|michael cole||08/07/2014 13:58:59|
|164 forum posts|
I am just about to cut the keyway in a 4 inch scale little Samson flywheel. My qustion is, what clearance if any is needed in the vertical height. This is for a 1/4 inch key. Side to side fitting is tight, I just need to know about the vertical distance.
|Nigel McBurney 1||08/07/2014 14:26:07|
965 forum posts
I would have thought that the little sampson would have followed usual practice and used a tapered keyway ,the taper being 1 in 96( normal imperial) or 1 in 100 and a taper key machined and fitted to suit, machine the flywheel key first then make and fit the key which is the hard part,the tapers must match to ensure the key stays in place. when finally ftting the key do not belt it in place as too much force will crack the flywheel hub.
22011 forum posts
I think Edward just shows a parallel (height) keyway and the gib head key when fitted just gets a fraction taller over the last 1/3rd of its length so it tightens up when driven home, thats how I usually do mine rather than make a tapered bush to get a tapered keyway and matching tapered key.
Provided you have the right bush which is a good fit in the bore and the correct shims to go with your key then driving the broach right through until all the shims are used will give you the correct depth of keyway. I'm assuming you are broaching as I saw you asking about for one a week or two ago.
Although Gib head keys can be bought ready made I use rectangular keysteel, mill most of the profile and then finish fit with files and engineers blue. It helps to leave the keysteel full length then you have more to get hold of to remove the key while test fitting
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