrocket.com/p/5f05515c5009f/

12 Likes

Now I’ll post the project that ended up being the whole reason I got into CNC stuff.
I wanted to have the ghost from Destiny for my desk. But around the time I wanted one, I had gotten rid of a bunch of plastic stuff so I had decided 3d printing was out. Here’s what the ghost looks like:

In game you have different shells, so they change the look of the outer wing bits.
Eventually googling what is the opposite of 3d printing got me into CNC, and decided I was going to make this in wood.
I can’t tell you how terrible an idea it was that this was going to be my first project. Difficulty of learning combined with learning at a makerspace (because my wife didn’t want me buying a several hundred dollar tool without making sure I knew what I was doing), meant it took me quite a while to figure this out. Also random streaks of burning out. I think all told it took about 1 and a half years to go from “I want to do that” to “I did it!”
I also made a post about it a while back when I finally was able to complete one: Destiny Ghost on the Nomad

Here’s one of the newer ones I’ve done finished:


I’m going to outline current process, because it’s what I have more pictures for.
So I start off with moving stock down to a known size. Also flattening them in the nomad. But while I’m cutting the stock down to the shape I also have 4 flip pin holes machined into the corners of the stock. Stock size measures 140x130x34 (or 36)mm. I set a square up in carbide create of 140x130 with those flip pins positioned slightly into the square and then surface the face and cut out the stock.


Lately I’ve been getting two woods glued together. I have to make sure I know where the seam on the wood is so it doesn’t collide with the part where the triangle tip is, more for aesthetic reasons than anything else.

Tape and super glue have been my go to holding method. The pins help me align it to the board. I usually only use 2 pins out of the four.

I have 2 setups for fusion, same stock size, just flipped on the corners:

I also use heights tab to control how deep the first side machines


Not sure if you can see it, but pocket 3 and pocket 3 (2) are part 1 and 2 of the same job above. Pocket job 3(3) is ~4 and a half hours depending on how dense the hardwood is on my poor nomad, so I like to be able to knock that out in 2 hour chunks depending on my schedule.
After all the machining is done I’m left with a decent finish of the parts, but I need to cut off the supports and sand them down.

Then I need to cut a better hole for the magnet to attach to the center shpere:


I had to 3d print a jig to help me get the exact angle correct on that.

Then I machine the triangle tips which is also from the stl bundle, and then glue magnets and the tips to the body of the different wings, or insert the 3d printed part into the channel, add finish and boom ghost done:

STL file I started with: https://www.thingiverse.com/thing:747305
Fusion file link: https://a360.co/2SQ3A47

Realizing after looking things over, I could likely remove the supports and just have the model be flush with the bottom, which would save me some time.

Edit: Here are 2 that I finished last night.



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Modeled by Me in Fusion 360, Programmed in Fusion 360. Shapeoko Stock Machine.
Used Pin method to flip.
I don;t have the finished product it was a gift


https://a360.co/2DopzrK

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I feel we all are going to be shown our places when this post drops.

Second place is the new first place!

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If there’s one thing I’ve learned after joining this forum is that you can’t underestimate anyone. The amount of creativity and sheer diversity of ideas in this group is really astonishing and we definitely have a few wild cards around!

Plus a contest like this is the perfect opportunity to try something new, dare to step out of your comfort level and grow.

I won’t be posting anything old. I’m trying something fresh and a little scary. Something that has a large opportunity for failure but will help learn and adapt work holding and machining strategies. Also if anyone feels my entry could potentially stifle their creativity or drive to make something, I’ll happily disqualify myself.

Working on the CAM tonight, it’s a doozy :grin:. Best of luck to everyone and its awesome to see the entries already coming in!

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That moment when you realize you better order a new end mill fast to take it to the next level…

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Im calling this one “twisted bowl”

Twisted bowl file

26 Likes

To get an entry in, a piece I call “magnetic door catch for Snap On KR274”

The cabinet is a side hanger of a certain age that never had any door latch provision except the cam lock. This is REALLY annoying, since it meant that to keep the door from opening, the key must be used. It rattles if bumped. The lock cam turns on it’s own if the key is left in, which makes opening and closing more annoying, and also scrapes up the paint.

So, a magnet.

The model:


A rare earth magnet in the hole is attracted to the center shelf of the box when this in mounted in the flange of the door:


to hold the door closed

No fasteners used. It pops into the hole in the flange and is held with no play by the door skin.

How this was machined:

A pocket was cut in the wasteboard to hold a chunk of Nylon rod:



The pocket stock-to-leave was adjusted for the bore operation (the last op) several times and the operation repeated to get the correct fit.

The origin is in the pocket, centered in x-y, but level with the bottom of larger bore. This will be shown later. Setting zero to bore the pocket required finding the wasteboard surface and setting the z there to be 5mm t get a 5mm deep pocket. This made it unnecessary to reset the zero at all.

The stock:


fixtured

for these operations:

The setup for the first end allows for the stock oversize on the other end, so there is bottom extra stock as well as top.


The nubbin and edges are chamfered using a ball end, since it is a small chamfer. Just enough to break the edge to install the part when done and make inserting in the fixture hole for the other end easier

The machining:



Then came the other end. The same fixture was used. so the origin is actually within the part.

This allowed the origin for the first end to be at the surface of the raw stock, which makes things a lot easier. It was easy to place it for this setup, since it is a point on the plane cut on the first setup, a plane in the model

There is less surface to grip and more flex since it isn’t the full round. For a one off, I just reduced the tool engagement a lot to avoid pulling the part out. May not have been needed, but whats an extra 15 minutes?

followed by boring the hole for the magnet. The bore was done with an adaptive operation, and I adjusted the parameters for periodic retraction (by limiting the pass depth) to help clear chips.


Note the skin left over. I expected this as a possibility, but didn’t worry about it. Came off real easy. Minor dimensional adjustment would take care of it on a repeated job.

Installed the magnet using a wood dowel as a punch (I have no brass punch small enough)

and installed in the cabinet. The hardest part was putting the hole in the door flange. It is 18Ga (nearly 1.5mm) steel.

I didn’t bother to fancy the model up. Just a quick job to meed a need. No artistic merit here. Just

mag-catch.zip (1.9 MB)

should anyone want it.

10 Likes

First post on the forum! I have been lurking around here for a few months learning many things from other users so I thought I would try to contribute and share a small part machined on the Nomad this weekend. The cover for the lamp on the stove was broken when I moved in to my apartment so I thought I would machine a part that would shield the lamp and diffuse the light. To try and achieve this I modelled a part in fusion 360 with a “pyramid pattern” on the inside of the cover using two perpendicular V-grooves and rectangular patterns. (Perhaps this could be readily machined using a V-bit instead of the hours I spent machining it with ball end mills).

I machined the part in polycarbonate and flipped the part once using 4 mm dowel pins to locate the part using the bed as Z0.

The part is pushing the smaller build envelop on the Nomad a bit so I did a dry run with the end mill 5 mm over the bed to see that I did not hit any end stops with the first toolpath. I used 2mm and 3mm flat end mills to try different speeds and feeds to clear out the majority of the material and a 2.5mm and 1mm ball end mill in succession to machine the light diffusion pattern. There were some small strands of polycarbonate still attached to the pyramid pattern after finishing with the 1 mm ball end mill, perhaps I should have done a spring pass with the same end mill to clear that out but I was too eager to see the part finished.

!

I cut out the part using tabs but should probably have used double side tape or the machined screw holes for holding the part down as the tabs left small blemished on the part that light up a bit when light is passing through the cover.

I was mindful to not machine the bottom surface of the part as I wanted it as transparent as possible. The idea was that the light diffusion pattern would diffuse the light but I think the majority of the light diffusion is done by scattering caused by the ridges left by the finishing toolpath (1mm ball end mill with 0.1 mm stepover).

Before and after picture!

Link to CutRocket (Pretty specific for my stove lamp haha… But perhaps it could be useful for someone to look at the speeds and feeds or the modelling of the “pyramid pattern”: https://cutrocket.com/p/5f14c01312573/

21 Likes

Brilliant. I am going borrow that idea for my stove hood!

And welcome aboard another Nomad owner!

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Team Nomad is on fire !
It’s interesting to see such diverse entries, yet another testimony to the versatility of our machines.
(and welcome @Olle! no better way to make a first post)

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Thanks for the welcoming guys! I’d love to see that part if you end up machining something similar @PhilG!

1 Like

Why not throw another one in, since at the moment I don’t think I’ll have the time to do something artsy. Another part for a comparator. This time a riser with a fine vee-groove for inspecting and measuring small round things (tools for the Nomad, among other things, but actually made so I can inspect pars I am working on for actual work)

This is based on the same base model I posted the other week. All I changed in the model was the height (parameter value) and the groove profile.

The model:

This was machined in two setups. The first was from raw stock. Here, the stock was pocketed into the wasteboard,

using the same socket as the last time (put in by the scheme bore, measure, rebore and test fit, repeat until proper snug fit). Again, I didn’t bother cleaning up the stock much. The ends were square enough to finish-- flat within 1.5mm stock allowance either end.

Machined the bottom side, bored holes for 3mm dowels,

and surfaced new location for the second side mounting and bored fresh dowel holes to insure perfect zero (drill at 0.9mm, then bore using 2.4mm flat mill)


then pop in the part for setup 2 with double-sided tape to keep it down:

For both, the zero is center and at the mating surface with the wasteboard. The first setup had stock allowance on the bottom, as it was rough, so the zero was on a stock point. The second, being a finished surface, the zero was on the model. The machining on the first setup did the perimiter a bit over half way down. The second setup did the same.

Then the vee groove using a 45 degree chamfer bit

perimeter with a ball end, and a narrower vee bit (60 degree vee carving) to clearance groove the center of the vee slightly. The bit has a slight flare at the tip to make the 0.1mm flat, and in this case, it the ideal tool for a narrow clearance groove, much better than the smallest ball end I have on hand.

The product:


The top is dead flat though there is shadowing of the tool path. There is flat patterning due to the interpolation, but the size of the flats relative to the size of the part (100mm-ish) looks large, but the max error is less than 0.02mm on the round surfaces.

Setup on the machine with a tool for inspection (a 135deg split point drill. Done several hundred holes in T-11 chrome-moly material, looking at condition. Tough to photograph, as the HDPE is SO bright when the illumination is on):

IMG_0081
IMG_0082
IMG_0083
IMG_0084

The models and setup sheets (inventor) for those interested:

riser2-with-cam.zip (2.3 MB)
riser2-with-cam-setups.zip (2.1 MB)

8 Likes

This is my favorite project I worked on with my kid. We made iPhone cases on our Nomad 883, and our own two sided jig to help us get repeatable results.

So let’s start by looking at 8x8 Nomad 883 waste board we modified. The left side of the waste board was pocketed to perfectly hold 3" by 5.5" blocks of wood (two sided tape in the middle for insurance).

We could then CNC one side of the iPhone case.

Once one side had been cut, we could flip it over onto the right side of our waste board. The slots on the right side of the waste board held the iPhone case in place so we could CNC artwork onto the back side of the case.

We then got into different inlay materials, and could customize cases with unique designs. The “Cold Coffee” case was my kid’s, we inlaid a circuit board that was pulled from a dead inkjet printer. And then added a copper inlay as it was somewhat like the color of coffee.

I think that case got even better looking as it aged. This is what a teenager does pulling a phone out their pocket a million times a day.

The very first photo of the “Visual PLB” case (that I took today) is my current iPhone case. I have used this case for over 2 years. I’ll admit I cleaned it up for this photo, but the brass and bamboo have held up WAY beyond my expectations. Bamboo is by far my favorite material to CNC.

iPhone5.mcf (20.0 KB)

iPhone5 PLB.zip (1.6 MB)

24 Likes

Oh boy, now I have to try “PCB inlays”, that looks fantastic
The “side by side flip jig” is very nice too :+1: