When I was an apprentice learning the boring mill, my journeyman told me to keep the spindle when running at lunch etc. Now I understand why. Thank you.
Hello Rusty. It turns out, that being 48" long, the boring spindle grows .0003" for every degree Fahrenheit of temperature increase. It would only have to warm up by .0025/.0003 = 8.3 degrees to increase the .0025" I saw. Ken
Interesting….curious how you would produce an estimate for a client or just straight T&M and an open client checkbook,,,,thanks for sharing/discussing setups
Nice one Ken . Great point with the spindle temp . Your boring mill seems to be holding great tolerances . Do you know if the casting has been stress relieved ?
Thanks Max. My customer did some preliminary scraping on the angled surface. Although the scraping is incomplete and he would have to finish it to be sure, he estimated that it was likely holding flat to a bit less than a thou over 48". I'm very happy with that. My customer stated that the casting had been stress relieved once. Ken
I'm excited to finally see the machine in action. Do you have any theories as to why you still got some measurable difference after letting the machine warm up? It seems like there's something consistently different about the first third of the machining path, maybe in the gib or something? I know you rebuilt the machine so I'm curious where the error is coming from. Also, are there detents for rotating the table to common angles and, if so, how accurate are they? Thanks.
I'm not sure why it still had a movement of .0005" in the first third of the cut. At 48" long the boring spindle would grow .0003" for every degree Fahrenheit increase in temperature. It is possible that the small amount of extra power to take the cut caused the boring spindle to increase in temperature by .0005/.0003 = 1.67 F in the first third of the cut. You can see why temperature control becomes the dominant variable at high tolerance levels. There is an indexing pin and four sockets for it to register in. This allows you to index the table every 90 degrees. I haven't tried to measure the accuracy yet but it appears to be very good. Ken
When I was an apprentice learning the boring mill, my journeyman told me to keep the spindle when running at lunch etc.
Now I understand why.
Thank you.
Thanks for giving your considerations as you machined this. I'm thinking about doing similar job. Thanks!
I agree with using the jackscrews with points.
I would never have thought that the spindle gets longer while running. But, of coutse, it makes perfect sense.
Hello Rusty. It turns out, that being 48" long, the boring spindle grows .0003" for every degree Fahrenheit of temperature increase. It would only have to warm up by .0025/.0003 = 8.3 degrees to increase the .0025" I saw. Ken
Wow you’ve got to be happy with that. all the time and work rebuilding that machine was well worth it 👍👍
Yes, very much so. I could have put the same amount of work in and had a dud (from an accuracy point of view). Thanks, Ken
Interesting….curious how you would produce an estimate for a client or just straight T&M and an open client checkbook,,,,thanks for sharing/discussing setups
Nice one Ken . Great point with the spindle temp . Your boring mill seems to be holding great tolerances . Do you know if the casting has been stress relieved ?
Thanks Max. My customer did some preliminary scraping on the angled surface. Although the scraping is incomplete and he would have to finish it to be sure, he estimated that it was likely holding flat to a bit less than a thou over 48". I'm very happy with that. My customer stated that the casting had been stress relieved once. Ken
@@hmw-ms3tx Great result . Even temperature change over that length , i guess would have an effect . 👍
I just bought a 24" and 36" straight edge castings but can't seem to find time to work on them.. I'm jealous.
I'm excited to finally see the machine in action. Do you have any theories as to why you still got some measurable difference after letting the machine warm up? It seems like there's something consistently different about the first third of the machining path, maybe in the gib or something? I know you rebuilt the machine so I'm curious where the error is coming from.
Also, are there detents for rotating the table to common angles and, if so, how accurate are they?
Thanks.
I'm not sure why it still had a movement of .0005" in the first third of the cut. At 48" long the boring spindle would grow .0003" for every degree Fahrenheit increase in temperature. It is possible that the small amount of extra power to take the cut caused the boring spindle to increase in temperature by .0005/.0003 = 1.67 F in the first third of the cut. You can see why temperature control becomes the dominant variable at high tolerance levels. There is an indexing pin and four sockets for it to register in. This allows you to index the table every 90 degrees. I haven't tried to measure the accuracy yet but it appears to be very good. Ken
Nice. 👍
Thanks Tom.