cutting pistons

[dmaxfireman]

gonna be trying to cut and de-lip my first set of pistons on the lathe sometime in the next few days... any tips from you guys who have done this before? if there a trick to cutting that 3/16" radius (is it really needed?)

 

[02bigstrokin]

mine is a .125 radius(per guy) and yes its important. you dont want any sharo edges, thats where cracks would be most likely to start.

 

[dmaxfireman]

i was going to cut off square, then cut a 45* then a 22.5* on each side of that and then smooth out with a stone or something. gotta do a little math to get that right size radius tho.

is there a better way?

 

[JOHNBOY]

i was going to cut off square, then cut a 45* then a 22.5* on each side of that and then smooth out with a stone or something. gotta do a little math to get that right size radius tho.

is there a better way?

CNC

Or a cap radius tool.
http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=17545376&PMT4NO=75161276

 

[dmaxfireman]

all i have access to is a logan lathe and southbend lathe and a bridgeport mill

 

[JOHNBOY]

all i have access to is a logan lathe and southbend lathe and a bridgeport mill

How big of a hurry are in? I can send you a cap rad endmill Monday if you return it when finished. You mount in your lathe tool holder and use it like a single edge tool.

 

[dmaxfireman]

not much of a hurry at all. i think i may try to build a radius cutter first that way i have my own around to use. i'll definitly let you know if i need it that would be awesome! :hug:

 

[JOHNBOY]

not much of a hurry at all. i think i may try to build a radius cutter first that way i have my own around to use. i'll definitly let you know if i need it that would be awesome! :hug:

I have cutters at the shop. Just let know.

 

[malibu795]

keep as much of the crown for quench :thumb:

less quench means more power

 

[Utahski]

That lip is there to direct fuel into the bowl/combustion area. If it were mine I'd take enough off to where the lip isn't thin, but leave a little bit of undercut and not go any larger than about 1/16" radius on the top edge.

 

[02bigstrokin]

That lip is there to direct fuel into the bowl/combustion area. If it were mine I'd take enough off to where the lip isn't so thin, but leave a bit of undercut and not go any larger than about 1/16" radius on the top edge.

the whole idea behind delipping the pistons is because the "lip" is where heat builds up and cracks usually start. you want to make sure and get the lip out and not leave any sharp edges.

 

[Utahski]

the whole idea behind delipping the pistons is because the "lip" is where heat builds up and cracks usually start. you want to make sure and get the lip out and not leave any sharp edges.

That's why I said to not leave the lip thin. Take out most of it but leave a little bit of undercut. The undercut is there for a reason. A 1/16" radius is 1/8" dia. and that's not a sharp corner.