As of the writing of this post (July 17th 2026), we have the production run of CF1 Cook Frames, however they are all affected by a design issue that we are actively working on remedying. We have been experimenting with a collection of solutions over the past couple weeks to find something that we are satisfied with and that we would be proud to release to you.
If this update is too vague, feel free to keep reading.
The CF1 Cook Frame is a cooking system that I designed to pair with the SP1 propane adapter for flat pack fire pits. It includes a frame that can be used with woks and a grate for other flat-bottomed cookware.
We have been excited to bring this product to you for a little while now. We developed a prototype that performed very well and was fun to use, but had manufacturing and user experience shortcomings: notably, an intermediary part that the user would have to screw and unscrew with each setup. Through several iterations, we decided to tweak the design to remove that additional fitting, allowing us to simplify the experience (as we've done with the SP1) and save some material. The end result is the CF1 as seen below, with a central ring that simply slides around the middle part of the SP1 burner and 3 arms that rest on the burner itself.
We had a local machine shop make a prototype of this version for us and it worked wonderfully. The simplicity of it was very attractive from a design perspective. The tolerance of the inner ring combined with the engagement on the burner ensured that gravity alone was enough to hold this frame in place, even with spirited wok cooking.
I created the drawings and specifications needed for our supplier to start production, discussed tolerance and material considerations with them and moved forward. This was back in spring, when production lead times were starting to be real considerations to make sure we had the CF1 ready for summer. This is also where I made a design and production mistake that, unfortunately, is delaying the release of this product even more.
When discussing this seemingly minor design change with our supplier, I requested a production sample. It became evident that for them to make a production sample, ship it, for us to review it, and then start production, we would likely be well into summer. Although our supplier is continuing to do excellent work, Zutto Fire is likely one of their very smallest clients with the smallest orders (we always order their MOQ). This often means that projects like these get dropped down on their own priority list should something happen, which also played a role in deciding to move forward. The irony of me sharing this experience with you mid-July, as I am deciding to hold the CF1, is not lost on me.
The specifications in the drawings, together with our working prototype, gave me confidence that unless our supplier completely missed the mark, it was safe enough to place this production order and our supplier started work shortly after. They had their own quality control issue during production, which they rectified but created additional delays, but eventually the CF1 Cook Frames finally shipped! About 30 days later, I helped our UPS driver deliver 31 large boxes full of stainless steel frames. I couldn't wait to open these boxes up and start shipping our outstanding pre-orders out!
To my disappointment, that was not to be... The frames looked great and matched the specifications I put in the drawings, but once I placed one on a burner, they felt noticeably more wobbly than our prototype, to the point where, in some cases, the frame could come off the burner. This was obviously unacceptable so I started digging.
What eventually transpired was that, although there were no obvious dimensions out of specification, I had been slightly too conservative with the tolerance on the ring's inner diameter and, except for bend radius and other minor dimensions, I didn't add tolerances to the exact dimensions of the 3 arms. In hindsight, I am not entirely sure that fully locking dimensions for those arms would have made a difference as they are thin enough to allow for some bending, especially when heated. However, the result is that some variability in these arms along with the ring's inner diameter tolerance meant the cook frame could unintentionally lift off the burner in the right conditions. Although this would only happen if someone placed a pot on the very edge of the grate with the frame in a specific position, or if someone was spiritedly cooking with a wok, it was enough for me to hold shipment.
And so began the exploration of various solutions to this problem. Modifying the burner would likely be the easiest path, but that would mean compatibility issues with all the SP1 we've sold up to now. The solution has to be with the frame itself.
At first, I tried tweaking the bend in the 3 arms to change the way the frame contacted the burner with mixed results. Although there might be something here, the simple fact that the bend could be affected with a cook frame smashed into the back of a heavily packed car ready for camping made this solution not viable.
Then I experimented with trying to reduce the inner diameter of this ring. Placing a 0.08 mm stainless steel shim between the ring and burner all but solved this issue and seemed very promising (so much so that I almost announced that we had a solution). The ring installed securely and I couldn't get it to come off. Now I had to figure out how to add 0.08 mm to the entirety of the inner ring, which is no easy feat. Making it larger, no problem, but smaller... I designed and 3D printed a collection of progressive press dies to form the shims to the inner diameter, which would likely require a tack weld. This seemed quite tedious and I wasn't convinced of longevity.
I've considered chrome plating the frames to add just the right thickness. I learned about adding some metal with flame spray techniques, which would likely require reaming the inner diameter as an additional step. I considered reaming the ring to a larger diameter, having a precision brass bushing made to then press into the enlarged bore, then reaming the new hole to the right spec. I've also considered knurling the inside surface to create peaks and valleys that likely would make the overall diameter smaller. I also tried compressing the ring, first punching one side with a mallet to deform the ring, then using a large 3-jaw lathe chuck and a hardened shaft so the inner diameter was always the same.
All these solutions led to a tighter fit that was satisfying to press onto the burner, but eventually turned out to be very difficult to remove from the burner especially as it heated up. Additionally, while I was able to install the cook frame onto the SP1 when they were both cold, it was nearly impossible if the burner was already hot. Hitting that inner diameter dimension so precisely with so many geometrical and temperature variables eliminated the solution of adjusting the inner ring's diameter. Interestingly, this was not an issue that I encountered when using our prototype, but these "torture" tests showed me that it could be an issue should there be some variance in the burner diameter, or the precise shape of the cook frame arms.
At the same time, I was exploring solutions using an additional part. While less desirable, I was trying various cap designs that would sit atop the burner and prevent the cook frame from jumping off. Some designs worked better than others, but none were quite right.
I also tried drilling and tapping the side of the ring to include a brass thumb screw, which worked quite well but would be a burning hazard for removal.
Another similar option would be using a set screw with an Allen wrench, although it requires an additional tool which I have been trying to avoid, and requires tinkering in the vicinity of hot metal parts.
Then I considered making another brass insert to be retained into the inner ring, which would have an 8 mm diameter pin sticking out of it. That pin would fit in the hole that is on top of the SP1 burner and would be the sole piece holding the CF1 Cook Frame up. This is, ironically, a full circle back to the very first design I made for this part. One reason why I had steered away from this design had to do with the fact that when packed, this 8 mm protrusion would likely damage the SP1 carrying bag over time. That concern was why the first prototype was a 2 piece design so the 8 mm pin could be removed when packing. This also meant that it would be an extra step for the end user and another part to potentially lose, which would make the cook frame unusable.
Despite these drawbacks, I designed a different style insert that would function similarly but would be permanently secured to the frame. I would then press the frame slightly to cheat the inner ring upward, reducing the distance that this 8 mm pin protrudes out of the overall envelope. Combined with some strategic packing, the concern for bag wear is virtually addressed. This proved to be a promising solution.
I chose brass in part to avoid potential galling between two stainless steel surfaces. The 8 mm pin design worked very well with our very first prototype and so far, I am having a similar experience with the current insert prototypes I have. They need some refining as the dissimilar metals expand at different rates, which means that simply pressing the brass insert into the stainless steel ring, while incredibly solid when cold, loosens up after heat cycles. This will likely be alleviated by peening the top surface of the brass to effectively catch the ring on the top and bottom. The brass insert may eventually be able to rotate slightly within the ring after heat cycles, but it will remain permanently retained.
That left me with two directions that still seemed promising. One is refining a mechanically retained brass insert that uses the existing 8 mm bore in the SP1 burner to positively locate the cook frame. The other is continuing to explore a screw-retained approach if I can find a way to make it secure without requiring tools or compromising the user experience. At the moment, the brass insert is the direction receiving most of my attention, but I haven't completely ruled out the screw-based approach if it ultimately proves to be the better long-term solution.
This is a significant design change that I wish I had been better at foreseeing. It has certainly been a learning curve in more ways than one, and I truly am sorry for the additional delays in getting you this product as each of these potential solutions takes a considerable amount of work to implement and explore. That has been my focus over the past two weeks since receiving the cook frames and I feel like I am getting very close to a workable solution. Hopefully the next update will be one of shipments.
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