Advice on 1 1/4 type A R8 milling arbor for BPT Rt angle.
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  1. #1
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    Default Advice on 1 1/4 type A R8 milling arbor for BPT Rt angle.

    I have a 1 inch type A R8 arbor for my Bridgeport with right angle and arbor support.
    I came into a bunch of 1 1/4 cutters so I started to hunt down an 1 1/4 arbor with R8.
    Seems that they don't exist in R8 but are plentiful in 30,40,and 50 tapers and have seen a few in Jarno taper.
    I only see 1 1/4 R8 stub arbors which are fine in the BPT spindle, but unsupported in a right angle I think would put the work at risk as it doesn't seem a rigid set up. I would be afraid to crank the right angle down on the quill to prevent rotation and risk the right angle casting from breaking

    It seems Dorian used to make one which is no longer available.

    What are my options?

    Can I regrind one of the available tapers into an r8 or is that ridiculous?

    was also thinking to turn or grind the taper end to 3/4 and just using a 3/4 R8 collet?

    pros /cons?

    Thanks,

    Mike

  2. #2
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    Take one with a No. 30 shank and add an extension to it with a 7/16-20 thread for the draw bolt. They are the same taper and diameter at the gage line. Only thing missing is driving keys. As long as your careful it shouldn't pose a problem. Just don't take heavy cuts.

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    Thanks 4GSR that makes the most sense.
    I never bothered to calculate and compare taper angles and gauge lines.
    CAT taper always shown as 7/24 or 3.5/ft whereas R8 always displayed as 16 deg 51 min.
    Easy enough to turn and thread an extension.
    I'm not worried about the lack of drive keys, I don't plan on heavy cuts, I just want straight ones.

    Mike

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    They both possess the same taper per foot. That is 3.500" TPF.

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    You have a 1'' and it's recommended not to use keys, so make some reducing sleeves for the cutters (1.250 OD x 1 ID) and some larger clamping washers.

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