Saturday, July 7, 2012

Ferrules

For my set of screwdrivers I decided I wanted custom ferrules. I'm not a fan of store bought, and I think that ferrules made of plumbing fittings always look like plumbing fittings. I have turned them on my wood lathe with high speed steel tools and files, but my success rate wasn't very good. Brass work hardens, and it is tough to shape the thin walls to completion without them self-destructing.

While at school I was able to stay ahead of the program and I found myself with some spare shop time to work on personal projects. I took advantage of this time to use the metal lathe to make my ferrules. Brass likes high RPMs, keen tools with zero rake, and cutting oil. Drill bits benefit from a light honing on the cutting edges to raise the cutting angle, reducing its tendency to grab.

I bought a length of 3/4" brass stock, and held it in a three jaw chuck. The end was faced flat, and centre drilled.



Then drilled with a bit with a slightly larger diameter than the screwdriver shaft. I wanted this fit to be as tight as possible.



That was followed by a bit with a slightly larger diameter than the handles tang portion, and drilled to a depth the same as the tangs length.



I then used a champher tool to undercut the edge of the ferrule, so it would seat tight against the handle bead.



I used a parting tool to cut a groove.



This groove is to allow room for the tool used to taper the ferrule. I can't remember the exact angle, I think it was about 5° included. The taper is cut with the compound.



I used an Acme threading tool to part them off. The zero rake cut cleanly, and as a bonus it left a pleasing angle to the end instead of it being left blunt.



Just off the lathe.



I got them all cut at school, and took them back to my shop for finishing. Mounted on a pen mandrel, I cleaned up the machining marks, and buffed them with honing compound on a rag.



After almost two years I'm finally done!











Screwdriver Handles

I've had a busy couple of months, I managed to complete my schooling and earn a Certificate with Great Distinction. I started working a new job a couple of weeks before school ended, and have been there full time since. I'm happy to be there, of all the machine shops I've toured it is by far the brightest, cleanest, and best organized. My new co-workers all seem to be friendly and intelligent, and I'm looking forward to continuing my education there.

I have been in the wood shop, although the projects lately haven't been too thrilling. I've refinished a few tables and repaired some chairs, quick jobs for a little spending money but nothing worth taking pictures of or writing about. In 2010 I made two sets of screwdrivers, one for my Father-in-Law for Christmas in walnut, and a set for myself in beech. Time constraints made me abandon mine to ensure his would be done, and they sat unfinished until this spring when I had the opportunity to get them done.

I began by handling as many screwdrivers I could find and using the most comfortable as a starting point for size and dimension. Then I selected a piece of stock large enough to yield all nine handles. This would ensure a colour and grain match. For optimum strength and beauty in turned work the grain must run as straight as possible. I laid out lines on the stock parallel to the grain.





I then bandsawed to these lines.



These faces became my reference face after jointing.



The blanks were then planed to size. For best appearance the grain must be as close to perfectly rift sawn (end grain lines running corner to corner) or quarter sawn (end grain lines running perpendicular and parallel to the faces) as possible.



I wanted octagonal handles, as they don’t roll and are comfortable in the hand. The stock is shaped with a 45° bit in a router. For small jobs like this I like to make a miniature router table by attaching a scrap of Baltic birch plywood to my router base. The router itself is clamped in my end vise. This is more convenient than trying to clamp the stock and balancing the router on it, and it brings the work table up to a height that makes detail work like this easier to see and handle. I start by making a shallow pass on all four corners of the three pieces of stock.



I make two passes, and then my third pass is the last on the small handle stock. I make a short test cut on the very end and slowly raise the bit until all eight faces are the same width. Keeping the test cut short keeps the blank from being ruined if I advance the cutter too high.



The process is repeated until all three blanks are octagonal. The largest blank is larger than the capacity of the bit, so a handplane finishes the facet. While I’m at it I use the plane to remove milling marks from the rest of the faces.



A stop block at the mitresaw allows me to cut the blanks into three equal length parts with square ends.



The blanks were then laid out so that the same quartersawn face would be at the top, and labeled with which shaft they would receive, S for Slotted, P for Philips, and R for Robertson.

The shafts themselves have a pair of 1/16” x 1/16” wings which anchor them in the handle and prevent them from spinning when torque is applied. These wings are not in the same plane as the driving tip, so the off angle must be compensated for so that the driver will look square to the handle. The exact centre is marked, and the wing holes are laid out on the angle, the distance from centre to centre is the same as the diameter of the shaft itself.





The blank is then clamped in a vise and the drill press is used to drill a 1/8” hole for the two wings. The bit is withdrawn frequently to clear chips and advanced slowly. It is important to have the holes square to the end and without wander.



The turned portion is then laid out on all three blanks at the same time using a square. A mark is made at the transitions between the ferrule and the end bead, the end bead and the finger cove, the cove and the octagonal part of the handle, the octagon and the end dome, and at the end of the handle.



The blank is then placed between centres on the lathe, and as it turns, the reference marks are continued all the way around. A parting tool is used to set the reference diameters, a set of rounded nose calipers are used to determine the correct cut depth for the ferrule.



The diameters are set for the bead, the cove, and the end dome in the same fashion; these calipers are used without change for all three handles to ensure common dimensions.



The details are turned; a simple template is made to match the sweep of the finger coves.



The handles are sanded but not completely parted off yet.



I don’t like the way the octagonal facets have a nice semi-circular end near the cove, and a blunt end near the dome. I decided a nice touch would be to hand carve the ends to match. I started by laying the half circles out with a pencil and a pattern. I used a combination of wheel gauges and washers.



A gouge with the correct sweep was chosen. Because this is a straight chopping cut, I sharpened the edge with a single low angle bevel and honed frequently. The cut began with a straight downward chop, and then the gouge is leaned over to wrap the cut around the end dome.



A sharp paring chisel removes the chip and rounds the background to match the curve of the end dome.





Now the handle is placed in the drill press vise and the shaft hole is drilled. Note that the shafts are different lengths so for a common appearance the holes need to be drilled to different depths. They are then returned to the lathe, finish sanded, and the end parted off. I’m pleased with the way they turned out, they are comfortable in my hand, and the carved ends have a floral look. I like the feminine aspect it lends to the tool.

I used store bought ferrules for my father-in-laws walnut set. I also made a walnut presentation box for them, leather lined. Usually he gets a tie and a bag of licorice allsorts for Christmas, so these were a nice surprise that I was happy to give.







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I'm a woodworker on the Canadian prairie.