Setting up to drill 8 holes on a 56mm PCD

Jan 06, 2007 4 Replies
S

The holes are to be drilled as fixing holes for the front half of the Nemmett OHC engine crankcase in ME recently. The advice is to use a rotary table, but not having one I intend to co-ordinate drill on the mill/drill.



The crankcase is bored through at 25mm. The little excel spreadsheet I built (anyone want a copy?) that calculates the hole co-ordinates for me has the circle centre at (0,0).



How do I accurately centre the workpiece? I was simply going to set it up square on the table, then use the MT3 dead centre off the lathe to locate centre on the crankcase.



(Embarrassingly I also have a wiggler, but still haven't made any sense of the thing!)



Best Regards



Steve


Vote
Twitter Facebook LinkedIn
M

Stick an appropriate sized offcut of bar into the drill chuck. clamp your DTI with he adjustable arm off its stand onto the bit of bar. lower it down until it's in the hole and adjust until you get a reading. Turn the spindle by hand and lean over/squint/use a mirror to see how the reading changes. Adjust table accordingly.

:-)

Mark Rand RTFM

Vote
Twitter Facebook LinkedIn
S

Snipped

Why didn't I think of that!!!

Many thanks

Steve

Vote
Twitter Facebook LinkedIn
N

Build something like this?

That isn't very precise.

Nick

Vote
Twitter Facebook LinkedIn
S

I also discovered that the dead centre is smaller than the bore - not very precise at all!

Steve

Vote
Twitter Facebook LinkedIn

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required