Here I have collated a number of handrail profiles, Most of these come from traditional handrail profiles that I have scanned to recreate for repairs or to continue existing stairs up to loft conversions or down to basement dig outs.
I have listed where possible the area and period they have come from: so as to help match a suitable profile to the property you wish to use it in.
Some have been on core rail some on spindles, they will work for either. The only thing to consider is if they are for a continuous wreathing handrail then the top of the spindle may not sit parallel with the sides of the handrail, thus making the spindle wider than the base.
To pre empt this if you have the rod for the staircase then you can draw the parallels for the base of the handrail, the square for the top of the spindle and set them over each other to confirm the spindle will sit under the handrail correctly.
Should they not fit there is no reason why you should not scale the handrail either in width to accommodate the spindle or both width and height to maintain the scale for the handrail profile chosen.
Most profile will survive being just widened without the additional height being added.
I have saved copies that are downloadable to be dropped into your cad layout. These have been created in Rhino 3d, should for any reason the file type you require is not here Rhino is available as a free evaluation version. This will work for a limited period but allow you to open the original file and save it in a format you can use.
Detail pages include.
a brief description.
PDFs of plates.
full size images for detailed inspection.
3D files for download into your own design package.