Tools - routing aluminum

[lowell]

I have a rotozip and a dremel. Also have "metal" bits for them but they really suck. Curious if anyone has success routing with either and if so what bits do they use. Im considering buying this - https://jet.com/product/product/0379...gKDRoCECfw_wcB Anyone used it? Would like to know if it works before blowing another $20 online.

[hylaphone]

What shapes are you routing?
The Dremel carbide tile bits work really great routing/milling aluminum, but you need a steady hand or jig to avoid the "dance of death"

[Enzo]

Yeah, I wouldn't try to hand hold the Dremel for that, get a router rig for it or mount it in a drill press like assembly.

[lowell]

Thanks guys. I am using punches, but they aren't big enough for the holes I need. The holes have snap-in grommets that surround the tube, which is mounted to PCB internally, and pokes through the chassis. So I use the punch, and then need to enlarge the punched hole. I'll give that bit a try then. I have the dremel router attachment for keep things steady. Thanks for giving me confidence in spending the $20!

[hylaphone]

How much are you enlarging the holes?
I have a large half round file that makes quick work of this

[Leo_Gnardo]

How much are you enlarging the holes?
I have a large half round file that makes quick work of this

Step drill bit works great too, you can get 'em at Home Despot and Harbor Fright. My large step-bit goes up to one inch diameter. If the price seems a bit high for just one job, don't worry, they come in handy again and again over the years, just get it. Sometimes I have to enlarge the hole a little bit more, then the big rat-tail or half-round files come in handy, also Dremel sanding barrel so it doesn't look like a rabid beaver chewed thru the metal. Aluminum is a pain, the filed and sanded-off particles tend to clog whatever you're using, but eventually you get thru it and it works & looks OK.

[lowell]

Maybe I'm lazy but that's some serious elbow grease. I've done it. Maybe it's my cheapo mintcraft file. What file are you using?

[hylaphone]

Something like this would work well:
Nicholson 05125 12" Half Round Second Cut File - American Pattern Files - Amazon.com

Step drills are great, but unless your drill press does low RPM the larger diameters can get wacky

Another option if you can't find the right size chassis punch is to look at standard knockouts, their measured sizes are different and may be just the ticket. If you are scribing your layouts it's easy to line up the marks for a bigger punch

Here is the Dremel bit I mentioned, works great with a little beeswax
http://www.amazon.com/Dremel-562-Til...remel+bit+tile

They should have a similar one for RotoZip

[lowell]

Thats like a rasp!! Nice! Exactly what Im looking for. And "who" makes these knockouts you speak of? I haven't heard of knockouts....interested. Gonna do a lil ugoogaly search.

[hylaphone]

You might find used set of Greenlee's. Harbor Freight sells them too, might work ok for aluminum.
They are for conduit holes, so one marked 1/2" will actually punch for the OD of the pipe -- .885".
3/4" = 1.115", so on and so forth..

[Chuck H]

For enlarging small holes the files are good. For larger holes I like the Dremel mini barrel sanders. It helps accuracy A LOT to draw the profile you want on the surface being cut. Round chainsaw files work well, make finer cuts and are usually made from good stuff that stays sharp. Hand working metal is a PITA. I do it for every amp because everything I make is custom. IMHE aluminum chassis are inconsistently hard, having spot hardened areas. The Dremel "metal" buts cut inconsistently when you want to enlarge larger round holes. The irregular shape then exacerbates the problem. The barrel sanders are much better (if the hole is large enough) and it's important to trace your shape.

[lowell]

I've been trying the barrell sanders and rotozip metal bit. Barrel sanders dont even begin to take off material. This is a hammond enclosure with black powder coat. Must be an extra hard version of aluminum.

[Chuck H]

When using the barrels, trying to apply too much pressure, burring down on it, results in a sandless, useless groove in the barrel. Better to apply less pressure and raise/lover the barrel across the surface your cutting. Then you're using the WHOLE barrel. Please forgive if you're already past this. I also use a large chamfering bit made for counter sinking screw heads to enlarge holes. It's about 3/4" diameter, tapered to a point and cuts without drifting. I always under size with this and remove the chamfer out to the correct hole size by other means.

I'll admit that it's often a struggle. I still go through a series of trial and error with every chassis I cut. Thinking that there must be a better way because it's taking too long and feels too clumsy. And yes, I still try the Dremel metal cutting bits sometimes.

The step bits proposed by Leo work well. I don't own any but intend to get some. I've used them in someone else's shop. If you're not using a press, it helps to punch a dent with an awl and drill a small pilot hole first to minimize drift. But there's always drift. If I were doing this professionally I would have a butt load of punches, step bits, a press, etc... As it is, working with sub standard tools, I usually have holes and cuts that are very slightly off the mark. Experience has taught me how to minimize, but not prevent this. It sucks for faceplate mating too. You'll either need to spec odd locations for the holes (accurate measurements are a PITA) or adjust the holes in the faceplate to mate up with the chassis (graphics will be a little off). This is why it's better to trace the cuts, undercut the size with initial gross material removal, and then use a finer method to clean up the cuts to meet of the trace. I never have the patience for this except on large, critical things like pilot lamp holes, IEC mounts, prefab jack busses, etc. Sorry I don't have a more pleasant solution for doing it the hard way . I really should get some proper chassis tools.

[Leo_Gnardo]

The step bits proposed by Leo work well. I don't own any but intend to get some. I've used them in someone else's shop. If you're not using a press, it helps to punch a dent with an awl and drill a small pilot hole first to minimize drift. But there's always drift.

Slow drill speeds with those step bits, also keep the cutting edges lubed. I keep a hobby "glue applicator" about 2 ounce bottle with needle tip applicator which I load with the final drips from oil cans when I change/add oil in the car or lawn mower, so there's some 30W and 10W30 mixed. I've read that bacon grease makes a great cutting lube, must smell wonderful when in use, will have to give it a try sometime. Bacon, bacon, I smell bacon! One caution: might be a problem if you have pets... I can imagine little Fluffy or ol' Rover licking a freshly drilled bacon-scented chassis yum!

Definitely a good idea to punch a start spot, I use a pointed metal punch. The smaller 1/2 inch step drill bit seems to work just fine "finding" the start point & going right through whether aluminum or steel, it must be made of very hard stuff and has proven to be a star performer in my workshop. Once you have a small hole start up with the bigger step bit. One of these days I'll set up a little drill press I bought at Sears years ago for a cheap $125 or so, about time I put it to use.

And thanks hylaphone for suggesting those conduit punches, those sizes sound just about right for typical tube socket holes 9-pin and octal.

Sanding barrels for smoothing rough edges, de-burring. True it's difficult to increase the hole size by much without hours of tedious sanding.

[hylaphone]

As for chassis layouts, a few things that have helped me the most:

Always indicate your hole locations with a scratch awl, center punch, then pilot hole. Also helps to know which way the drill bit wants to walk.
A full set of chassis punches pays for itself pretty quickly (if only I could find an affordable IEC punch!!)
If the control plates are custom made, it's worth the extra fee to have pilot holes pre-drilled for you. Then just line up the plate, scratch the hole locations, center punch and drill.

Also IMHO, a used older drill press by Rockwell, Walker Turner, Clausing, etc. is a much better investment than the current imported offerings - which often have sloppy quills, cheap bearings, etc.