Here is a link to that saw at the tool company's web site: http://www.hartvilletool.com/product/12372
The tension on the blade can be adjusted by turning the turnbuckle attached to the two threaded rods at the top of the saw.
The problem I've had with this is that turning the turnbuckle sometimes turns the nuts at the end of the rod as well, and a few times a nut has completely turned off the end and fallen on the bench.
Yesterday, I wasn't paying attention and the nut fell off again. I looked for it a while and couldn't figure out where it went.
My first reaction was to get a new nut. I looked at the nuts I had in my nuts and bolts drawer and couldn't find one. I got the thread gauges out of the tap and die set I have (thanks, Dad) and discovered the threads were 3/16 - 32, meaning the rod is 3/16" in diameter and there are 32 threads per inch.
I tried to use the 3/16-32 tap in the tap and die set to convert an existing nut in my drawer to the desired threads, but it didn't work. I didn't have anything that gave me a good start, and I couldn't get a clean cut.
I went to the hardware store, but the smallest nuts they sell in their normal displays are 1/4". I finally found some 3/16 nuts in some of the specialty drawers, but they were 24 threads per inch.
Plan B: Get some brass rod and thread it. I checked the dies I had before I left and I knew I had a 10-24 die. This is about the same as 3/16-24. The problem with this is that I could make the threaded rods but the turnbuckle wouldn't fit them. It's 32 tpi.
(Update 3/2/09: Previously I wrote that 10-24 means 10mm, 24 tpi. It doesn't, and I clearly didn't do the metric conversion before I wrote that. 10mm is about .4 inches, not 3/16" (.1875 inches). The "10" is a value that specifies a special diameter used in sizing tap and dies which in this case equals .19". See http://www.micromark.com/html_pages/instructions/tap-die.pdf for how to compute what "10" means.)
I decided to buy the brass rod, some new nuts and some washers, and make a new rod. Instead of using a turnbuckle, I'm running the rod all the way across and tensioning the blade using a wrench.
This picture shows the saw, and the two rods (click on it to see a bigger version). The original adjuster is second from the right, and you can see the turnbuckle that connects the two smaller rods. The new rod is on the right. The die is at the middle top - once I got it started, it just required turning and a little oil to keep it lubricated.
A close-up of the new threads:
The only thing I have left to do now is to shorten the new rod a little so it doesn't stick out so much.
1 comment:
Just another example of how and why every project takes longer than you think it will.
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