MadModder

Thanks for that Art.  That's helpful to compare to.

I decided to try another part in the same piece of aluminum, but this time at 16 IPM instead of 8. It cut perfectly fine except for the fact that in redrawing the part I forgot to put in tabs.  Luckily I noticed it at the very last pass, and was able to stop and withdraw the spindle before the part came loose. It's still a usable part, with just a thin skrim of aluminum on part of the bottom.

So since that worked out, I added tabs to the drawing, rewrote the g-code, this time with a .032" depth of cut instead of .020". The machine got a few passes down, but got wonky at one point, so I hit e-stop, and withdrew the spindle. I'm not sure exactly what happened. I checked the flutes and didn't see any aluminum welded onto the bit.

I checked the router in the mount because I thought I might have seen it rise slightly. Seemed solid. I took it out of the mount and checked shaft play. It clicked when pushed sideways, so I'm thinking maybe the bearings have had it. Could be. It's ten years old at least, and humidity in the shop is high, plus cutting aluminum is going to be hard on router bearings.

Not sure what to do now, try to repair, or think about a better spindle. I know I said at the outset I didn't want to buy a new spindle, but now I might have to. I do have one of those little 500 watt 100VDC fan cooled motorized spindles which I use for milling on my lathe. But they seem even lighter weight than the Bosch Colt router. I wonder if they can cut the mustard for milling up to 1/4" in aluminum? They don't look too rugged.

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I hadn't considered a mini gun Andrew, but now you mention it.  Keep the pigeons and other vermin at bay...

That's a great idea, Bill! I bet 90% of what I want to do in future will be small parts. I could make up some bracing clamps that are removable. Also good idea about asymmetry! 

Thanks Country Bubba! 

I have to think about this part. I thought I'd done calculations that showed chip load around .001 but after playing with Little Machine Shop's calculator I see I was still thinking single flute, rather than the change to two flute, and my speed of 8 IPM is wrong by half for 8000 RPM.

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All I did there was limit artificially the speed of the machine to 8000 RPM. The chipload at 16 IPM will be the recommended .001" then. I'll try doubling the speed. The mfr also gives a max depth of cut in slotting of 1/2D, which is .062" I'm presently at .020" but I'll try .032" next.

I wonder about the Little Machine Shop's calculator's results for the very high speeds you found for an 1/8" milling cutter. While it may be theoretically correct for optimal cutting, I wonder if a 1/8" mill shaft would snap under the kind of side force that would generate when slotting.

The depth of cut at that speed must be very low. I could probably snap a 1/8" dia carbide milling cutter held in a vise with my hand. Not that I would try!

But thanks for that calculator, if the other adjustments go well, I might eventually bump the router speed up a notch and the IPS to suit.

GREAT! very appreciative of any and all advice!

Been away from the forums for quite a while, busy playing with my peddle car and other stuff.  I put some extra solar panels up on the wife's Studio/Shed a few years back using both sides to make better use of afternoon sun.  It didn't perform as well as I had hoped especially during winter months.  Don't get me wrong it did produce, no longer needing to top up the battery during winter just to keep it alive.

So, onto Plan B (sub project 359) installing a tracker mount in our urban garden.  Not a huge amount of space and with fencing and buildings around, could be a bit challenging.

New project, start with a big hole, serves dual purpose if project goes tit's I have somewhere to bury it.  The tracker used is a commercial one from Eco Worthy, I just couldn't fabricate it for the cost !!!

Get measuring the base and work out hole positions, as it is supplied with 10mm expansion bolts for drilling into your concrete slab.   Hmmm, sod that, it needs to be able to survive earthquakes and tornadoes.

I fabricated an M12 stainless steel frame with 3D printed spacers for the whole lot to be cast in the foundation.  A template was cut for the hole pattern as the tracker base was not symmetrical (correct spelling), laser cut out of card, this being the third attempt.  It was used for spacing the holes in the 3D printed rings holding the stainless steel studding.

The actual supplied tracker mount was of course modded, to improve fit and finish plus shim for bearing surface to remove slop.  It has no quality bearings and not expected for the price, but it has room for improvement.  I am putting a smaller array than it is designed for, keeping the loading and area reduced should allow it to function longer in windy conditions.  It is supplied with sensors for tracking the sun and also monitoring wind conditions so it can go level if gusts start to pick up.   One fly in that idea is the fact it goes to an extreme location, before motoring back to level on an estimated time, not great if the wind has picked up, plus the location I would fit the anemometer would be quite shielded.  So we level it manually based on conditions and forecasts, it really produces a lot of power just looking straight up.  We don't need it tracking every day so it is lashed level with rope that also acts as shock absorber in windy conditions.

Finally got the tracker installed after wife and me mixed about 800kg of concrete in a large plastic bucket....  She's a keeper....      All the frame work above the tracker is modified from that supplied and fitted with 100W panels as they are manageable as I get older.  The added benefit of a tracker is being able to keep the panels clean and free of snow.

At last fully installed and producing power, better than I had hoped for on a bright day and installed a few weeks before the current UK heatwave.   Great, more power for tools and toys....  Uh oh, wife bought an air conditioner for the dog (long haired Shepherd)  The air con is now run off the tracker mount, both wife and dog very pleased...      Not my intended use, but hey I get to use more power outside of crazy hot days.

 

Rigidity, rigidity, rigidity.

Since you are cutting small parts you might get som milage out of bracing the guide rods (effectively reducing their length ) .

If you can do asymmetrically on the X it might reduce resonance in the paired rods (there is zero torsional strength in the pair  because of the bearings)