Router milling aluminum, need advice

[Flamingtaco]

I was wondering if I could pick some brains for setting up a router table to mill aluminum. I will be doing basic edge work, removing small amounts or material so pieces fit together, and rounding corners for appearance. For example, I may remove 0.125x0.25 to slip a tube onto a piece.

I see having control over bit speed is where I need to start. What about power? I will be feeding pieces by hand along a fence and can do multiple passes if needed.

Is there a particular type of base required for the router to fit to one of the tables? Are the tables router specific? I can build a table myself if required.

Is there a specific type of mill bit I should use?

My sears drill press stunk from the start, have to use piloted bits, and my larger ones (0.75-1.50) aren't. Can I use a plunge router for this purpose? Can a plunge router be installed in a table? Easier to find decent bearings for the press?

Thanks for reading and helping out everyone!

David

 

[gadget_lover]

If you are familiar with routing hardwoods, similar speeds and feeds apply to aluminum. Many say that router bits for wood are OK to used for edge work on Aluminum. I've done it myself and I was successful. The edge was no worse than when I did the same while woodworking. Be sure you are feeding it correctly. Climb milling will grab that sucker and shoot it across the room, or even worse into your belly.

The router tables I've used have come with adapter plates that the routers attach to, and work with a variety of brands.

Using a plunge router for drilling can be scary. I would not try it. You have 1 or 2 HP spinning at 25,000 rpm, and if it jams in the aluminum there is nothing to keep the aluminum from becoming a big dangerous club spinning at high speed.

The difference between milling and routing is that milling allows you to firmly fasten the work to a surface and then move it with great precision even against great cutting pressure. Routing holds the work to a surface and uses your body as part of the fulcrum that applies force as the router moves. The movements are much more erratic and larger increments.

Dan

 

[Flamingtaco]

Great info Dan, thanks for that.

I guess then, that I will be routing, rather than milling. I will be confining the pieces between two fences at most, but no precision movement controls. Might add a ball screw later if I need a better finish.

I've routed a lot, but never with a proper router. I've used the drill press, and also a dremel and rotozip lashed down or set in a jig. Hard and soft woods, plastics, and resins. Have never (intentionally) climb routed, my fingers don't like being tossed aside while a piece goes flying, never to be seen again.

If I use a plunge router to drill holes, the piece would be secured in a vise attached to a frame that secures the router and vise to each other. The same problem occurs when being too aggressive with a drill press. I always clamp anything thicker than 1/16. My question was whether a plunge router is ok for attachment to a routing table, or if I must use a fixed router due to sloppiness in the slide mechanism of a plunge router.

Thanks again!

 

[8steve88]

A plunge router is fine to use in a routing table, you tighten the router down using the clamping lever and the threaded rod with a top and bottom stop, tighten the nuts down at the required depth of cut and you are good to go. your imagination is the only limit when making your own routing table, one important thing, put the power feed through an emergency stop button that you can easily reach, don't rel on the router switch. I had a big old Hitachi 1/2" router that got used for just about everything. There are specialized router bits for routing aluminium, ask about speeds when you buy them, they will be more reliable than normal TC bits. You can set it up like a mini spindle moulder with pins or straight and circular fences or run with the bearing guided bits. In the U.K. I'd direct you to Trend for bits and info but there must be a few specialist suppliers wherever you are.

 

[borrower]

I haven't yet stepped up to cutting aluminum with a router, so take all of this with a grain of salt.

However, I'm a working carpenter with plenty of wood/router experience, and I've been pondering this subject for a while.

As noted, a plunge router in a table is fine. If you were getting fancy and had a compatible router, you could eventually get a top adjuster setup. The router table can be as simple as a 4' x 1' hunk of 3/4 plywood with a hole drilled in it for the router bit. Remove the plastic on your router base, find some longer machine screws and attach it to the underside. Clamp or screw a sturdy (and straight) stick (1.5" x 1.5" is the minimum I'd use) for a fence and you're good to go. Slightly fancier and more sturdy is a fixed pivot point with a mechanical fastener and a good clamp or two on the other end of the fence.

Consensus on the net seems to be that slightly lower speeds are good, but I'm not sure. Very small bites seem like a good idea.

While some routers seem decent at keeping wood chips out of their motors when inverted, I'd be cautious about the amount of metal shavings getting into the motor. Any kind of vacuum setup you can come up with would probably be a good thing.

Lastly, I'd avoid long, thin bits (or bits overextended in the collet) on the possibility of breakage and flying shrapnel.

Good luck, and please keep us posted.

 

[will]

I have done both metal machining and wood work. I have a router that I mounted in a table. I have a drill press and I use a vice whenever I am working with metal. Somehow - working with a router on aluminum just does not sound like a good idea to me. Most routers run at 20,000 rpm which may be too fast to cut aluminum safely. Any how - that's my 2 cents..

 

[Flamingtaco]

Picked up a used Dewalt DW621 yesterday (2hp, variable speed, plunge). I won't get enough use out of it to warrant a top adjusting plate. I just threw down $50 on repair parts, so I'll make a plate of 7075 and a fence of 6061.

The router has integrated vacuum, and I'll make a mount for the fence as well, at some point. I can also mount some aluminum flashing between the collet and housing, so I don't expect any issues keeping metal out of the internals.

This looks to be a long, but fun project.

 

[precisionworks]

As I see it there are three methods of shaping aluminum using a high speed spindle:

Free hand (& this includes using fences, clamps, etc.) using wood router bits. The word "wood" is a good indication that the bits have all the wrong geometry. Wood bits have an aggressive helix angle that makes the bits self feeding. A wood bit used on aluminum will eventually damage the router motor, the bit, the work or the operator. Know the location of the nearest Emergency Room if you decide on free hand routing, you'll end up there sooner or later.

Inverted routing using a router table. Better than free hand for edge detailing. The 45° chamfers shown below were cut with a wood bit on a router table. As long as the part is big & heavy & the cutting edge contact is minimal this isn't too bad. Every now & then something goes Tango Uniform but that's part of using the wrong tool to do the job.

Milling machine routing is the third method & the only one that gives consistent results with a decent degree of safety. The part is clamped either to the milling machine table or the part is held in a fixture as shown below:

I understand that you have to work with what you've got. Just be aware of the hazards & don't be too surprised where there's a high speed come apart.

 

[will]

Know the location of the nearest Emergency Room if you decide on free hand routing, you'll end up there sooner or later.

+1

 

[Flamingtaco]

Hand fed edge work will be on a table, double fenced. I may eventually add a ballscrew drive. I've done freehand work on ABS plastic, not going there with aluiminum. Don't have time to skin 1/1000" per plunge, nor have a router that is that precise. It's marked to 1/256, but I'll be surprised if the tolerance isn't twice that.

I think I've settled on getting a Rockler blank plate, as soon as they go on sale. A top sandwich of 1/8" 7075 ~ 3/4" MDF ~ 1/8" 6061 is the plan. Rolling cart (aluminum), might build some drawers it later.