Those Bicycle Speedos and Drilling Stainless Steel

OK, two completely unrelated questions but thought id keep in one thread.

First off, how reliable does anyone think that those halfords type
electronic speedos are?
Ive fitted one to the lammy as the traditional lammy speedo is well, mmmm
epileptic lets say and hence particularly unreliable especially when running
in a new engine.
the bumph does say its accurate up to 199mph +/- 1

Secondly, im trying to drill a couple of holes in some stainless steel
shelving which I got from work so I can make use of it in the workshop /
shed. However, ive blunted 5 drill bits, all metal drilling ones and can
barely make a dent!

anyone know if there is a particular drill bit type I need???

 

The accuracy of those speedos is only as good as your measurement of the
outside diameter of the tyre (when loaded) that you attach it to. It's
quite difficult to get this accurate, as it changes depending on load and
tyre pressure/heat.

 

One that is harder than Stainless Steel.

Err Tungsten Carbide is it ?

 

Did all the circumference measuring, must admit I forgot about the expansion
re the heat build up :-/
Still that should still be more accurate than the actual lammy speedo.
Believe me I mean epileptic when referring to the needle, it will literally
go from 20kph to 45-50 and back every second or two.

 

Just calibrate it by driving past a few 30mph Gatso's flat out and then
compare your indicated speed with whats printed on the ticket.

 

Look for Cobalt Steel drills, basic HSS drills struggle with some SS grades.
You might see some ordinary HSS drills coated with (gold coloured) Titanium
Nitride, these might (or might not) go through as the TiN is harder but the
coating will only last for the one job on SS at best. Any decent Merchant
will be able to sell you a single Cobalt drill of the right size.
or
http://www.machinemart.co.uk/product.asp?p=060230383&r=2123&g=115

 

Yeah, I was more contesting the accuracy quoted on the box (of 199mph +/- 1)
which is obviously theoretical based on complete accuracy of calibration.

 

But this would also apply to any speedo that uses wheel speed, so it would
probably be as good, if not better than the original. At least you can
calibrate it.

Surely soon someone will use the speed of the ground passing underneath,
optical mouse style, and create a fool proof system.

--

KillaHedgeHog AKA Paul Hendrick
YZF750R Bultaco Sherpa Fantic200
BONY#3 BOTAFOT#101

Remove KHH to reply by email

 

flashgorman wrote:
[snip]

On a Lambretta? They probably won't even flash.

 

Had one on the Monster, and IME wasn't really an issue. Was a *damn*
site more accurate than the factory one, about the same as my mate's
Triple.
Of course, we have no idea how accurate that was.

--
Catman MIB#14 SKoGA#6 TEAR#4 BOTAFOF#38 Apostle#21
Tyger, Tyger Burning Bright (Remove rust to reply)
Alfa 116 Giulietta 3.0l. Really, Sprint 1.7
Triumph Speed Triple: Black with extra black bits
www.cuore-sportivo.co.uk

 

They're fine, by all accounts.

I use good quality HSS bits 'cos they're cheaper and less brittle than
the exotic types. But I go careful, like. Loads of lube/coolant
(which _always_ helps drilling), very gentle pressure and about 10rpm.

I always start with a pilot hole too, using a very small drill - and
then open it up. Just go steady and don't try to lean on the drill or
force it and you'll be surprised how easy it becomes.

 

I have known several people use this on motorbikes, and they worked ok. You
do need to fine tune them to get the accuracy right - a portable GPS
receiver is very handy for this. Potentially, you could get it a lot better
than your average standard speedo.

Rick

 

OK, two completely unrelated questions but thought id keep in one thread.

Secondly, im trying to drill a couple of holes in some stainless steel
shelving which I got from work so I can make use of it in the workshop /
shed. However, ive blunted 5 drill bits, all metal drilling ones and can
barely make a dent!

anyone know if there is a particular drill bit type I need???


Drilling SS......
HSS drill bit will do but it's best to grind the cutting angle to about half
what it usually is....make it almost flat.... Personally, I wouldn't drill
a pilot hole but I'd make a good centre mark with a punch and file the
surface flat ........
Next, drill as slowly as possible with not much pressure applied. If you've
ground the drill right the SS swarf will come off as a pair of slowly
twisting spirals.
Finally, if it's over 5mm thick stick a marble sized lump of plasticene on
the mark, poke your finger in it and fill with paraffin. Now the drill
won't burn out or go blunt and you'll get a cleaner breakthrough when you
get that far.....
HTH
Cheers
DP

 

"flashgorman" said to "Donegal Paul"

Heh, smartarse

 

"Hog" said toDonegal Paul wrote:
SNIP

They look like the business, Ill hunt about for the bit I need, cheers Hog

 

"Rope" and others replied to Donegal Paul spoke:
Cheers you lot, id been giving it lots of speed thinking that was best, doh!

on the issue of the speedo, as someone said it'll need calibrating, as the
max speed it recorded was 74mph!!!

Don't fucking think so

 

It usually isn't when it comes to metalwork, mate. Slow and easy, let
the tool do the work without you trying to influence it too much.
Gentle pressure, just keep it lined up and the fagsmoke out of your
eyes.

Chuck loads of coolant/lube (paraffin, 3in1, WD40 - whatever you have
to hand) at it mind; that'll extend the life of your drill bits many
many times over in any case - just like lubing a chain.

 

I have drilled stainless and initially had the same problem. When I spoke
to the fabricator he advised me that the key is to drill slowly and use
plenty of lubrication (and a good quality drill bit). This worked fine for
4mm holes, anything bigger and you would need one of those wind-in / punch
out jobbies.

--
Oldbloke

My Bike - 2000 Honda CB500
M'boy's Bike - 1990 Suzuki TS50X
i Bike - MotoRumi Junior Gentleman

BOTAFOT #140, DIAABTCOD#26
"He's like Robbo's chubby kid brother"

 

I need???

Most times the problem is that a pilot hole has not been drilled first.
Depending on the size of the finished hole as to the size of the pilot.
The first hole could be drilled with a 2mm 60 degree centre drill, they
are about £3 at hardware shops or in RS.

 

First centre punch

Second a pilot hole - about 3mm

Than next about 5mm bigger and then again until you get to the size you want

Brian