Output shaft tapping

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old_chopper
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Output shaft tapping

Post by old_chopper » Wed Jul 29, 2015 1:57 pm

I need to drill and tap the output shaft on a Muncie 3 speed with a 3/8"-24 thread. I've done 4 so far and they are drill and tap eaters. I've been using random carbide drills and HSS taps we had left from previous jobs with poor success. They are machined in an engine lathe with a steady rest, decent setup. Any advice on tools? Any idea what material the shafts are?

BigBlocksOnTop2
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Re: Output shaft tapping

Post by BigBlocksOnTop2 » Fri Jul 31, 2015 5:51 pm

Try the TiN coated taps.

autogear
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Re: Output shaft tapping

Post by autogear » Mon Aug 10, 2015 3:38 pm

Shafts are (if they're OEM) CLOSE to 8620 steel ( maybe 4027 for example) and heat treated to something like 58-62 RC

old_chopper
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Re: Output shaft tapping

Post by old_chopper » Tue Aug 11, 2015 8:56 am

They are OEM and that info sure helps! I used to work for John Deere and I thought they used a lot of 8620 on the shafts too. I plan to work on a shaft this afternoon, I'll post my results.

mdabbott2009
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Re: Output shaft tapping

Post by mdabbott2009 » Wed Aug 12, 2015 8:18 pm

Bolt on yoke slider?

old_chopper
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Re: Output shaft tapping

Post by old_chopper » Fri Aug 14, 2015 1:31 pm

Yes, bolt on yoke. Shaft drilled just fine. I counter bored it with a 3/8" end mill to get past the case hardening then tried to tap it. The tap went on strike and said no thanks. I tried several styles of plug taps, absolutely no luck. I enlarged the hole and welded a 1/2" mild steel plug in it, going to drill and tap the plug. I'm considering a design change to incorporate a snap ring for yoke retention on future units.

Straight Shooter
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Re: Output shaft tapping

Post by Straight Shooter » Sun Aug 23, 2015 7:01 pm

You will have to start it with a good tap. Try to use a taper to do the majority of the cutting. Finish with a new quality plug at the end of the job. For really hard stuff they have solid carbide taps. They are 200+ for one tap but the cut like nothing else and will cut lots of holes. MSC is the place and buy the most expensive one they list. They cost that much for a reason. They also deliver overnight so not long to wait. Plug and bottom taps do not work well in hardened steel. I tap hard stuff all the time as a gunsmith and I charge out a brand new tap for each hole on some actions. Anything less and an irreplaceable action could be ruined. With carbide taps I have been able to tap Mark Williams axle flanges. Anything less and the taps just smears.

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