Tuning FX Impact Mk2 PP valve seat porting

[bigHUN]

Im talking from memory now after two years but I think the ValveHouse ID is about 10mm + a hair. I did so many changes I wrote down everything in a book. Ya know we have that joke in my language: literate people writing it down - illiterate remembering
A 8.3-8.4 OD poppet is working well.
Was that a 7.3 bore size on my drawing and ended up with 7.5 mm ID hole in the Valve House? The problem there is to drive in a drill but the edge is cutting very little and want to push the center, especially that piece is a titanium....... you have a lathe, I would suggest bore that hole...

Usually whenever I give my drw to a machinist friend, I am never getting my parts within my specs. I was pißed so many times wanted to buy my own mini lathe just because of this. But stepped back because I may have 2-3 parts in a year and doesn't justify the cost for the machine.

 

[rcs9250]

“ The machine shops here in Canada all using the stupid fraction sizes.”

I love it.

“ I was pißed so many times wanted to buy my own mini lathe just because of this. But stepped back because I may have 2-3 parts in a year and doesn't justify the cost for the machine.”

Yeah, that’s just another rabbit hole to pour money into. Then you need a knurling tool, then boring bars, then end mills, then live and dead centers. The list goes on and on.

 

[bigHUN]

“ The machine shops here in Canada all using the stupid fraction sizes.”

I love it.
................

Just look at the table how much is a gap between two sizes. You need to buy two boxed sets one in fractions and one numbered bits to cover the dimensions. And don't mix them up...

The metric drill/mill/reamers tooling goes in 0.1 increments, taps in 3 sizes #1-#2-#3 depend how tight thread you want.

 

[rcs9250]

Just look at the table how much is a gap between two sizes. You need to buy two boxed sets one in fractions and one numbered bits to cover the dimensions. And don't mix them up...
View attachment 290899
The metric drill/mill/reamers tooling goes in 0.1 increments, taps in 3 sizes #1-#2-#3 depend how tight thread you want.

Yeah, not sure about that shop you’re dealing with. I was a toolmaker for 30+ years, we had gage pins every half thousandth of an inch so could produce any size and closer than half thousandth. Dimensions were held to tolerance always or it was scrap unless the customer gave a variance. The drawing tolerance was law no matter what system spec’d.

 

[bigHUN]

Yeah...The drawing tolerance was law no matter what system spec’d.

Yeah, my engineering game started in '82 with DIN and ISO, but left during a Civil W and arrived to Canada in '96. I was a Toolmaker for several years, after that CNC programmer for several years and finally back to Design about 15+ ago. I learned to compare the two systems. Just saying it is not about tolerances but the standards and tooling.