Drilling 5mm holes in a hardened Brescia crankshaft . Drills up to 50cm long , especially made for this jop . To have a more modern oil system .

last 5mm hole

2 questions, just out of curiosity:

-hardened crankshaft: Hardened throughout, or surface hardened?

-how do you make sure the holes will be drilled nice and straight? If I were doing this, I would definately end up with the other end of the hole mm's if not cm's away from the centre.

_________________
Vive la Marque !!

The crankshaft is surface hardened , but the inside is chrom nickel steel , very tough .
This drill bits , are not normal ones .The tip has a special design and the spiral is made to get the best chip flow from a deep hole . So to drill a long straight hole is not a problem .

You will have to drill the long holes for me on my daughters cambox! I always had trouble with them.

I know its a very different idea but meme process.
When I used to teach technology, the process of making standard lamps was similar using a long auger with self centering tip..[ the item turned and the auger held still] it was possible to come out at the other end totally centred...even through hardwood with unknown insides such as knots and grain direction.
sorry if it is off subject ! just my 2 pence worth

I made this Wright 1908 crankshaft from 42crmo4 .The worst material to drill long 5 mm holes . The crankshaft is 1 meter long .The old design drill bit for this kind of long holes has a tip with only one knife , but it takes houers to drill the hole . The new design is much faster .

Another question, I am learning.

I see the piece of steel you made the crankshaft from. When you start to machine, will internal stresses that are relieved due to the removal of material, bend the workpiece? And how to counteract for that? Work your way to the final dimensions slowly?

_________________
Vive la Marque !!

for a 4 cylinder you buy a rectangular piece of steel , for 6 and 8 cylinder you need a round piece of steel . For a 4 cylinder you start with a milling machine .After the crankshaft is 70 % ready , the crankshaft need head treadment, to get the tension aut . If the crankshaft is to much aut of shape you have to straighten it with a hydraulic press .After 90 % ready , again head treadment to get the tension aut and to bring the steel to 120 kg to the square mm .

This is a Wright 1903 crankshaft , 1 meter long and the journals have only 32mm diameter . So very long and skinny .Most difficult one to make . 1903 with 5 main bearings .At the end the crankshaft is so unstable , I can take off in one go max 0,5mm

How long is the hole in your cambox ? The longest hole we drill in alluminium , is in our diesel aircraft engine , 8mm diameter and 520 mm long .

For drilling the big end jounals , I build the drill bits myself . With a very short head , 4 to 5 cm spiral and after the spiral , 0,05mm smaler in diameter . Sometimes this drill are up to 1 meter long .