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  #1  
Old 06-27-2020, 08:45 AM
RV701775 RV701775 is offline
 
Join Date: Jul 2019
Location: Boston, MA
Posts: 51
Default VS-Rear Spar Hing Bracket Attach Holes

When drilling the VS-410 hinge brackets to the rear spar and doubler, the holes came out slightly oblong despite having everything clamped tightly and the drill held parallel. Some of the oblong holes are around, 0.139 diameter in one direction which is slightly above mil-spec. A #29 drill bit (0.136) will not fit thought the hole though, but these will get larger after dimpling. Am I still able to use this spar in the current condition?

https://photos.app.goo.gl/CSLo4oJVFao19AWE6

Last edited by RV701775 : 06-27-2020 at 08:56 AM.
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  #2  
Old 06-27-2020, 02:18 PM
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PaulvS PaulvS is offline
 
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Location: Western Australia
Posts: 244
Default Ok

I think they look OK.
Generally, I try to use a drill press whenever possible, it takes a little more time, but the results seem to be more consistent.
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  #3  
Old 06-27-2020, 03:13 PM
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wirejock wirejock is offline
 
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Location: Estes Park, CO
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Default Oblong holes

I would continue and would suspect Vans would say Build on but they are the definitive resource.
Consider using a reamer.
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  #4  
Old 06-27-2020, 04:39 PM
RV701775 RV701775 is offline
 
Join Date: Jul 2019
Location: Boston, MA
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Default

I am not sure what the issues is. This is my third rear spar. Here is my process:

1) Cleco together every other hole. I cleco all holes on the hinge brackets.
2) Drill all holes top down. I clamp the spar down to the bench, but it does sit on the ends of the clecos.

A few things I guess I could be doing incorrectly,

1) Do I need to sit the holes on wood blocks between the cleco and back the thin spar skin with a wood block instead of sitting it on the ends of the clecos?
2) I am drilling through the heavy steel brackets first then into the doubler and spar. Should I do this in reverse?
3) Do I need to round the edges of the doubler prior to drilling? It seems to sit flat in the spar and this is not called out in the instructions.
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  #5  
Old 06-27-2020, 05:49 PM
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wirejock wirejock is offline
 
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Location: Estes Park, CO
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Default Spar

Quote:
Originally Posted by RV701775 View Post
I am not sure what the issues is. This is my third rear spar. Here is my process:

1) Cleco together every other hole. I cleco all holes on the hinge brackets.
2) Drill all holes top down. I clamp the spar down to the bench, but it does sit on the ends of the clecos.

A few things I guess I could be doing incorrectly,

1) Do I need to sit the holes on wood blocks between the cleco and back the thin spar skin with a wood block instead of sitting it on the ends of the clecos?
2) I am drilling through the heavy steel brackets first then into the doubler and spar. Should I do this in reverse?
3) Do I need to round the edges of the doubler prior to drilling? It seems to sit flat in the spar and this is not called out in the instructions.
1. Ideally. It's possible the parts are separating a little allowing the bit to wander.
2. The steel should keep the bit centered unless it's been enlarged. Sounds right.
3. Ideally it should be flat against the spar before drilling. I thought it said something about it on the plans or manual.

Couple if things.
1. Are the drill bits sharp? A dull bit will wander.
2. Use a drill bushing. It holds a smaller bit centered in the hole then the hole is enlarged. Several pieces of brass tubing inside each other works great. There's a link to the tip on my blog.
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Larry Larson
Estes Park, CO
http://wirejockrv7a.blogspot.com
wirejock at yahoo dot com
Donated 12/03/2019, plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #6  
Old 06-27-2020, 06:40 PM
Taltruda Taltruda is offline
 
Join Date: Oct 2017
Location: Las Vegas, NV
Posts: 295
Default

Donít sharpen your drill itís, throw them out and buy new. A sharpened drill bit may wonder if the point isnít split perfectly. Also try starting the hole with the right size of the steel hinge just to get the center, then switch to a smaller drill to make the hole. Then upsize to the final size and see if that makes a better hole.
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  #7  
Old 06-27-2020, 07:10 PM
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PaulvS PaulvS is offline
 
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Location: Western Australia
Posts: 244
Default Drill chuck concentric?

Another thing to check is the drill chuck for concentricity. Sometimes the drill motor and chuck is not manufactured to hold the drill bit perfectly centred and the drill bit can wobble, which makes it difficult to drill a good hole. The easy way to check is to put a small bit in the chuck and look at it side on with the motor running. I've had several with too much runout for fine work.

If you're onto your third spar I think it would be worth having a second set of eyes visit your shop, there must be other RV builders or an EAA chapter in Boston. VAF is great for help, and you can also pick up a lot directly from other builders.
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  #8  
Old 06-29-2020, 06:03 AM
CoolDadTed CoolDadTed is offline
 
Join Date: Apr 2019
Location: Littleton, MA
Posts: 14
Default

Quote:
Originally Posted by RV701775 View Post
I am not sure what the issues is. This is my third rear spar. Here is my process:

1) Cleco together every other hole. I cleco all holes on the hinge brackets.
2) Drill all holes top down. I clamp the spar down to the bench, but it does sit on the ends of the clecos.
When I took the EAA sheet metal class, I learned to drill these straight into the work table (I use MDF fiberboard as a sacrificial, replaceable cover over my table).

Doing this allows you to put the clecos into the table which holds everything firmly and squarely to the surface. I've had good results using this method on spar doublers and skin stiffeners.

-Ted
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