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  1. #1
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    Default Bridgeport clone's boring head boring diameter capacity

    Hi All, I had a job come into work that I'm knocking back as my lathe (AL-960B) and Mill (BM-20E) don't have the capacity to do it. The job was to increase the bore of a 280mm-OD stainless steel pipe backing flange from 170mm-ID to 180mm-ID. The flange is 17.5mm thick and the water board dropped one in for me to look at and there is something like 12 that need doing. The OD is to big for my lathe chucks and although it would fit on the faceplate the holes in the faceplate don't suit. I have a boring and facing head for the mill which is supposed to have a capacity of 5mm to 250mm but looking at this Brochure https://www.engineeringx.pitt.edu/up...20machines.pdf it says the Boring range in mild steel is 6" (152mm). I only have brazed carbide boring bars at the moment for my boring & facing head (I ordered a set of carbide insert boring bars for it this morning.
    Sorry I'm being a bit long winded I know. My question is the 152mm boring range the actual capacity of the mill, because if you extended further than that it's going to be too much imbalance on the mill and likely to cause vibration and therefore chatter as well ?.
    All The Best steran50 Stewart

    The shortest way to do many things is to do only one thing at once.

  2. #2
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    90mm radius I'd do that on my HM52 without thinking.

    I'd rather do it on my 12x36 lathe though.
    If it's a good paying job drill the faceplate, or make a sub plate fixture.

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  3. #3
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    Just to add, this is why I fitted the 250mm chuck to a spare face plate I had many years ago, it helps with these bigger jobs.

    It's not used often, but when you need it you need it.

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  4. #4
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    The torque the mill will need will be controlled by DOC, although for stainless you need to be careful with that too. I suspect that limit is there because of spindle speed - To bore in SS at 180mm diameter, you need something like 50rpm if using HSS. Carbide you can probably bump that up by 3x, so 150rpm?

    If you can get that sort of speed then you might get away with it.

    Michael

  5. #5
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    Just a thought in case it helps, your lathe has D1-4 camlock so could you find a faceplate from another with the same mount but bigger diameter?
    I have two for my AL960B - the standard as supplied, and a larger one that came from a Harrison lathe.

  6. #6
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    I'm with Dave, I'd make an adapter plate to fit on the existing face plate.

    If you think you can make these ideas work then cost it into the job.

    Simon

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  7. #7
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    Thanks for the replies guys. My mills four slowest speeds are 67, 115, 134 and 180 RPM so it seems it would be achievable on the mill. I would much rather do it with carbide insert bars than brazed carbide boring bars considering the amount of flanges that has to be done and the amount of material to be removed. My carbide insert bars won't be here for about two weeks according to the expected delivery time frame and they need the job done sooner than that.
    I agree that making a sub plate or having a bigger face plate would be the way to go as I know myself that this job would be much easier to do on the lathe than the mill. I will keep my eye out for a bigger face plate or I might even look at making something in the future for future use from a Camlock backing plate. Hey Nadroj what is the OD of the harrison face plate that you have ?. Thanks again
    All The Best steran50 Stewart

    The shortest way to do many things is to do only one thing at once.

  8. #8
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    Quote Originally Posted by steran50 View Post
    Thanks for the replies guys. My mills four slowest speeds are 67, 115, 134 and 180 RPM so it seems it would be achievable on the mill.
    I would not even consider doing this on a B/port type milling machine. It's going to chatter like crazy IME.

    Make a faceplate fixture and do them on the lathe. Quick & dirty method, get a spare flange and bolt it to the faceplate with conveniently located CSK bolts then use through bolts in the flange holes. You could probably stack maybe 4 flanges up and bore them out in one go rather than doing 1 at a time.

    Even with a horizontal boring mill and a ton of fixturing gear I reckon I'd still do a job like this in the lathe.

    PDW

  9. #9
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    Quote Originally Posted by steran50 View Post
    what is the OD of the harrison face plate that you have ?
    300mm
    Slots are 14mm wide.
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  10. #10
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    Thanks Nadroj for that info. I will keep a watch out for a bigger faceplate, for possible future use. I passed the job onto a friend who owns the Welding shop down road as he can do the job easily as he has a much bigger lathe than me. I've since had a look at other lathes and unless something good secondhand comes up I will probably look at getting a AL-410 Lathe later next year or the year after.
    All The Best steran50 Stewart

    The shortest way to do many things is to do only one thing at once.

  11. #11
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    You will have a very tough time doing them on your mill, it just wont have the rigidity.

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