I bought a car awning that attaches to the roof racks a week or so ago. The mounting system consisted of 4 x 8mm S/S bolts, These are supposed to pass through the roof rack rails via an 8mm hole drilled at the appropriate spots along the bars. I didn’t like the idea of drilling holes in the rack so set about making some T nuts that would locate in the channel of each bar. I had some 25mm S/S bar so chucked it, turned it down to the appropriate diameter and length and then loaded up the change gears to cut the thread.
The thread chart lists an 80 tooth gear in the train so I went through the gears selected the one I ‘thought’ was an 80 ( the numbers aren’t too easy to read on some of the gears) and set about cutting the thread. After cutting the thread I found the nut wouldn’t spin on so cut the thread a little deeper, still no go so cut the thread deeper still – and so on, and on, and on. In the end I got out the thread gauge and checked – wrong TPI. So then I checked the gear train - don’t you just hate it when you’ve put a wrong gear in the train.
The number looked like 80, but as it turned out it was an 85 – dam. Surely there can’t be a lot of difference I thought so perhaps I could replace the 85 gear with an 80 and re thread over the top Not to be, whilst it worked it just didn’t look ‘nice’ so no go, start over.
Finally finished one and this is the result – just another three to go. I’m thinking perhaps I should re stamp the gears whose numbers aren’t legible, got to be better than this!
For a job like this I would normally cut the thread using a die, but as I haven’t cut a thread on the lathe for a while I used the lathe, and of course you get a better fitting thread on the lathe. As it turned out I didn’t even have to clean up the thread afterward (wire brush excluded) it came out pretty good I think.
The thread chart lists an 80 tooth gear in the train so I went through the gears selected the one I ‘thought’ was an 80 ( the numbers aren’t too easy to read on some of the gears) and set about cutting the thread. After cutting the thread I found the nut wouldn’t spin on so cut the thread a little deeper, still no go so cut the thread deeper still – and so on, and on, and on. In the end I got out the thread gauge and checked – wrong TPI. So then I checked the gear train - don’t you just hate it when you’ve put a wrong gear in the train.
The number looked like 80, but as it turned out it was an 85 – dam. Surely there can’t be a lot of difference I thought so perhaps I could replace the 85 gear with an 80 and re thread over the top Not to be, whilst it worked it just didn’t look ‘nice’ so no go, start over.
Finally finished one and this is the result – just another three to go. I’m thinking perhaps I should re stamp the gears whose numbers aren’t legible, got to be better than this!
For a job like this I would normally cut the thread using a die, but as I haven’t cut a thread on the lathe for a while I used the lathe, and of course you get a better fitting thread on the lathe. As it turned out I didn’t even have to clean up the thread afterward (wire brush excluded) it came out pretty good I think.
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