Aluminium newbie week-end

Nice! Any other changes to the machine other then air? Z axis upgrades or anything?

I tried to get bigger chips with my machine which limited DOC due to the side load. I may try to get more but take less aggressive cuts.

BH

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Matthew,

I used exactly the feeds and speeds from Winston’s video, and for the 102Z 1/8" ZrN coated endmill and an adaptative clearing toolpath, that’s 10.000 RPM, 762mm/min feed, 0.305mm optimal load.

I did not limit the depth of cut, so Fusion generated a toolpath that cut the full depth of pockets in one go.

Right, I should have mentioned that, as I am cheating there a bit too:

  • I have the HDZ, which probably helps.
  • I replaced the stock belts by steel-reinforced belts (see other thread on this topic)
  • I replaced the MDF bed by an aluminium one

so overall, far from a stock machine by now.

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The HDZ definitely helps with this type of work. Awesome job! For a first aluminum project, this is really nice work.

If you tweak the optimization in the adaptive, you can slow down around corners and certain radii to avoid chatter in these areas.

Do you have any cut video for sound? Adaptive just sounds so good when programmed right.

Also I would just like to point out that the deepest cut path is not always the best one for our machines. Long chips are awesome (welcome to the club :wink:) but due to side loading limitations, usually speed has to drop considerably for full depth. This isn’t a problem on smaller parts but start getting into bigger blocks of material and it will make a difference.

What’s project #2??

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Thanks for the pointers.

I did capture a few videos during this first cut (originally intended for forensics in case something bad happened!), but the sound of the air compressor may have ruined them. I’ll try and check tonight if some are not too painful to listen to and upload one, but as far as I could tell I was getting a nice regular chatter-free sound.

Depth of cut: how do you characterize this side loading limitation / compute the compromise you are making between depth and speed ?

Project #2 is…more of the same (I need four of these) but I’ll use the opportunity to try more aggressive settings to characterize how far I can push things with my setup (and this 1/8 endmill)

Project #3 will be buying thread mills and learning how to use them.

Here’s a video
As you can tell I have no clue how to embed a video in this forum, how is it done ?

EDIT:

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I stumbled on a method using Google photos. Don’t know if you use it but it’s extremely easy.

Once Google Photos is installed your video will be automatically saved. Navigate to GP and choose share, create link, copy link. Then paste link into your post.

i put it on youtube and just drop the link in my reply.

Example:

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indeed, couldn’t be any simpler, I made the mistake of inserting it as a link but I should have tried just pasting the link. Thanks!

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I have a question about this piece, that I have cut three times since then with quite repeatable results. The expected dimensions look like this (Sketchup screenshot, not Fusion, long story):

The dimensions I actually measure with a caliper on the finished piece are as follows:

40.07mm (expected 40mm)
20.05mm (expected 20mm)
~9.2mm (expected 8.75mm)
~15.5mm (expected: 16mm)

Though my X/Y calibration could be better, the ~0.2% error I get on the outer dimensions (40mm & 20mm) is ok. What’s not ok with that I am 0.5mm off for the other two measurements.

So I am thinking, the machine is fine but my toolpaths are incorrect somehow:

  • a 3D adaptive clearing with 0.5mm radial and axial stock to leave, does most of the job
  • “Horizontal” toolpath as a finishing pass of all inner features, with no stock to leave => this should take care of the remaining 0.5mm on vertical walls & flat surfaces.
  • toolpath for the holes (not relevant here)
  • 2D adaptive clearing to do the profile cut, no stock to leave (actually done in two toolpaths, one that cuts around leaving 1mm at the bottom, and a final one at the very end that cuts the remaining 1mm)

Any hints as to why my profile cut (with no stock to leave/no finishing) gives me the exact right dimensions, but my 3D clearing toolpath + horizontal finishing pass leaves an extra ~0.5mm everywhere, radially ?

The Fusion360 design is here in case someone is willing to look at the toolpaths

Probably because horizontal isn’t the best strategy for finishing walls.

All my vertical walls get 2d contour pass with spring. After that, adjust with negative stock to leave

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Allright thanks, I’ll try a 2D contour finishing instead and see if this gets me closer. Is it common from your experience to have to adjust with a negative of stock to leave to get the right dimensions? I remember Winston discussing the topic of internal stock tension release while cutting, which could alter final dimension versus what was expected (and justify having to shave off a bit more than anticipated with a negative stock to leave)

I haven’t quite got to the point of trying Aluminum yet, though I have tried and succeeded in working with Brass. I found G-Wizard extremely helpful in determining the proper Speeds Feeds and Offsets to use when Cutting.

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Due to our machines deflection and type of cutting you’ll usually be undersized, also take into account the belt stretch variable and imo its always better to cut undersize and dial in with stock left adjustments.

This isn’t new stuff, the s3 can be extremely repeatable but tight desired tolerances usually require a manual input. Kinda like our “cutter compensation”, usually easy to get within ±5thou and even less with adjustments.

Now, if you are using a vise to workhold then internal stressed definitely need to be taken into account. You’ll see most big cnc guys use a gripped jaw or dovetail to minimize clamping forces and that in turn minimizes internal stresses.

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It makes sense, and I’m fine with manual tuning to get right tolerances. I was just surprised to get this 0.5mm difference on one inner pocket dimension while the outer profile that supposedly has the largest amount of deflection is within 0.05mm. But that may be my toolpath and I still did not have time to do more test cuts.

In recent weeks, the interest in milling aluminum on the Shapeoko appears to have increased very much, probably due to the great projects and results from @Vince.Fab, @RichCournoyer, @wmoy and others. More recently @griff and @julien have made the plunge. I guess it is also in part due to the recent offering by Carbide of new quality ZrN endmills made for cutting aluminum and Winston’s videos.

I’m still learning the ropes with the Shapeoko and while I’m doing fairly well in CC and VCarve, I’m still learning about feed and speed, I mostly use known recipes (defaults) then adjust. I can successfully carve what I need out of wood and engrave different materials.

I have yet to seriously jump in the F360 pool where I only dipped my toes because I find that pool very deep and can’t swim very well.

I’m not ready to make the jump to aluminum yet but I hope to in a few months. I already have a few ideas of things I need to make.

There is a lot of good information scattered between the many posts here, the wiki and other online sources. For a relative beginner, it can be hard to follow as many people have highly modified machines, they use advanced tools with relatively complicated parts. Many online sources are not Shapeoko specific so the information may not be relevant to the Shapeoko.

I wish that someone would create a page with videos, maybe kind of a Shapeoko cookbook series.
People can learn (define the basic toolbox, material, F&S, etc.) to start, read the recipes (projects), get the ingredients (tools and materials) so they can try a few simple 2-2.5D projects. For example, Winston had a project with a bottle opener that I think Julien tried. A video guiding people through the whole process from creating the part in CC (since it is the tool every Shapeoko owner has and is probably familiar with) to calculating feeds and speeds using a free calculator, what material to get, choosing your endmills, setting the job (preparing the workspace, securing part, cooling, etc.).

That means not going into F360 or get into advanced toolpaths techniques right away. That would be left to the second section called: Milling aluminum with Shapeoko for the simple-minded along with more advanced tools and mods available to the Shapeoko to make it a better machine for the task.

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Which is why I think Winston is the best resource currently for stock-Shapeoko aluminum milling. He has very few mods on his machine and has good recipes that he shares in his videos. I started there to get comfortable with aluminum and an increasing gradually in my aggressiveness.

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I agree that Winston’s video are a place to start and if this is the only thing we have, I guess it is a start but let me give my constructive criticism. Winston’s videos are interesting well edited and to the point but they relatively short, with tight edit they skip some details, in most (not the last one on aluminum), the settings are quickly mentioned. He uses F360 (good software but not for most newbies) and designs something in 3D with intricate tool paths. The video mentions what was done they do not how to do it.

In contrast, John Clark’s YouTube videos (for wood and engraving), as an example as he maybe not as well known, take you from concept to finish product showing you how to do it using the basic tools providing tips and tricks along the way. This IMO would be the type of instruction that would be beneficial to aluminum newbies. Unfortunately, I guess he’s not milling aluminum yet.

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I guess the difficulty is coming up with learning content that is not too obscure but still detailed enough, when there are so any different kind of Shapeoko users, that have different expectations…Winston’s videos have always been great and are getting better each time. But I agree that the missing part in all the content out there is a kind of learning roadmap, so as not to feel lost/overwhelmed in the first months/year.
This being said, this forum is probably the next best thing !

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@Julien

Here is a photo of the difference in horizontal VS contour. The horizontal is calculated in Fusion with an offsetting path and that might be what you are seeing.

Horizontal- its only really useful for finishing on the flat areas of your part. I like to use a manual stepover similar to what opt load I use for adaptive on the same tool. Also morph spiral option usually brings out the best surface finish.

Now I’m still a newb at fusion and only self and youtube taught so there might be better ways to use these paths and actually dial in a comp if you really need it.

@luc.onthego
The information is out there and if you really want to cut aluminum it’s not hard. Winston is doing a fantastic job and imo Carbide is already going out of their way to provide support for a material the machine wasn’t really designed for. The shapeoko runs g code like a large machine. Design your parts like they being made by a large machine, fixture your parts like a large machine, adjust cutting loads to what your personal machine likes.

You’re ready to cut metal now, buy some $7 hss Amana bits and just do it. Mistakes will be your best teacher. Its almost impossible to hurt the s3, you can afford to be brave :slightly_smiling_face: (maybe have some spare v wheels)

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