The International Cessna 170 Association

What are the better techniques (short of using a slip roller) to form the curves in fuselage skins?

Tail cone skins?? If you don't have access to a slip roll, source anything you can that is the right diameter (2024-T3 has a lot of "spring back", so the diameter of whatever you use will be significantly smaller than the radius you need for the skin). Use some practice pieces

Tail cone skins, yes.

Thanks. I have a 4" diameter post but it might have been too small and/or I might have been a little too aggressive with it as it started to crease the skin.
I'm doing the last four top skins so (Hail damage) so maybe I should make friends with someone with a slip roller before I end up buying twice as much material.

T3 has so much spring back, when you begin to wrap it around something, it'll pucker out right about the middle of the radius you are trying to achieve, leaving you a less than symmetrical radius; a bit lumpy.
It helps a lot if you can "bed" it down on a table; lay a piece of dense foam on the table. Lay your sheet on top the foam. Then lay your "roll form" tool/pipe/post on top the sheet. The tool should be longer than the sheet, so you can drill it and the table. Bolt the tool/pipe/post down to the table TIGHT, sandwiching the sheet and foam so the sheet nest down tightly into the foam. This alone already starts the forming process. Then simply continue to roll form by hand, working each side of the sheet protruding from each side of the tool.

Thanks! Thats a great idea and I have a bunch of 6" thick dense foam to use.
The 4" post I was using is currently holding up the second floor of my house so I might want to find something else.

If you don't think that will turn out most guys that make custom HVAC ducts have a slip roll. Might be worth a hours pay. make a template of each end.

Tim

If you can't find a piece of round steel stock the right diameter, you can use PVC pipe but you need a rigid piece of steel tube (round or square) to route thru the PVC. Schedule 40, even 80, will flex too much without support

Do you think 4" is the right diameter?

Aryana wrote:Del giving away his secrets! Something tells me even if he wrote a step by step "Sheet Metal for Dummies" I'd still never get it right

If it's not clear, I am a terrible sheet metal fabricator. It takes me ten times as long to get half as nice of a result

I'm much better with fabric and dope.

You're not too shabby with balsa and fiberglass, either.

Speaking of which, when do we get to see that beauty fly Aryana??

Aryana wrote:Del giving away his secrets! Something tells me even if he wrote a step by step "Sheet Metal for Dummies" I'd still never get it right

If it's not clear, I am a terrible sheet metal fabricator. It takes me ten times as long to get half as nice of a result

I'm much better with fabric and dope.

You can get tips and tricks like this off the internet, but sheet metal is something you learn by making scrap until you get it right.

Aryana wrote:All my projects have been dying on the vine for a bit while we get the hang of this parenting thing Karl. Even the big 170 has sat dormant.

I was hoping to see that little girl solo the little 170 before she outgrows it. but where do you find a quarter scale CFI??

cheers,
Pete