Nose cones help

**CardboardCat** · #1 12-27-2012, 02:54 AM

I'm working on a rocket and having trouble with the nose cones. After cutting out the parts I find that the cones are always too small to fit properly on the cylinder part. It seems as they are always too small to cover the cylinder completely and the result looks sloppy. I don't know how else to describe this and I don't have a digital camera to use to post a picture. If you can visualize what I am referring to I would appreciate any advice.

**Tim Crowe** · #2 12-27-2012, 03:36 AM

Might be worth trying to form the part on thinner paper

If you use the original as a template, and make several copies and use them to practice on and pick the best one to use.

Tim

**Retired_for_now** · #3 12-27-2012, 05:20 AM

Quote:

Originally Posted by CardboardCat

I'm working on a rocket and having trouble with the nose cones. After cutting out the parts I find that the cones are always too small to fit properly on the cylinder part. It seems as they are always too small to cover the cylinder completely and the result looks sloppy.

The answer depends on just how far off the fit is and how the join is made. If the gaps are large the parts of the cone are probably off. Try the cone-o-matic from Jon at http://jleslie48.com/faq.html to draw the parts. If it's not your design you'll need to make some modifications (or try printing the parts page with the conics at a 101% enlargement if the parts are actually incorrectly sized).

If the conic fits over tabs that are part of the lower cylinder (or conic) you can cut off the tabs and replace them with a tabbed joiner strip. I often draw parts with tabs because it's quicker and reduces the parts count, but the tradeoff is in the fit (see Falcon9 in our downloads for tabbed parts - Currell's SpaceShipOne for internal joiner strips for conics).

If the fit is off by about the thickness of the card you have a very precise set of parts (and great cutting skills). What you need to do is to replace the tabs at the top of each conic section with an internal connector strip. Make a curved strip of card (same radius as the top of the large conic you're connecting) with tabs on the inner edge. Glue that band of card inside the top of the lower (larger) conic with the tabs out and slip the upper (smaller) conic over it. This better blends the seam and allows the parts to distort a bit as you gently push the conics together. The internal strip also closes any visible spaces between the parts.

Yogi

**CardboardCat** · #4 12-27-2012, 06:51 AM

This stuff isn't nearly as easy as it seems at first glance. Thank you both for the replies. I'll keep at this until I get the parts right. Your advice will be a great help. Love this forum.

**jleslie48** · #5 12-27-2012, 10:22 AM

the other answer for a tight fit is to shim the cone as well. take a strip of paper and and layer up the either the insert section of the cone or line the inner part of the cylinder with a turn or two (or 3 or 4) of cardstock to narrow the diameter. the has the added benefit of strengthening the parts as well.

look at the former design I use, its the same thing, make the former a small diameter on purpose, and then put layers of shim material to build it up for an exact fit:

**dhanners** · #6 12-27-2012, 10:31 AM

This may sound like a stupid question, but are you sure the cylinder is the right size?

Yogi's points are great ones and there isn't much to add. If the nosecone parts are genuinely too small, then print them out at a larger percentage. But you don't need much larger. And if the joining tabs are still attached, cut them off and make your own tabs.

Another thought I might have involves your printer settings. Are you fitting to the page? If so, the propensity exists that you're winding up with distorted parts when the printer/computer software shrinks or enlarges the model page to fit the printer page. (Trust me, I know about this first-hand....) That's why I am a HUGE fan of designers who include both horizontal and vertical scale references on their pages.

**CardboardCat** · #7 12-27-2012, 01:31 PM

Quote:

Originally Posted by dhanners

This may sound like a stupid question, but are you sure the cylinder is the right size?

Yogi's points are great ones and there isn't much to add. If the nosecone parts are genuinely too small, then print them out at a larger percentage. But you don't need much larger. And if the joining tabs are still attached, cut them off and make your own tabs.

Another thought I might have involves your printer settings. Are you fitting to the page? If so, the propensity exists that you're winding up with distorted parts when the printer/computer software shrinks or enlarges the model page to fit the printer page. (Trust me, I know about this first-hand....) That's why I am a HUGE fan of designers who include both horizontal and vertical scale references on their pages.

I use "actual size" setting on the print dialogue. It may be that I sized the cylinder incorrectly. I'm new to this and mistakes are still pretty common for me. I like the idea of cutting off the tabs. They were the main problem. I'll try that on the next rocket I attempt. This one turned out ok for a first attempt at a rocket. It doesn't look as nice as some I have seen on here but not too bad overall. I think I could cover the messy seams with paint.

**dhanners** · #8 12-27-2012, 08:04 PM

Quote:

Originally Posted by CardboardCat

I use "actual size" setting on the print dialogue. It may be that I sized the cylinder incorrectly. I'm new to this and mistakes are still pretty common for me. I like the idea of cutting off the tabs. They were the main problem. I'll try that on the next rocket I attempt. This one turned out ok for a first attempt at a rocket. It doesn't look as nice as some I have seen on here but not too bad overall. I think I could cover the messy seams with paint.

Don't worry about how your first one looks -- all of us here have built models we'll never show to anyone. That said, don't be shy about sharing your builds here. You'll find us very supportive and we do our best to help one another. I can't begin to list the help, support and guidance I've gotten here over the years. The people here have made me a better modeler.

**Bionic Modeler** · #9 01-02-2013, 06:38 PM

Jleslie's method is a good one. just cut the top part of the tab strip to a sawtooth so it will bend inward to match the angle of the cone. Or another method is used a lot by airplane designers for the fuselage. Cut two identical formers one for the cone the other for the cylinder. Glue them flush to the edge and then glue the formers together to join them.