コミュニティが MiniCPM5-1B を微調整し、657MB の思考モデルを公開

A community developer, GnLOLot, has published a 1B model that runs fully on local hardware. The model is MiniCPM5-1B-Claude-Opus-Fable5-Thinking, with GGUF builds for llama.cpp-compatible runtimes. It needs no API key and makes no cloud calls.

The Proposed Model

The model is built on openbmb/MiniCPM5-1B. That base is a real, documented release from OpenBMB. It is a dense 1.08B-parameter model using a standard LlamaForCausalLM architecture. It has 24 layers, grouped-query attention, and a 131,072-token context length. OpenBMB reports 1B-class open-source SOTA within its own comparison set.

The base already ships a native thinking template. Reasoning is toggled through enable_thinking, giving both a Think and a No Think mode. The derivative model keeps that template and MiniCPM5’s tool-call format.

On top of that base, the developer applied a fine-tune. The card states the model is ‘further fine-tuned on Fable 5 data’ to improve coding and instruction following. The GGUF card repeats this as ‘post-trained on Fable 5 data.’

How it is actually built

The described method is not classical distillation. You do not shrink the original model. Instead you generate many conversations with a teacher model. You capture its replies and reasoning traces as text. You then supervised-fine-tune a smaller base model on those traces.

This distinction is important for accuracy. Classical distillation transfers signal from a teacher’s logits or weights. No one has access to Claude’s weights or logits. So this is supervised fine-tuning on generated outputs, not weight-level distillation. OpenBMB’s own base model, by contrast, uses a documented On-Policy Distillation stage between its own teacher and student checkpoints.

The practical effect is that the 1B model learns to imitate response format and style. It does not absorb the teacher’s underlying capability. A 1B parameter budget cannot hold frontier-scale reasoning.

The specs that check out

The context window is 128K tokens, inherited from the base config.json (131,072). The GGUF repository ships four quantizations. Q4_K_M is roughly 657MB and is labeled the smallest footprint. Q5_K_M is roughly 751MB. Q8_0 is roughly 1.1GB and is the maintainer’s recommended default. F16 is roughly 2.1GB.

The ‘657MB footprint’ is the smallest quant, not the default build. The model loads directly in llama.cpp, Ollama, LM Studio, jan, and KoboldCpp.

Interactive: how the build works

The explainer below walks the build pipeline, the footprint tradeoffs, and the honest split of what a fine-tune can and cannot carry over.

(function(){

window.addEventListener('message', function(e){

if(e.data && e.data.mtpId==='fable5-explainer' && e.data.mtpHeight){

var f=document.getElementById('mtp-fable5-explainer');

if(f){ f.style.height = e.data.mtpHeight + 'px'; }

}

});

})();

How to run it

The GGUF card gives a one-line path through Ollama:

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ollama run hf.co/GnLOLot/MiniCPM5-1B-Claude-Opus-Fable5-Thinking-GGUF:Q4_K_M

The same repository documents llama.cpp, LM Studio, jan, and KoboldCpp. Recommended sampling for Think mode is temperature=0.9, top_p=0.95. The model may emit reasoning blocks before the final answer, which downstream apps can strip.

Key Takeaways

The model is a supervised fine-tune of OpenBMB’s MiniCPM5-1B on Claude Fable 5 traces, not a weight-level distillation.

Real specs: 128K context, GGUF quants from ~657MB (Q4_K_M) to ~2.1GB (F16), Q8_0 the recommended default.

Fine-tuning on outputs transfers format and style, not frontier reasoning or broad knowledge.

No benchmarks or training dataset are published, so capability claims are currently unverifiable.

Apache-2.0 covers the base weights only; training on Claude outputs raises a licensing question the card leaves open.

The post Someone Fine-Tuned OpenBMB’s MiniCPM5-1B on Claude Fable 5 Traces to Ship a 657MB Local Thinking Model appeared first on MarkTechPost.