New Shaft Needs Mating Taper Hole
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I have never fit a taper pin to a new shaft and a wheel hub. The problem is – how to match the new shaft's taper hole with the existing taper hole in the pulley hub?
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m. allan noah
In the past, I have clamped the pulley in vise, with the reamer resting in the hole. Get the reamer vertical by eye and centered under the drill chuck by moving the milling machine table. Then, remove the reamer, and insert the shaft into the pulley without moving anything. Use auxiliary clamping mechanism to hold the shaft. Then drill to various depths with the right series of drills, right through the existing hole in the pulley. All of this is difficult if you are talking about the large diameter pulley, due to clearance issues. In cases like this, I have created temporary drill extenders from a piece of shafting and an old chuck. allan
-- "well, I stand up next to a mountain- and I chop it down with the edge of my hand" |
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Rick
I have done it like Allan, but I also bought the proper tapered drill bit and ream. Came out really nice. I found the drill and ream on eBay for cheap.
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Just a note on buying tapered reamers. The Imperial standard for taper pins etc. is a nice round 1/4" on diameter per foot, 1 in 48. The metric standard is a nice round 1 in 50. If the application matters, BEWARE. A colleague runs a small fleet of class 20 locomotives on the main line here in the UK. These date from the early 1960s and the engine is an English Electric V8 of 1000HP at 850 RPM, 10" bore x 12" stroke. (That's about 15 litres per cylinder.) The DC generator is flange mounted direct to the end, but each one is hand fitted. He had to swap a generator recently. The instruction is to snug the flange bolts and shuffle the generator around until the deflection between the drive end crank webs is only 0.001". His very skilful fitter had done all this before. It is then time to ream the dowel holes over sized and drive in tapered dowels. He could only get a metric taper reamer in the required size, and in the early '60s we hadn't even heard of metric in this country. I put his new reamer between centres on our 14.5" SB toolroom lathe and set the TTA to give zero deflection on a DTI over its length, then put the blank pins in for tapering. I forget the exact size - somewhere around 1" diameter, all 4 different of course.
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Thanks for the help. It's a 10-1/2" flat belt pulley and the extender with a second chuck will work I think. Work holding is always a challenge - I'll have to clamp the shaft in the hub somehow (shaft is very tight in the hub, but not fixed) The old taper pin was No. 4 and I'm going oversize, up to No. 5, to improve overall alignment between existing and new taper holes. I turned a new No. 5 taper pin on the SB (why not!) rather than purchasing 10 (minimum quantity). Yes, I found a No. 5 helical taper reamer on eBay at a decent price; good enough for my needs - from Vermont. Eddie - I enjoyed to story |
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William Nelson
Super glue works great as a temporary fixture. Just glue the shaft in place, make sure the glue is hard (I have proceeded to machining before the glue was fully cured and regretted it), then drill and ream. To remove a little gentle heat on the shaft will release the glue. I use this trick all the time in machining. Just make sure you don't get the part too hot while machining or it will come apart (ask me how I know that ☹).
-- Bill From Socal |
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Rogan Creswick
I've done this op on a bandsaw with a hand drill, in-situ, and it seemed to work fine, but I'd clamp it up if I could. In that situation the wheel was too large for my tools, but I could get a cordless drill in there well enough -- I just used the wheel pin holes as a guide bushing, drilling the diameter of the small exit hole, roughly, then reamed slightly over size, with a fresh pin. If I remember correctly the pins were over-length anyway, so driving them a little deeper (not much, mind you) wasn't an issue. Reaming took ages, though, because there wasn't room for the tap handles to rotate 360, so there was a lot of handle sliding involved. On Wed, Mar 23, 2022 at 8:35 AM William Nelson <wnnelson@...> wrote:
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Thanks Bill. I managed to step drill the new shaft for a No. 5 taper pin by vertically aligning my drill press with the pulley hub holes. Then I put the new shaft in the hub and taper reamed both thru holes to size, in place. I did have to fab an 8” extension to lengthen the No. 5 taper reamer to clear the outer pulley. Only small problem I had was that I left too much shaft stick out and it was rubbing the belt guard ( yikes! ). Thanks to all who helped inspire me to a good solution.
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Sent by my iPhone On Apr 4, 2022, at 11:46 PM, Rogan Creswick <creswick@...> wrote:
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