19 replies to this topic

[ACDodd]

I use a Magnaflux testing kit. Or more specifically magnetic particle inspection.

Ac

[Hpal]

Hi all,

similar to the above i am going to purchase various HSS cutter (not doing hardened seats) for a 202 head i'm doing up to 295 spec. I'll get a 9/32" reamer as well, but i wanted to know what spindle size on the cutters i should get, I thought 7.1mm would be perfect with a touch under 0.002" clearance to keep the cutters straight, sound about right? and i take it I install the guides, then ream them, then cut seats? Thanks

 

7.144mm = 0.28125" (9/32")

7.1mm = 0.2795 (spindle size)

0.0017" clearance

[Turbo Phil]

The pilot for the cutter needs to be a snug fit in the guide. Nearly 2thou clearance is far to slack, you’ll never cut an accurate/concentric seat with that much play.
Those cheap HSS cutters are usually garbage to. Do you not have a local machine shop that can cut you a decent seat once you’ve done the rest of the work?

Phil.

[Hpal]

Thanks Phil, so maybe 0.001" clearance after reaming, ream first though? Yes i can take it somewhere but i kinda wanted to have a go myself as buying the gear would be cheaper than paying for the work to be done. But i see your point, they'd probably do a better job.

[Turbo Phil]

Yes ream the guide first. As an example I charge £6 a seat for a multi angle seat, so £48 for 8.
It’s unlikely you’ll get any kind of decent tooling for less than that?

Phil.