The sizes aren't daft, it's pointless making them in sizes that slide precisely because of the weld and welded tube isn't perfectly round, they're simply not intended for the job you want to use them for. As you say It's better to broach it (but pull it through rather than push) or make a self guiding boring bar that uses what has already been cut to guide and stabilise it.
I had to deal with boring off the weld in a recent project too. Nowhere near as long as that tube, but it was a sample of something that would have gone into a short production run. It made sense then to record at what depth of cut was needed to remove the weld ( as well as recording similar measurements for all the other operations. ) It was a steel tube that would hold a door key and be locked to a gate or something.
This is interesting, we had this exact problem on a small project in the summer except we were trying to use thick wall gas pipe. In the end we thought it was too difficult and used mechanical tube and in our case we used 25mm rod inside 1-inch mechanical tube which has a 25.4mm ID
The end of the stock sticking out of the left side of your head-stock is also going to contribute to overall FLEX. There are a number of UA-cam videos that addresses the weld seam found on square, rectangle and round tubing. ua-cam.com/video/ozSE7Wrdb1o/v-deo.html Wakodahatchee Chris
The sizes aren't daft, it's pointless making them in sizes that slide precisely because of the weld and welded tube isn't perfectly round, they're simply not intended for the job you want to use them for. As you say It's better to broach it (but pull it through rather than push) or make a self guiding boring bar that uses what has already been cut to guide and stabilise it.
I had to deal with boring off the weld in a recent project too. Nowhere near as long as that tube, but it was a sample of something that would have gone into a short production run. It made sense then to record at what depth of cut was needed to remove the weld ( as well as recording similar measurements for all the other operations. ) It was a steel tube that would hold a door key and be locked to a gate or something.
This is interesting, we had this exact problem on a small project in the summer except we were trying to use thick wall gas pipe. In the end we thought it was too difficult and used mechanical tube and in our case we used 25mm rod inside 1-inch mechanical tube which has a 25.4mm ID
Good thinking. Mixing imperial & metric sizes sometimes works out really well!
The end of the stock sticking out of the left side of your head-stock is also going to contribute to overall FLEX. There are a number of UA-cam videos that addresses the weld seam found on square, rectangle and round tubing.
ua-cam.com/video/ozSE7Wrdb1o/v-deo.html
Wakodahatchee Chris
I don't think I'd seen that video before but had seen some others & yes, I could have done with a bush or spider in the back end of the spindle...
What is the minimum diameter?
Using the bar in the video, I would think about 38mm.