Power Saw

I had been thinking about adding a power saw to the workshop for some time because I do quite a bit of milling these days and I often find myself needing to laboriously hacksaw large pieces of stock. I don’t do this every day and I wanted something with a small footprint, ie, not a large bandsaw or a big second hand, usually 3 phase, reciprocating saw of the type that can be found on eBay, so I fancied the idea of making my own machine. I almost never make anything that I have not designed myself because for me it's more than half the enjoyment of the project, and in any case I’d much rather make my own mistakes and learn something than copy someone else’s and wish I hadn’t. However, I made an exception. I am a woodturner who makes other things from wood from time to time and very rarely something from metal that doesn’t help me make something else from wood. If I were to design and build it would be quite difficult to source the parts I can’t construct, and too risky to design something that I am not that knowledgeable about, so I decided to buy a Hemingway kit, based on a 1964 design by Edgar Westbury.

The kit

The first observation is that the kit is rather expensive at £450 all but ten pence. I could have bought a second hand saw from eBay, or even a new one for much less. But hey, I wanted to make my own for the learning experience and I really fancied having a go at it. The kit, shown set out in the picture below, comes with a very nice set of drawings and good quality bought parts: motor and gearbox especially. The rest is sawn blanks and rough castings. Anyone expecting a quick dash around with a bag of tools and the jobs a ‘good un’ will be very disappointed, because you need to make literally everything except standard hardware. I needed to buy a few tools too: 11, 12 and 16mm reamers amongst them.

The kit (picture above)

The drawings are in part metric, but mostly the design is in imperial units, so I spent a fair bit of time converting the design to metric where needed, to prevent the tooling bill being even higher. The stock is imperial sized, and the hardware is metric. It is not that much of a problem, but it is a pain, and for that money and in this century it should be all metric. There is also the odd error, again not major and easily spotted, and the internal diameter of the damper piston rod material was over size, again no problem I just made my own.

Making it

The instructions are definitely not blow by blow, so this is not for the beginner. You do need to work out in which order to make it so that high accuracy is obtained where necessary, or it will not easily fit together and work. There are phosphor bronze bushings on the drive shaft but many parts in the design have rotating steel against aluminium, which I just don’t like, so I made brass bushes for most of them.

I have never had to machine castings before, and it turns out that holding them is a very interesting challenge often requiring a lot of thought and ingenuity. So, I found myself having to make low profile milling clamps, and other tools just for this job.

I do not like the design of the damper, but I’m not saying it doesn’t work, and there are a couple of undercuts inside the piston that I have no clue how to make, so I didn’t, and I don’t think it makes any difference other than a slight increase in weight. The needle valve mounting needs a re-design so that it is secured near the pointy end, and not just by the hole in the bottom nipple. That last sentence will doubtless mean little to anyone who has not tried to assemble it, for which I apologize but it does not make it any less true. One of these days if I get the energy and enthusiasm I may have a go at re-jigging it, but I doubt it.

I started this project at the beginning of November 2021 and finished it 3 months later, having worked on it on most days. I saw someone’s estimate of the job taking 200 hours. I must be very slow because it took me a lot longer than that.

As a learning experience it was great, and it certainly made me scratch my head a few times, but it is not a challenge to be taken lightly or by someone without a lot of spare time available.

But that’s enough of that. Back to woodturning and more comfortable ground.

April 2022.