Power Hack Saw help needed

[Jon]

In the US, even a still valid patent does not prohibit you from making one for your personal use, you just can't make them to sell.

We often see people saying that we are allowed to reproduce patented inventions for personal use; I would criticize you for repeating this, but I've made the same mistake myself! After researching it more thoroughly, here's what I think is happening:

First of all: US patent law forbids making or using patented inventions, even for personal use. These days, this is usually for a period of 20 years.



More: https://www.law.cornell.edu/uscode/text/35/271

Why do we get this wrong so frequently? My theory: it's caused by conflating patent law with the fair use doctrine of copyright law. Certain uses of copyrighted material are considered to be perfectly legal "fair use". There are four factors used to weigh fair use in copyright:

1. purpose and character of the use
2. nature of the copyrighted work
3. amount and substantiality
4. effect on the market

The "purpose and character" factor specifically includes whether the use is commercial or non-profit. And of course the "effect on the market" factor focuses on commerciality. So, if you have a non-profit use of a copyright that's not significantly impacting the market of the copyrighted work, you often have a strong claim to fair use.

Here's the rub: the concept of fair use applies to US copyright law, but NOT to US patent law. I'm not sure why this is, but I think that's the source of the frequent confusion.

Internet armchair lawyering aside: litigation over someone making a patented device for personal use is extremely rare, and usually not cost-effective. The worst I've ever seen, in almost two decades on forums, is a patent owner complaining to a forum admin about someone posting a how-to about making the patent owner's invention. It is almost never worthwhile to sue over this type of hobbyist use.

I believe there is also another nuance regarding making patented inventions solely for the purpose of research, but I would need to confirm this with an IP lawyer before understanding it fully. Let me know if anyone knows more about this.

I agree with all of your other points. The vast majority of patents are expired, searching patents is a great way to get ideas, and - in a healthy society - the government wants people to examine all of the public patent documents and drawings so that we can advance each others' inventions.