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KBs PensNmore
12th Jan 2021, 11:28 PM
To get a nice consistent point on my Centre Punches, I put them in the DP at around 600 rpm, and use a small angle grinder held at the correct angle, for a short period.
Taking off the mushroom head can also be done on the DP, with good results.
Kryn

azzrock
13th May 2021, 09:42 PM
Cool Merrill try that

BobL
14th May 2021, 12:51 AM
Both my spring loaded centre punches won't run true in my drill press, while the non-spring loaded ones have square shanks

BaronJ
14th May 2021, 05:39 AM
Both my spring loaded centre punches won't run true in my drill press, while the non-spring loaded ones have square shanks

Hi Bob, Guys,

The spring loaded ones, I remove the punch, its also easy to make new ones for them !

I sharpen my centre punches in the lathe using a Dremel in the tool post. About the only time that I've used the drill press is to hold a short length of silver steel when I've already made the point by turning and I'm heating it to harden the tip. I spin the silver steel and then get it red with a cooks torch, then plunge into a tin of oil ! Usually the cooking oil that the wife throws out of the chip pan, smells of chips... mmm. I've made several transfer punches this way.

BobL
14th May 2021, 08:35 AM
Useful tip about removing the tip on a spring loaded punch to sharpen it.

To sharpen tips on stuff that fits in a cordless drill I spin the tips against an unsupported part of a Linisher belt.
Sometimes I sharpen TIG tips against a diamond wheel.
The tips on the tines of this wool carding comb were made this way.
The tines are pieces of TIG rod

392095
Which is why I wanted to get the all the same length.
392096

nadroj
16th May 2021, 05:29 PM
Note that grinding should be parallel to the axis of the punch, not across it.

jack620
16th May 2021, 07:46 PM
Note that grinding should be parallel to the axis of the punch, not across it.

I canít picture what that means. And even if I could, I donít think Iíd understand why. Can you elaborate please Jordan?

SurfinNev
16th May 2021, 08:00 PM
I can’t picture what that means. And even if I could, I don’t think I’d understand why. Can you elaborate please Jordan?

Grinding along shank toward tip I assume. Didn't know that 'till now. Thanks.

BobL
16th May 2021, 08:37 PM
Note that grinding should be parallel to the axis of the punch, not across it.

I grind/shape across a coarser belt first, and if possible also use an unsupported part of the belt to avoid getting a flat. Then switch to a finer belt along the line of the work

nadroj
17th May 2021, 09:30 AM
I read it in a few different places, that grinding a centre punch should be such that any grooves (tiny but there) should be towards the conical tip.
I thinks it's to minimise the effect of any stress risers weakening the tip.

BaronJ
17th May 2021, 05:29 PM
Hi Guys,

I have a centre punch that does not have a conical point !

Instead it has a three sided pyramid shaped point and is quite sharp compared to the conical point ones. Its also very easy to find the intersection of scribed lines with it. You can easily feel the scribe mark.

swarfless
18th May 2021, 11:11 PM
Hi Guys,

I have a centre punch that does not have a conical point !

Instead it has a three sided pyramid shaped point and is quite sharp compared to the conical point ones. Its also very easy to find the intersection of scribed lines with it. You can easily feel the scribe mark.

Meant for centre punching stainless steel .. as are 4 sided. Theory is it's easier for the drill point to cut thro' the work hardening.

mick21
25th Jul 2021, 01:29 PM
To get a nice consistent point on my Centre Punches
Kryn

just curious, why does it need to be a nice consistent point ?
i sharpen drills 3mm to 60mm on a bench grinder, whats wrong with a bench grinder?
cheers

elanjacobs
25th Jul 2021, 10:03 PM
You want to make it consistent so it's easier to line up on your scribe lines. Nothing wrong with a bench grinder at all

mick21
26th Jul 2021, 12:33 PM
You want to make it consistent so it's easier to line up on your scribe lines. Nothing wrong with a bench grinder at all
i think i understand, i would call it a "fine" point

BaronJ
26th Jul 2021, 05:41 PM
Hi Guys,

One of the reasons that I like my pyramidal shaped one is that the point is very sharp which make it easy to find a scribed line or intersection. Its also easy to touch up the flat sides. The conical point on the normal ones tend to round off particularly if you are heavy with the hammer blows.

nadroj
30th Jul 2021, 09:35 AM
Is it tricky to grind a pyramidal point, in terms of getting all flat surfaces to intersect perfectly at the point?
For a conical point, I chuck a centre punch in a pistol drill.

BaronJ
30th Jul 2021, 09:49 PM
Hi Jordan,

No I would say not ! I've never had any problem, but I do use a 45 degree angle plate on the DE bench grinder table as a guide.

The harder part might be deciding whether you want three or four sides to the point. My punch was originally purchased with three sides, so all I do to touch it up is set the flat to match the side of the wheel, though I have occasionally stoned the flats to get the tip sharp again after being a bit heavy handed with the hammer. The trick is to treat it like a prick punch and re-punch with a normal cone tipped punch if you want a larger marking.

The only other thing I would mention is hardness ! Because the tip is so small its easy to destroy the hardness when grinding, so you have to be careful not to overheat it.

Zeth4500
15th Sep 2021, 05:36 AM
if a drill fits in a hand drill, and you can really FUBAR'd it, skewing the sides up or messed up the angle you can use this trick
ideally you wanna run it counter clockwise while sharpening it on band grinder so it doesnt bite into the belt itself
you can adjust the angle of the tip with this and both sides will be equal lenght. then you just gotta touch both sides to get the cutting part of the drill done

Zeth4500
15th Sep 2021, 05:54 AM
indeed making it 3-4 sided helps, reference arrows used for hunting.
one place i worked we had to make some sharpened rods for penetrating something- i truly cant remember what the hell it was, but the conically sharpened spears didnt do much, but the ones that were 3 point or was it 4 point went right through, because as it expanded the material, the points would make a weakpoint and actually cut the material, causing it to breach and break rather than expand while adapting and pushing against- if that makes any sense
i believe it was some kind of fabric we had to punch through, but on the nano scale im sure steel can work the same way but surely wont "cut" as easily