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Post by electrosteam on Mar 7, 2010 9:52:07 GMT
The attached two images show one of two demountable axle pulleys made for a 5 inch gauge boxcab electric loco. In use, the centre four axial capscrews were not used and the remainder of the axial fixings were changed to machine screws because of the tight space between the axleboxes. They work fine, not a hint of wobble or misalignment. Happy machining, John. Attachments:
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Post by electrosteam on Mar 7, 2010 10:03:34 GMT
The pulley component parts. The 55 toothed pulley made from a blank of aluminium 6061 cut with flycutters in the vertical mill. Rotary table used for for indexing according to an xls spreadsheet generated angular settings. MS for the remainder. No special machining except great care on the precision of boring and hole drilling. But, a wonderful demonstration on the build-up of tolerancing errors, why is always against us ?. The next one will be simpler and designed to avoid error accumulation. Happy machining, John. Attachments:
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kwil
Part of the e-furniture
Posts: 383
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Post by kwil on Mar 7, 2010 10:38:48 GMT
Are the drilled holes really all over the place or is it just the photograph?
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Post by electrosteam on Mar 7, 2010 21:43:32 GMT
kwil,
The holes are symmetrical about centrelines, to the limit of the leadscrews and dials on my small vertical mill, but not on a grid.
I drew the shape twice full size to make sure there was clearance between fixing heads, shaft, drilled holes and the keyway.
It was a bit of a juggle.
The removeable pulley idea was to enable a change in pulley size in the future, if required.
The loco has siderods with wheels glued on and keyed.
Removing wheels was not attractive.
I am new to machining, so this was treated as a learning exercise.
I learned that, no matter how rigid the setup and care with the machining, the tolerances will get you in the end.
But, persistence does pay off.
I will repeat the exercise, after assessing optimum design and machining sequence.
Happy machining,
John.
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