[NorthernRV4]

I'm pleased to report I'm making progress again, albeit sloooow. After much playing around trying to position the elevator centre hinge brackets so they were perfectly inline and wouldn't move when I clamped them down I finally drilled the first hole. Wouldn't you know that the clamp let the assembly slip about 1/16 to the left but only after the drill bit started to cut. So now I have a thru hole and a problem. That wasn't a good morning but I'm sure I can save it. This hole gets drilled out to accept a 3/16" bolt so if I'm REALLY careful I should be able to drill away all my worries. Just wondering if there is a drill bit I'm not aware of that would be less likely to follow the pilot hole. I think if I split the difference and feed extremely slowly with 135deg split point bit it should be ok. I've considered making a drill jig block that clamps in place to keep the bit from "wandering" but I'd love some suggestions. I plan on clamping the whole assembly in my drill press to keep things from moving.


More HS spar by jim_soutar, on Flickr

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Untitled by jim_soutar, on Flickr


Untitled by jim_soutar, on Flickr

 

[newrv-4]

Endmill?

How about block to guide the drill but use a 2 flute endmill instead of a drill bit. An endmill will not have a tendency walk, but it will be impossible to use without a guide. It may be overkill, but I have endmills on hand, so that is what i would try.

 

[Mel]

If you have a hole that will be drilled larger and needs to be moved slightly, first move the hole with a rattail file.

If the hole is in a part that contains other holes, match drill the other holes first.

 

[WAM120RV]

No problem

Jim,

This can be sorted out really easily. This is how I would go about it.

First drill out the offending hole on the bracket slightly undersize. Then clamp the tow brackets together with the correct bearing and spacers called out on the plans. Cleco the bearing assembly and brakets to the spar through the good holes. You will then see how the slightly undersize hole matches up with your troublesome hole.

The choice then is either to just use the bracket as a guide for your undersize drill through the spar, or to gently use the rat tail as Mel suggests with the bracket as a guide first, then drill through initially undersize when the mis aligned hole is more round and less likely to drag your drill off in a direction you dont want it to go.

Remember, the key to drilling is right angles in all axis to the workpiece. I had a small block I could place next to the drill shank to ensure I was at 90 degrees, before I learned to do it by eye. Secondly, light pressure on the drill let the drill do the work, do not try to push it through.

Sorry if I am teaching you what you already know.

 

[NorthernRV4]

Thanks fellas. The idea of using and end mill occurred to me but wasn't sure how to guild it. I could certainly use a rat tail file or rotary tool to slowly get the hole round and a bit undersized then drill to final size through both the hinge bracket and the offending hole. Trouble is once I Cleco the completed centre hinge assembly in place it hides the hole I need to drill (shown in red). I think I will try that method though. Oh, lesson learned here is to NEVER trust a quick grip bar clamp to hold a part for drilling, c- clamps from now on!

 

[NorthernRV4]

There was one other issue I found after marking and drilling all the holes in HS-409 bars. I misinterpreted the drawings when laying out the holes and positioned a hole at station 19-7/16" from centre. At the time I knew a rivet here would interfere with the HS-412 hinge bracket but at the time thought, well a rivet has to go there so I guess I could countersink the head so it wouldn't interfere. Now looking at the plans (#3a) again I think they are trying to simply indicate the position of the hinge bracket and I goofed. Now onto the question. I centre punched the hole position but did not drill it so do I simply leave a centre punch mark or follow through with my original plan? Does it create a place for a crack to start if a CP doesn't get drilled through? My guess is no but it's fairly easy at this point to follow through with plan A.

I have a similar situation with a few holes I marked and centre punched on HS-410 that I've made but doesn't match the holes drilled in the forward spar by the previous builder. Again, if you don't follow through and drill them out does the CP weaken the part?