Carbide burrs and aluminum

It's true. The carbide burrs that are made for steel will clog up with aluminum in a heartbeat. I don't know that it ruins them, but you'll spend a hour with a sharp pick prying the wadded-up aluminum out of the grooves in the bit. The bits that are made for aluminum are much coarser, and tooling suppliers sell a wax stick to coat them with to keep them clean. They'll still clog up sometimes, but there's only a few big grooves to pick the aluminum out of instead of a whole bunch of little ones.

Cheers, Walt

I should backtrack and qualify this. What Jerry said is correct. If you just have a little metal to remove, and go very careful, a regular carbide burr might be a better choice. The rough-fluted burrs will take a lot of aluminum away in a hurry.

Walt

Jerry & Walt - thank you for the info. I spent quite a bit on my set of carbide burrs for steel. I think I'll do some more digging at Enco and MSC and see what they have.

If you have any recommended vendors, please let me know. I use regular 1/4" die grinder bits and I'm just going to get 2-3 to get the job done + the wax or whatever lube is recommended by the maker.

--George

It depends to some extent on the aluminum alloy, and the nature of the work. Soft aluminum, such as unalloyed (1000 series) used for extrusions and soda cans are almost impossible to cut with conventional cutting tools. Annealed aluminum alloy can also be a pain. Solution heat treated alloys such as 2024-T5 and 6061-T6 are much easier to machine.

The second trick is to NEVER let the workpiece get hot! When it heats up even a little, it gets much softer and gummier, and the ball or snarled aluminum is the result. Various coolant schemes can be used, from a squirt bottle of water to immersion in a tank. Just keeping the tool moving so you don't develop local heating.

Cylinder heads will usually be a silicon aluminum alloy, often with a lot of silicon and other alloying elements, and are pretty tough. The mass of the head probably allows pretty good heat removal, too. The wax idea is good, although cutting oil or "Edge-Lube" (a waxy hydrocarbon cutting lube in a stick form) is probably better for this. Keep the cutting tool loaded down at a lower speed, especially with an air die grinder. With an electric flex-shaft or Dremel tool, you can regulate the speed, so keep it moderate, and take light cuts. I think you will find your friend is wrong, if you follow these general suggestions.

Jon

The project in question involves doing a quick port job on a Toyota cylinder head's exhaust ports. The block is a cast alloy, but I have no idea just what kind it would be.

I see Enco has what they call "Carbide Aluma Cut Burs" and I'm thinking of just getting the four I need, some wax and then have them on-hand for the future.

First & most important thing to remember is if you use any cutter on steel it will not cut very well (cleanly) from then on any aluminum. Any softness or grade of steel will take the micro fine sharpness/edge off a cutter. Price mentioned for your cutter would indicate a pretty cheap tool. (Harbor Freight?) Find a machine shop tool supplier & buy a better grade of cutter. More money but- Much better to use & better finishes also. Fine to medimum teeth on cutter is safest. H.S.S. cutters cut cleaner then carbide ones also. Better (sharper) edge on H.S.S. in new condition. Same for drills, lathe tools etc. Carbide last longer generally. Either type will work reasonably well. Dampening the surface /cutter is best way to help stop clogging of teeth. Wax, bees wax, WD40 etc work well. WD40 cleans up easier on the many times you will have to clean out & inspect the progress of work you are doing. Keep chips/swarf cleaned out so you don't cut it all a second time. Wear good eye protection also. Best to do any larger size job at different times if you can. Git tired & a lot of damage can happen real fast from a mistake. I usually do any larger job of your type in three different segments if time allows. I think my eyes git tireder quicker now after all those years of metalworking & motor work. Dave

has a huge variety of carbide cutters for every conceivable use. I believe MSC is a distributor.

Randy

For cleaning Al out wouldn't it be easier just to stick the burr in a NaOH solution (Lye, Caustic soda) and dissolve the Al in a few seconds.

regards

jc

I've never tried it. Would it attack the brazing that's used to fix the carbide cutters to the steel tool? That'd be a bummer to stick your cutter in the solution, pull it out and have all the carbide teeth fall off

Walt

Thanks Randy. I'll check them out. I didn't hear back from anyone last night so I went ahead and ordered three of Enco's "Aluma Burrs" to get the job done.

--George

George wrote in news: snipped-for-privacy@4ax.com:

IF you use the steel carbide burrs, reduce your spindle speed to keep from melting the alum.

He said it, and it sailed right over your head: "Paraffin" in the UK is "Kerosene" in the USA - the liquid form that can be used in Dietz Railroad Lanterns, tiki torches and space heaters.

When we talk "Paraffin" in the USA, you're thinking PAROWAX - the same basic stuff but in a formula that is a solid at room temperature. I have a bar out in the shop for screw threads, neater than soap.

I'll bet either one would work for the purpose.

-->--

Should be OK on metals other that Al (and Mg?). I'm not aware of any brazing alloys containing these and even then if the Al is only a few% (ie as intermetallic compounds) it should be OK. It works well with solid carbide (actually I think they are fine WC in a Co matrix) and HSS mills and drills

regards

jc

Amen to that. Bigger is not necessarily better, smooth is not necessarily better than rough. Etc. A flow bench tells part of the tale, but even that can be misleading since the flow in an operating engine is a series of pulsations rather than a smooth flow. Frequently, a deliberate mismatch is desirable to prevent reversion. Intake flow is also wet flow, and that's different from dry flow.

Gary

Here is a decent book on cylinder head work:

"How to Build, Modify, and Power Tune Cylinder Heads" by Peter Burgess & David Gollan. ISBN 1-901295-45-1.

I have this book, it's not great but overall is worth having. There are plans for a home-made flow bench included, along with lots of examples on how misleading the flow bench figures can be relative to actual engine performance. The overall conclusion is that flowbench work is "suggestive" of actual performance. At least it gives a person a place to start. There are other books that address the topic of cylinder heads but without info on flow benches and how to use them. A good one is "Four Stroke Performance Tuning" by A. Graham Bell. Sorry, don't have it handy so I can't give you the ISBN.

Second, about those burrs... In my experience, nothing works better than beeswax to reduce clogging by Al. You need pure, solid beeswax, not the fou-fou crap that is sold for making candles. I found a pound of it (enough for, oh, 15 years or so of steady use) at an artist's supply store.

To apply the wax, heat the burr gently, then touch a lump of wax to the burr. The wax will melt and flow into the grooves. Don't overdo it, you don't want to fill the gullets because the cutting edges require some relief to work correctly.

The burr will still clog up eventually, quicker in some types of aluminum than others. To unclog the burr brush it gently with a stainless wire brush ( a small brush like welders and platers use) or heat it gently with a torch or hot air gun. When the wax melts, the Al comes right off with the wax. Reapply the wax every second or third cleaning. You will find that this combination will work well on some alloys such as 5052 or 6061, but it will clog quickly on very soft or "sticky" alloys.

Beeswax is also excellent for lubricating taps. In fact, I got the idea from a commercial product called "Tap Stick," a solid tap lubricant that I suspect is mostly beeswax with some coloring and perfume added to make it seem like a high-tech, proprietary formula. I don't know, maybe they do put something else in there, but beeswax works just as well and it's about 20X cheaper.

Also, I have found that double-cut burrs don't clog as easily as single-cut burrs. Of course, the ideal are the "Aluma-cut" burrs, but they are quite expensive, on the order of 3X a quality double-cut burr.

JB

Get "Practical Gas Flow" by John Dalton. Well worhtwhile. I also have some planes for flowbenches if anyone wants a copy. Geoff