Anyone have experience putting a frame into a frameless pack?

I've got an old model 25L ascensionist. It's completely frameless. The back panel might have some thin foam but as far as I can tell it's just a nylon bucket with a drawstring. 

I want to put a frame in there. I'm sick of cam lobes and waterbottles poking me in the back, and the pack deforming and being all lumpy if I don't pack it perfectly. Anyone have resources for this? 

I'm thinking of just a piece of thick foam, but I don't know how I'd attach it to the pack, what type of foam to get, and how to measure it so it fits well. 

Why don't you want to buy a new pack?

I’ve used a piece of closed cell foam from a cheap sleeping mat which works rather well. If you want to stiffen things up even more you can purchase a sheet of 3/32” to 1/8” HDPE or Kydex and glue it to the foam.

Neither give you the full support of a real frame but they do eliminate the bulgy pokey problem.

Turn the pack inside out. Trace or measure the dimensions of the back panel. Then get a piece of closed-cell foam and a piece of ripstop that’s slightly larger than the back panel. Most pack frame sheets are made with 3/8” or 1/2” 2-3lb cross linked polyethylene foam. Sew the ripstop onto the back panel on three sides to create a sleeve, then turn the pack right side out, cut the foam to fit, and slide it into the sleeve. 

Total cost if you find the parts locally would probably be under $30. Plus you don’t need to get rid of an otherwise perfectly good pack.

If you don’t have access to a sewing machine, you could try the same thing except glue the foam onto the back panel rather than sew a sleeve. 

If the pack is shaped like a cylinder and only accessed from the top, line the inside with a single sheet of closed cell foam. A lot of frameless backpacking packs are designed this way because they assume you are carrying a pad to sleep on at night. If you are carrying a sleeping pad just roll it up, slide in into the pack before anything else and the pack the rest of your stuff inside of that. The cheap rolled foam pads want to spring open, so they add a surprising amount of rigidity to a pack and protect it as well.

If you want extra back padding, cut the foam so that it goes around the inside of the pack once, plus the amount of the back panel a second time. If you want a rectangular shape to the pack, cut part of the way through the foam along the pack seams so the foam can fold easier.

No sewing required. If you dont like it, just pull it out and try something different. If you want more ideas, check out Gossamer Gear. Their larger packs have removable hip belts, frames, and back padding

FrankPS wrote:

Why don't you want to buy a new pack?

I've tried a lot. I just haven't found many in this volume that work quite as well. 

Thanks for the input everyone

Frameless packs become quite rigid when you stuff them completely full and tight. So carry more and jam that shit in there. Protect your back with a piece of foam and enjoy your OG Experience.

Ironically, on the JMT Backpacking FB group, I am giving advise for people to use frames packs to save weight.   

A frameless pack may come with a sleeve to put a inflatable sleeping pad, which acts as a back cushion and a loose frame.  

So, what Matt Z said.    

Deuter AC lite 26.

BD creek 35

BD creek 20

I feel like you haven't actually looked at alternatives. 

That sleeve is to keep a hydration bladder in place nothing to do pads or make shift frames. 

Cherokee Nunes wrote:

Frameless packs become quite rigid when you stuff them completely full and tight. So carry more and jam that shit in there. Protect your back with a piece of foam and enjoy your OG Experience.

This.