Match Drill vs. Final Drill definition

Freightdawg · #1 09-25-2014, 04:01 PM

OK, I thought I understood the difference between match drilling and final drilling, but page 15-4 has me doubting that. I thought match drilling meant one piece of metal had a hole and the other didn't, so you use the established hole as a guide in drilling; final drilling meant both pieces of metal had holes but the holes needed to be enlarged to final size.

If I have the definitions correct, step one calls for match drilling where all the parts already have holes in all the pieces.

What am I missing?

Thanks.

aarvig · #2 09-25-2014, 04:11 PM

Number one: Make sure you indeed have the right parts.
Number two: I came across this during my build. Instructions would ask me to do something that very obviously had already been done. If this is the case, refer to the plans and final drill to the appropriate size.
If you are in serious doubt, call Vans.

flion · #3 09-25-2014, 04:33 PM

Sometimes 'match-drilling' means final-drilling through two matched pre-punched holes. 'Final drilling' may mean drilling out a single hole to final size, like some screw holes in parts on the RV-10. If I read through the plans through the whole relevant assembly, it usually is fairly clear what they mean. English is not an exact science.

Jesse · #4 09-25-2014, 07:28 PM

Match drilling does refer to using one hole as a guide to drill a new hole in another part. Final drilling is opening up an undersized hole to final size, whether in a single piece or multiple pieces. I wouldn't be surprised if they have made some mixing of those terms with the number of times they are used in the plans, but it is also possible that in earlier versions of the kits it truly was a match drill and now is a final drill because they have changed some of the parts.

Freightdawg · #5 09-26-2014, 07:05 AM

Thanks for the replies.

sahrens · #6 09-26-2014, 08:17 AM

I would add there are locations were you need to match drill two or more parts and then drill to a much larger size. For example, the pre-punched hole is 3/32 but ultimately the fastener is a AN509 or larger.

Match drill the parts to establish the proper alignment and fit. Then drill to final size.