[Biggs427]

Feed too slow, too many flutes, RPM too high, DOC too big. Recipe for disaster.

This looks like my first attempts with alu.

What is the rpm, feed and DOC you are running?

[user834342]

Wow, thanks for all the replies!

Here I'll attach some more pics. It's just the standard OpenBuilds C-Beam Machine but I added extra brackets to help with rigidity.

I tried lower feed rate but it didn't really help.

[user834342]

plus not using some type of coolant

I don't really space for a coolant system, it's a just a small DIY setup. Perhaps I'll try some WD40?

Yeah but it looks like you should choose a down spiral bit

What does that mean? Is the end mill the wrong type?

The Endmill is out of the collet to far, by what is showing in the photo,

OK I'll try and insert it further. Thanks.

HSS is not ideal here, eh?

You mean for cutting aluminium?

[user834342]

Oh there is one other gotcha here, Aluminium varies vastly in the way it cuts baseed on the alloy, temper and other factors. if the bar you are milling today is different than the bar from a month ago you iwll see differences.

OK, I see, that's annoying!

- - - Updated - - -

You simply do not use down cut bits in Aluminum. Trying to use such would lead to swarf jamming, mill breakage or other problems.

Is this bit "down cut"?

[user834342]

Edit/ I looked at a feed/speed calculator for HSS and you're kind of between a rock and a hard place with the available rpm.

The Makita 700C has RPM adjustment but I have no way to tell what the rate is, I can just make it faster and slower.

Should I an end mill made of different material?

[ger21]

Try a bit like this, with the router set to it's lowest speed.

https://www.amanatool.com/51401-soli...outer-bit.html

[Biggs427]

I tried lower feed rate but it didn't really help.

It probably make the problem worse. What is "lower feed rate"?

I had this router on my first machine and the lowest rpm is around 10000 rpm.

[skrubol]

Occasionally squirting some WD-40 can help keep chip welding at bay and maybe in cleaning up those feathered edges. Won't help for chip clearing though.
There's been a bit of back and forth on downcutting bits. Normal bits (like what you've got,) are up cutting. (turn the bit clockwise, like it would be when cutting and see if it spirals up or down.) Downcutting bits are good for keeping the top surface of what you're cutting with a crisp edge, especially on materials prone to chipping/pull-out (like wood.) Problem is that they push what's been cut down into the cut rather than pulling it out, so with metals (Especially gummy ones like aluminum,) they lead to chip re-cutting which will wear out the bit faster, but usually just cause chip welding and break the bit in pretty short order. I'd echo the recommendations for 1 or 2 flute cutters as well. Higher quality (sharper,) cutters are your friend as well, they will do better at the low feeds per flute you're stuck with because of the lack of rigidity you've got.
Looking at the construction of your router, I'd try and keep your workpiece centered over that central beam under the machine table, over wherever it's attached. That should be the stiffest part of the table.

[wizard]

The Makita 700C has RPM adjustment but I have no way to tell what the rate is, I can just make it faster and slower.

Some of the smart phones these days have tachometer apps. You really need to ahve some idea of the tools speed under opration or you will never be able to determine ideal feed rates. finding an ideal combination of feed rates and spindle RPM's has never been perfect operational science as machines of old seldom hand continuously variable RPM's. Even today optimal feedrate and rpm combos are often achieved by tuning the machining operation. However you need to go through the steps to get close to the right figures or you will never learn optimal conditions.

So you need to determine those spindle RPM's to some extent and then calculate the suggested feedrates. It is very likely that you will never achieve the calculated feedrates though. You need to get as close as possible though. at that point try experiementing with depth of cut. On a flimsy machine like this I would start with one tenth of the cutter diameter for depth of cut and work up from there.
[quote}
Should I an end mill made of different material?[/QUOTE]

It always help to buy end mills designed fothe material you are cutting. Given that you can buy end mills for aluminum built from different materials and with different coatings. YOu will likely need a single flute cutter due to high spindle RPM's and slow potential feed rates. However be careful because a single flute cutter could introduce harmonics that are not desirable.

By the way yes WD40 can be a good lube/coolant for aluminum processing. However it will get everywhere at these spindle RPM's.

Im still of the opinion that you have chuip weldign or a worn out end mill. It might help to post picitures of that end mill. close ups.

[user834342]

Just an update to this thread...
Simply having the cutting tool inserted further into the router solved the problem for me. Now I have very good results :cheers: I even managed a manual tool change, which is a massive pain on a DIY CNC.

Thanks again for the help.

[ger21]

Much better results.

I even managed a manual tool change, which is a massive pain on a DIY CNC.

It's actually very simple with better (more powerful) control software. Change tool, press button, software automatically measures tool, and continues cutting.

[Ntl]

Much better results.



It's actually very simple with better (more powerful) control software. Change tool, press button, software automatically measures tool, and continues cutting.

Yes, my tool change macro in CNC12 makes tool changes simple, you just need a fixed tool setter and a movable touch plate. Works fantastic I don't know what I would do without it.

Dan