Tip: Transfer Punches - Page 2

rv9builder · #11 10-23-2006, 06:24 PM

Rick and Gil, thanks for the info.

Wouldn't a #40 transfer punch be slightly undersized, since a #40 hole will expand after dimpling? I'm assuming a #40 transfer punch is the same diameter as a #40 drill bit.

az_gila · #12 10-23-2006, 06:28 PM

Quote:

Originally Posted by rv9builder

Rick and Gil, thanks for the info.

Wouldn't a #40 transfer punch be slightly undersized, since a #40 hole will expand after dimpling? I'm assuming a #40 transfer punch is the same diameter as a #40 drill bit.

Yes... but they are available from a machinists shop in the number drill sizes.

Use your drill index to see which size is best for your dimples...

gil in Tucson

Rick6a · #13 10-24-2006, 06:02 AM

Quote:

Originally Posted by rv9builder

Rick and Gil, thanks for the info.

Wouldn't a #40 transfer punch be slightly undersized, since a #40 hole will expand after dimpling? I'm assuming a #40 transfer punch is the same diameter as a #40 drill bit.

Yes, that is why I mentioned it may move about the hole a bit but will settle on the center of the dimple well enough. As Gil mentioned, transfer punches "per se" are available in any number of sizes and shapes. The intent of my discussion was to describe the practical use of the small type illustrated at the start of this tread as an alternative to using a duplicator strap. In most situations, the use of standard nominal size transfer punches (like I illustrated) such as 3/32",1/8", 3/16" and even 1/4" transfer punches will normally suffice. In practice, I've never used any sizes or shapes other than those mentioned.

LettersFromFlyoverCountry · #14 10-24-2006, 08:27 AM

I've run into a couple of cases in the last week where I THINK one of these tools would help me, perhaps you can confirm.

First case. I had to make a new elevator stop, but I'd already drilled the first one to the aft deck. No way can you get down underneath that aft deck to use the existing holes as a drill guide, so wouldn't this tool have helped me make the appropriate hole from the elevator stop down?

Second case. Similar deal. I need to make new rudder stops. The first version was already drilled to the fuse (I don't know why I did that, but I did it early in the fuselage process, I must've just got carried away by the plans). Now I need to drill the new stop to the old holes. but I can't use the fuselage skin interior as a drill guide.

Is this tool the answer?

I'll hang up and listen.

Rick6a · #15 10-24-2006, 09:08 AM

Quote:

Originally Posted by Bob Collins

I've run into a couple of cases in the last week where I THINK one of these tools would help me, perhaps you can confirm.....Is this tool the answer?

Absolutely Bob.

Both cases are prime candidates where transfer punches can save the day. For example, in the case of making up a new rudder stop, let us assume for the sake of illustration, you can only afford to buy 1 transfer punch making sure it is the same diameter size as the holes in the fuselage are.

#1. Insert transfer punch into any one of the holes in the fuselage rudder stop pattern.
#2. Place the new rudder stop part generally into place, locating it as best you can, then tap it gently to assure a mark is left.
#3. Remove rudder stop, drill hole up full size using the mark the transfer punch left as your reference.
#4. Relocate transfer punch to the next hole location, then cleco the rudder stop back into place using the hole you just drilled into it. Tap again to generate mark at the next hole location.
#5. Repeat process until all the holes are drilled.

You described all too common situations when back drilling is not possible, the use of transfer punches is the next best way to proceed.

Good luck.

AlexPeterson · #16 10-24-2006, 05:21 PM

A couple thoughts -

Transfer punches are a great tool, I've been using them all my adult life. However, the typical punches have one issue which is pertinent to aircraft building - the point is too long to allow the tool to be used to transfer holes from a thin sheet to something else. This is because the cylindrical portion of the punch has not yet engaged the existing hole when the tip contacts the target surface. I suspect that short tip ones are available (for those of us without a metal lathe).

What I have done in cases like that is to tape some sort of shim between the surfaces, just next to the hole (a washer works well around the hole), to give the extra "thickness" needed.

Regarding simply drilling through the existing holes in a sheet - use caution if you want the holes to align and be the same size. The same problem exists for drills that exists for the transfer punches as described above, i.e., the cylindrical portion has not yet engaged the cylindrical part of the hole.

az_gila · #17 10-24-2006, 05:52 PM

Quote:

Originally Posted by AlexPeterson

A couple thoughts -

Regarding simply drilling through the existing holes in a sheet - use caution if you want the holes to align and be the same size. The same problem exists for drills that exists for the transfer punches as described above, i.e., the cylindrical portion has not yet engaged the cylindrical part of the hole.

But if it's a dimpled sheet, just lay the old sheet on top of the new one with the dimples facing up....

Also the good quality transfer punches have a very small "pointy bit" ... the cheaper ones are just machined to a cone. Check out the picture in my earlier post. My #40 punch has an end as pictured. I believe it will sit inside a 0.025 sheet hole and contact the sides.

gil in Tucson - guess how I found this out....

AlexPeterson · #18 10-24-2006, 08:07 PM

Quote:

Originally Posted by az_gila

gil in Tucson - guess how I found this out....

Ok, let me guess, you looked at the sign on the road into town?

The idea of laying the dimpled sheet on top is great! I figured that somewhere out there one could find transfer punches with a shorter point. Thanks.

az_gila · #19 10-24-2006, 10:19 PM

Quote:

Originally Posted by AlexPeterson

Ok, let me guess, you looked at the sign on the road into town?

Not quite....

It had a lot more to do with over-trimming the aft plexi on the tip up. The curve didn't match, so I have a slightly custom shape to my aft canopy with the replacement sheet....

No pre-punched stuff in my kit,all the holes in the replacement sheet were transfer punched.....

gil in Tucson....handling the RV-6 plexiglas canopy was the hardest task so far...

Rick6a · #20 10-27-2006, 08:02 AM

Quote:

Originally Posted by AlexPeterson

Transfer punches are a great tool, I've been using them all my adult life. However, the typical punches have one issue which is pertinent to aircraft building - the point is too long to allow the tool to be used to transfer holes from a thin sheet to something else. This is because the cylindrical portion of the punch has not yet engaged the existing hole when the tip contacts the target surface........

Alex,

I must confess to being initially confused by your comments. I do not doubt what your experience has been. I too have used transfer punches all my adult life and never encountered situations like you describe. The various tasks, (not counting the extensive workout they got while building my RV) include replacing a leading edge cuff on a friend's C-170 to replacing wing skins on a tired old C-182. Upon reflection, I now think we are comparing apples and oranges here. You must be describing a different type of transfer punch. The thread did go off into an unanticipated tangent with descriptions of a wholly unsuitable alternative tool for what sheet metal tasks I meant to address, and likely source of my initial confusion. The "typical" transfer punches I use have always worked perfectly, at least the specific tool type illustrated below and as originally described as the basis for my comments.