View Single Post
Old 29th Mar 2008, 5:52 pm   #1
Rest in Peace
igranic's Avatar
Join Date: Jan 2005
Location: North Bedfordshire, UK.
Posts: 395
Default Making Replacement Knob Brights.

Having spent far too much time fruitlessly looking for knobs to replace those missing their brass trims, I decided to make my own. Here is how I did it.

Raw material. 0.5mm thick brass strip, obtainable from model shops.
Rough blanks, cut from strip with tin snips, ready for pressing.
Click image for larger version

Name:	Raw_Material.gif
Views:	436
Size:	85.3 KB
ID:	16093

Convex press tool, made on lathe to be the same outside diameter as the finished item. Concave press tool. Made larger than finished item in order to ensure even curvature at the edges.
Click image for larger version

Name:	PressTools.gif
Views:	454
Size:	77.3 KB
ID:	16094

Pressing blank between convex and concave tools using 6" bench vise. This would be better done in a hand press or fly press but, as I don't have either to hand, careful alignment by eye allows an acceptable result.
Click image for larger version

Name:	Pressing.gif
Views:	429
Size:	121.3 KB
ID:	16095

Concave lathe arbor. Same outside diameter as finished part.
Click image for larger version

Name:	Concave_Arbor.gif
Views:	425
Size:	42.7 KB
ID:	16098

Trimming the part in the lathe. The pressed part is held between the concave arbor and the convex tool under pressure from the the ball-bearing 'live' tailstock centre. Double-sided adhesive fixes the part to the convex tool and helps prevent slipping and consequent scoring. The surplus material is trimmed off and the part finished to the correct diameter.
Click image for larger version

Name:	Trimming.gif
Views:	462
Size:	120.3 KB
ID:	16099

igranic is offline