Facing Aluminum on Avid CNC Router - REVISITED!

[@Frentru]

So the conventional milling is often better on less rigid machines, though it's less about the rigidity and more about the leadscrew. If you have a leadscrew instead of a ballscrew or some other reason the machine has significant backlash the conventional cut is better. On a climb cut the cutter will attempt to drag the spindle to the front of the backlash, but the feed pressure is coming from the back of it because the screw is effectively pushing the spindle around, not pulling it. This will cause the spindle to vibrate back and forth inside the backlash range, which can cause a number of effects. On a conventional cut the cutting action will push the spindle back instead of pulling it along. This causes it to be pushed against the back of the screw contact, which is already in contact because of the feeding. This reduces the vibration produced by the tool impact. Climb milling produces a better finish in most cases because if the chip hasn't quite cleared the endmill and it gets rammed back into the part, it gets rammed into the next bit you're cutting so you'll cut it back off again. Conventional milling rams this onto the finished part of the cut, which can sometimes leave the entire chip there so you have to come back and do a finish pass to remove it. Most of my stuff has been side milling on a machine rigid enough to do nothing but climb cuts, but facing I've done both ways and both have worked equally well. The things I found to have the most effect on surface finish on the mill I used to run were the sharpness of the cutter, the tramming (alignment) of the spindle, some degree of lubrication (I used WD40) and an extremely high RPM for the tool. I saw on the second cut the signs of it being well trammed, but not on the first one so my guess is the difference there was machine rigidity, it was just a little too much pressure for the spindle to stay perfectly straight. I'd actually check the tramming on the tormach because the rippling I actually found to happen more when the passes were closer to each other, not less.

[@Mr1bassman1]

I started my 5 year apprentiship in 1968 and now after over 50 years of machining I am watching the internet full of amateurs pretending they know enough to teach.

[@combin8or]

@Joshua Beavers Super on point and concurred. Thanks for your detailed explanation- I couldn’t have said it better myself.

[@combin8or]

@@Mr1bassman1 Sounds like you have no business teaching.

[@Warren_Elrod]

I understand this video is for facing but the rule of thumb is - Conventional tends to work better for less rigid machines. Conventional “scoops” the chip out with the chip starting thin and ending thick. Climb “Bites” the the chip out going from thick to thin. Climb milling is preferable as it leaves more heat in the chip but a less rigid machine will tend to vibrate, or worse, bounce through a climb cut. It’s usually good to run finishing passes as climb though because conventional can lead to smearing (not enough material to really grab into so the cutting edge will slide along the surface some, especially with a less ridged machine. If you’re cutting wood or most foams/ plastics then you want to stick with conventional as a climb cut is likely to cause lots of fraying/fuzzies/hairs, etc.

[@danmartinrc]

I agree. Conventional milling is better for less rigid machines. If the machine has any backlash, climb milling will pull the cutter away and you will lose accuracy as well as get chatter. Conventional milling always pushes the tool into the work so it has better support.

[@RedShoesSmith]

I enjoy these test run videos, very educational. Thanks man.

[@osianleahycnc]

Have you considered lowering the spindle speed? You showed different chiploads but from my experience cutting speed can also have a p significant impact on surface finish.

[@randycox4633]

Seems like you should check the nod on the Avid. The steps you see across the face would make me think the nod needs to be shimmed.

[@RobertCowanDIY]

It's VERY slight. I have a separate video where I trammed everything and it's as close as I can get it. There's just some inherent play in the Z axis. I might go back and re-check everything though, sometimes it's easier to get something right when you DON'T have a camera in your face.

[@stevenschmelling5597]

@@RobertCowanDIY You mentioned being able to feel the ridge. If that was only on the Avid, you may be right about it being a rigidity cause. But if that was on the Tormac as well, I would be more concerned about the tram on that,. Or, maybe a not perfectly straight shaft on the bit? If it felt the same on both, what else would be common between the two setups. I could be mistaken, but I think you should be able to test the rigidity theory by adjusting the depth of cut. The ridge should increase/ decrease in height when taking a bigger or shallower cut if rigidity is the issue. I would think it would stay about the same if it was a tramming (or bit shaft) issue. I know these are such a fine an amount it would be very difficult to measure.

[@PiefacePete46]

Excellent, thanks. At 3:50, if you can feel a "step" at the edge of each pass, maybe you need to check your spindle tramming. Any shortfall in rigidity will also produce this result, but you are taking such light cuts that I don't think that is the cause. A thought for the future if you are planning to use it for aluminium a lot; make another dust-shoe that uses silicon (or similar) flaps, rather than bristles... less for the curly little chippie-beggars to cling to. :o)

[@backyardengineer916]

Yep. Exactly what I was thinking. That spindle needs tramming. Had same issue

[@OneMinuteWorkbench]

Thanks for putting this video together - good stuff!

[@TheVFXAssault]

A little late but having faced a ton on a router, you want to go lower RPM. I run a 25mm facing tool (2flute) at these f&s: 12000 RPM 2400 mm/min 1mm DOC and 90% WOC - that is my roughing but gives a decent surface And for finishing i use: 12000 RPM 800 mm/min 0.1mm DOC and 90% WOC.

[@RobertCowanDIY]

Cool, I'll try that out next time.

[@OldVetCreations]

I always learn something from your videos!! Good stuff!

[@mv3dnerd]

Can you do a similar video using a 1/4 in endmill. Showing a pocket cut or adaptive clearing?

[@DavidLindes]

4:57 - could the roughness be your brush fibers getting into the cutting path and creating wobble (ref 2:46)? Maybe it's time to make the brush retractable, to match the tool depth?? (And/or, you know, chips - re 6:18.) Granted, I'm mostly guessing here, my machining experience is very limited. Just sharing thoughts/questions I had while watching.

[@elburrona]

Great video!. I just purchased an avid pro router and I will do some aluminum machining for fun. I wonder if the Benchtops PRO which are smaller and look beefier will have a more similar performance as the thormac

[@AlChemicalLife]

Look up breaking taps on KZbin. He owns one with a ATC. He did a video on it cutting aluminum and steel

[@elburrona]

@@AlChemicalLife thank you!

[@_ghosthat_2532]

Hey just a question but have you ever thought about making a easy, simple and affordable combat robot Tutorial for anyone who wants to get into the sport but doesn’t know where to start

[@Jonnywoods_049]

I feel famous now 😂 thanks for the test ! Another great vid👍🏻 every recipe seemed to be useable . Alcohol mql and no dust shoe is about the only way to do better it seems. I just unboxed my new spindle and slowly getting it hooked up. I feel like maybe I should get a video out to looks like your having fun 👌🏻

[@RobertCowanDIY]

OH, it only LOOKS like I'm having fun. About 10 years ago I started making videos on KZbin and I get nice comments from time to time and that has kept me making them. Nearly a decade in, I wish I could just build something without the camera. Please send help.

[@Jonnywoods_049]

Robert Cowan has its challenges no doubt . I need two more small packages and then maybe I will try 👍🏻

[@Silverturky]

Hey man i have my avid machine on the way and this is super useful for me! I do have a question though. Have you ever tried using their rotary 4th axis to machine aluminum? Do you think that could be a good application for that?

[@minskmade]

robert... love the channel. .. i don't know if you looked into getting a different spindle. Im personally getting a s30 atc spindle for my build. i believe its iso 30 and is bit more rigid. there will still be tad bit flex in the avid build..its aluminum.. im also wondering if a bigger/wider fly cutter would also help with a cleaner /smoother cut. also is your spindle head trammed perfectly to the bed ? keep up the great content.

[@EleanorPeterson]

I moved on from early basic training in a machine shop (all manual, no computers) to cabinetmaking. So, umm... nothing really comparable there because everything was planed by hand. Abrasives were strictly forbidden, so getting the perfect finish was all about grain orientation, honing and stropping irons, and mounting rigidity. Some tropical hardwoods are quite a bit harder than aluminium. I remember working one East African timber (non-commercial - it was too hard and didn't even have an official name) that rang like brass, sparkled with silica/ quartz, and stank like a dead dog. Terrible stuff. I loved it. This Comment is on entirely the wrong Channel. Sorry. Carry on, chaps.

[@piccilos]

You could make dust shoe out off thin gauge plastic strips, for cutting aluminum

[@RobertCowanDIY]

Good idea. I'll have to come up with something. THANKFULLY, I have about 2,000 CFM worth of airflow right here, so that's not a problem.

[@danielwilson-rains1807]

Dude what you're doing the cuts with the dust guard on?! wth?

[@saltysoulcreations8537]

So I'm looking at buying an avid CNC and I want to be able to cut aluminum with it. I'm not looking for machine shop quality but I am wondering what kind of tolerances I can expect in my aluminum parts? most of it's going to be art work if you will but some stuff will need to be fairly precise. Any feedback be much appreciated I really enjoy your videos thank you for taking the time to share.

[@RobertCowanDIY]

I've not had an issue with getting parts to be accurate, but getting a nice (professional) finish is tricky. If you're removing a lot of material, expect the floor finish to be pretty mediocre. Wall finishes are pretty good though, generally. Cut I can easily cut a bearing pocket, or how two parts mate together perfectly fine. You will just need to plan it out, go slowly and making make one or two final passes to get it where you need to go.

[@saltysoulcreations8537]

@@RobertCowanDIY Thank you very much. That's exactly what i was looking for. " I can easily cut a bearing pocket". I figured surface finish would be challenging but not really my concern from a cnc router. Thanks again and keep the great videos coming.

[@RobertCowanDIY]

@@saltysoulcreations8537 Thanks! I'll be doing more with it for sure. I have an upcoming project that can show off what you can do with it. Check back this coming Sunday. It's a multi-part series, but the end result is pretty cool (I think).

[@flikflak24]

Remove the dust sho and add a vaccum clener ( maybe setup a box around it machine) And I would recommend going to between 92-95% ( dependingin the nose radius on the corner) stepover ( to get a more even pressure on the tool) and less doc

[@flikflak24]

And if you build a complete cabinet for the avid then add some air bast at the cutting tool ( prefer from 4 sides at ones to make sure that you get those chips away)

[@nathanking2484]

Thanks for a great video

[@RobertCowanDIY]

you're welcome!

[@doyounglee6990]

I'm wondering how much a rigidity gap would a smaller Avid machine (such as benchtop pro 2' x 3') have closed. I am in the market for a CNC/mill, and m leaning towards Avid, as I'll be working with both wood and aluminium.

[@RobertCowanDIY]

From what I understand from talking with them, the benchtop and the 4848 are pretty much the same in terms of rigidity.

[@doyounglee6990]

@@RobertCowanDIY Would be interesting to see accuracy comparison between the two via machining 2 identical objects...

[@RobertCowanDIY]

@@doyounglee6990 same! email them and see what their thoughts are. from what I've seen, the z axis has the least rigidity, and I don't think there's much difference there between the two.

[@mulberryworkshop]

Hi Robert, are you using the standard spindle from AVID?

[@RobertCowanDIY]

Yep, the 2.2KW one.

[@crimpers5543]

would be nice if you took off the dust boot so we can see the spindle.

[@RobertCowanDIY]

Would you be willing to come over and clean up the shop? Joking aside, it will spray chips in a 10-15' radius without the dust shoe.

[@fawkyooo7377]

Correct me if I'm wrong I'm a CNC plasma guy not a VDF guy. Why not remove the bristles for a test and see if the loaded up of chips is the cause? [yes I know it'll make a mess but it would provide a conclusion to this theory.]

[@RobertCowanDIY]

Fair point. It was pretty obvious. When I lifted up the head after the cut, it was just completely clogged, and the bit was surrounded by chips. Anytime there's a chance of recutting a chip, it's bad.

[@RioElMystic-999]

Would this be a good machine for small aluminum parts production or takes to long ?

[@RobertCowanDIY]

For aluminum, it works well. The only real issue I have is indicating parts, since the spindle doesn't allow for quick tool changes, and you need to re-indicate after every tool. BUT, you can get around this.

[@Mitch3D]

I like the new glasses! Great CNC videos!

[@RobertCowanDIY]

Ha, thanks! I think you're one of the few people to notice!

[@Mitch3D]

@@RobertCowanDIY it doesn't require a logo change either with round or square glasses, clever :-)

[@Zebra66]

It costs $20 to add mist coolant to a cnc machine. It's essential for getting a good finish with aluminum. Like night and day. It's as important as rigidity. Also, you could run the Avid at 8000-10,000 rpm which would work better for that size tool. It's hardly a meaningful test when you run the Avid at over 2x the sweetspot for the tool. The results would be about the same if you did that (and fixed the tramming).

[@ewildgoose]

You seem to be showing that you need to tram your machine to improve surface quality? Also are you aware that you can get quite small index cutter heads? Check your fav Chinese online shop...

[@raimogeel9497]

Can you use cutting fluid on the Avid? As when i cut aluminum on the mitersaw it makes day and night difference.

[@RobertCowanDIY]

Check out my video on the fogbuster. I am using cutting fluid (isopropyl alcohol) for these cuts. I can switch out to a different coolant as well.

[@mavigogun]

When trouble shooting and/developing a recipe, change one thing at a time. One.

[@RobertCowanDIY]

Not all of them all at once?!

[@abcd-gg6jz]

first comment, also can the same cnc machien that you have be used to make parts for a 250 battlebot?

[@RobertCowanDIY]

Sure, as long as the parts can be cut on the machine. I haven't tried it with steel, but I suspect it would be better to outsource steel parts.

[@FaithfulMC]

FLY CUTTER, Spin fast, cut slow

[@BaldurNorddahl]

At 90% step over you are practically slotting so there is little difference between conventional and climb.

[@Casiyounadatube]

I don't know much about CNC machines but I think the problem you have is that the tool is not parallel to the piece you are machining. You can find many videos showing how to fix the problem such as kzbin.info/www/bejne/hmW5p5iogb2jeas around minute 5 (winston Moy). Thank you for your channel it is very informative.

[@rickeaston3228]

How about lube????? A router is not a Bridgeport milling machine!!! No even close!

[@RobertCowanDIY]

Both are using a fogbuster. Just because it's not flooded with coolant doesn't mean I'm not using any.