1/8" G10 - How STRAIGHT does it need to be?

Hey everyone,

I need some guidance here regarding G10 please:

I'm working on a L2 build (4" upscale AT Warthog) and have been trying to acquire a sheet of 12" x 24" G10 for the fins. The problem I've encountered is that the G10 I'm receiving is bowed, warped, or both. The first sheet I received was not horrible, but noticeable. So, I sent it back to the vendor.

Today I received the replacement sheet (after a $12 cost to ship the first back), and this one is worse than the first sheet: more bowed and has a twist to the whole sheet. To give some perspective, when I lay the 12x24 sheet on a flat surface, one corner is 1/4" off the surface.

Is that normal? Should I expect G10 to be true and flat/straight? This rocket will have a 54mm motor mount and will fly on motors as large as a middle K. Shouldn't the fins be straight and true for something that will fly (at times) close to Mach based on simulations???

Please give me your thoughts TRF...

It shouldnt be that warped... keep in mind though that the fins are a smaller subset of the sheet and thus won't show nearly as much deflection as the sheet has. I have quite a bit of 1/8 here that is pretty flat... it should be quite good, but storage of the pieces matters. Lean a sheet up against a wall with a decent angle for a while, it will sag.

Nat Kinsey
UpscaleCNC

I have heated it on a flat service with a heat gun to get it flat, most of the time it will stay flat after that.

Where are you getting it from?
Maybe it's the shipping company not the supplier?

Personally I've never had this sort of problem.
I've bought my sheets from McMaster.



JD

JDcluster said:

Where are you getting it from?
Maybe it's the shipping company not the supplier?
JD

Click to expand...

I'm not going to throw the supplier under the bus because they've been more than willing to assit with getting this corrected, but having to send a 2nd sheet back doesn't make me so happy.

I've considered that it might be the shipper, and it's coming in a FedEx box that each time seemed to be too small (the sheet was sorta "wedged" into the box, so I just don't know where the problem lies.

Finally, Getmore confirmed what I suspected, that the sheet can be heated slightly to straigten it, but I'm concerned about strength. Also, with the warp in this one, I think straightening it is not going to be as easy as it sounds...

I've considered that the fins will not be the size of the sheet, but this amount of warpage will be easily visible looking at the fin surface from the edge. I'm concerned with aerodynamic stability, and I fully believe it's a supplier storage issue. This 2nd sheet wasn't on the truck with FedEx but for a day or so...

You are building a 4in rocket with 54mm motor mount tube.

Cut slots tight and accurate. When inserting the fins, what little bit of warp should be held straight by the slot.
In fact there is so little warp in that sheet [from what I could see] by the time you cut out the fins...odds are fins themselves will be just fine.
I have been through this with 3/16 wood sheet stock.
Bought a section 2x 4 with the same issue & cut 4 Little John fins.

They all were straight and true when stacked & eyeballed. A 1/4in. warp over 2 ft is less than 1/8 per foot & 1/16 per 6in. Barely noticeable.