# Routing aluminium (slightly OT)



## Woodsmith (Jun 5, 2008)

I know this question is off topic but I will see anyway.

I have an 11" motor without a DE cap.









My plan, given I can't use the DE built into the axle gear case, is to make a replacement from some 19mm aluminum plate.

The problem is that I can only fit 10 3/4" diameter in my lathe with the disc rubbing in the well. 10 3/4" is too small as the bolt holes will be too close to the edge. I would also prefer the DE cap to have a lip on the outside of the motor frame so it would be at least 11 1/4" diameter.

I could use a hand router (a spare from my wood shop) and a jig to cut the plate into a neat circle with a rebate to fit the motor frame.

Has anyone used a wood hand router to route aluminium? Any advice?
I have had a look on YouTube but the vids seem to be mainly thin stock or CNC controlled routers with liquid coolent.

I am avoiding paying for an engineering company to do the work, at the moment, if I can. If this is not worth it then I will try to find someone local to take on the work.

Cheers.


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## toddshotrods (Feb 10, 2009)

I know a guy who used a router to cut aluminum step plates for his (stepside) truck bed. I have always meant to give it a shot, but never got around to it. He said he just used very small feeds (many passes) and it worked fine. I wanted to try it with a speed control and a 1/4" end mill. I think it should be fine if you can slow the spindle speed down, use a real end mill, and be patient. I would cut in a bunch of really, really, small bites, and stop to let it cool frequently.

A router table might be better because you could actually bolt the plate to it with a bearing and concentrate on feeding it as smoothly as possible, instead of trying to keep the router true. Or maybe make an aluminum or steel circle cutter that bolts securely to the plate, and is stiff enough to not let it wiggle. If it wiggles deep inside the channel, and starts bouncing off the walls, you'll either break bits/tools or have a rough experience at the least.

A lot of cool beverages, a few cans of spray lube, good fixturing (a breeze for you ), and a truck load of patience is all it takes.


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## major (Apr 4, 2008)

Woodsmith said:


> I could use a hand router (a spare from my wood shop) and a jig to cut the plate into a neat circle with a rebate to fit the motor frame.


Hi Wood,

Sounds like a bad plan to me  The important part or feature is the pilot, or I guess rebate as you call it. This must be a close fit to the ID of the frame. And it must be concentric and square to the bearing journal and location pilot to the mating assembly. This is impossible to accomplish without a lathe, or maybe NC mill. 

The fixing bolts to the frame only provide a clamping force to keep the end plate on. I would simply allow the through holes in the plate break through the OD and mill them into slots, like notches.

Just my thoughts,

major


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## DIYguy (Sep 18, 2008)

yes, I have done it. Carbide saw and router blades cut Al just fine. No problem. I would recommend a solid carbide up-spriral (actually down-spriral would be fine also since you will be through the material....I hope) I would cut it out with a jig saw first so you don't have to plunge. Make a jig to go 'round and 'round.... with adjustment. 

better yet, take it to a shop... it's cheap enough...


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## Woodsmith (Jun 5, 2008)

I will check shop prices and see.
If it is costly or awkward to sort out then I will make it under size with slotted mounting holes as major suggests.

If it is affordable and easy I will, depending on cost, either get the whole plate cut and finished or get the important parts machined and then hand route the pretty bits.

Means I will have to get an accurate drawing done.

I will have a go and see if I can route out some scrap. If I can get nice grooves and edge finishes then I may use that method to pretty up the plate.

Thank you.


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## rwaudio (May 22, 2008)

This guy (robolop) makes some pretty nice aluminum (and carbon fibre) parts using a router table and hand tools....
The bottom of this page shows the start of some aluminum pedals, the next couple pages shows the amazing results.
http://www.diymobileaudio.com/forum/diyma-member-build-logs/30321-one-badassed-bmw-330-a-24.html

If you have the time to look through the whole thread there are some projects that I wouldn't even atempt with my cnc router. His skill is nothing short of amazing, not to mention the ideas that go with them.

The first 3 pages of this thread (same guy) show some pretty awsome work in all fronts, the aluminum trim ring is what I thought of right away when you described what you wanted to cut.
http://www.audiogroupforum.com/csforum/showthread.php?t=66958

I don't have the skill with my hands so I built a small cnc router to do it for me. But aluminum does cut pretty nice with wood working tools as long as you cut at a slow rate, or a bit faster with cutting fluid, or even WD40 if you have nothing else. Just keep the bit cool or it will start to gum up.


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## Woodsmith (Jun 5, 2008)

Those are great links!

I think I will have to give this a go.
I can't use my router table though, got to keep that clean and metal free for woodwork.
I may be able to sacrifice one of my routers to my machine shop.


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## toddshotrods (Feb 10, 2009)

I think you can do it. I have more confidence in a skilled craftsman with a router, than I do a CNC router table, cutting aluminum. The CNC is going to keep cutting whether it's going right or not, whereas the person can feel what's happening and adjust.

The biggest problem is aluminum gets hot and starts to melt so fast. If you can't, or don't want to, use a speed control pay close attention to how warm the plate is getting as you cut. Stop and come back later - it's cheaper and less frustrating than trying to push through anyway. That's critical anyway, but mandatory if your spinning at wood cutting speeds.


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## Woodsmith (Jun 5, 2008)

You have great faith in me, Todd.

If it was wood I would be as confident. I will have to have a go and see if I can feel cutting metal in the same way.

First off I will practice, and then I will see if I can make a circle template and a compass jig.


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## toddshotrods (Feb 10, 2009)

Woodsmith said:


> You have great faith in me, Todd.
> 
> If it was wood I would be as confident. I will have to have a go and see if I can feel cutting metal in the same way.
> 
> First off I will practice, and then I will see if I can make a circle template and a compass jig.


Yup, I do.  It will speak to you through the tools, and communicate very well what's going on, you just have to learn its language. I love working with aluminum. Once you get the hang of it it is fascinating what can be done with it. I have also toyed with wood (nowhere near your level) and aluminum doesn't seem to be too far beyond Purple Heart - that's some hard stuff!

I think the thing that gets people is they don't realize just how fast aluminum will heat up, and that heat will transfer through the entire part. So, instead of a bit of localized heat, you end up with a whole piece that is smoldering hot. When it gets hot it expands a lot, meaning the space the bit, tool, or blade, is working in starts closing in on it. People keep going and push harder, which causes more friction, more heat, less progress...

I believe you'll do well because you obviously have a natural sense for what is going on with your work (or your woodwork would look like crap). If you "listen" to the part and the tools, you'll be fine.

Now start machining!


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## Alexander_B (Oct 19, 2010)

that 10 3/4 limit on your lathe is that the claw diameter or centerpoint to rail diameter? theres some tricks to sticking bigger things in that the claw can fit (I recall making a 12" disk on the lathe here, I'll go over and measure sometime soon, probably just for my own plate, different continent and all..)


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## Coley (Jul 26, 2007)

For machining aluminum, I use a bottle of rubbing alcohol as a coolant.
Put a small hole in the cap and put a small stream right on the cutting tool.
Has worked for me for 20 years.


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## Woodsmith (Jun 5, 2008)

Alexander_B said:


> that 10 3/4 limit on your lathe is that the claw diameter or centerpoint to rail diameter? theres some tricks to sticking bigger things in that the claw can fit (I recall making a 12" disk on the lathe here, I'll go over and measure sometime soon, probably just for my own plate, different continent and all..)


That is as much as I can put on a faceplate so that the edge of the disc is rubbing in the well in the bed. It really is as much as I can fit without changin the shape of the lathe.
I turned some 10" steel disc brakes for my tractor before and it was already too tight to skim the edge so I left it rough.




Coley said:


> For machining aluminum, I use a bottle of rubbing alcohol as a coolant.
> Put a small hole in the cap and put a small stream right on the cutting tool.
> Has worked for me for 20 years.


Rubbing alcohol? I have some 10 year old Aberlour scotch!
I will see if I can get some, at least it will evaporate away and leave no marks.
Thanks for the tip.


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## Alexander_B (Oct 19, 2010)

means the lathe I work on is (slightly) bigger. ah well, there are other methods of getting a nice round disk, especially if the roundness is less critical compared to the placements of the holes


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## Woodsmith (Jun 5, 2008)

Yes, the snag is that I can make a DE cap that does what it needs to do but I can't make a DE cap that looks the way I want it to look.
Like Todd, I feel the looks are important too.

If it was just a case of not getting the cutting tool to the edge then that wouldn't matter. Unfortunately I physically can't get the plate to fit.
It is so tempting to cut a clearance notch in the lathe frame.


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## toddshotrods (Feb 10, 2009)

Woodsmith said:


> ...It is so tempting to cut a clearance notch in the lathe frame.


That sounds like something I would do!


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## Alexander_B (Oct 19, 2010)

how do you want it to look then, except very cleanly cut? (as opposed to bandsaw cut and filed) anything special? maybe one of the forummers here has a bigger lathe?

I'm not so much a fan of destroying tools, but if you can make the mod without breaking it, why not?


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## toddshotrods (Feb 10, 2009)

Alexander_B said:


> how do you want it to look then, except very cleanly cut?...


Like a very cleanly sculptured piece of art deco.


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## Woodsmith (Jun 5, 2008)

toddshotrods said:


> Like a very cleanly sculptured piece of art deco.




The easy way is to ask Todd to design it in CAD and then I find someone reliable over here to mill it out on a CNC.

I have access to a Mazak but the chap who has it didn't do a good job on the 12" motor hence now having bought an 11" to replace it.

If I could do it myself then I would be shaping it by feel, after the critical edges, surfaces and locators have been made.
Asking someone else requires designing it all first and then deciding if I like the end result when it appears.
I would also like to make a matching cover for the CE as well, if the DE works out well.

MDF is my friend here.


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## toddshotrods (Feb 10, 2009)

Woodsmith said:


> ...The easy way is to ask Todd to design it in CAD...


We really need an {{evil grin}} emoticon here. 





Woodsmith said:


> ...I have access to a Mazak but the chap who has it didn't do a good job on the 12" motor hence now having bought an 11" to replace it...
> 
> ...Asking someone else requires designing it all first and then deciding if I like the end result when it appears...


That's the drawback of CAD/CNC, it takes a lot of time to develop a successful relationship between the designer and machinist. I guess that's true even for manual machining projects, but once you press the button on a CNC the job had to have already been understood and properly interpreted. Any miscommunication will show up in the final product. Even if the designer and machinist are one in the same there still has to be a translation from the customer's needs and desires to materials and tool paths.

Whew! I'm getting tired just thinking about it.


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## piotrsko (Dec 9, 2007)

My $.02 (USD):

You have all those tricky tools, just make it yourself. M2 carbide bits, 1 fluted twist or straight, slow bit speeds (rpm)to <3000 or less and really slow feeds, perhaps 1 or 2 inches per minute. cooling air to blow away the bits and keep everything cool and either wax or paraffin to keep it lubed. Routers work well for this especially with circle cutter attachments. It will make a mess.

FWIW I used to really annoy my cabinet guy making aluminum parts on his equipment.


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