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Inspection plates
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pacificpainting(at)comcas
Guest

Posted: Sat Sep 30, 2006 6:43 pm Post subject: Inspection plates

I am trying to make some round inspection hole  covers with no hole in the center. I have had some success using large hole saws  on a drill press. Just clamp everything down tight and put the drill press on  slow speed and use cutting oil. It kind of works but will start to grab easily.  It leaves a very rough edge. Then I smooth it down with a Scotchbrite wheel.  There must be a better way. These are 4 to 5 inch holes and the saws are really  expensive. I really don't want to cut them with tin snips.

  

 Dave in Salem

 801

   [quote][b]

craig(at)craigandjean.com
Guest

Posted: Sat Sep 30, 2006 8:11 pm Post subject: Inspection plates

Won't a fly cutter also work with its center drill bit  removed if you use a press and everything is tightly clamped? By fly cutter I  mean the tool with a center drill bit of about 1/4" and a cutting tool on the  end of an adjustable arm. Harbor Freight sells one with two bits that might be  more stabile in this configuration.

  

 -- Craig

  



 [img]cid:421205603(at)01102006-1783[/img]  From: owner-zenith-list-server(at)matronics.com  [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of Dave  Ruddiman

Sent: Saturday, September 30, 2006 8:44 PM

To:  zenith-list(at)matronics.com

Subject: Inspection  plates

 

 I am trying to make some round inspection hole  covers with no hole in the center. I have had some success using large hole saws  on a drill press. Just clamp everything down tight and put the drill press on  slow speed and use cutting oil. It kind of works but will start to grab easily.  It leaves a very rough edge. Then I smooth it down with a Scotchbrite wheel.  There must be a better way. These are 4 to 5 inch holes and the saws are really  expensive. I really don't want to cut them with tin snips.

  

 Dave in Salem

 801

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pacificpainting(at)comcas
Guest

Posted: Sat Sep 30, 2006 8:21 pm Post subject: Inspection plates

Craig,

  

 I am just about to try that. I think if I put it in  the drill press and turn it by hand, it might work. I can get the speed down to  200 RPM's, but I think that may be to fast. Anyway, here goes.

  

 Thanks for the suggestion,

  

 Dave

  

  

  

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craig(at)craigandjean.com
Guest

Posted: Sat Sep 30, 2006 8:32 pm Post subject: Inspection plates

The edges will be beveled. May not be a problem in such  thin material. Otherwise flip the cutting tool around.

  

 -- Craig



   From: owner-zenith-list-server(at)matronics.com  [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of Dave  Ruddiman

Sent: Saturday, September 30, 2006 10:21 PM

To:  zenith-list(at)matronics.com

Subject: Re: Inspection  plates

 

 Craig,

  

 I am just about to try that. I think if I put it in  the drill press and turn it by hand, it might work. I can get the speed down to  200 RPM's, but I think that may be to fast. Anyway, here goes.

  

 Thanks for the suggestion,

  

 Dave

  

  

  

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pacificpainting(at)comcas
Guest

Posted: Sat Sep 30, 2006 8:34 pm Post subject: Inspection plates

So, I'm guilty of trying to do things the hard way  first. Just cut one out with the fly cutter on the drill press turning it by  hand. It works really good and doesn't really take any longer than using a hole  saw. Still have to smooth them out either way. By the way my Scotch Brite wheel  is GREY colored.

  

 Dave

  

  

  

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p.mulwitz(at)worldnet.att
Guest

Posted: Sat Sep 30, 2006 8:51 pm Post subject: Inspection plates

Hi Dave,



 My inspection plates are all "Oval" - actually a combination of half circles and a straight line between the tangents.   These are very easy to form with layout and snips.  They are also easy to mount inside the skin by attaching a temporary handle with double stick tape (rolled up 200 mph tape).



 Perhaps the circle was not the best choice.



 Paul

 XL fuselage

 do not archive



 

 At 07:43 PM 9/30/2006, you wrote:

  	  Quote: 	
		  I am trying to make some round inspection hole covers with no hole in the center. I have had some success using large hole saws on a drill press. Just clamp everything down tight and put the drill press on slow speed and use cutting oil. It kind of works but will start to grab easily. It leaves a very rough edge. Then I smooth it down with a Scotchbrite wheel. There must be a better way. These are 4 to 5 inch holes and the saws are really expensive. I really don't want to cut them with tin snips.

  

 Dave in Salem

 801

 	
 

 ---------------------------------------------

 Paul Mulwitz

 32013 NE Dial Road

 Camas, WA 98607

 ---------------------------------------------

     [quote][b]

pacificpainting(at)comcas
Guest

Posted: Sat Sep 30, 2006 9:10 pm Post subject: Inspection plates

Paul,

  

 I'm just trying things out. Oval sounds like a good  idea also. What do you mean about attaching inside the skins. Are you attaching  them permanently with rivets or using nut plates or what? Just  curious.

  

 Dave

  

  

 [quote]   ---

jhstarn(at)verizon.net
Guest

Posted: Sat Sep 30, 2006 11:00 pm Post subject: Inspection plates

With the HRII looking at 230 kts or so we went the "doubler" route on all  the inspection plates. Cut the hole, make a doubler ring/donut out of scrap .040  that was 1" wider than the hole. 1/2" inside & riveted to the skin. 1/2"  exposed within the hole with nutplates on the backside of the ring. Ring is 1"  wide. Depending in the size of the inspection hole we spaced nutsplates in the  four corners (most were rectangular with rounded "corners") and along the  edges. With the inspection plates made of the same material as the skin we have  a flush, strong installation. We were using flush rivets, nut plates so we  did have to drill & dimple to get the flush finish. 

 Figured with all the extra weight we lost approx .00031 kts.   8*)

 Do Not Archive.  KABONG

 [quote] [b]

jean-paul.roy4(at)tlb.sym
Guest

Posted: Sun Oct 01, 2006 3:11 am Post subject: Inspection plates

Just had an idea but i wonder if that would  work.

 Cut 2 templates out of plywood of the dimension of  the inspection plates.

  

 Sandwich the amount of plates to be made between  the templates. Use a router with a cutter with a bearing to cut around the  templates. Would make perfect cuts.

  

 Just an idea

  

 Jean-Paul

 [quote]   ---

p.mulwitz(at)worldnet.att
Guest

Posted: Sun Oct 01, 2006 3:26 am Post subject: Inspection plates

Hi Dave,



 I wish I could take credit for the design, but Chris Heintz deserves all the credit.



 The inspection plates are attached with nut plates installed on the inner side of the inspection plate with countersunk solid rivets.  I decided to use the soft aluminum rivets and set them with a one ton arbor press I already had in my shop for other purposes.  The oval shape allows you to put the finished plate through the hole in the skin and then attach it to the skin with pan head machine screws.  If you need the actual AN numbers for the screws and nut plates, just let me know and I can get them from the shop.



 The procedure I use:



 1.  Decide on the inspection plate size (or take it from the drawings).



 2.  Lay out the outline on the sheet metal, and cut out the plate with snips.  File the edges smooth.



 3.  Lay out the position of the screws -  Typically 3 at each arc and one or two on the flat sides of the plate.  A 10 mm edge distance is fine.  Drill #40 pilot holes for the screws.



 4.  Position the plate on the skin.  Attach with duct tape (I prefer 200 mph tape since it has more easily removable adhesive).  Match drill the holes in the skin for the screws.  Mark the plate to show which side is up and which end points forward.



 5.  Remove the plate from the skin.  Lay out the mounting holes for the nut plates and drill pilot holes for them.  Countersink the nut plate mounting holes and enlarge the screw holes.



 6.  Mount the nut plates.  This ends the construction of the inspection plate.



 7.  Lay out the hole in the skin - 10 mm inside the screw holes.  Cut the hole using snips, files, and a step drill to start the snips.



 8.  Enlarge the screw holes in the skin.



 At this point, the construction is done.  The inspection plate is inserted in the hole and attached with screws through the skin.  This is where the trick with double stick tape and temporary handle is used to hold the inspection plate in place while starting the screws in the nut plates.



 After you have done this once or twice you should be able to do the whole thing from start to finish in about an hour.



 Have fun,



 Paul



 

 At 10:10 PM 9/30/2006, you wrote:

  	  Quote: 	
		  Paul,

  

 I'm just trying things out. Oval sounds like a good idea also. What do you mean about attaching inside the skins. Are you attaching them permanently with rivets or using nut plates or what? Just curious.

  

 Dave

  	
 

 --    [quote][b]

dredmoody(at)cox.net
Guest

Posted: Sun Oct 01, 2006 3:44 am Post subject: Inspection plates

Try using a fly cutter on the drill press. The fly  cutter usually has the pilot drill secured with a hex socket screw and can be  removed just like your hole saws. 

  

 When the cutter first penetrates the aluminum in  one part of the circle, it is usually an indication that it is time to finish  "tearing" the circle out by hand. It's a lot like the way the OLFA knife  works. Try it but make sure the work table of the drill press is as  perpendicular to the drill axis as possible. You can check that with the fly  cutter in the chuck.

  

 Second choice is to use the hole saw to cut through  a hard wood board (no lectures on hardwood terminology please.. I don't care).  Use one hard wood board under the piece of aluminum and the one with the hole on  top. With the whole mess clamped together you may have more control and a  smoother edge. 

  

 Third option.... (perhaps the best) cut the hole  size you want in a piece of heavy stock..... .035" or thicker. Use that as a  cutting guide and cut your round plates out with an OLFA knife.... very smooth  edges with minimal sanding.

  

 Ed Moody II

 [quote]   ---

dredmoody(at)cox.net
Guest

Posted: Sun Oct 01, 2006 3:46 am Post subject: Inspection plates

If you flip the cutter around I think you'll need  to turn the tool backwards.

  

 Ed Moody II

 [quote]   ---

dredmoody(at)cox.net
Guest

Posted: Sun Oct 01, 2006 3:48 am Post subject: Inspection plates

Install nutplates on the backside of the hatch  cover itself. Use flush rivets for that. Drill the screw holes first then instal  the nutplates.

  

 Ed Moody II

 [quote]   ---

rstone4(at)hot.rr.com
Guest

Posted: Sun Oct 01, 2006 4:17 am Post subject: Inspection plates

Craig,

      Yes, you can remove  the bit and clamp it down good, then cut a circle in wood or metal.  Just  go slow, that is minimum pressure on the work and put the drill press on the  slowest speed.  I do it all the time when I want a circle without a center  hole.

  

 Bob Stone, Harker Heights, Tx

 ZodiacXL

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n801bh(at)netzero.com
Guest

Posted: Sun Oct 01, 2006 4:53 am Post subject: Inspection plates

You are going about it the correct way. The trick to not get it to grab is the run the drill press in reverse. if you use a brand new hole saw the teeth are nice and sharp and will cut through the aluminum while  spinning in reverse. Worked great for me.. YMMV... 

do not archive

Ben Haas

N801BH

www.haaspowerair.com



-- "Dave Ruddiman" <pacificpainting(at)comcast.net> wrote:

  I am trying to make some round inspection hole covers with no hole in the center. I have had some success using large hole saws on a drill press. Just clamp everything down tight and put the drill press on slow speed and use cutting oil. It kind of works but will start to grab easily. It leaves a very rough edge. Then I smooth it down with a Scotchbrite wheel. There must be a better way. These are 4 to 5 inch holes and the saws are really expensive. I really don't want to cut them with tin snips.

  

 Dave in Salem

 801

[quote]



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[b]

leinad

Joined: 19 Sep 2006
Posts: 283
Location: Central Virginia

Posted: Sun Oct 01, 2006 6:20 am Post subject: Re: Inspection plates

Draw a circle on a scrap sheet and cut it out with snips.  A little filing and know one will know you did it by hand.



Dan Dempsey

_________________
Scratch building XL with Corvair Engine

craig(at)craigandjean.com
Guest

Posted: Sun Oct 01, 2006 8:13 am Post subject: Inspection plates

Good point. My press doesn't reverse so would only work if  turned by hand.

  

 -- Craig



   From: owner-zenith-list-server(at)matronics.com  [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of Edward Moody  II

Sent: Sunday, October 01, 2006 5:46 AM

To:  zenith-list(at)matronics.com

Subject: Re: Inspection  plates

 

 If you flip the cutter around I think you'll need  to turn the tool backwards.

  

 Ed Moody II

 [quote]   ---

dredmoody(at)cox.net
Guest

Posted: Sun Oct 01, 2006 8:21 am Post subject: Inspection plates

Shame on you and a pox on your progeny for taking the simple approach. We're 

amatuer aeronautical engineers, by God!



Ed Moody II



---

craig(at)craigandjean.com
Guest

Posted: Sun Oct 01, 2006 8:29 am Post subject: Inspection plates

We could discuss (ad nauseam) whether you should cut clockwise or

counter-clockwise.



-- Craig 



--

dredmoody(at)cox.net
Guest

Posted: Sun Oct 01, 2006 8:45 am Post subject: Inspection plates

Somebody got nauseated already? Wimp!



Ed



---

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