Cutting instrument panel holes

ColinC · Post by **ColinC** » Tue Apr 21, 2009 10:59 pm

Having recently risked my digits cutting panel holes with a fly-cutter I wish I'd seen this video earlier: http://www.eaa.org/video/homebuilders.h ... 9541820001 The method proposed would have worked well for me (assuming I could have found the approriate size holesaw).

Rod1 · Post by **Rod1** » Wed Apr 22, 2009 10:02 am

I have a collection of the standard ones if you need to borrow them.

Rod1

ColinC · Post by **ColinC** » Fri Apr 24, 2009 2:52 pm

thanks Rod, have done with the Tcraft one for now but it will come up again later I expect and I'll take you up on that.

regards

Rob Swain · Post by **Rob Swain** » Wed Apr 29, 2009 11:16 am

This is a topical thread for me as I'm about to make a couple of bits of aluminium panel.

For standard 2 1/4" and 3 1/8" instrument cutouts Avery supply a die that punches them out. As I understand it drill a 5/8" hole in the centre of where you want your instrument hole, assemble the punch on both sides and graunch up the bolt until the hole is punched out to perfect size.

The downsides:
You have to make the extra cutout for Altimeter and DI knobs yourself.
It costs around £150. Ouch!

Gloster Airparts are the UK agent for Avery and their website says they offer a hire service for some tools, including this one.

However, seeing as I am a cheapskate : has anyone bought one that I can borrow?

ColinC · Post by **ColinC** » Wed Apr 29, 2009 10:33 pm

Rob,

as an alternative to home fabrication, have you got sufficiently organised with your layout that you could draw in in a cad package, create a dxf file of the panel and have it cnc cut? This can be relatively cheap if you find a friendly company willing to slip a job in. Abrasive water-jet cutting is ideal for many aircraft applications.

The idea of having everything down to the mounting holes pre-prepared must be quite attractive surely?

I have prepared cnc files for a number of projects now and its incredible how much time and material can be saved, particularly with fittings, a panel is an easy project in comparison.

regards

Rod1 · Post by **Rod1** » Thu Apr 30, 2009 11:41 am

I used standard hole cutters and an electric drill! Provided you take your time, mark and centre punch accurately and do not try to “force” it you get very good results. Hole cutters are not too expensive, and you have them when you decide on the inevitable upgrade…

Rod1

Dave Johnson · Post by **Dave Johnson** » Thu Apr 30, 2009 1:53 pm

The punch works a dream - beautifully clean holes and I still have the standard complement of fingers.

If you are around this way, you are welcome to borrow mine.

I'm near Faringdon, Oxfordshire (SN7 8HE)

Dave Johnson

mike newall · Post by **mike newall** » Thu Apr 30, 2009 10:18 pm

If you have a panel to lay out and cut, look at this

http://www.experimentalair.com/store/in ... roductId=6

We used them for our RV7 panel - drag and drop assembly, check layout, pay, they send a cnc file across and as above, get it water jet cut, it even does the little nibby thing on the ignition switch !

AlanR · Post by **AlanR** » Fri May 01, 2009 7:49 am

Wimps!

I cut 12 instrument holes with a flycutter...easy, and all came out perfectly. Just take your time, measure and re-measure and centre-dot carefully. Cut half way through and then turn the panel over, no problems at all.

Alan.

Rob Swain · Post by **Rob Swain** » Fri May 01, 2009 10:24 am

If I had a CNC mill then I'd definitely use it as then I could still say I'd made the panel. Can't shake the feeling that getting somebody else to do it it just cheating.

For the job currently in hand it would probably be overkill as well as I'm only replacing a part of the panel at the moment. The engine instruments are tired (becoming erratic) and I've managed to accumulate a full set of new matching Van's ones, rather than the old tatty mixture currently in it.
As part of this I'm starting the process of making the panel modular as it's a single panel at the moment and access is just awful (sliding canopy). It was probably assembled before the coaming was fitted at build time.

AlanR: where did you get a decent fly cutter? All the ones I've found for sale in the UK would be dead in no time on T3 or T6, being primarily for wood and (normal) aluminium at a pinch.

Dave Johnson: Will PM you to arrange to get the punch.

AlanR · Post by **AlanR** » Sat May 02, 2009 10:10 am

Rob,

Flycutter was bought from Aircraft Spruce. It came with a spare cutter blade which I have yet to use.
As I said, straightforward operation, no probs ,don't see what the fuss is all about in using one.

Alan Radford

Rob Swain · Post by **Rob Swain** » Mon Jun 08, 2009 12:03 pm

I've become a convert to the holesaws (in a pillar drill, on a very slow speed).
Engine instrument panel came out beautifully with its 2 x 3 bank of 2.25" gauges. Holesaw (57mm, I think) came from Screwfix (Erbauer).

I've just ordered a 79mm holesaw for the 3.125" instruments that are next on the agenda. Screwfix don't do one that size so I've ordered a Starret one from somewhere on the web.

OK you have to be careful to get the mounting screws in exactly the right place, but it's not that difficult. Making the screw holes a size larger might make life easier, but where's the fun in that?

ColinC · Post by **ColinC** » Wed Jun 10, 2009 1:22 pm

Rob,

Aircraft Spruce (via LAS) sell a template for setting out the mounting holes that works very well. I'm sure someone here will lend you one if you ask around.

Colin

Rob Swain · Post by **Rob Swain** » Thu Jul 09, 2009 12:11 pm

I can confirm that the 79mm (3 1/8") holesaw does just as good a job as the 57mm (2 1/4") one, with a couple of provisos.

The holesaw I got ended up as a looseish fit on the arbour. Trying to use it like that and just plonking the plate to be drilled on the drill bed ended up with chatter, wander, and a pretty ghastly looking hole.
I've put a .032" shim between the cutter and its arbour, with a couple of bits of tape as well to pad it out. This has firmed things up and together with firmly clamping the piece to the drill table had cured any chatter problem.

I've become a convert to cone drills as well for cutting sizable holes in thin sheet. My VOR indicator needs a semicircle cutout in the hole for the adjuster. Just drilled this with the cone drill before doing the main hole cutting. Quick dress with a file where the 2 holes merge and it fits beautifully. The largest cone drill in the set has made a lovely job of the 1" cutout for the vacuum gauge as well!

As regards the instrument mounting screw holes, careful use of geometry, compasses and a rule has worked pretty well perfectly.

Who'd have thought that drilling holes could result in such debate, or job satisfaction, come to that.
Or do I need to get out more!

cardiffrob · Post by **cardiffrob** » Thu Jul 09, 2009 4:10 pm

I cut holes oversize in the ply sheet and then layered on a sheet of ally before tin-bashing the edges over to make a stiff laminate. Any imperfections were taken up when the instrument was shoved in. The crinkle finish was done from a spray can of Crackle-Black paint.

This panel is obviously towards the bottomend of the market!