An 8x8 fixture plate for my hybrid base, first attempt at a “proper” one @jepho. Just need to tap the holes.
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That surface finish looks great, Griff!
Well thanks but…it’s the as-delivered finish on cast ATP 6061. Got it from Midwestern Steel.
If you achieved that surface finish, I’d probably just sell my SO and call it a day 
Hmm, challenge accepted, stay tuned, may take a while, other things to do.
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Insomniac or early riser?
Holes are on 20mm centers, 5.01mm, 6mm threads. I’m hoping it’ll slot right in using dowel pins on one edge to align with my HDPE base. The MDF in the pic above is a secondary waste board I use when workholding with CA tape.
Saunders makes killer fixture plates no question. I just enjoy the challenge of making my own when I can. Says the guy who made two Mr Beaver (@Luke) HDZ’s.
In any event, my Pro with hybrid bed is pretty rigid, unlike my old XL. Which was rigid enough for all my woodworking.
@Vince.Fab and I go back a bit though I will never come close to his abilities. I backburnered aluminum a while ago, only recently have I jumped back in. You might enjoy this old 2018 thread.
Haha! Ok I see what you did there. I have a 32x16x5/8” ATP from Mid Western that I have to machine still - been sitting on that for over a year.
I am also curious if you’re going to hand tap or thread mill that.
@jepho I read an earlier comment of yours in another thread about how SMW chamfered the holes on their fixture plates. Something I’d tried with improper tooling on a few holes in the past with poor results.
Soooo, watched a video from Saunders about chamfering toolpaths Fusion 360 Chamfering: The Nitty Gritty FF111 - YouTube and decided to give it a try on my own plate. This is my first project to accomplish that.
I really like the look too but in reality, the ones I did are just ok. If you look closely they are a bit “chattery” not shiny-shiny. A function I believe of workholding and tool plus speeds and feeds. We’ll get better with practice.
@RoughDraft40 I’ll probably hand tap this plate. I’m awaiting delivery of some cheap chinese thread cutting mills to practice with. Or, I may re-read @RichCournoyer thread on making one. Seems like it wasn’t so hard to do.
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I’ve found a couple of things that improved my results chamfering Aluminium on my machine
- The effective feed rate as the chamfer toolpath runs round the edge of the hole can be way higher than the ‘feed rate’ shown in Fusion (I broke a few things that way…) I now slow down the feed rate to account for the effective speed
See the Haas video that Kevin linked to in this thread
- When using a stepover to do multiple passes of the chamfer cut, each stepover increases the surface area of the cut thanks to the geometry, so a small final stepover leaves small enough chatter for the repeat finishing pass to clean up
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So far this is the best surface finish I got across a 6x6 block of 6061 aluminum with a uncoated 6mm single flute. You can see a slight line in 2 spots that highlight small flat spots on my V wheels from having them too tight and leaving the machine sitting for a month while I was recovering after surgery but you can’t feel them with your eyes closed.
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Thanks. And, I had seen that Haas video but I still ran too fast 
.
My chamfers were in the CAD so I chose the contour path with the chamfer bit tip 1mm below the edge.
I’m curious which method/cutter(s) you prefer for chamfering?
Fusion 360 templates are GREAT for these small holes - boring, chamfering. You can do the math once and then just whip out the templates.
So far, I have one for M6 countersunk holes with 1/4" and 1/8" mills and the appropriate reduced feeds.
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Here’s a toolpath on Aluminium doing a final chamfer on a weak part that was prone to lots of workpiece vibration
It’s right at the small end of feed per tooth and low WoC too but I’ve found high RPM, low WoC and moving reasonably fast all leads up to a nice smooth chamfer.
I have a couple of 4mm and 6mm 45 degree 2 flute carbide cutters I got from eBay but the cutter I’ve used most for chamfers on wood and Aluminium is, believe it or not -
Which I’m sure you’re not meant to use on metal but it really does work well 
I try to push the chamfer tip offset as far as the geometry allows me to in order to get a higher surface speed and not only wear down the very tip of the cutter.
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Yet another F360 feature I need to learn.
Another lake map test in pine. I’m going to test out the epoxy on this one now. The first depth (which is the lake contour) needs to be deeper (at least 3mm, maybe 5mm if the thickness of stock allows) as trying to pour epoxy with 1mm of clearance will be a nightmare, and I also need some allowance for sanding the top.
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Good question, I’ve not changed it so whatever the default is on the Shapeoko.
Does Fusion 360 output arcs, I seem to recall some discussion about tolerances and things in Fusion interacting with this arc size in CAM.
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I have not checked what default value the latest CM versions embed for $12 sent in the configuration, but it used to be 0.01mm
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So well below the min step size for the motors then and not the accuracy constraint.
Thx
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