Tool recommendation for chassis cutting

Help Support GroupDIY:

Potato Cakes

Well-known member
Joined
Jul 1, 2014
Messages
1,922
Location
Nashville, TN
Hello, everyone,

I am looking for a solution to do custom cuts in blank rack chassis, namely vent slots. I have a Dremel tool that I use for doing small square shape for things like IEC connectors, but this option is quite laborious when trying to long straight cuts in aluminum. Any recommendations would be greatly appreciated.

Thanks!

Paul
 

cyrano

Well-known member
Joined
Sep 6, 2010
Messages
1,553
Location
Europe
An electric nibbler?

Mine's not electric. I got it from Radio Shack (called Tandy over here). It still works fine, despite decades of abuse. If you want to cut vent slots I'd go for an electric one though. Cutting long slots would result in sore hands with the one I have as it requires a fair amount of force.
 

Script

Well-known member
Joined
Nov 27, 2008
Messages
1,779
Location
Japan
+1 for just drilling holes.

Depending on how hot it gets inside the case and on your rack real estate or how you intend to rack the unit, ventilation holes on the sides and the back might make sense too/more (some units even have hot air escapes in the faceplate).
 

Rusan

Well-known member
Joined
Aug 18, 2020
Messages
89
Location
U.S.A.
I've made vent slots by laying them out and scribing the lines with a caliper, drilling two holes to make the radiused ends, and then connecting them with a sheet metal nibbler and cleaning it up with files and sandpaper. It's labor-intensive, unforgiving and very difficult to get really clean, pro-looking results. A major issue is that the nibbler wants to distort and bend the metal between the slots as you're working, unless you space them quite widely.

An easier method that has yielded nice looking results is to simply cut a rectangle and use wire screen or perf metal on the inside. I lay out and drill 4 holes to make the radiused corners of a rectangle, connect them with a sheet metal nibbler, and then finish by filing and sanding. Then, you lay out the screw holes for mounting the wire screen or perf metal, and countersink them and use #4-40 flathead screws so it's flush on the outside of the chassis. Not quite as slick looking as professionally punched or laser cut vent slots, but not bad at all.
 

Newmarket

Well-known member
Joined
Oct 10, 2016
Messages
1,166
Location
Brighton Sussex UK
+1 for just drilling holes.

Makes sense. And, although this may be marginal wrt your application, may also be better for EMC considerations.
fwiw I've 'dremelled" DSub cutouts previously for prototyping at work and it's quite a challenge to do that in 1.2mm steel that turned out to be a particularly hard type and have the tolerance for the circular holes for the screws !
Ideally I'd have used a "Pull Through" but couldn't really justify the cost for a 1 or 2 off. Production was external subcon.
 

Tubetec

Well-known member
Joined
Nov 18, 2015
Messages
3,890
Definately drilling out the corners first is the way to go,
Ive used the dremmel cutting wheels too ,fairly brittle so it shatters easily .
also tends to skid around the place a bit .
I was thinking about getting one of the smaller battery powered grinders and a drill press type mount ,
with the work piece secured in place you should be able to get good accurate cuts .
and only a minimal cleaning up with the file should be required.

A mini plasma cutter might be an option if you have a compressor, a cheap milling table with the cutter head securely clamped in position above only minor tidying up around the edges would be needed . You probably wouldnt need to pre drill either which would save a good bit of time ,
Theres videos of the Lidl plasma cutter up , its like a hot knife through butter , the guy carves up steel 2-3mm thick , so it would do a chassis very easily .
 

Attachments

  • Drill press.JPG
    Drill press.JPG
    17.2 KB · Views: 23
  • Table1.JPG
    Table1.JPG
    30.1 KB · Views: 22
Last edited:

Gold

Well-known member
Joined
Jun 23, 2004
Messages
2,946
Location
Brooklyn
I’d probably use an angle grinder with a cutoff wheel about the length of the slot I wanted. That way you center the wheel and let it do the work.
 

Brian Roth

Well-known member
Joined
Aug 20, 2005
Messages
2,086
Location
Salina Kansas
or a Greenlee knockout hole punch.
Back in the 1980's, the studio where I worked added a Klark Teknik DN 780:


It was a very nice complement to our Yamaha REV-1 and Echoplate units. However, it had a VERY poor cooling design.

A tiny fan at the rear panel attempted to exhaust the waste heat, but there were no "inlet" vents. What little airflow there was attempted to enter via the small openings surrounding the pushbuttons on the front panel. I discovered this after the unit failed and I inspected the innards.

The PSU circuit board was seriously "browned" and there was lint around the front panel slots where the switches protruded. I forget what failed on the PSU board....maybe the bridge rectifier.

I used one of my Greenlee punches (probably a 15/16" diameter I used for making holes for XLRs) and made several holes in the top cover plate. Then I used silicone adhesive on the rear of the top plate to attach a grille to minimize the chances of something falling into the guts.

For that grille, I used a product like this:


I happened to have some on hand at home that I used to keep leaves out of the rain gutters on my eaves!

I rearranged the rack so I could add a vented 1RU panel above the DN 780. The unit then ran flawlessly for many more years.

Bri

EDIT...I forgot that I used that same vent design for a custom racking project I did many years later. You can see the grille below the holes punched on the top of the chassis:

 
Last edited:

Newmarket

Well-known member
Joined
Oct 10, 2016
Messages
1,166
Location
Brighton Sussex UK
I forgot to add:
Whatever drilling / cutting method you use. Do use a little cutting fluid.
I'm always surprised when I "smell the burn" when people try this sort of thing without it.
 

pinebox

Well-known member
Joined
Mar 11, 2015
Messages
51
Whats your budget? Im eyeing a mini mill right now for 750 used that would do all this, Im sick of hand drilling and cutting rack panels, never looks as good as it could that way.
 

Redhouse

Member
Joined
Nov 17, 2008
Messages
8
Ask around your local machine shops and find out who does "Water Jet" cutting, it is a great way to cut steel in the manner you need done, results are immaculate and very little touch up needed afterward, usually only needing a deburring tool run around those cut edges.
 

mobyd

Well-known member
Joined
Jan 27, 2006
Messages
177
Location
Auckland NZ
Depending on how much metal munching you intend doing, it might be a good idea to look out for a flypress. I bought mine for peanuts when all the plumbers merchants were hell bent on turning into supermarkets and have never regretted it. One tool which brings a smile to my face every time I use it.Fly.JPG
 

Tubetec

Well-known member
Joined
Nov 18, 2015
Messages
3,890
A cnc plasma cutter will run into big money ,
what about a thing similar to a router jig with handheld plasma torch , you do your mounting holes then bolt on the jig and run around with the plasma , not as tidy as a laser or water jet but so what if you need to spend ten minutes with a file cleaning up after ,much better than trying to nibble or cut with a wheel
 

swpaskett

Well-known member
Joined
Jun 2, 2021
Messages
85
Location
Mesa Arizona
A vertical mill is made exactly for this kind of job. A distant second would be a cross-vise on a drill press.
And an even more distant third is what I use: a handheld router. Set it for a slow speed and use a spiral bit no bigger than 1/4 inch, which the metal working crowd will recognize as an end mill. And only do this with aluminum, never steel unless you have a death wish. And, seriously, I DO NOT RECOMMEND THIS, it is very unsafe, but I have done it and gotten very professional results.
You would be much better off with the cheap mini-mill mentioned above, but it costs ~7X as much as a decent router. This is why I need life insurance.
 

Disco Volante

Well-known member
Joined
Jun 20, 2021
Messages
80
Location
Sweden
I second the handheld router. Make a parallel guide for it and lower the speed. Use a sharp bit and only in aluminium. works great for one-offs or hacking existing gear. Otherwise, any cnc-equipped machine shop should be able to either nibble, punch, lasercut or scratch out those slots with a pro finish, though expensive if you're only doing single "diy" pieces...
 

Tubetec

Well-known member
Joined
Nov 18, 2015
Messages
3,890
A router is one of the most dangerous pieces of kit , the kinetic energy because of the rpm , those things can kick like a mule , wood is dangerous enough , metal I wouldnt have the confidence to do .
 

Disco Volante

Well-known member
Joined
Jun 20, 2021
Messages
80
Location
Sweden
A router with proper guiding and sharp tooling is no more dangerous than a big mallet.
Accidents happen to sloppy people, people in a hurry. Take your time, make a proper setup and you'll be safe.
Most of the time spent with a router is spent making jigs and templates to get the level of control you need for a good professional finish. Incidentally, that will also ensure your personal safety.

I have trained numerous young craftsmen, they all still have their fingers intact. One colleague was always a sloppy sod and lost two fingers... He's still sloppy, but not doing machinework anymore, got a new job restoring windows, caulking and painting;-)

Happy tinkering!
 

Latest posts

Top