"tungsten carbide or diamond grit coated or carborundum?"
I need to cut a couple of circular holes (150mm dia) in some 0.5mm thick
"304" grade stainless steel sheet which has been formed into a curved
shape and polished (which I think means it has likely been work hardened).
I have decided upon a Dremel type of tool, perhaps with some lubricant
on the work piece, and adjustable speed. I think a grinding type of
bit, e.g. a 3mm cylindrical "burr", will suit. This is the sort of bit
shape I hope to try:
I can buy them made from tungsten carbide, or diamond grit coated, or
the "carborundum" type of grinding stone.
Which is likely to be best? I can see that the cost of any of the types
if affordable for me and I don't need to make hundreds of cuts - I want
to use which is going to give me the least heating distortion and is
likely to be the fastest to cut.
Thanks for any advice on which type to choose!
The problem I always have with burrs and grindstones is keeping them on
All 18-8 stainless steels are buggers for finishing with hand-held
tools. The curved shape implies some work hardening, but the original
sheet will have already been work hardened by rolling. The benefit from
the shaping means that it will be much stiffer than a flat sheet, hence
on balance easier to work.
If it was thicker, I think I might rough them out with a slitting disk
in a 125 mm angle grinder. At 0.5 mm, I'd be inclined to start by using
a Dremel with the fibre-reinforced slitting disk, without lubricant. The
disks won't last all that long. I say no lubricant because of the
difficulty of maintaining supply. You will get the fastest cut using the
thin, brittle, non-reinforced disks but they will break if you apply any
One you have roughed out the cut, I would use a cylindrical abrasive
bit. The ones which fit a dremel will be rather small for cleaning up a
peripheral length of half a metre. You would be better off with a die
grinder, and abrasive bits perhaps 25 mm diameter.
You might be able to do the stage between Dremel "rough cut" and Dremel
"final finish" using a standard grinding disk on a 125 mm angle grinder.
Much faster metal removal. Some care needed!
0.5 mm is *probably* just too thick to use a shears. You can get
"Gilbow" type shears with curved blades to help making curved rather
than straight cuts.
IIRC this "universal" type will also cut curves, at a price!
(Amazon.com product link shortened)86142651&sr=8-8&keywords=gilbow+shears
Might be worth checking if you happen to have a normal (straight) shears.
You've made some good points and your mentioning of "die grinder" has
shown me that this might be a better purchase than a dremel. I can see
some very affordable ones, and the bits for them are likely to be
heavier duty. I remember coming across the term before but I didn't
know what it meant. Now I can see it might suit me very nicely.
My plan is to fix the rotary tool (of whichever type I buy) to a bench
and then, by hand, introduce to the bit and then rotate the work piece
about its axis, in order to be able to control the feed rate. The axle
can be bolted to the same bench and I am confident that I will be able
to form a nice circle.
I think a die grinder with suitable clamping should work very well, and
thanks for the advice. I shall look into the cutting disks you mentioned
& I'll see what types of other cutting bits are available (I still think
a burr approach might well suit this particular task).
dennis, F Murtz - I didn't realise that that sort of "nibbler" would be
as affordable. I will see if it would work for my particular set of
circumstances. Thanks for the suggestion and recommendation.
Yup. One of the speakers on my old Rover as I discovered after having a
new rear wing fitted. The type of car speaker with a concentric tweeter -
so no grill over the pole pieces. Which filled up nicely. ;-)
*I couldn't repair your brakes, so I made your horn louder *
Dave Plowman email@example.com London SW
A discovery from 55 years ago (apprentice tour of duty in the instrument
dept.) a sharp steel pointed tool (broken dart ideal) is that you can
pick out bits of steel from a circular magnet.
Presumably the magnetic field is stronger at the point.
I had one of them (from Machine Mart). The "bit" broke after rather
limited use and I couldn't get a replacement. They are certainly good on
steel or aluminium and should work on 0.5 stainless, but as I said
before it is a really difficult material to work with in this way.
Probably a bit fiddly compared with a purpose-built tool, whether manual
There are two sorts of devices described as nibbler
The "shears" type is OK for making a linear cut, the punch and die type
which takes out a little rectangle at a time is best if you are cutting
out "features" like a square recess or a T-feature.
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